Volume 59, Issue 11-12

The synthesis of the heterobimetallic hafnium(IV)-nickel(0) complexes {[Hf](μ-σ ,π- C≡CR) 2 }Ni(CO) ( 3a , [Hf] = (η 5 -C 5 H 5 ) 2 Hf, R = Ph; 3b , [Hf] = (η 5 -C 5 H 4 SiMe 3 ) 2 Hf, R = t Bu) in which an early (Hf) and a late (Ni) transition metal atom are bridged by σ - and π-bound alkynyl groups succeeds by treatment of [Hf](C≡CR) 2 ( 1a , [Hf] = (η 5 -C 5 H 5 ) 2 Hf, R = Ph; 1b , [Hf] = (η 5 -C 5 H 4 SiMe 3 ) 2 Hf, R = t Bu) with equimolar amounts of Ni(CO) 4 ( 2 ). The reaction chemistry of 1 and 3 towards different substrates is discussed. Treatment of 3b with P(OMe)3 ( 4a ) affords the mononuclear nickel monocarbonyl complex Ni(CO)[P(OMe) 3 ] 3 ( 5 ), while the reaction of 1a or 1b with MCl 2 ( 6a , M = Fe; 6b , M = Ni; 6c , M = Co) produces by an cyclopentadienyl transfer from hafnium to M the sandwich compounds (η 5 -C 5 H 4 R’) 2 M (M = Fe: 7a , R’ = H; 7b , R’ = SiMe 3 ; M = Ni: 7c , R’ = H; 7d , R’ = SiMe 3 ; M = Co: 7e , R’ = H). Addition of KOH to 1b or 3b , respectively, affords the homobimetallic hafnium complex {[Hf](C≡CR)} 2 O ( 8 ) in which two [Hf](C≡CR) fragments are bridged by an oxygen atom. Possible reaction mechanisms for the formation of 5 , 7 and 8 by starting from 1 or 3 will be given. The result of the X-ray structure analysis of 8 is reported. Complex 8 crystallises in the monoclinic space group C2/c with the cell parameters a = 24.437(8), b = 14.655(5), c = 14.123(4) Å, β = 101.67(2)◦, V = 4953(3) Å 3 , Z = 4 and D = 1.454 g cm−3. Complex 8 contains a linear Hf-O-Hf unit with pseudo-tetrahedral coordinated hafnium atoms.

Indirect nuclear spin-spin coupling constants J ( 11 B, 1 H) and J ( 11 B, 11 B) in neutral and anionic boron hydrides 1 - 17 , calculated at the B3LYP/6-311+G(d,p) level of theory, are in good agreement with experimental data if available. This is shown for [BH 4 ] − ( 1 ), B 2 H 6 ( 2 ), B 4 H 10 ( 3 ), B 5 H 9 ( 4 ), or [B 2 H 7 ] − ( 12 ). The calculations can be used to obtain values for those coupling constants for which experimental information is hardly accessible. This applies to complex spin systems involving the quadrupolar 11 B nuclei such as in [B 6 H 6 ] 2 − ( 11 ), to fast dynamic processes such as in B 6 H 10 ( 5 ), [B 5 H 8 ] − ( 10 ), [B 6 H 7 ] − ( 11-H ), [B 3 H 8 ] − ( 13 ), Be(BH 4 ) 2 ( 14 ), (η 5 -C 5 H 5 )BeBH 4 ( 15 ), Be(B 3 H 8 ) 2 ( 16 ), Me 2 AlB 3 H 8 ( 17 ), or to instable species such as [B 2 H 6 ] 2− ( 6 ), B 2 H 4 ( 7 ), B 3 H 7 ( 8 ), and B 4 H 8 ( 9 ). The experimental 11 B NMR spectrum reported in the literature for the dianion 6 does not resemble the spectrum predicted on the basis of the calculated coupling constants.

The new monoclinic oxide borates Na 2 RE 2 (BO 3 ) 2 O (RE = Dy, Ho) were synthesized using standard solid-state reactions in the temperature range 900 - 950 ◦ C. They are isotypic to the known phases Na 2 RE 2 (BO 3 ) 2 O (RE = Y, La, Nd, Sm-Gd, Er). The single crystal X-ray structure determination of Na 2 Dy 2 (BO 3 ) 2 O revealed: P2 1 /c, a = 1063.9(1), b = 626.2(1), c = 1025.3(1) pm, β = 117.76(1) ◦ , Z = 4, R1 = 0.0221, wR2 = 0.0402 (all data). The corresponding lattice parameters of Na2Ho2(BO3)2O determined from powder data are a = 1061.2(5), b = 623.7(2), c = 1022.5(3) pm, and β = 117.7(1) ◦ . The structure consists of infinite sheets of REO8-polyhedra in the bc-plane, which are seperated by sodium atoms. The BO 3 -groups are isolated forming layers in the bc-plane. The results of IR-spectroscopic investigations, temperature-resolved in-situ powder-diffraction measurements, and DTA/TG measurements on Na 2 Dy 2 (BO 3 ) 2 O are also presented.

Solutions containing TeCl 4 and [NEt 4 ][PF 6 ] in CH 2 Cl 2 were investigated by means of UV/vis and NMR spectroscopy in order to study the complex chemistry of TeCl 4 with the [PF 6 ]− anion. The results show formation of [TeCl 5 ] − and strong interactions of [PF 6 ] − with a tellurium containing species, presumably [TeCl 3 ] + . The life time of the Te IV -PF 6 complex is long enough to give different signals in the 19 F NMR spectrum of a solution containing excess [PF 6 ] − . Even a fivefold excess of Cl− ions over [PF 6 ] − does hardly lead to a dissociation of [TeCl 3 ・ ・ ・PF 6 ]. Crystals of [NEt 4 ] 2 [Te 2 Cl 10 ] were obtained from a 4:1 solution of [NEt 4 ]PF 6 and TeCl 4 in CH 2 Cl 2 . The compound crystallizes in the triclinic space group P1, a = 0.82626(7), b = 1.04260(8), c=1.9915(3) nm, α = 84.641(9), β = 84.891(9), γ = 75.208(6) ◦ (T = 295 K). Slight variations in the molecular environment can have a substantial influence on the interatomic distances within the Te 2 Cl 2 bridge of the [Te 2 Cl 10 ] 2− ion. This conclusion is confirmed by ab initio calculations.

Hydroalumination of H 5 C 6 -C≡N with di(tert-butyl)aluminum hydride 1 or the corresponding diethyl compound 2 yielded the products tBu 2 Al-N=C(C 6 H 5 )H 3 and Et 2 Al-N=C(C 6 H 5 )H 4 , respectively, both of which form dimers possessing Al2N2 heterocycles with two exocyclic C=N double bonds. NMR spectroscopic data indicate the occurrence of cis/trans isomers in solutions of compound 4 . The dimerization of the imide via Al-N interactions was prevented by employing the hydride [(Me 3 Si) 2 HC] 2 AlH 6 bearing the bulky bis(trimethylsilyl)methyl substituents. Its reaction with benzonitrile yielded the compound R 2 Al-N=C(C 6 H 5 )H(N≡C-C 6 H 5 ) 7 [R = CH(SiMe 3 ) 2 ], in which the coordinative saturation of the aluminum atoms was achieved by adduct formation with one molecule of the starting nitrile. In these cases the C≡N triple bond inserted completely into the Al-H bond of the hydride. In contrast, the reaction of tert-butyl isonitrile afforded the product tBu 2 Al-C(H)=NC 6 H 5 8 by the insertion of its terminal carbon atom into the Al-H bond. Hence, it has a geminal arrangement of the aluminum and hydrogen atoms. Dimerization of 8 yielded a six-membered heterocycle. Hydroalumination does not occur upon treatment of the hydride 1 with trimethylsilylnitrile. Instead, the Si-CN bond was cleaved, and the aluminum cyanide (tBu 2 Al-C≡N) 4 9 was isolated in a high yield.

Three optically active Molybdenum (VI) dioxo complexes with tetrahydro salen and substituted tetrahydro salen derivatives as ligands were synthesized and examined as catalysts for asymmetric epoxidation. Complexes of the type MoO 2 (L)(Solv) and WO 2 (L) (L = tridentate, trans-2- aminocyclohexanol derived chiral Schiff base, Solv = alcohol) were prepared and characterized by elemental analysis, NMR and IR spectroscopy. These complexes are applicable as catalysts for olefin epoxidation reactions with tert-butyl hydroperoxide (TBHP) being the oxidizing agent. In case of cis-β -methylstyrene moderate enantiomeric excesses of up to 26% can be reached when the reaction is carried out at 0 ◦C.

The ammonium salt of cyanourea NH 4 [H 2 NC(=O)NCN] has been synthesised via an acid-base route from the parent acid and characterized by single-crystal and powder X-ray diffraction,NMR and vibrational spectroscopy, mass spectrometry as well as thermal analysis. The molecular salt (P2 1 /c, a = 388.95(8), b = 1121.0(2), c = 1096.4(2) pm, β = 92.57(3)◦, V = 477.5(2)・106 pm3, Z = 4, T = 140 K) which may formally be derived from the related compound ammonium dicyanamide NH 4 [N(CN) 2 ] by addition of one molecule water, consists of isolated ammonium and cyanoureate ions which are assembled via H・ ・ ・N and H・ ・ ・O hydrogen bonds, forming a three-dimensional arrangement. At elevated temperatures, ammonium cyanoureate undergoes a complex transformation affording the formation of urea and cyanoguanylurea H 2 NC(=O)NHC(NH 2 )=NCN or the isomeric ammeline (C 3 N 3 )(NH 2 ) 2 (OH) as the main products, depending on the reaction conditions. The transformation is accompanied by consecutive reactions such as proton transfer and the dis- and reassembly of molecular fragments, yielding a macroscopic segregation of the reaction products. The conversion represents yet another example of a complex reaction proceeding in the solid-state.

The compounds [Ti(OPr) 3 (isoeugenolate)] 2 and [Ti(OR) 3 (OCH 2 CH 2 NH 2 )] 2 (R = i Pr, Et), obtained by reaction of titanium alkoxides with isoeugenol (2-methoxy-4-propenylphenol) or 2- aminoethanol, are centrosymmetric dimers with a central Ti 2 (μ 2 -OR) 2 unit. The isoeugenolate and 2-aminoethanolate ligands are chelating, with the uncharged donor group (OR or NH 2 , respectively) axial to the Ti 2 (μ 2 -OR) 2 ring.

Deprotonation of N,N’-dicyclohexylformamidine with methyl lithium yields dicyclohexylformamidinyl lithium ( 8a ).The X-ray crystal structure analysis of 8a shows an unsymmetically formamidinato-bridged THF-stabilized dimer in the crystal. Treatment of diphenylformamidinyl lithium ( 8b ) with Cp 2 ZrCl 2 gives the (K 2 N, N’ -dicyclohexylformamidinato Cp 2 ZrCH 3 ( 7a ). Treatment of (K 2 N, N’ -diphenylformamidinato)Cp 2 ZrCH 3 ( 7b ) with [Bu 3 NH + ][BPh 4 −] gave the salt [(K 2 N, N’ -diphenylformamidinato)Cp 2 Zr + ][BPh 4 −] ( 9B ). Its X-ray crystal structure analysis revealed a symmetrical bonding of the formamidinato ligand to the zirconium metal center.

1-(Nitrophenyl) functionalized 2-(3-pyrazolyl)pyridines were obtained by a nucleophilic aromatic substitution and could be reduced to the corresponding aminophenyl substituted derivatives. These compounds can be used to co-ordinate transition metal sites or for the generation of building blocks for supramolecular chemistry. The solid state structure of a 1,1’-functionalized ferrocene, which was obtained following this route, is discussed in detail.

Synthetic and room temperature single crystal X-ray structural characterizations are recorded for adducts of copper(I) cyanide formed by crystallization of copper(I) cyanide from (unidentate) pyridine (‘py’) bases L, of 1:2 (L = py; new phase), 1:1.5 (L = 2-methylpyridine, ‘2mp’) and 1:1 (L = quinoline, ‘quin’) stoichiometries. All are single-stranded polymers, with successive copper atoms linked by single linear cyanide bridges (C,N disordered, individual components not resolved), with four- or three-coordinate N 2 Cu(CN) 2 or NCu(CN) 2 copper environments in the 1:2 and 1:1 adducts, these alternating in the 1:1.5 (2:3) adduct. The present and previous related studies providing a basis for a systematic survey of their vibrational spectroscopy. The IR spectra of the infinite polymers show bands that are assigned to vibrations of the CuCN chains in these complexes: ν(CN), ν(CuC/N) (the CuC/CuN stretching mode, involving vibration of the CN group between its two neighbouring Cu atoms), δ (CuCN) (the restricted rotation of the CN group), and δ (NCuC) (the counter-vibration of the Cu substructure against the CN substructure). Gravimetric and vibrational spectroscopic studies following loss of the base molecules from these complexes show that ligand removal occurs in several stages via a series of well-defined adducts, some of which have unusual stoichiometries and structures. Conversely, solid CuCN may be “activated” towards adduct formation by prior reaction with pyridine bases.

Crystalline materials obtained by the crystallization of silver(I) cyanide from/with a variety of (oligo-)pyridine bases, L, of various bulk, have been characterized by room temperature single crystal X-ray structure determination. From L = quinoline (= ’quin’), AgCN : quin (1:2), is obtained, the structure being a single-stranded polymer, the successive silver atoms located on two-fold axes linked by linearly bridging cyanide groups and four-coordinate, the other two coordination sites being occupied by symmetry related quinoline nitrogen atoms. From L = 2,4,6-trimethylpyridine (‘collidine’ ≡ ‘coll’) AgCN : coll (1:1) is obtained; it is similarly a one-dimensional polymer with bridging cyanide linkages, but now with three-coordinate silver(I), the one ligand nitrogen being coordinated. The adduct for L = pyridine (= ‘py’), is of novel AgCN : py (10:9) stoichiometry; it also is a onedimensional polymer, with three-coordinate silver(I) atoms also coordinated by pyridine nitrogen, but with periodic ‘errors’ in a wave-like array (similar to that recently reported for ‘LT-CuCN’), here associated with the incorporation of occasional two-coordinate silver(I) lacking the pyridine - an unusual coordination complex example of a ’modulated’ structure? 1:1 adducts are obtained with L = 2,2’-bipyridine, ‘bpy’, 1,10-phenanthroline, ’phen’, and 2,9- dimethylphenanthroline, ‘dmp’, the latter two adducts being ’solvated’ with additional moles of phen and pyridine respectively. AgCN : bpy (1:1) is a single-stranded polymer with four-coordinate silver atoms linearly bridged by cyanides. The complex components of AgCN : phen (1:2) (≡ AgCN : phen (1:1). phen) and AgCN : dmp (: py) (1:1(:1)) are both mononuclear 1:1 species, [LAgCN], with threecoordinate metal atoms. With 2,2’:6’,2”-terpyridyl, ‘tpy’, a pyridine solvated adduct of AgCN : tpy : py (8:2:1) stoichiometry is found, the pyridine being incorporated in the one-dimensional polymer which comprises an . . .Ag’(NCAgCN)Ag’(NCAgCN)Ag’. . . spine, with (tpy)Ag(NCAgCN)Ag’ and Ag’(NCAg(py)CN)(tpy) units pendant to either side at alternate three-coordinate Ag’. In all of the oligodentate ligand complexes, the molecular packing is of interest, being dominated by the usual interleaving and perpendicular aromatic planar moieties. The IR spectra of the one-dimensional polymers show bands that are assigned to vibrations of the extended AgCN chains in these complexes: ν(CN), ν(AgC/N) (the AgC/AgN stretching mode, involving vibration of the CN group between its two neighbouring Ag atoms), δ (AgCN) (the restricted rotation of the CN group), and δ (NAgC) (the counter-vibration of the Ag substructure against the CN substructure). The ν(CN) and ν(AgC/N) bands in AgCN : py (10:9) occur in the ranges 2096 - 2154 and 360 - 460 cm −1 respectively, and show splittings that can be attributed to the unusual structure of this complex in the solid state. The Raman spectra of the py complex in the solid state and in solution are also discussed. In the other two unidentate ligand complexes, single bands are observed for the ν(CN) and ν(AgC/N) modes at 2140, 392 (AgCN : coll (1:1)) and 2140, 422 cm −1 (AgCN : quin (1:2)) respectively. The monomeric AgCN : bidentate ligand complexes AgCN : phen (1:1) and AgCN : dmp (1:1) show lower ν(CN) and ν(AgC/N) frequencies than the polymeric AgCN : bpy (1:1), despite the fact that the Ag-C/N distances in the former are shorter than that in the latter, in agreement with previously observed trends in AgCN/ER 3 compounds.

Single crystal room temperature X-ray structure determinations are described for three adducts formed between copper(I) cyanide, pyridine (‘py’) and triphenylphosphine of (p : q : r =) 1:1:1, 1:1.5:0.5 and 1:0.5:2 (plus py hemisolvate) stoichiometry. The latter is binuclear [(Ph 3 P) 2 (py)Cu(μ- CN)Cu(PPh 3 ) 2 (CN)]. py; the others are linear polymers with . . .Cu(μ-NC)Cu(μ-NC)Cu. . . spines with four-coordinate copper atoms, the coordination sphere of every copper atom in the first being completed by pendant py and Ph 3 P ligands, while the second has those of alternate copper atoms coordinated by a pair of py ligands. Assignment of bridging CN in all cases is crystallographically ambiguous. The IR spectra of the infinite polymeric complexes show bands that are assigned to vibrations of the CuCN chains in the complexes: ν(CN), ν(CuC/N) (the CuC/N stretching mode, involving vibration of the CN group between its two neighbouring Cu atoms), δ (CuCN) (the restricted rotation of the CN group) and δ (NCuC) (the counter vibration of the Cu substructure against the CN substructure). The ν(CN) and ν(CuC/N) frequencies show correlations with the Cu-C/N bond lengths that are similar in form to those recently established for a range of AgCN complexes.

A number of adducts of copper(I) cyanide, CuCN, have been synthesized by crystallization from its solutions in various unidentate organic nitriles, RCN. Low temperature single crystal X-ray structure determinations are recorded for a number of these, of the form CuCN : RCN (m : n) for R = Me, Et (m : n = 1 : 1), and Ph, o-tolyl (3:2). The 1 : 1 adduct with acetonitrile is a two-dimensional polymeric web, (CN)Cu(μ-CN) 2 Cu(NC) units being linked by the peripheral nitrogen and carbon atoms, with a fourth coordination site about each copper having MeCN pendant. The other three adducts are onedimensional polymers, the propionitrile adduct being of the form . . .Cu(NCEt)CNCu(NCEt)CN. . . with trigonal planar copper, the bridging cyanide groups being replaced in the benzo- and o-toluo nitrile adducts by linear Cu(CN)− 2 moieties. The vibrational spectra of bulk samples are largely consistent with the single crystal structural results, but reveal the possible existence of adducts of higher CuCN content in the case of the CuCN/benzonitrile system.

Syntheses and room-temperature single crystal X-ray structure determinations are recorded for an array of complexes formed between copper(I) perchlorate and benzonitrile of CuClO 4 : PhCN (1:n) stoichiometry. Copper(I) perchlorate crystallized from neat benzonitrile solution yields a 1:5 CuClO 4 : PhCN adduct, shown by the X-ray study to be of the form [Cu(NCPh) 4 ](ClO 4 ). PhCN, and, on recrystallization from dichloromethane, the 1:4 adduct, shown to be [Cu(NCPh) 4 ](ClO 4 ), the copper(I) atom in both the n = 4,5 adducts being in a quasi-tetrahedral four-coordinate environment, < Cu−N > 1.99 Å . Heating of either of the above materials under vacuum to 70 - 80◦ or 85 - 90 ◦C (Care!) yields 1:3 and 1:2 adducts respectively which may be crystallized from dichloromethane. The 1:3 adduct is shown to be of the form [(PhCN) 3 Cu(OClO 3 )], the CuN 3 array quasi-trigonal planar (Σ N-Cu-N 358.0 ◦; Cu-N 1.906(4)-1.958(4), <> 1.93 Å ), with a long unidentate perchlorate oxygen approach (Cu. . .O 2.404(4) Å). The 1:2 adduct comprises a pair of quasi-linear [(PhCN)Cu(NCPh)] moieties (Cu-N 1.884(6), 1.866(5) Å ; N-Cu-N 158.6(3)◦] linked about an inversion centre by a pair of oxygen atoms from centrosymmetrically related perchlorate groups, so that a weakly bound fourmembered Cu(μ-O) 2 Cu central ring is obtained (Cu. . .O 2.445(4), 2.502(6) Å ). The structural data provide a basis for a comprehensive vibrational spectroscopic study across the whole array. These spectra show features that can be attributed to the structural changes that are observed with the change in the number of benzonitrile molecules in the compounds. The vibrational spectra of the acetonitrile complex [Cu(NCMe) 4 ](ClO 4 ) have also been recorded and used to assist in the assignment of the spectra of the various stoichiometries of the benzonitrile compounds.

The new thioantimonate(III) [C 6 H 17 N 3 ][Sb 10 S 16 ] (C 6 H 17 N 3 = 2-piperazine-N-ethylamine cation) was obtained under solvothermal conditions showing a unique anionic framework. The compound crystallizes in the monoclinic space group P2 1 /c with four formula units in the unit cell. The lattice parameters are a=11.530(2), b=25.042(5), c = 13.709(3)Å, β =111.25(3)◦,V = 3689(2) Å 3 . The thioantimonate(III) anion is formed by interconnection of nine trigonal pyramidal SbS 3 units and one SbS 4 moiety. These primary building units share common corners and edges yielding Sb 3 S 3 and Sb 2 S 2 hetero-rings. Further condensation leads to strong undulated two atoms thick layers extending in the [010] direction, with a modulation period of about 14 Å. Very large Sb 31 S 31 rings within the layers show a ‘double-ellipsoidal’ shape with approximate dimensions of 8.9 ・ 9.3 Å. The cations are located at the inflexion points of the layers and act as pillars between successive layers. The layers are stacked onto each other in a way that channels parallel to [001] are formed accommodating the organic cations. A remarkable observation is that the 2-piperazine-N-ethylamine cation is formed by cyclization of tren molecules (tren = tris(2-aminoethyl)amine) under in-situ conditions.

An interesting 3-D supramolecular architecture has been constructed through O-H・ ・ ・O and S・ ・ ・S weak interactions based on a neutral 1-D coordination polymer, [Cd(pyta) 2 (H 2 O)]n (pyta = pyridylthiocarboxylate), by self-assembly of the Cd 2+ ion and Hpyta ligand. This supramolecular approach is achieved in combination of coordinative bonds, O-H・ ・ ・O and S・ ・ ・S interactions. The tetragonal unit of 1-D coordination polymers forms a 1-D channel structure with a dimension of 5.35×6.86 Å 2 in the solid state, leading to the formation of zeolite-like materials. In combination with the zeolitelike nature of the title compound as well as its luminescence behavior, it is expected to find useful applications in luminescence sensing for VOCs (volatile organic compounds).

The new copper(I) coordination polymer poly[tri-μ 2 -cyano-C,N)-bis(μ 2 -2,3-dimethyl-pyrazine- N,N)] tricopper(I) ( I ) was prepared by the reaction of copper(I) cyanide with 2,3-dimethylpyrazine in acetonitrile. In the crystal structure of I a novel CuCN substructure is found which is connected by the dimethylpyrazine ligands into a three-dimensional coordination network. The thermal properties of I were investigated using simultaneous differential thermoanalysis (DTA), thermogravimetry (TG) and mass spectrometry (MS) as well as temperature resolved X-ray powder diffraction. On heating, compound I looses a part of the dimethylpyrazine ligands in an endothermic reaction to form the known ligand poor compound (CuCN) 2 -(2,3-dimethylpyrazine) II as an intermediate which decomposes to CuCN on further heating.

Organosilicon polymers having a regular alternate arrangement of -Hex 2 Si-π-Hex 2 Si-π’-(π, π’ = π-electron system) were prepared by successive treatment of Hex 2 SiFCl with dilithiated π- conjugated compounds, Li-π-Li and Li-π’ -Li (π = diethynylanthracene, diethynylpyrene, diethynylcarbazole; π’ = bithiophenediyl, terthiophenediyl). UV-vis absorption spectra and cyclic voltammograms of the resulting polymers indicated that the two π-electron systems, π and π’, are electronically isolated, while the emission spectra indicated that energy transfer between the π-electron systems occurred in the excited states.

The reactions of N,N’-dimethylethylenediamine 1 and N,N’-diphenylethylenediamine 2 with equimolar amounts of 1,2-dichlorotetramethyldisilane 3 give six-membered heterocycles. Fivemembered rings are formed in the reaction of the diamines 1 and 2 with 1,1,2,2-tetrachlorodimethyldisilane 4 as well as with hexachlorodisilane 5 . Whilst the conversions of the disilanes 3 and 4 with the diamine 2 gave no products of a disproportionation reaction, the treatment of the disilane 4 with the diamine 1 and of the disilane 5 with both diamines resulted in cyclic aminosubstituted monosilanes which originate from the disproportionation of 4 and 5 beside the expected five-membered cyclic disilanes. All compounds have been characterized by multi-nuclear NMR, IR and mass spectroscopy. In case of the N-phenylsubstituted compounds 6 , 7 and 9 the crystal structures have been determined by X-ray diffraction analysis. Bis-[N,N’-diphenyl-2-methyl-1,3-diaza-2-silacyclopentane] 6 crystallizes in the chiral orthorhombic space group P2 1 2 1 2 1 (Z = 4). Both silaimidazolidine rings in 6 show half chair conformation. All nitrogen atoms of this molecule are almost planarized (sum of angles: 356.3◦ at N1, 359.5◦ at N2, 356.7◦ at N3 and 357.5◦ at N4). Bis-[N,N’-diphenyl-2-chloro-1,3-diaza- 2-silacyclopentane] 7 , resulting from the reaction of disilane 5 with diamine 2 , crystallizes in the orthorhombic space group Pbcn (Z = 4). Its nitrogen atoms are almost planar (sum of angles: 357.9◦ at N1, 356.7◦ at N2). N,N’-diphenyl-2,2,3,3-tetramethyl-1,4-diaza-2,3-disilacyclohexane 9 crystallizes in the chiral monoclinic space group P2 1 (Z = 2) and shows a twisted conformation. One nitrogen atom has a trigonal planar environment (sum of angles: 359.9◦ at N1), while the angle sum of the second one indicates a trigonal pyramidal conformation (sum of angles at N2: 350.6◦).

Two novel compounds containing pentacoordinate alkylsiliconium-cations with an 〈O, N, O 〉- chelating ligand of salen-type were prepared by reacting the trimethylsilyl derivatives of the ligand with alkyltrichlorosilanes. Pentacoordination of the silicon atom is found in solid state as well as in solution. Crystals of compound 2a , ethylene-N, N’ -bis(2-oxy-4-methoxybenzophenoneiminato) methylsiliconium chloride, were obtained from chloroform solution. This complex crystallizes in monoclinic space group P2 1 /n. The chloride ion is surrounded by three chloroform molecules in the solid state. The siliconium cation has trigonal bipyramidal geometry in the solid state, although the signals of two chemically equal half-sides of the salen-type ligand were revealed in 1 H and 13 C NMR spectra of its chloroform solution. Therefrom two different Si-N dative bonds within the same molecule arise. The reaction of methyltrichlorosilane with two non-linked “half-ligands” of the salen-type leads also to a siliconium complex with similar cationic coordination sphere motif.

Homoleptic dinuclear lanthanide siloxide complexes [Ln(OSitBuPh 2 ) 2 (μ-OSitBuPh 2 )] 2 (Ln = Y ( 1a ), La ( 1b )), [Ln(OSiHtBu2)2(μ-OSiHtBu2)]2 (Ln = Y ( 2a ), La ( 2b ), Nd ( 2c ), Lu ( 2d )), and {Ln[OSi(OtBu) 3 ] 2 [μ-OSi(OtBu) 3 ]} 2 (Ln = Y ( 3a ), La ( 3b )) were synthesized according to the silylamide route in yields between 67 and 92%. Their bis(siloxide)-bridged molecular arrangement was proven by variable temperature 1 H NMR spectroscopy as well as by an Xray structure analysis of 2c . The IR spectra of complexes 2 feature low-energy Si-H stretching vibrations (1965 - 1915 cm −1 ) indicative of β (Si-H)· · ·Ln agostic interactions. Complexes 2 and 3 readily form monomeric bis(donor) adducts with tetrahydrofurane, triphenylphosphine oxide, and N-methylimidazol as shown for fully characterized Ln(OSiHtBu 2 ) 3 (thf) 2 (Ln = Y ( 4a ), La ( 4b )), Y(OSiHtBu 2 ) 3 (OPPh 3 ) 2 ( 5 ), Ln(OSiHtBu 2 ) 3 (N-MeIm) 2 (Ln = Y ( 6a ), La ( 6b )), and Y[OSi(OtBu) 3 ] 3 (thf) 2 ( 7 ). Treatment of complexes 1 - 3 with excess of trimethylaluminum (TMA) generated several alkylated rare-earth metal species including homoleptic Ln(AlMe 4 ) 3 as indicated by 1 H NMR spectroscopy. La[OSi(OtBu) 3 ](AlMe 4 ) 2 (AlMe 3 ) ( 8b ) was isolated by crystallization and analyzed by X-ray diffraction.

The reaction of Fc(S 2 CNEt 2 ) 2 (Fc = Fe(η 5 -C 5 H 4 ) 2 ) with [Ag(OTf)(PPh 3 )] (OTf = trifluoromethanesulfonate) or [Au(OClO 3 )(PPh 3 )] in various molar ratios gives complexes of stoichiometry [Ag(PPh 3 ){Fc(S 2 CNEt 2 ) 2 }]OTf, [Ag(PPh 3 ) 2 {Fc(S 2 CNEt 2 ) 2 }]OTf, [Ag 2 (PPh 3 ) 2 {Fc(S 2 CNEt 2 ) 2 }](ClO 4 ) 2 or [Ag 3 (PPh 3 ) 3 {Fc(S 2 CNEt 2 ) 2 }](ClO 4 ) 3 . Treatment of Fc(S 2 CNEt 2 ) 2 with Ag(OTf) gives the complex [Ag(OTf){Fc(S 2 CNEt 2 ) 2 }], which can easily react with bidentate ligands such as 1,10-phenanthroline (phen), bis(diphenylthiophosphoryl)methane ((SPPh 2 ) 2 CH 2 ) or NaS 2 CNEt 2 to afford the cationic complexes [Ag(phen){Fc(S 2 CNEt 2 )-}]OTf, [Ag{(SPPh 2 ) 2 CH 2 }{Fc(S 2 CNEt 2 ) 2 }]OTf or the neutral [Ag(S 2 CNEt 2 ){Fc(S 2 CNEt 2 ) 2 }]. The crystal structure of [Ag(PPh 3 ) 2 {Fc(S 2 CNEt 2 ) 2 }]OTf reveals that silver coordinates to the dithiocarbamate sulfur atoms of two ferrocene ligands, thus forming a chain polymer.

The coordination chemistry of the unusual, pyrrole-stabilised thioaldehyde molecules, 3,5-dimethylpyrrole-2-carbothioaldehyde (HSPy MeHMe ) and 3,5-dimethyl-4-ethylpyrrole-2-carbothioaldehyde (HSPy MeEtMe ) has been investigated with nickel, palladium and platinum in the complexes [M(κ 2 - SPy MeRMe ) 2 ] (M = Ni, Pd, Pt; R = H, Et). The structure of the cyclometallated derivative [Pd(η 2 - C,N-C 6 H 4 CH 2 NMe 2 )(κ 2 -SPy MeEtMe )] was determined by X-ray diffraction.

Heteropolynuclear gold(I)-thallium(I) complexes of the type [TlL n ][Au(C 6 F 5 ) 2 ] (L = py (2), 2,2’- bipy (3), 1,10-phen (4) or 4,4’-bipy and THF (5); n = 1, 2) have been obtained from reactions of the corresponding N-donor ligands with the precursor {Tl[Au(C 6 F 5 ) 2 ]} n (1). The crystal structures of complexes 3 - 5 have been determined by X-ray diffraction showing one- (3, 4) or three-dimensional (5) arrays. All complexes are photoluminescent in the solid state at RT and at 77 K. The strong visible emissions of complexes 2 - 5 are displayed over a wide range of wavelengths (460 - 620 nm) depending on the environment of the thallium(I) centres and on the nature of the N-donor ligand.

Ba 3 Pt 2 has been synthesized by reaction of a 3 : 2 mixture of Ba and Pt at 1223 K in argon, and characterized by single-crystal X-ray structure determination and electrical resistivity measurements. Ba 3 Pt 2 crystallizes in the Er 3 Ni 2 structure type (space group R3̅ with a = 962.40(6), c = 1860.6(1) pm, Z = 9, R(F) N′ = 0.063, N′(hkl) = 777), and is isotypic to Ca 3 Pt 2 and Sr 3 Pt 2 . The Pt atoms occur in pairs at a distance of 303 pm. According to the analysis of the Electron Localization Function and the Crystal Orbital Hamilton Population obtained from DFT band structure calculations, covalent bonding can be assumed in the Pt-dumbbells, although it is weaker in Ba 3 Pt 2 than in Ca 3 Pt 2 . The peculiarities of the platinum compounds due to relativistic effects are elaborated by a comparison with theoretical results for Ca 3 Pd 2 . Ba 3 Pt 2 exhibits metallic conductivity (ρ 270 = 0.7 mΩ · cm), which is in accordance with band structure calculations.

N,N,N′,N′-Tetramethylethylenediammonium diiodide [Me 2 HNCH 2 ] 2 I 2 (1) as well as a set of I/Br- (2) and Br/Cl-mixed-halide salts (4 and 5) have been prepared, and their structures determined by single crystal X-ray diffraction. The results show the [Me 2 HNCH 2 ] 2 2+ dication to be a highly flexible template for halide inclusion, thereby tolerating the assembly of anions of different size, with phase widths of 0 ≤ x ≤ 2 for a monoclinic form with [Me 2 HNCH 2 ] 2 I 2−x Br x and 0 ≤ x ≤ 1 for a triclinic form with [Me 2 HNCH 2 ] 2 Br 2−x Cl x . The isotypic mixed halide compounds [Me 2 HNCH 2 ] 2 IBr (2) and [Me 2 HNCH 2 ] 2 BrCl (4) exhibit a statistical distribution of the anions in a structure of space group P2 1 /c which is also found for the pure diiodide [Me 2 HNCH 2 ] 2 I 2 (1). With an excess of chloride (x>1 for Br 2−x Cl x ) this structure is converted into that of the pure dichloride, [Me 2 HNCH 2 ] 2 Cl 2 (6), with space group P1̅. In all cases the halide anions are trapped in voids between the dications and fixed to the ammonium centers by strong N-H· · ·X and weak C-H· · ·X hydrogen bonding.

The tris(dimethylaminomethyl)-substituted alcohol (R 2 NCH 2 ) 3 COH (R = Me: 1) was synthesized by reaction of 1-chloro-2,3-epoxy-2-chloromethylpropane with a large excess of 40% aqueous HNMe 2 in 95% yield as colorless liquid (b.p. 87 ­­°C/1 mbar). Similar syntheses led to the respective amino alcohols with R = Et, CH 2 Ph. The dimethylamino alcohol 1 was characterized crystallographically as hydrochloride salt 2. Reaction of 1 with elemental sodium in toluene gave the tetrameric alcoholate [(Me 2 NCH 2 ) 3 CONa] 4 (3) which has a heterocubane structure in the solid state. In addition to three oxygen atoms, each sodium atom is coordinated by two amino groups from two different adjacent ligands (Na-N 2.529(3)/2.628(3) Å ). Reaction of 1 with LiNMe 2 afforded the lithium alcoholate which crystallized as dimeric mixed-anion aggregate [(Me 2 NCH 2 ) 3 COLi·LiNMe 2 ] 2 (4). It has a four-rung ladder structure consisting of two four-membered Li(NMe 2 )LiO rings connected through a central LiOLiO ring. All ligand amino groups are lithium-coordinated (Li-N 2.117(6)/2.101(6)/2.218(6) Å) as is the amido nitrogen atom (Li-N 1.964(6)/2.027(6) Å). Reaction of 1 with LitBu in n-hexane also led to deprotonation at oxygen. In addition, in one ligand one methyl group is deprotonated, in a second one two methyl groups are lithiated leading to doubly and triply charged anions, respectively. The product crystallizes as the dimeric mixed-anion aggregate [( − H 2 CN(Me)CH 2 )(Me 2 NCH 2 ) 2 CO − ·5 Li + · ( − H 2 CN(Me)CH 2 ) 2 (Me 2 NCH 2 )CO − ] 2 (5) having a core of 10 Li + cations, 4 alcoholate oxygen atoms, and 6 N(Me)-CH 2 − groups.

Pentaphenylphosphorus crystallizes from tetrahydrofuran (THF) as P(C 6 H 5 ) 5 ・0.5 THF (triclinic space group: P1̅, a = 10.095(4), b = 10.252(3), c = 12.725(3) A° , α = 71.21(1), β = 76.98(3), γ = 87.12(1)°, Z = 2). Its molecular structure is an almost perfect trigonal bipyramid with significantly longer axial than equatorial P-CPh bonds (P-C ax 1.982(2)/1.979(2), P-C eq 1.853(2)/1.845(2)/1.847(2) Å). It differs from the well established structure of solvent-free P(C 6 H 5 ) 5 (P. J. Wheatley, J. Chem. Soc. 2206 (1964)) in the relative orientation of the phenyl rings with respect to each other (axial rings) and with respect to the equatorial PC 3 plane (equatorial rings) but not in the trigonal-bipyramidal (tbp) geometry at phosphorus. Differences in the geometry around the central atom had been found previously for Sb(C 6 H 5 ) 5 (square pyramid) and Sb(C 6 H 5 ) 5 · 0.5C 6 H 12 (tbp) but not in As(C 6 H 5 ) 5 and As(C 6 H 5 ) 5 · 0.5 C 6 H 12 (both tbp).

1,5-Bis(methylsulfonyloxi)-3-aza-3-p-toluenesulfonylamidopentane (1) reacts with 4-benzyl-1,7- bis(p-toluenesulfonyl)diethylenetriamine (2) and 4-benzyl-1,7-bis(p-nitrophenylsulfonyl)diethylenetriamine (3) and Cs 2 CO 3 yielding 1-benzyl-4,7,10-tris(p-toluenesulfonyl)-1,4,7,10-tetraazacyclododecane (9a) and 1-benzyl-4,10-bis(p-nitrophenylsulfonyl)-7-p-toluenesulfonyl)-1,4,7,10-tetraazacyclododecane (10a), respectively. The corresponding dimers 1,13-bis(benzyl)-4,7,10,16,19,22- hexa(p-toluenesulfonyl)-1,4,7,10,13,16,19,22-octaazacyclotetracosane (9b) and 1,13-bis(benzyl)- 4,10,16,22-tetra(p-nitrophenylsulfonyl)-7,19-bis(p-toluenesulfonyl)-1,4,7,10,13,16,19,22-octaazacyclotetracosane (10b) could not be isolated but detected by mass spectroscopy. The reactions of 1 with 4-heptyl-1,7-bis(p-nitrophenylsulfonyl)diethylenetriamine (5) and Cs 2 CO 3 results in the formation of 1-heptyl-4,10-bis(p-nitrophenylsulfonyl)-7-p-toluenesulfonyl)-1,4,7,10-tetraazacyclododecane (11) and 1 reacts with 4-benzyl-diethylenetriamine (4) and Cu(O 2 CCH 3 )2 forming the dimeric copper complex [{C 6 H 5 CH 2 N(CH 2 CH 2 NH 2 } 2 Cu(μ-Cl)OSO 2 CH 3 ] 2 (12). The 1 H and 13 C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of 9a, 11, and 12 are reported and discussed.

4-Iodo-L-phenylalanine gives with the chloro bridged compounds [(Et 3 P)PtCl 2 ]2, [(Et 3 P)PdCl 2 ] 2 and [Cp*IrCl 2 ] 2 the N,O-chelate complexes (L)(Cl)M[NH 2 -C(H)(CH 2 C 6 H 4 I)CO 2 ] (M = Pt, Pd, Ir; L = PEt 3 , Cp* ) (1 - 3). Oxidative addition of N-protected 4-iodo-L-phenylalanine methylester to Pd(dba) 2 in the presence of 2,2’-bipyridyl or of triphenylphosphine affords the p-phenyl metallated amino acids (bipy)(I)Pd[C 6 H 4 CH 2 C(H)(NHR)CO 2 Me] (4,5) and (PPh 3 ) 2 (I)Pd[C 6 H 4 CH 2 C(H)(NHR) CO 2 Me] (6,7). Oxidative addition of the coordinated 4-iodo-Lphenylalaninate in (Et 3 P)(Cl)M[NH 2 C(H)(CH 2 C 6 H 4 I)CO 2 ] to Pd(dba) 2 was also observed.

Three structures of the form bis(thione)gold(I) di(methanesulfonyl)amide [thione = imidazolidine- 2-thione, 1; 1-methyl-imidazolidine-2-thione, 2; thiazolidine-2-thione, 3] were determined; all crystallize with one formula unit in the asymmetric unit. Each N-H hydrogen bond donor forms one classical two-centre hydrogen bond with an anion acceptor. Compound 1 thereby forms a complex layer structure with a layer thickness of 10.17 Å ; the packing may be analysed in terms of thinner subunit layers consisting of interlinked, hydrogen-bonded chains and rings. Compound 2 forms a chain structure consisting of a series of “hairpin bends”, a common feature in the gold complexes of 1-alkyl-imidazolidine-2-thiones. Compound 3 forms a corrugated ribbon structure in which the central region consists of parallel S-Au-S axes linked by aurophilic interactions; the anions exercise a “clamping” function by forming hydrogen bonds at the periphery of the ribbons. Further short contacts can be classed as weak hydrogen bonds C-H ··· X, with X = N, O, S or Au.

The title compound [H 7 O 3 (bis-dibromo-dibenzo-30-crown-10)][Se 2 Br 9 ] ·1.5CH 2 Cl 2 (1) was isolated from a solution of SeBr 4 and dibenzo-30-crown-10 in CH 3 CN/CH 2 Cl 2 containing a small amount of hydrobromic acid. During the reaction the crown ether is brominated by HBr. The compound crystallizes in the monoclinic space group P2 1 /n with a = 17.688(11), b = 14.921(6), c = 20.521(12) Å , β = 97.71(5)°, and Z = 4. 1 is a novel example in the series of supramolecular halogenochalcogeno acids prepared in our group in which different oxonium cations are stabilized and encapsulated by crown ethers. Especially in this class of superacids complexation by cyclic polyethers offers covenient and variable possibilities for the controlled synthesis of oxonium cations. In the present case the large dibenzo-30-crown-10 ring systems are able to stabilize trinuclear [H 7 O 3 ] + cations within their cavities. Besides the macromolecular cations and some dichloromethane solvent molecules, the crystal structure of 1 contains molecular [Se 2 Br 9 ] − ions with approximate D 3h symmetry, each consisting of two face-sharing SeBr 6 octahedra.

Thermolysis of α-[diisopropyl-1-(methylvinyl)oxysilyl]-α-diazoacetate 5a at 160 °C yields mainly 2,5-dihydro-1,2-oxasilole-3-carboxylate 6a and 3-[diisopropyl(methoxy)silyl]-2(5H)-furan- 2-one 7. From the thermolysis reaction of α-[diisopropyl-1-(phenylvinyl)oxysilyl]-α-diazoacetate 5b, only 1-oxa-2-sila-3-cylopentene-3-carboxylate 6b could be isolated in low yield. UV-irradiation of 5a,b generates 6a,b as the main products. The Rh 2 (C 3 F 7 COO) 4 -catalyzed decomposition of 5a provides primarily the ketene 2-[diisopropyl(methoxy)silyl]-pent-1-ene-1,4-dione (9) in high yield. After work-up, 3-[diisopropyl(methoxy)silyl]-2(3H)-furan-2-one 10a and 2(5H)-furanone 7 are obtained in relative amounts that depend on work-up conditions. Mechanistic pathways leading to the various products are proposed.

The ternary stannide SrAuSn 2 was synthesized by induction melting of the elements under an argon atmosphere in a sealed niobium ampoule in a water-cooled sample chamber of a high-frequency furnace. The structure of SrAuSn 2 was investigated by X-ray powder and single crystal diffraction. It was found to be favourable to describe as a commensurately modulated structure. The 3+1 dimensional superspace group symmetry P : Cmcm(α, 0, 0) : 0s0 with the unit cell dimensions a = 460.20(14), b = 2038.8(8), c = 460.34(19) pm and the modulation wave vector q =¼ [100]*. The Sn1 atoms were those with the strongest modulation while the rest of the atoms showed rather small deviations from the average structure. The SrAuSn 2 structure is closely related to the CeNiSi 2 type. Geometrically these structures are built up from distorted ThCr 2 Si 2 and AlB 2 slabs. The gold atoms are located in the ThCr 2 Si 2 slab. They have a distorted square pyramidal tin coordination at Au-Sn distances ranging from 266 to 294 pm. These pyramids are condensed via common edges forming two-dimensional layers. The latter are condensed via the Sn1 atoms within the AlB 2 slabs that form one-dimensional zigzag chains with Sn1-Sn1 distances ranging from 282 to 288 pm. These chains show the strong modulations. Together, the gold and tin atoms build up a three-dimensional [AuSn 2 ] network, in which the strontium atoms fill distorted hexagonal channels.

The complex (M)-(-)-[Pt 2 {(R,R)-tetraphos} 2 ](CF 3 SO 3 ) 4 · 4.5 H 2 O, where tetraphos = 1,1,4,7, 10,10-hexaphenyl-1,4,7,10-tetraphosphadecane, has been isolated and structurally characterized. The compound crystallizes in the space group C2 with two crystallographically different, but very similar, cations in the structure, each of which contains a 2-fold axis coincident with the crystallographic 2-fold axis. Each independent cation of the salt consists of a double-stranded, diplatinum(II) helicate that completes a ca. one-eighth turn of a double α-helix in the M direction, as evidenced by the angle between the two, non-orthogonal PtP 4 square planes in each of the independent molecules. A feature of the structures is the 10-membered ring containing the two platinum atoms and the four chiral phosphorus stereocentres of R configuration; this ring has a distorted twist-boat-chair-boat conformation of λ helicity, which is responsible for the M twist of the helicate.

Reactivity and side products of reactions of diorganodihydridostannanes (R 2 SnH 2 , R = Me, n Bu, t Bu)) with various alkali metal compounds have been discussed. Alternatively, the synthesis and characterization of a family of novel potassium stannides are described as well. The compounds of type (RR’ 2 Si)R” 2 SnK (R, R’= Me, Ph; R”= , Me, t Bu, Ph) 4 - 9 were synthesized by reaction of potassium hydride with bis(silyl)stannides ((RR’2Si)2SnR”2). All compounds were characterized by multinuclear NMR spectroscopy. In addition, the tri-tert-butyltin compound 3 (LiSntBu 3 ) and the unsymmetrical silyl substituted stannane 10 were characterized by X-ray crystallography.

A ‘carbanion’ can coordinate to a metal like an ‘amide’ if there is a nitrogen atom present to withdraw electron density from the formally negatively charged carbon center. On the other hand, shifting the negative charge from the amido nitrogen atom to the carbon substituent should convert an ‘amidic’ into a ‘carbanionic’ coordination behavior. This seems feasible with various substituents at the aromatic ring in a primary amide. This paper is concerned with the influence of aromatic substitution, as well as with the nature of the metal ion on the coordination mode of an amide ligand. Discussed are the parent lithium anilide [(thf) 2 LiNH(C 6 H 5 )] 2 (1), the pentafluorinated lithium anilide [(thf) 2 LiNH(C 6 F 5 )] 2 (2) and the lithium amino benzonitrile [(thf) 2 LiNH(C 6 H 4 p CN)] 2 (3). All amide ligands coordinate the lithium cation exclusively with their amido nitrogen atom. In the dimeric structure of 1 the atom can be regarded to be sp 2 -hybridized. Fluorine substitution of the ring results in a slightly more pronounced coupling of the negative charge to the aromatic ring. A para-nitrile group further enhances quinoidal perturbation of the C 6 -perimeter from six-fold symmetry. Consequently, the ipso- and ortho-carbon atoms of the ring are partially negative charged. Those carbon atoms are only attractive for the soft rubidium cation in an aza allylic coordination in [(thf) 2 RbNH(C 6 H 4 p CN)] n (4) but not to the hard lithium cation.

Oxidative-addition of methyl iodide, CH 3 I, to the dinuclear gold amidinate [Au 2 (o-Me 2 -form)2] in THF generates a metal-metal bonded Au(II) product, formulated as [Au 2 (o-Me 2 -form) 2 CH 3 I], in quantitative yield under nitrogen at 0 °C and in absence of light. The product is characterized by 1 H NMR, elemental analysis and preliminary X-ray crystallography.

Three new modifications of trimeric perfluoro-ortho-phenylene mercury (2) have been investigated by single crystal X-ray diffraction. In each of these modifications, the molecules of 2 form extended stacks. Within each stack, the successive molecules are parallel and separated by approximately 3.3 - 3.4 Å. The packing observed in the different structures is rationalized on the basis of secondary mercury-π interactions, mercuriophilic interactions and electrostatic interactions. Altogether, little preference is given for one particular type of interaction. The packing appears to be dominated by non-directional van der Waals interactions between molecules of 2 which are largely aromatic and whose overall polarizability is magnified by relativistic effects at the mercury(II) centers.

The new dialkynyldigold(I) complexes [Ar(OCH 2 C≡CAu) 2 ]n {Ar = 1,4-C 6 H 4 (CMe 2 -4-C 6 H 4 ) 2 , 4,4’-C 6 H 4 C 6 H 4 and 1,5-C 10 H 6 } react with diphosphines LL = Ph 2 P(CH 2 ) n PPh 2 (n = 1 to 6) and trans-Ph 2 PCH=CHPPh 2 to give luminescent macrocyclic digold(I) or tetragold(I) complexes with bridging diphosphine and diacetylide ligands. The digold(I) complex [1,4-C 6 H 4 (CMe 2 -4- C 6 H 4 OCH 2 C≡CAu) 2 (μ-LL)], with LL = trans-Ph 2 PCH=CHPPh 2 , forms a 28-membered ring, and the rings associate through aurophilic bonding in the solid state. In contrast, the tetragold(I) complex [4,4’-C 6 H 4 C 6 H 4 (OCH 2 C≡CAu) 2 (μ-LL)], with LL = Ph 2 PCH 2 PPh 2 , forms a more rigid 42-membered ring.

The Staudinger reaction of the N-heterocyclic carbenes 1,3-di-tert-butylimidazolin-2-ylidene (1a), 1,3-dimesitylimidazolin-2-ylidene (1b) and 1,3-diisopropyl-4,5-dimethylimidazolin-2- ylidene (1c) with trimethylsilyl azide in boiling toluene furnishes the corresponding 2- (trimethylsilylimino)imidazolines 2a - c. Treatment of Re 2 O 7 with a twofold excess of these N-silylated imines results in the formation of the imidazolin-2-iminato trioxorhenium(VII) complexes 3a - c and hexamethyldisiloxane, Me 3 SiOSiMe 3 . The molecular structures of 2a, 3a and 3b are reported. In addition, the X-ray crystal structure determination of complex 3c · H 2 O is presented, which has formed by hydrolysis and cleavage of the metal-nitrogen bond in 3c. 3c · H 2 O consists of 2-aminoimidazolium cations and tetraoxorhenate(VII) anions, which are linked by N-H-O hydrogen bonds.

O-(Dichlorosilyl)-N,N-dimethylhydroxylamine, Cl 2 HSiONMe 2 , was synthesised by the reaction of O-lithio-N,N-dimethylhydroxylamine with an excess of trichlorosilane. The compound was characterised by multinuclear NMR spectroscopy ( 1 H, 13 C, 15 N, 29 Si), gas-phase IR spectroscopy and mass spectrometry. The structure of Cl 2 HSiONMe 2 was determined by gas-phase electron diffraction. It exists as two conformers in the vapour, named anti and gauche after the position of the SiH hydrogen atom relative to the SiON skeleton. The anti:gauche ratio in the vapour was determined to be 40:60. The anti conformer shows only a weak attractive interaction between the geminal donor and acceptor centres N and Si [angle Si-O-N 111.1(20)­°], whereas these interactions are stronger in the gauche conformer [angle Si-O-N 98.8(12)°]. Further structure-determining forces from weak hydrogen bridges of the Si-Cl ···H-C type and van der Waals repulsive forces are also discussed. The experimental results are in reasonable agreement with ab initio calculations at the MP2/6-311++G** level of theory.

The cation Al 2 Cp* + descending from the tetrahedral Al 4 Cp* 4 Cluster after using LDI as ionisation method in an FT-ICR mass spectrometer reacts with Cl 2 in the gas phase. The investigation of this reaction together with quantum chemical calculations gives a new approach to the question of existence and stability of an aluminum-aluminum double bond.

The unsymmetrically substituted imidazolium salt 1-ethyl-3-allyl-imidazolium bromide 1 was synthesized by treatment of imidazole with one equivalent each of n-butyl lithium and ethyl bromide followed by treatment with one equivalent of allyl bromide. The symmetrically substituted derivatives 1,3-diallyl-imidazolium bromide 2 and 1,3-bis(3-methyl-2-butenyl)-imidazolium bromide 3 were obtained from imidazole and two equivalents of allyl bromide or 4-bromo-2-methyl-2-butenyl bromide, respectively, in the presence of sodium hydrogencarbonate as a base. The imidazolium bromides 1- 3 react with Pd(OAc) 2 to afford the palladium(II) dicarbene complexes trans-[PdBr 2 (L)2] (L = 1- ethyl-3-allyl-imidazolin-2-ylidene, 4; L = 1,3-diallyl-imidazolin-2-ylidene, 5; L = 1,3-di(3-methyl-2- butenyl)imidazolin-2-ylidene, 6) by in situ deprotonation of the imidazolium salts. The X-ray structure analyses of 4- 6 show all three complexes to be mononuclear with palladium(II) coordinated in a square-planar fashion by two carbene and two bromo ligands.

Tetramethylformamidinium trichlorogermanite, [CH(NMe 2 ) 2 ][GeCl 3 ], tetramethylformamidinium trichlorostannite, [CH(NMe 2 ) 2 ][SnCl3], bis-(tetramethylformamidinium hexaiododigallate, [CH(NMe 2 ) 2 ] 2 [Ga 2 I 6 ] and bis-(tetramethylformamidinium hexachlorodiindate, [CH(NMe 2 ) 2 ] 2 [In 2 Cl 6 ] have been prepared by the reactions between tetramethylformamidinium chloride, [CH(NMe 2 ) 2 ]Cl, and the corresponding low valent halides GeCl 2 (as dioxane adduct), SnCl 2 , “GaI” and InCl. Their crystal structures have been determined by single crystal X-ray diffraction. [CH(NMe 2 ) 2 ][GeCl 3 ] aggregates in a centrosymmetric dimeric structure, in which two trigonal pyramidal GeCl 3 units are connected together by two weak Ge···Cl bonds and each Ge atom is bonded to one cation by a weak Ge···N contact. Two sets of weak hydrogen bonds C-H···Cl are observed with bond lengths of 2.87(2) Å and 2.85(2) Å . In [CH(NMe 2 ) 2 ][SnCl 3 ], the SnCl 3 − units adopts a (3+3) coordination with three normal Sn-Cl bonds and three weak Sn···Cl contacts. [CH(NMe 2 ) 2 ] 2 [Ga 2 I 6 ] and [CH(NMe 2 ) 2 ] 2 [In 2 Cl 6 ] contain metal-metal bonded anions with distorted staggered ethane-like conformations. The metal-metal bond lengths are 2.423(1) Å (Ga-Ga) and 2.719(1) Å (In-In). Their Raman spectra contain intense bands at 118.7 cm −1 (Ga-Ga) and 174.7 cm −1 (In-In) associated with metal-metal stretching modes.

The compounds Me 3 Al-Me 2 NCH 2 NMe 2 -AlMe 3 (1) and Me 3 Ga-Me 2 NCH 2 NMe 2 -GaMe 3 (2) were prepared by reacting Me 2 NCH 2 NMe 2 (TMMDA) with two equivalents of the metal trialkyls in hydrocarbon solutions.With the ether adduct Me 3 Ga·OEt 2 Me 2 NCH 2 NMe 2 reacts to give the monoadduct Me 2 NCH 2 NMe 2 -GaMe 3 (3). These compounds were characterized by NMR spectroscopy ( 1 H, 13 C and 27 Al) and by elemental analyses. Crystal structure investigations show 1 and 2 to be monomeric and to a adopt a trans,trans-conformation for their M-N-C-N-M backbones. 3 is also monomeric in the solid state, but adopts a cis,trans-conformation. Tetramethylformamidinium chloride and also chlorotetramethylformamidinium chloride reacts with lithium aluminium hydride to give the mono-adduct [Me 2 NCH 2 NMe 2 -AlH 3 ] 2 (4), which is dimeric and can be regarded as a double TMMDA adduct to Al 2 H 6 with five-coordinate Al atoms. Ab initio calculations on the MP2/6- 311G** level of theory have been performed for the model compound H 3 N-H 2 Al(μ-H) 2 AlH 2 -NH 3 to obtain its molecular structure and vibrational spectrum for comparison with 4 and for the assignment of its vibrational spectrum.

Reaction of TiCl 3 (THF) 3 with 3 equivalents of LiOSi(O t Bu) 3 produces the Ti(III) siloxide Ti[OSi(O t Bu) 3 ] 3 (THF) 2 (1), and a 1:4 ratio of the same reagents gives {LiTi[OSi(O t Bu) 3 ] 4 } x . Upon heating to 95 °C, compound 1 converts via THF ring-opening to [( t BuO) 3 SiO] 3 TiO(CH 2 ) 4 Ti[OSi(O t Bu) 3 ] 3 . The pyridine adduct Ti[OSi(O t Bu) 3 ] 3 (pyr) 2 , and polymeric {Ti[OSi(O t Bu) 3 ] 3 (4,4’-bipyridine)}n, are also described. Electronic spectra for the Ti[OSi (O t Bu) 3 ] 3 L 2 complexes indicate D 3h symmetry, and similar results for the 4,4’-bipyridine adduct suggest a linear polymeric structure.

The metalation of tri(tert-butyl)silylphosphane with diethylzinc yields quantitatively the title compound tetraethyltetrakis(tri(tert-butyl)silylphosphanediido)hexazinc (1) with a novel Zn 6 P 4 cage with two Zn 2 P 2 rings interconnected by two zinc atoms.

Compounds that feature the metal atom substructure of “La 5 B 2 C 6 ” are known for most rare earth metals (Ln). They are characterized by two types of voids surrounded by large bicapped tetragonal antiprisms and smaller distorted octahedra, respectively. For many rare earth elements, a huge variation of lattice parameters has been observed for the corresponding compounds. A series of structure determinations has beed performed in order to elucidate the reasons for this remarkable stability range. The compounds of the earlier lanthanoids (La-Nd) exhibit broad ranges of homogeneity that are due to varying occupancy of octahedral voids which can be empty or filled by varying amounts of C atoms or C 2 groups. However, the larger voids are fully occupied with disordered C 3 B groups. In most cases the disorder is completely statistical with only a few exceptions. In contrast, two different phases have been observed in the case of late rare earth metals (starting from Gd). Their ranges of homogeneity are moderate, and the larger voids are fully occupied by ordered CBC entities. The difference between these two types of phases concerns the octahedral voids which contain C atoms in the case of compounds with the idealized composition Ln 5 B 2 C 5 and C 2 groups for Ln 5 B 2 C 6 , respectively. Positional disorder is possible for both C atoms and C 2 groups. Therefore, no single well-defined compound is known that possesses the metal atom arrangement of “La 5 B 2 C 6 ”.

The cyclometallated digold(I) complexes [Au 2 (μ-2-C 6 H 4 CH 2 PPh 2 ) 2 ] (10) and [Au 2 (μ-2-CH 2 C 6 H 4 PPh 2 ) 2 ] (11) have been synthesized by the reaction of Li[2-C 6 H 4 CH 2 PPh 2 ] and Li[ 2 -CH 2 C 6 H 4 PPh 2 ], respectively, with [AuBr(PEt 3 )]. A single crystal X-ray structure analysis of 10 shows the linearly coordinated gold(I) atoms to be separated by 3.0035(9) Å in a puckered ten-membered ring. Both complexes add one mol equivalent of iodine to form initially gold(I)-gold(III) complexes [Au(μ-2-C 6 H 4 CH 2 PPh 2 ) 2 AuI 2 ] (14a) and [Au(μ-2-CH 2 C 6 H 4 PPh 2 ) 2 AuI 2 ] (17), which isomerize to the corresponding salts [Au(κ 2 -P,C-C 6 H 4 CH 2 PPh 2 ) 2 ][AuI 2 ] (13a) and [Au(κ 2 -P,C-CH 2 C 6 H 4 PPh 2 ) 2 ][AuI 2 ] (16). In 13a the gold(III) cation is planar coordinated by a pair of chelate P-C donor ligands, the phosphorus and carbon atoms being, separately, mutually cis, as shown by X-ray structural analysis. From the reaction of 10 with 2 mol equivalents of bromine, the neutral chelate complex [AuBr 2 (κ 2 -P,C-C 6 H 4 CH 2 PPh 2 )] (15) has been isolated and structurally characterized.

Bis(lithiomethyl)germanes, R 2 Ge(CH 2 Li) 2 , tris(lithiomethyl)germanes, RGe(CH 2 Li) 3 , and tetrakis( lithiomethyl)germane, Ge(CH 2 Li) 4 , were prepared by the reductive C-S bond cleavage with lithium naphthalenide (LiC 10 H 8 ) or lithium p,p’-di-tert-butylbiphenylide (LiDBB) and characterized by trapping with Bu 3 SnCl. The bis(lithiomethyl)germanes were used for the synthesis of 1,1-dimethyl-3,3-diphenyl-1-germa-3-silacyclobutane, 1,1-diethyl-3,3-diphenyl-1-germa-3-silacyclobutane, 1,1,3,3-tetraphenyl-1-germa-3-silacyclobutane and 1,1,3,3-tetraphenyl-1,3-digermacyclobutane. The single-crystal X-ray diffraction studies of methyltris(phenylthiomethyl)germane and tetrakis(phenylthiomethyl)germane, starting materials for the corresponding poly(lithiomethyl) germanes, indicate tetrahedrally arranged substituents at the germanium atoms.

Reduction of C 60 with the alkali metals A = K, Rb and Cs in tetrahydrofuran as a solvent and addition of [2.2.2]crypt [1], dimethylformamide and cyclohexane lead to the formation of crystalline samples of [A([2.2.2]crypt)] 2 [C 60 ](C 6 H 12 ) 2 (C 3 H 7 NO) 2 (C 4 H 8 O) 2 (A = K, Rb, Cs) 1a, 1b and 1c as major fractions. As a by-product of compound 1a, a second minor fraction containing [K([2.2.2]crypt)] 2 [C 60 ](C 3 H 7 NO) 4 2 was obtained. The structures of the four compounds have been determined by single-crystal X-ray analyses. The [C 60 ] 2− dianions are predominantly ordered. As the main structural motif the structures of compounds 1a, 1b and 1c contain pseudo-hexagonal layers of [C 60 ] 2− dianions. Compound 1c contains a rare example of a Cs + sequestering [2.2.2]crypt molecule. The packing of the ionic units in compound 2 also shows layers of distorted hexagons formed by [C 60 ] 2− dianions which arranged in pairs with short contacts of 10.3 Å between their centers of gravity.

The binding of sulfanyl and alkylsulfanyl model ligands to gold clusters was studied for the case of Au 13 (SR)n with R = H, CH 3 and n = 4, 6, 8. Accurate all-electron electronic structure calculations and geometry optimizations of these gold-thiolate clusters have been performed with a scalar relativistic Kohn-Sham procedure as implemented in the density functional program PARAGAUSS. In all structures obtained, bridge coordination was preferred for both types of ligands; no higher coordinated sites where occupied. While in many cases ligand decoration did not change the overall structure of the Au 13 core, also more open structures with Au-Au distances elongated beyond the bulk value have been obtained. The effects due to increasing ligand decoration were small: a small decrease of the binding energy per ligand does not exclude higher ligand coverages. The differences between the model ligands SH and SCH 3 were consistent in all cases considered: SCH 3 exhibits weaker binding and a slightly smaller charge separation between cluster core and ligand shell, which amounts up to about 1.5 e for 8 ligands. Overall, the Au 13 core of the clusters was found to be quite flexible. This can be rationalized by the fact that the calculated binding energy per ligand is comparable or even exceeds the binding energy per atom in Au 13 .

In the context of derivatisation studies of the pentaamine ligand 2,6-C 5 H 3 N[CMe(CH 2 NH 2 ) 2 ] 2 (2-(6-(1,3-diamino-2-methylpropan-2-yl)pyridin-2-yl)-2-methylpropane-1,3-diamine, 1), we explored its zinc(II) coordination chemistry. With ZnBr 2 in hot aqueous ethanol, in the absence of Lewis acid, the aqua complex [Zn(1)(H 2 O)]Br 2 (2) is obtained, in which the pentaamine ligand acts as a square-pyramidal coordination cap. Single crystal structure data for the dihydrate of 2 are reported. In methanol solution, the complex is reactive towards carbon dioxide, and spectroscopic data (IR, 13 C NMR) indicate the reversible formation of the dinuclear methyl carbonate complex [(Zn(1)) 2 (μ 2 -(η 1 -O,η 1 -O)O 2 COCH 3 )]Br 3 .

A series of neutral dinuclear and mononuclear gold(I) complexes with phosphine and N-bonded 9H-purin-9-ate or 9H-purin-6-ylamine-9-ate have been synthesised under basic conditions and characterised by gHSQC, 1 H, 13 C gHMQC and 1 H detected 1 H, 15 N gHMQC experiments in addition to ESI-MS and IR spectroscopy. Intermolecular aurophilic interactions are present in the structures of polymeric 1,2-bis(diphenylphosphine)ethane(9H-purin-9-ate)gold(I) 1, (3.1641(4) Å ) and 1,3- bis(diphenylphosphine)propane(9H-purin-9-ate)gold(I) 3, (3.52Å ). The N-Au-P angle in 1 is exceptionally small (166.3(1)°). Intramolecular aurophilic interaction (3.63 Å ) complemented by hydrogen bonding dictates the non-oligomeric structure of 1,3-bis(diphenylphosphine)propane(9H-purin- 6-ylamin-9-ate)gold(I) (7). Dimeric aurophilic interactions appear in the structure of (tributylphosphine)( 9H-purin-9-ate)gold(I) (11) (3.2311(7) Å ), while the structure in the other mononuclear compound, (triphenylphosphine)(9H-purin-9-ate)gold(I) (9) is organised by Au. . .N-interactions.