Volume 52, Issue 2

It is shown that the trigonal compound “BaNb 3 O 6 ” described earlier actually is the cubic perovskite BaNbO 3 with an unusually small lattice constant of 4.039 A. Furthermore, the refinement of the single crystal data prepared by CO 2 -LASER techniques did not reveal defects at the Ba position, but defects at the positions of niobium and oxygen, corresponding to the composition Ba(NbO 3 ) 0.9 or Ba 1.08 NbO 3 .

[Cu 2 L] (L=N-2-hydroxy-4-methylphenyl-4-oxo-2-pentalketimine) was synthesized and its crystal structure determined. C 24 H 26 Cu 2 N 2 O 4 monoclinic space group P2 1 /n with a= 10.978(2), 17.045(3), c= 11.958(2) Å, β = 101.89(1)°, V = 2189.6(7) Å 3 ,Z = 4. Two copper(II) atoms in a distorted square-planar coordination are bridged by two oxygen atoms to form a dinuclear unit. The copper(II) centers are separated by 3.025(1) Å and antiferromagnetically coupled (J =-222.3 cm -1 ), which follows from temperature-dependent magnetic susceptibility measurements in the range 4.2 to 300 K.

Depending on the reaction conditions, the condensation of triphenylphosphonium bis(trimethylsilyl)methylide 1 with phosphorus trichloride and phosphorus tribromide gives the cyclic trimers (Ph 3 P=CP-X) 3 , X = Cl, Br, trihalo-tris(triphenylphosphoranediyl)-1,3,5- triphosphinanes 3 and 5. In solution the compounds dissociate to give the ionic forms 4 and 6 which rapidly exchange the halide between the halophosphine and the phosphenium moieties. The exchange is slowed down when the halide ion is replaced by a tosylate ion. Substitution of the covalent chloride of 4 for diphenylphosphino groups gives again an ionic product 10, while the introduction of a morpholino group as well as the replacement of all chloride by triflate give dicationic compounds 12 and 13. Reaction of 3 with gallium trichloride finally leads to the tris(triphenylphosphonio)-1,3,5-triphosphinine trication as a major equilibrium participant.

The methanolothermal reaction of Rb 2 CO 3 with As 2 Se 3 and black selenium leads to the formation of Rb 3 AsSe 4 and the new selenidoarsenate(V) Rb 3 AsSe 4 · 2Se 6 (1), which crystallizes in the cubic space group Fd3̄ (No. 203) with a = 16.660(2) Å, V = 4624.1(1) Å , Z = 8. The structural features are isolated tetrahedral AsSe 4 3- anions and Se 6 rings in a chair conformation. Whereas the similar reaction with Cs 2 CO 3 only affords the known selenides Cs 3 AsSe 4 and Cs 4 Se 16 , replacement of As 2 Se 3 by As 2 Te 3 leads to a compound with similar lattice constants to 1 (Fd3̄, a = 17.275(2) A), containing disordered AsSe 4 3- and As 2 Se 4 2- anions, the latter of which exhibit a four-membered As 2 Se 2 ring with m-positioned terminal selenium atoms. The six-membered chalcogen ring is likewise disordered with Se and Te site occupation factors of respectively 0.333 and 0.667 with the result that 2 can be formulated as Cs 3 AsSe 4 · 2Cs 2 As 2 Se 4 · 6Te 4 Se 2 . 2 provides the first example of a Te x Se 6-x ring to be characterized in the solid state.

Twentyfive new perovskite carbides have been obtained either by arc-melting cold-pressed pellets of the elemental components with subsequent annealing at 900 °C or by heating stoichiometric quantities of the elements in a high-frequency furnace. Also, thirtyseven compounds of this structure type are confirmed and their lattice constants are reported. The crystal structures of SC 3 MC (M = Al, Ga, In, Tl) were refined from X-ray powder data, and in all cases only the octahedral voids formed by scandium atoms were found to be fully occupied. The hydrolysis of the carbides Sc 3 GaC, Y 3 SnC, Y 3 PbC and Ho 3 PbC with diluted hydrochloric acid resulted in about 84 - 97 (wt-)% methane and 3 - 16 % saturated and unsaturated higher hydrocarbons. The cell volumes of the ternary carbides A 3 MC and the corresponding binary Cu 3 Au type compounds A 3 M are compared and several inconsistencies are pointed out.

The crystal structure of [Zn(sac) 2 (py) 2 ] has been de termined by single-crystal X-ray diffractometry. It crystallizes in the monoclinic space group C2/c with Z = 4. We propose and discuss an assignment of its IR and Raman spectra, compatible with the structural characteristics. Its thermal behavior was investigated by means of TG and DTA methods. Some comparisons with related compounds are made.

New tridentate ligands of the type N-alkyl-N,N-bis(2-pyridylmethyl)amine (alkyl = me­ thyl, benzyl, adamantyl) have been synthesized by reaction of alkylamines with 2 -(chlor-methyl)pyridine in alkaline solution. These amines are preferably isolated and stored as per­ chlorates. The perchlorate of the methyl substituted ligand has been crystallized in two modifi­cations that differ in the twisting of the aromatic rings and in the coordination of the perchlorate anions.

Triphenylantimony reacts with S 3 N 2 Cl 2 in dichloromethane solution to give yellow crystals of the cyclostibathiazene derivative [xxx], As a by-product orange single crystals of [(Ph 3 SbCl 2 ) 2 ·S 4 N 4 ] were isolated, in which the molecular compounds Ph 3 SbCl 2 and S 4 N 4 only form van der Waals contacts with one another. Both compounds are characterized by crystal structure determinations. [xxx]: Space group P2 1 /n, Z = 4; lattice dimensions at -80°C: a = 759.4(1), b = 1448.5(3); c = 1557.6(2) pm; β = 91.09(1)°, R = 0.026. The complex has a molecular structure in which the Sb atom is coordinate in a distorted trigonal-bipyramidal fashion with one phenyl group and one of the nitrogen atoms of the planar [xxx] ring in the apical positions. [(Ph 3 SbCL) 2 ·S 4 N 4 ]: Space group C2/c, Z = 8 ; lattice dimensions at -60°C: a = 1549.3(1), b = 1017.7(1), c = 2623.9(1) pm, β = 105.56(2)°, R = 0.050.

(CuI) 2 P 14 is a new adduct of copper iodide to a neutral phosphorus polymer. It is obtained by reaction of Cul and P red at 400 °C. The compound crystallizes monoclinically, space group P2 1 /c (No. 14), a = 9.919(2), b = 9.718(2), c = 16.478(3) Å, β = 105.71(1)°, V = 1529.0(7) Å 3 , with Z = 4. The crystal structure was refined to R1 = 0.029 for 2680 reflections and 173 parameters. It contains a new polymeric phosphorus allotrope with the translational unit P 14 ±0 consisting of experimentally unknown [P12] groups which are linked by [P2] fragments. The phosphorus rods consist of five-and six-membered rings, and are coordinated only by copper atoms.

The reaction of 2-diphenylphosphino-pyridine (1) with AgBF 4 in an equimolar ratio affords the cyclic, dinuclear complex 2 with mixed P,N-coordination of the metal atoms. With two equivalents of 1 the 2:1 complexes 4a,b are formed which have the metal atoms solely Pcoordinated. The previously reported gold complex (3), an analogue of 2, or [Au(tht) 2 ]ClO 4 (tht = tetrahydrothiophen) also give the 2:1 complexes (5a,b) when treated with an excess of ligand 1. Addition of AgClO 4 to a solution of 5a in acetone, or treatment of 4a with [Au(tht) 2 ]ClO 4 in dichloromethane, give the same mixed-metal complex 6, where the Au atoms are exclusively P-coordinated, while the Ag atoms are coordinated by the two pyridine nitrogen atoms. In the crystal there are also weak interactions of the perchlorate counterions with the silver atom. Addition of [Cu(MeCN) 4 ]BF 4 to compound 5b gives the Cu/Au-complex with P,P-coordinated gold and N,N-bonded copper centers. All products were characterized by standard analytical and spectroscopic techniques; the crystal structure of complex 6 was determined in a single crystal X-ray diffraction study.

Treatment of N,N′-diisopropyl-ethylenediamine or 1,4-piperazine with two equivalents of [(Ph 3 P)Au] + BF 4 - leads to binuclear complexes of the diamines: {[(Ph 3 P)Au]HN( i Pro)NCH 2 -} 2 2+ 2 BF 4 - (1) and {[(Ph 3 P)Au]HNCH 2 CH 2 } 2 2+ 2 BF 4 - (2), respectively. In the products each quaternary ammonium center bears one gold ligand, one hydrogen atom and two alkyl substituents. The crystal structures of both compounds have been determined. Compound 1 contains discrete ion-triples. The ethylene bridge in the dications is in an unfolded conformation, with a crystallographic center of inversion, and allows for weak hydrogen bonding N-H--F [2.085 Å; N-H--F 169.2°] between the NH functions and the counterions. The existing distant contacts F--Au [3.599 Å] are probably less significant for the aggregation of the ion triples, but will contribute through Coulomb forces. Compound 2 crystallizes with two solvent molecules CH 2 CI 2 . The dication has a crystallographic center of inversion with the piperazine ring in a chair conformation and the gold atoms in equatorial positions. There are hydrogen bonds N-H--F [2.076 and 2.457 Å] between the dication and the anions which lead to the formation of ion-triples, with further contacts between the BF 4 - anions and the solvent molecules [C-H--F 2.340 and 2.446 Å].

The complex of ReCl(CO) 3 (PhNH-NH 2 ) 2 shows an absorption band at λ max = 272 nm which is assigned to an IL (intraligand) transition of the coordinated phenylhydrazine. Upon IL excitation the complex undergoes a decomposition with ϕ = 0.03 at λ irr = 280 nm.

The reaction of tris(phenylthiomethyl)phosphine with equimolecular amounts of [AuPPh 3 ] + [BF 4 ] - affords the complex (tris(phenylthiomethyl)phosphine)(triphenylphosphine)- gold(I) tetrafluoroborate 1 in good yield. The X-ray diffraction analysis of this product shows an unusual conformation with the three ChLSPh arms of the phosphine folded back towards the metal atom shielding the P-Au-P′ unit. The reaction of the same substrate with Bis(tetrahydrothiophene)gold(I) perchlorate in a 1:1 molar ratio leads to the displacement of both weakly coordinated tht ligands, and a dimeric product [AuP(CH 2 SPh) 3 ] 2 (ClO 4 ) 2 2 is obtained.

The perchlorinated arsaboranes closo-1,2-As 2 B 10 Cl 10 and As 4 B 8 C 16 are formed in the co­ pyrolysis of B 2 C 14 and AsCl 3 at temperatures of 330-450°C. The icosahedral structure of closo-1,2-As 2 B 10 Cl 10 is confirmed by 11 B- 11 B-COSY-NMR spectroscopy. As 4 B 8 Cl 6 is suppo­ sed to be a conjuncto-borane (As 2 B 4 Cl 3 ) 2 with two boron-boron linked As 2 B 4 Cl 3 octahedra. The copyrolysis of B 2 Cl 4 andSbCl 3 or SbCl 5 yields Sb 2 B 10 Cl 10 , and the corresponding reaction of B 2 Cl 4 with S 2 Cl 2 gives the icosahedral thiaborane cluster SB 11 Cl 11 .

Single crystals of AgSr[B 7 O 12 ] were obtained by using a B20 3 flux-technique and Ag 2 CO 3 and SrCO 3 as starting materials in a silver ampoule at 800 °C. X-ray investigations on single crystals led to the space group C 2/c with a = 664.2(5); b = 1153.6(3); c = 2198.0(6) pm; β = 92,52(3)°; Z = 8. Ag + is fourfold coordinated by oxygen atoms and forms distorted AgO 4 tetrahedra while Sr 2+ has nine nearest neighbours. The compound contains a hitherto unknown two dimensional borate anion [B 7 O 12 ] 3- which contains four trigonal planar BO 3 groups and three BO 4 tetrahedra per unit.

Er 5 Re 2 C 7 , Tm 5 Re 2 C 7 , and Lu 5 Re 2 C 7 were prepared by arc-melting of the elemental components and subsequent annealing at 800 °C. Er 5 Re 2 C 7 forms only after the annealing process, whereas the other two carbides were already present in the as cast samples. They crystallize with a Sc 5 Re 2 C 7 type structure, which was refined from single-crystal X-ray data of Lu 5 Re 2 C 7 : Cmmm, a = 791.44(5), b = 1418.08(8), c = 332.79(2) pm, Z = 2, R = 0.037 for 544 structure factors and 21 variable parameters. The structure contains linear centrosymmetric C 3 units with a C-C bond length of 133(2) pm and isolated carbon atoms in octahedral coordination of four lutetium and two rhenium atoms. The rhenium atoms within the two-dimensionally infinite polymeric sheets [Re 2 C 4 ] n are electronically saturated as is indicated by the diamagnetism and the semiconductivity of this carbide. Yb 2 ReC 2 was prepared by reacting the elements in a sealed tantalum tube with a high-frequency furnace. It crystallizes with a Pr 2 ReC 2 type structure: Pnma, a = 645.91(6), b = 498.64(6), and c = 966.05(6) pm. Magnetic susceptibility measurements indicate the ytterbium atoms to be trivalent in this compound.

Tin(IV) complexes of diacidic azo and hydrazono compounds were synthesized by the reaction of these ligands with SnCl 2 acac 2 and SnCl 2 · 2H 2 O , respectively. The complexes were further characterized by Mössbauer spectroscopy. For bis[4-(2′-hydroxyphenylazo)-3-methyl-l-phenyl-pyrazol-5-onato(2-)]tin(IV) force field calculations have been performed and the crystal structure was determined by X-ray analysis.

The donor-acceptor complexes [ZnCl 2 (Me 3 SiNP(CH 2 ) 4 CMe 3 )] 2 (1)and [ZnI 2 (Me 3 SiNPEt 3 )] 2 (2) have been prepared from the zinc dihalides and the corresponding silylated phosphaneimines in CH 2 Cl 2 . Thermolysis of 2 leads to the formation of [ZnI 2 (Me 2 Si(NPEt 3 ) 2 )] (3). Znl 2 and ZnBr 2 react with the silylated phosphaneimines Me 3 SiNPR 3 (R = Me, Et) in the presence of NaF at elavated temperatures to give the phosphoraneiminato complexes [ZnI(NPEt 3 )] 4 (4), [ZnBr(NPMe 3 )] 4 (5) and [ZnBr(NPEt 3 )] 4 (6), respectively, which according to the IR spectra and to a crystal structure determination of 5 form heterocubane structures. The corresponding reactions with the more bulky phosphaneimine Me 3 SiNP(CH 2 ) 4 CMe 3 do not lead to a phosphoraneiminato complex of zinc. 1: Space group P2 1 /n, Z = 2; lattice dimensions at -60 °C: a = 903.3(2), b = 1217.9(3), c = 1591.6(2) pm, β = 93.94(1)°, R = 0.031. 2: Space group P2 1 /n, Z = 2; lattice dimensions at -70°C: a = 947.9(2), b = 1219.2(2), c - 1527.1(2) pm, 0 = 91.17(1)°, β = 0.045. 1 and 2 form centrosymmetric dimeric molecules via Zn 2 X 2 bridges (X = Cl, I); bond lengths Zn-N = 198.7(2) pm (1) and 199.0(6) pm (2). 3: Space group P4 1 2 1 2 1 Z = 8; lattice dimensions at -90°C: a = b = 965.4(1), c = 2796.9(2) pm, R = 0.019.3 forms monomeric molecules with the Me 2 Si(NPEt 3 ) 2 ligand as chelating agent to give a planar ZnN 2 Si four-membered ring with Zn-N distances of 207.0(2) pm. 5: Space group P4 2 /nmc, Z = 2; lattice dimensions at -70°C: a = b = 1146.9(6), c = 1437.9(7) pm, R = 0.060.

Coarse crystalline Ag 3 (PO 2 NH) 3 (1) and K 3 (PO 2 NH) 3 (2) are obtained by addition of an aqueous solution of AgNO 3 to an acidified solution of Na 3 (PO 2 NH) 3 · 4H 2 O and by diffusion controlled addition of ethanol to a solution of K 3 (PO 2 NH) 3 in water, respectively. The crystal structures of 1 and 2 have been determined by single crystal X-ray methods (Ag 3 (PO 2 NH) 3 : P2 1 /c; a = 1166.6(1), b = 786.4(1), c = 997.8(1) pm, β = 106.91(1)°; Z = 4. K 3 (PO 2 NH) 3 : R3̄; a = 1271.4(2), c = 1017.9(2) pm, Z = 6). In Ag 3 (PO 2 NH) 3 the cyclic anion is markedly distorted because of interactions between Ag + and one nitrogen atom of the anion. In K 3 (PO 2 NH) 3 the trimetaphosphimate ring shows a chair conformation and two cyclic anions are connected to each other by hydrogen bonds. DTA/TG investigations show thermal decomposition above 275 and 250 °C for 1 and 2, respectively.

The crystal structure of the title compound has been determined by X-ray diffraction methods. Due to the Lewis acidic character of the iodine substituent a “zig-zag” chain is formed via intermolecular interactions (2.933(4) A) between iodine and oxygen atoms of theocarbamate moiety. A three-dimensional network is formed through hydrogen-bridging (2.04 A) between NH-groups and the oxygen atoms of the neighbouring carbamate group of the next molecule.

The formation of the highly strained 1′ ,3′’-Dichlorodispiro[cyclopropane-1,2′-bicyclo[1.1.0]- butane-4′, 1″-cyclopropane] (2) by electrochemical reduction of the title compound 1, published by Strelow, Voss and Baum [2], turned out to be erroneous and has to be corrected. Instead of the formation of 2 a substitution of one chloro substituent by hydrogen takes place and the trichlorodispiro[2.1.2.1]octane 3 results. The structure of 3 is confirmed by an X-ray structural analysis.

The p-nitrosophenolate anion, PNPA (3), represents an excellent example of variable π-electron transfer demanded by a network of different hydrogen bonds. The limiting structures of mono-protonation in the solid state and in solution are either the p-nitrosophenol (1) or the p-quinonoxime (2) molecules. For the systems 1 to 3 and the related compounds 4 to 7 are results of ab initio 6-31G HF MO optimizations of molecular structures presented which are calculated additionally in variously rotated conformations. Solid state 13 C-CP/MAS NMR spectra of two PNPA salts 8 and 9 have been recorded at 7.0 Tesla. The protonation of 8 and 9 was studied in solution using a 400 MHz NMR spectrometer recording the variations in 1 H and 13 C NMR chemical shifts on changing the solvent from DMSO-d 6 to D 2 O in steps of 25%. The 2D 1 H- 13 C correlated spectrum leads to unambigous assignment of NMR signals. From the coalescence temperature of 1 H signals of 9 the experimental barrier of rotation in D 2 O was determined as 16.9 ± 0.1 kcal mol -1 . The calculated gas phase rotational barrier for free PNPA is with 26.9 kcal mol -1 much higher, but is lowered by calculations for the Li-salt 6 c to 14.5 kcal mol -1 and to 11.8 kcal mol -1 for the protonated PNP If. The in-plane inversion of PNPA through 3c is calculated to be extremely high with 52.4 kcal mol -1 . The effects of rotation of substituents to orthogonal conformations on calculated energies and on intramolecular distances were studied thoroughly.

From solid phase peptide synthetic approaches of mMIF(93-115) the C-terminal sequence turned out to be a typical „difficult sequence“ peptide. Various stepwise syntheses were performed with different resins and coupling reagents. The Peptide was synthesized in 90% yield by solid phase fragment condensation of protected mMIF(93-108) to mMIF(109-115) ‘2-Chlorotrityl’ resin bound.

Density Functional Theory calculations on E(SbMe 2 ) 2 , E = O, S or Se, Me = CH 3 , indicate that the equilibrium structures are syn-syn or near syn-syn conformers with over-all C 2 symmetry. The barriers restricting rotation about E-Sb bonds are very low, the equilibrium values for the dihedral angles ϕ(Sb-E-Sb-lp) where lp denotes the direction of the electron lone pair on one of the Sb atoms are probably less than 45°. The calculations further indicate the existence of syn-anti conformers some 4 kJ mol -1 above the more stable syn-syn. Gas electron diffraction data show that both conformers are present in gaseous O(SbMe 2 ) 2 , while the presence of the syn-anti conformer in gaseous Se(SbMe 2 ) 2 is uncertain; least-squares refinements yielded the mole fraction χ = 0.27(18). The Sb-O and Sb-Se bond distances are 197.6(14) and 255.1(5) pm respectively, the valence angles of the syn-syn conformers are <SbOSb = 122.3(16)° and <SbSeSb = 96.3(11)°. It is suggested that the wide <SbOSb angle is due to across-angle repulsion between the Sb atoms.

Treatment of tris[(triphenylphosphine)gold(I)]-sulfonium tetrafluoroborate with AgBF 4 (molar ratio 2:1) in tetrahydrofuran affords a hepta-nuclear mixed-metal cluster trication {[(Ph 3 P) 6 Au 6 AgS 2 ](thf)} 3+ as the tetrafluorobor­ate salt. The crystal structure of the compound has been determined by X-ray diffraction. The sil­ver atom is found in a bridging position between the two Au 3 S units with short contacts to both sulfur atoms and to three out of six gold atoms. The coordination sphere of the silver atom is complemented by a tetrahydrofuran molecule. In di(tri)chlorom ethane solutions there is rapid site exchange of the silver coordination as shown by virtual equivalence of the phosphine ligands on the NMR time scale at ambient temperature.