Volume 48, Issue 11

The reactions of indium trimethyl with the substituted pyrroles HNC 4 H 2 Me 2 -2,5 and HNC 4 Me 4 -2,3,4,5 (Me = CH 3 ) yield the solid, high melting dimethylindium azolides Me 2 In—NC 4 H 2 Me 2 -2,5 and Me 2 In—NC 4 Me 4 , respectively. Colorless and crystalline N-methyl-2-dimethylmetal pyrrolides have been prepared from Me 2 MCl (M = Al, Ga, In) and lithiated N-methyl pyrrole. All compounds were investigated by MS, NMR ( 1 H and 13 C), and vibrational spectra (IR and Raman). The X-ray structure determinations of Me 2 Ga—C 4 H 3 NMe and Me 2 InNC 4 Me 4 show the triclinic space group P T in both cases, with two formula units per cell forming “π-dimers” via short intermolecular M · · · C contacts of 248.1 (Ga) and 257.5 (In) pm.

The borio nitrile ylides Li[Ph 3 B—C =N—CH—R] (R = CO 2 Et, Tos) react with various dipolarophiles regio- and site-specifically to give boron complexes of carbenoid five-membered heterocycles which have been alkylated in order to accomplish their isolation. Thus, isocyanates and isothiocyanates/trialkyloxonium salts give rise to the imidazoline-2-ylidene complexes 2-5, CS 2 /Et 3 O + to the thiazoline-2-ylidene complex 6 and acetone/Et 3 O + to the oxazoline-2-ylidene complexes 7a,b. Aryldiazonium ions are added regiospecifically in the “wrong” orientation that leads to mesoionic 1,2,4-triazolium-3-ato-triphenylborate complexes (11a— e). The spectroscopic properties of the new complexes are discussed. Of (1-phenyl-4 H- 5-carbethoxy-triazolium-3-ato)triphenylborate (11a) an X-ray structure analysis has been carried out.

From N-(2,3,4,6-tetra-O-acetyl-β-ᴅ-glucopyranosyl)-thiocarbamate esters (L 1 ) the complexes (η 5 -C 5 Me 5 )(Cl 2 )M(L 1 ) (M = Rh, Ir), , trans-(n-Bu 3 P)(Cl) 2 M(L 1 ) (M = Pd, Pt), trans-Cl 2 Pt(L 1 ) 2 , [(Ph 3 P) 2 (Cl)Pt(L 1 )] + , Cl 2 Pt(μ-L 1 )PtCl 2 and ClAuL 1 have been obtained. β-ᴅ-glucopyranosylthiourea (L 2 ) forms the complexes (η 5 -C 5 Me 5 )(Cl) 2 M(L 2 ) (M = Rh, Ir), (Cl)Me 2 NCH 2 C 6 H 4 )Pd(L 2 ), (Et 3 P)Cl 2 Pd(L 2 ) and Cl 2 M(L 2 ) 2 (M = Pd, Pt).

Dinuclear complexes [(PR 3 ) 2 Cu(μ: η 4 -bpym)Cu(PR 3 )2](BF 4 ) 2 with the bis-chelating bridging ligand 2,2′-bipyrimidine (bpym) and various monodentate and bidentate phosphanes were synthesized via a four component “self assembly” reaction. The reversible electrochemical reduction to monocationic radical complexes was studied by cyclic voltammetry and electron spin resonance (ESR). Highly resolved ESR spectra revealed the presence of the bpym anion radical ligand via resolved hyperfine coupling with 1 H, 14 N, 31 P, 63 Cu and 65 Cu nuclei. The variation of phosphane ligands was accompanied by significant changes of electrochemical potentials which were rationalized considering electronic and structural effects. The configurational flexibility of Cu(I) in this environment is evident from the X-ray crystal structure analysis of [(PPh 3 ) 2 Cu(μ: η 4 -bpym)Cu(PPh 3 ) 2 ](BF 4 ) 2 - H 2 O• CH 3 OH for which the coordination at the metal can be described as 3 + 1 (NN′P + P′), qualitatively similar to the (NN′S + S′) arrangement around the type 1 Cu centers of “blue” copper proteins. Intramolecular cooperative π donor/π acceptor/π donor “sandwich” interactions provide parts of the driving force for this highly distorted coordination geometry which illustrates the proclivity of Cu(I) towards such an “entatic state” arrangement.

Cationic η 2 -thiocarbene complexes of molybdenum and tungsten [Cp(CO)PMe 3 [BF 4 ] (R = Me, Ph, Tol) add N 3 COOMe to the electron rich metal carbon double bond to yield the corresponding bicyclic system. The products have been characterized by 1 H, 13 C, 31 P NMR, IR and mass spectra. The crystal structure of 4b has been determined: space group P2 1 /n with a = 1749.9(7), b = 827.9(1), c = 1846.8(7) pm and Z = 4.

The photo-induced decarbonylation of Cp*Cr(CO) 2 NO in acetonitrile solution in the presence of excess sulfur leads to the cyclo-pentasulfido complex Cp*Cr(NO)(S 5 ) (1 a), while in the case of limited sulfur supply the binuclear bis(µ-disulfido) complex Cp* 2 Cr 2 (NO) 2 (µ-S 2 ) 2 (4a) is formed preferentially. The corresponding reaction with elemental selenium produces Cp* 2 Cr 2 (NO) 2 (µ-Se 2 ) 2 (4b), irrespective of the available amount of selenium. Photodecarbonylation of Cp*Mo(CO) 2 NO gives only the binuclear derivates Cp* 2 Mo 2 (NO) 2 (µ-E 2 ) (E = S (5a), Se (5b)) which are also obtained by treating Cp*Mo(NO)I 2 with H 2 S or H 2 Se, respectively. Nitrosyl loss predominates if the tungsten complex Cp*W(NO)I 2 is reacted with H 2 S; in an argon atmosphere the products are Cp*W(S)(S 2 )(I) (7a) and Cp* 2 W 2 (S) 2 (µ-S) 2 (8a), while in air some Cp*W(NO)(S 5 ) (3a) and the oxo compounds Cp*W(O)(S 2 )I (7c), Cp* 2 W 2 (O) 2 (µ-S) 2 (8c) and Cp* 2 W 2 (S)(O)(µ-S) 2 (8d) are formed. The analogous reaction with H 2 Se leads to Cp*W(NO)(Se 5 ) (3b), Cp* 2 W 2 (O) 2 (µ-Se) 2 (9c) and Cp* 2 W 2 (Se)(O)(µ-Se) 2 (9d), respectively. The binuclear tungsten complexes 8a,c,d and 9c,d contain a central W(µ-E) 2 W framework (E = S or Se) which is unaffected by air, while terminal sulfido and selenido ligands are quantitatively converted into the corresponding terminal oxo ligands in the presence of air in CH 2 C1 2 or THF solution. With the preparation of Cp* 2 W 2 (O) 2 (µ-E) 2 (E = S (8c) and Se (9c)), the series of dioxo complexes containing a pair of monochalcogen bridges (E = O, S, Se, Te) has become complete. The new complexes have been characterized by their IR (v(NO)), 1 H and 13 C NMR (Cp*) spectra as well as by electron-impact mass spectrometry. According to the X-ray structure analyses, the binuclear compounds Cp* 2 Cr 2 (NO) 2 (µ-S 2 ) 2 (4a) and Cp* 2 Mo 2 (NO) 2 (µ-Se 2 ) 2 (5b) contain two 14-electron [Cp*M(NO) 2 ] fragments which are connected by a pair of dichalcogen (η 1 ,η 2 -E 2 ) bridging ligands (M = Cr or Mo, E = S or Se). The central M 2 E 2 four-membered ring is not planar, and the binuclear molecules are chiral.

The boranato(hydrido) ruthenium(II) complex mer-[RuH(η 2 -H 2 BH 2 )(PMe 3 ) 3 ] (4) is prepared from trans-[RuCl 2 (PMe 3 )4], NaBH 4 and methanol. Compound 4 reacts with CO/NEt 3 , PMe 3 , HON=CHCH 3 and CH 3 OH/H 2 by elimination of BH 3 to give the octahedral complexes cis/mer-[RuH 2 (CO)(PMe 3 ) 3 ] (5), cis-[RuH 2 (PMe 3 ) 4 ] (2), mer-[RuH(η 2 -ON=CHCH 3 )(PMe 3 ) 3 ] (6) and cis/mer-[RuH 2 (η 2 -H 2 )(PMe 3 ) 3 ] (7), respectively. The reaction of 4 with alkynes HC≡CR (R = H, Me, Ph, tBu) and RC≡CCO 2 Me (R = Me, CO 2 Me) leads to the formation of the insertion products mer-[Ru(E–CH=CHR)(η 2 -H 2 BH 2 )(PMe 3 ) 3 ] (9, 10a, 11,12), mer-[Ru(CMe=CH 2 )(η/ 2 -H 2 BH 2 )(PMe 3 ) 3 ] (10b), mer-[Ru(C(CO 2 Me)=CHC(OMe)=O)(η 1 -HBH 3 )(PMe 3 ) 3 ] (14) and mer-[Ru(CMe=CHCO 2 Me)(η 2 -H 2 BH 2 )(PMe 3 ) 3 ] (15). From 4 and HC≡CCO 2 Me, the alkynyl ruthenium(II) compound mer-[Ru(C≡CCO 2 Me)(η 2 -H 2 BH 2 )(PMe 3 ) 3 ] (13) is obtained. The alkenyl complex 11 (R = Ph) reacts with phenylacetylene in the molar ratio 1:1 to give mer-[Ru(C≡CPh)(η 2 -H 2 BH 2 )(PMe 3 ) 3 ] (16) whereas with excess PhC≡CH the bis(alkynyl) compound trans-[Ru(C≡CPh) 2 (PMe 3 ) 4 ] (17) is formed. Treatment of 11 with 2 equivalents of PMe 3 affords cis-[RuH(E–CH=CHPh)(PMe 3 ) 4 ] (20) which reacts with CHCl 3 to yield an isomeric mixture of cis/trans-[RuCl(E–CH = CHPh)(PMe 3 ) 4 ] (22a, b). Attempts to prepare the vinylidene ruthenium(O) complex [Ru(=C=CHPh)(PMe 3 ) 4 ] by HCl elimination from 22a failed.

Reactions of 2,3-dihydro-1,3-diboroles 6a–h with (C 3 H 5 ) 2 Νi lead to µ,η 5 -2,3-dihydro-1,3-diborolylnickel triple-decker complexes 7a –h. By slow heating these oily, diamagnetic complexes in a rotating flask polycondensation with formation of black 8a–h as well as of bis(allyl)nickel and hexadiene occurs. The latter can be removed under reduced pressure. The constitution of the polymeric material follows from EXAFS studies. The Ni–Ni distance is 3,35 A, the ring atom Ni bonds are in the range of 2,13 to 2,15 A. Thermogravimetric measurements between 200 and 400°C show a mass loss of 20-40%, depending of the alkyl substituents of the heterocycle. In dynamic difference calorimetry an endothermic process occurs near 420°C. The powder conductivity of the amorphous, air-sensitive material is in the range of 10 -2 S • cm -1 . Doping with iodine or oxygen causes a decrease in the conductivity of these semi-conductors.

The electronic spectra of bromo complexes of main group metal ions with an s 2 electronic configuration (SnBr 3 - , PbBr 3 - , PbBr 4 2- , SbBr 4 - , SbBr 6 3- , BiBr 4 - , BiBr 6 3- ) in acetonitrile show long-wavelength absorption bands which are assigned to metal-centered sp transitions. Compared to the corresponding chloro complexes the sp bands of the bromo complexes appear at longer wavelength due to sp/LMCT mixing (LMCT = ligand-to-metal charge transfer). As a result of this mixing the luminescence which originates from low-energy sp excited states is much weaker than that of the chloro complexes. Moreover, some of the bromo complexes (e.g. BiBr 4 -) undergo a photochemical redox decomposition induced by LMCT excitation.

Concepts for linking ferrocene derivatives with conjugated squarate and propiolate based spacer systems have been investigated. Coupling of 3,4-dichlorocyclobut-3-ene-1,2-dione (squaric acid dichloride) with cuproferrocene • dimethylsulfide resulted in 3-chloro-4-ferrocenylcyclobut-3-ene-1,2-dione (ferrocenylsemisquaric acid chloride) and 3,4-diferrocenylcyclobut-3-ene-1,2-dione. Ferrocenylsemisquaric acid chloride was further treated with ethynylferrocene and 4-ethynyl-4-(ferrocenylethynyl)tolan, respectively, to form the corresponding mixed squaric diketones, which required Zn/Pd mediated coupling conditions for sufficient conversion. The symmetrically substituted derivative of ferrocenylacetylene was prepared by the same method. Cupration and subsequent coupling of dilithioferrocene with one equivalent of iodopropiolic acid methyl ester yielded 1′-iodo- 1 -ferrocenylpropiolic acid methyl ester, and with two equivalents 1,16-bis(methoxycarbonylethynyl)biferrocene. Nucleophilic addition of secondary amines to ferrocenylpropiolic acid ethyl ester gave aminoacrylates as intermediates, which rapidly converted to ketoesters during workup. Only in the case of morpholine the corresponding adduct (ferrocenylmorpholino acrylate) could be isolated. 1,3-Diferrocenylprop-2-ene-1-one has been obtained in a Bénary reaction of lithioferrocene with 3-diethylaminoethyl acrylate in quantitative yield. In order to provide alternative syntheses of already known compounds the substitution behavior of different metallated ferrocene intermediates has also been evaluated by reaction with other acid halides (oxalyl chloride, thiophosgene, ethyl chloroformate). All new compounds, 3-chloro-4-ferrocenylcyclobut-3-ene-1,2-dione (1); 3,4-diferrocenylcyclobut-3-ene-1,2-dione (2); 3,4-diferrocenylethynylcyclobut-3-ene-1,2-dione (3); 3-ferrocenyl-4-ferrocenylethynylcyclobut-3-ene-1,2-dione (4); 3-ferrocenyl-4-ferrocenylethynylphenylethynylphenylethynylcyclobut-3-ene-1,2-dione (5); 3-(N-morpholino)-3-ferrocenylethyl acrylate (6); 3-ferrocenyl-3-ketoethyl propanoate (7); iodoferrocenylpropargylic acid methyl ester (8); 1,16-bis(methoxycarbonylethynyl)biferrocene (9) and trans-1,3-diferrocenylprop-2-ene-1-one [105 404-21-5], have been characterized by IR, MS and NMR and in several cases by UV/VIS and DSC.

Fully heteroelement substituted carbanions, i.e. phosphinomethanides of the type [(Me 2 P)C(X)(Y)]- (X, Y = PMe 2 , SiMe 3 ) react with organoelement chlorides (X—Cl, Y—Cl) to give tetra-heteroelement substituted methanes and/or isomeric phosphorus ylides with an element-phosphorus bond. The latter in some cases are rigid, in others fluctional and in certain cases may rearrange to the isomeric methane derivatives. The results are explained by the involvement of pentacoordinated silicon derivatives, which only occur as transient species, however. A compound with pentacoordinated silicon in the ground state is obtained from Li[(Me 2 P) 2 C(SiMe 3 )] and RSiCl 3 (R = Ph), but it slowly rearranges to the isomeric methane derivate (Me 2 P) 2 (Me 3 Si)(Cl 2 PhSi)C within four weeks at + 20°C. Within six weeks, further rearrangement occurs to give the ylide Me 2 P —PMe 2 =C(SiMe 3 )(SiPhCl 2 ). For R = t Bu, only the analogous rearranged ylide is found. Its molecular structure was confirmed by an X-ray structure determination.

The organometal phosphine complexes ML 3 (L = [o-(Ph 2 PCH 2 )C 6 H 4 ] - ; M = Al 3+ , Ga 3+ , In 3a+ ) are obtained from MC1 3 and the lithiated ligand in diethyl ether. Tl[o-(Ph 2 PCH 2 )C 6 H4] 3 is prepared from T1C1 by a disproportionation reaction. M 1 species could not be detected with L as ligand. Al[o-(Ph 2 PCH 2 )C 6 H4] 3 is the first triorganoaluminum bis(phosphine) adduct where C 3 P 2 pentacoordination at aluminum has been definitely proven for both the solution (δ( 27 Al) =131 ppm, w 1/2 = 12 kHz) and the solid state (d(Al–P) = 2.676(3)/2.782(2) A). The trigonal-bipyramidal coordination geometry (C 3 P 2 ) at Al is achieved by two of the anionic phosphines acting as chelating ligands, spanning equatorial (C atoms) and axial sites (P atoms), while the third phosphine is only carbon-bonded. Like AlL 3 , the heavier congeners ML 3 (M = Ga, In, Tl) are stereochemically nonrigid molecules in solution. Surprisingly, in the solid state only InL 3 resembles the aluminum complex (C 3 P 2 penta-coordination) while GaL 3 and T1L 3 contain four-coordinate metal centers (C 3 P). This may be rationalized by the noticeably less polar Ga–P bonds as compared to Al–P and In–P bonds, while in T1L 3 the span of the ligand is not sufficient to allow for chelating coordination at a five- (or six-)coordinate Tl center.

7 Li solid state NMR spectroscopy of Ν,Ν,N′,N′-tetramethylethylenediamine-trimethylsilylcyclopentadienyllithium yielded an unusually large quadrupole coupling constant, that decreases with increasing temperature (188-165 kHz in the temperature range 210-335 K). Structural features, known from the X-ray analysis, are compared with the NMR results.

The reaction of [(cod)IrCl] 2 (cod = η 4 -cycloocta-1,5-diene) with n-C 3 H 7 Li gives non-isola-ble (cod)IrH species by β-elimination of (cod)Ir-n-C 3 H 7 intermediates; the stable final products of further reactions with RC = CR highly depend on the nature of the substituents R. With R = Me the 6-endo-H-hexamethylcyclohexadienyl complex 1 is obtained together with the iridacyclopentadienyl compound 2 and known {[(cod)IrH] 4 C 3 H 4 ) (3). In case of R = Et steric effects cause transfer of the hydridic hydrogen to the cod ligand, and the hexaethylbenzene species 4 is isolated which was characterized by crystal structure analysis. The reaction system with tolane again yields a 6-endo-H-cyclohexadienyl complex (5). In all cases free substituted benzenes are formed as cyclotrimerization products of the alkynes.

Pyrrole has been incorporated into the channel-like cavities of polymers of the type: [(Me 3 Sn) 3 Fe III x Co III 1-x (CN) 6 ] with 0 < x ≤ 1. The resulting black composites involving polypyrrole (Ppy) and Fe(II) display electrical conductivities σ between ca. 10 -5 and 10 -1 S · cm -1 . Usually, composites prepared in the presence of small amounts of H 2 O exceed those in conductivity resulting under strictly anhydrous conditions owing to notably lower thermal activation energies (0.04 to 0.08 eV). An oxidative polymerization mechanism differing from that assumed for “classical” modes of Ppy generation is likely, since the N(pyrrole)/Fe(II) ratio turns always out to be ≥ 1. Exposure of a composite with x = 1 to an atmosphere of NH 3 causes a decrease of σ from 1.5 · .10 -1 to 2.7 · .10 -6 S · cm -1 ; this NH 3 uptake, and the concomitant change of σ, appear to be partially reversible. 1-Methylpyrrole, 2,5-dimethylpyrrole and aniline are oxidized by, and incorporated into, the organotin polymer, too, but the resulting σ-values do not exceed ∼10 -9 S · cm -1 .

A concentrated solution of CsCI, 18-crown-6, and tol-N=N—N(H)—N=N-tol in aqueous ammonia affords Cs 2 (18-crown-6)(tolN 5 tol) 2 , which crystallizes in the triclinic space group P1̄ with a = 852.6(2), b = 1139.4(3), c = 1373.9(4) pm, α = 104.17(3), ß = 95.94(2), γ = 110.74(2)°, Ζ = 1. In the structure centrosymmetrical [Cs 2 (18-crown-6)] 2+ moieties are packed with pairs of 1,5-bis(tolyl)pentaazadienide anions to built up columns along [100]. The N—N distances N1 —N2 = 128 pm and N4—N5 = 129 pm in the pentaazadienide anions indicate localized double bonds, while the distances N2—N3 and N3—N4 of 134 pm can be assigned to single bonds. A mixture of Cr(NH 3 ) 6 3+ and tolNNN(H)NNtol in concentrated aqueous ammonia yields triclinic (NH 4 )[Cr(NH 3 ) 6 (H 2 O) 4 ](tolN 5 tol) 4 crystallizing in the space group P l with the lattice parameters a = 1561.1(1), b = 1619.3(3), c = 1703.3(2) pm, α = 107.03(1), β = 116.81(1), γ = 101.75(1)°, Ζ = 2. The structure contains tolN 5 tol- anions, NH 4 + cations and [Cr(NH 3 ) 6 (H 2 O) 4 ] 3+ complexes in which four triangular faces of the Cr(NH 3 ) 6 octahedron are capped by water molecules which are linked via hydrogen bonds. Within the pentaazadienide anions which are connected with the [Cr(NH 3 ) 6 (H 2 O) 4 ] 3+ complexes also via hydrogen bonds an indication for localized double bonds Ν1=Ν2 and N4=N 5 has been obtained.

Cocondensation of 2,3,5,6-tetramethyl-pyrazine with vanadium atoms affords [2,3,5,6-(CH 3 ) 4 -η 6 -1,4-C4N 2 ] 2 V (6) which has been studied by X-ray crystallography, EPR-spectro-scopy and cyclic voltammetry. As shown by unequal metal ring-atom distances (V—C = 219.6, V—N = 210.9 pm) the ligand in 6 is folded along the N—N axis (dihedral angle 13.6°). The conformation adopted by the cyclic ligands in the crystal has a torsional angle of 44.2° which comes close to the angle of 45° expected for maximum back-bonding, the filled vanadium orbitals 3 d x 2 -γ 2 and 3 d xy interacting separately with unoccupied b 3u (π*) orbitals of the individual pyrazine rings. The hyperfine coupling constant a( 51 V) = 4.45 mT attests to comparatively small spin density at the metal nucleus. It is proposed, that substantial transfer of spin density is effected by V 3d z 2 →a g (σ n+ ) overlap, the latter function representing the in-phase combination of the nitrogen “lone pair” orbitals. Contrary to bis(η 6 -phosphinine)vanadium 8, for the pyrazine complex 6 only the anion 6⁻ is formed reversibly in cyclovoltammetry, oxidation to 6 + being irreversible. However, in common with 8, the redox potentials for 6 show pronounced anodic shifts. Attempts towards η 6 -coordination of 2,4,6-trimethyl-1,3,5-triazine failed. Apparently, the 1:1 ratio of CH 3 /N is insufficient to furnish the triazine ring with the appropriate combination of π-donor and δ-acceptor properties essential for synergetic bond formation.

Chiral polyepichlorohydrin was obtained as a crystalline, optically active powder by coordinative polymerization of S(+)-epichlorohydrin. Subsequent reaction with lithium diphenylphosphide in THF resulted in substitution of about 90% of the chlorine atoms by the P(C 6 H 5 ) 2 group to give an insoluble polymer, which was characterized by elemental analysis, 31 P CP MAS NMR, and IR spectroscopy. On addition of solutions of bis(1.5-cyclooctadiene)-rhodium tetrafluoroborate to the polymer “heterogenization” of the complex occurred. The reason for the as yet short operational life time during the hydrogenation of α-acetamido cinnamic acid is the leaching of the metal complex moiety. The rhodium atom is coordinated to only one phosphorus atom of the polymer in the side group and rather weakly to one oxygen atom of the polymer chain.

N-Protected 3-bromo-2,5-dimethylpyrrols, accessible from low-temperature bromination using NBS or BTMABT, have been modified into pentacarbonyl[methoxy(3-pyrrolyl-car-bene)] complexes via sequential halogen/lithium exchange, addition to hexacarbonyl chromium and alkylation. These compounds react with alkynes and amines, resp., to give aminolysis and annulation products. The carbene annulation methodology has been exploited in the synthesis of a persubstituted isoindoloquinone.

Linking three nucleobases by two metal ions M of linear coordination geometry leads to metal-modified base triples. With M = trans-(amine) 2 Pt II , the bases are forced into an essentially coplanar fashion with interbase H bonding maintained in many cases. The model nucleobase triples described here are of general composition {[trans-(amine) 2 PtB] 2 (9-MeA)} n+ with two nucleobases B bound via Pt to N1 and N7 of 9-methyladenine (9-MeA). The X-ray structure of a precursor, ([trans-(CH 3 H 2 ) 2 PtCl] 2 (9-MeA)}(ClO 4 ) 2 , is briefly described. The generation of metalated, cyclic nucleobase quartets and their expected structures are discussed and ways towards larger macrocyclic metal compounds are pointed out.

Pentacarbonyl(thietane)tungsten complexes react with thiocyanate, [SCN] - , and SiO 2 /H 2 O by insertion of the CN group into a S—C bond of the four-membered heterocycle, 1,3-migration of the pentacarbonyltungsten fragment and protonation of the nitrogen atom to give tungsten-coordinated thiazinthione complexes. Analogously, the reactions of a thietane tungsten complex with [SeCN] - and SiO 2 /H 2 O affords a thiazinselone complex. A selenazinthione complex is obtained from a selenetane complex and [SCN] - (+ SiO 2 /H 2 O). The insertions are regiospecific and stereoselective. The structure of the trans-isomer of a pentacarbonyl-(thiazinthione) complex has been established by X-ray structure analysis.

The title compound, an octamer C 8 S 8 of carbon sulfide, is obtained by reacting diethyl dihydroxythieno[2,3-b]thiophenedicarboxylate with the Lawesson reagent in the presence of sulfur. The crystal structure shows three-dimensional sulfur-sulfur interactions.

The reaction of [C 6 H 4 CH 2 N(CH 3 ) 2 ] 2 SiCl 2 (1) with hydrogen chloride gives the singly protonated adduct 2. Its solid state structure has been determined by single crystal X-ray diffraction. Centrosymmetric 2 is orthorhombic, space group Pbca, a = 1694.9(2), b = 1161.7(2), c = 2501.7(3) pm; Z = 8. Controlled hydrolysis of 1 leads to the 1,3-siloxanediol 4, probably via the precursors 3a-3c which could not be isolated. The hydrogen chloride formed during the hydrolysis protonates two of the dimethylamino groups, while the other two dimethylamino functions form hydrogen bonds to the silanol groups. Centrosymmetric 4: monoclinic, space group P2 1 /c, a = 980.3(1), b = 933.9(1), c = 2177.5(2) pm, β = 99.94(1)°; Ζ = 4. If the hydrolysis is carried out in the presence of lithium naphthalenide, the metalated compound {[C 6 H 4 CH 2 N(CH 3 ) 2 ] 2 Si(OLi)OH} 4 •2 LiCl•2CHCl 3 (5) is obtained. The solid state structure of 5 exhibits two cube-like subunits which are held together by nitrogen and oxygen lithium contacts, hydrogen bonds between silanol groups and nitrogen atoms, and which are linked by the four silicon centres. Tetrameric 5: monoclinic, space group C2/C or C c ; a = 1523.6(2), b = 2440.2(1), c = 2534.8(2) pm, β = 93.83(3)°; Ζ = 8. These results show that the intramolecular donor capabilities of the dimethylaminobenzyl ligand at silicon can stabilize 1,3-siloxanediol and SiOLi substructures. Compounds like 1 serve as model compounds for the controlled formation of precursors for silicone synthesis.

Photochemical reactions of hexacarbonyl-μ-η 5:5 -fulvalene-dimolybdenum (1) with 1,3-butadiene (a), 2-methyl-1,3-butadiene (b), E-1,3-pentadiene (c), 2,3-dimethyl-1,3-butadiene (d), and E-3-methyl-1,3-pentadiene (e) yield the corresponding tetracarbonyl-η 4 -s-cisdiene-μ-η 5:5 -fulvalene-dimolybdenum complexes 3a-3e. In addition to 3a also η 4 -s-trans1,3-butadiene-tetracarbonyl-μ-η 5:5 -fulvalene-dimolybdenum (4) is formed. Similarily hexacarbonyl-μ-η 5:5 -fulvalene-ditungsten (2) forms with a and b tetracarbonyl-η 4 -s-cis-diene-μ-η 5:5 -fulvalene-ditungsten (5a, 5b) and bis(η 4 -s-cis-1,3-butadiene)-dicarbonyl-μ-η 5:5 -fulvalene-ditungsten (6). The complexes 3b —3e and also 5b are obtained as mixtures of the o- and u-isomers. Only for tetracarbonyl-η 4 -cis-2,3-dimethyl-1,3-butadiene-μ-η 5:5 -fulvalene-dimolybdenum (3d) an interconversion of the o- and u-isomers is observed with an energy barrier of ΔG 183 # = 73.9 kJ/mol. Both isomers of 3d show hindered inversions with energy barriers of ΔG # 313 = 66.1 kJ/mol (u-3d) and ΔG 183 # = 36.4 kJ/mol (o-3d). For o-3d the crystal and molecular structure was determined by an X-ray diffraction analysis. Hexacarbonylµ — η 5:5 -bis(cyclopentadiendiyl)methane-dimolybdenum (7), hexacarbonyl-μ-η 5:5 -bis(cyclopentadiendiyl)ethane-dimolybdenum and hexacarbonyl-μ-η 5:5 -bis(cyclopentadiendiyl)propane-dimolybdenum do not react with conjugated dienes. Upon UV irradiation 7 looses CO and forms by dimerization octacarbonyl-bis(μ-η 5:5 -(cyclopentadiendiyl-cyclopentadien-triyl)methane)-dihydrido-tetramolybdenum (8).

The symmetrically hydrocarbon-bridged complexes (OC) 5 M-(CH 2 ) n+1 -X-(CH 2 ) n+l -M(CO) 5 [n = 1, X = 1,4-C 6 H 4 , M = Mn (2a), M = Re (3a); n = 2, X = 1,4-C 6 H 4 , M = Mn (2b), M = Re (3b); n = 1, X = 1,3-C 6 H 4 , M = Mn (5a), M = Re (6a); n = 2, X = 1,3-C 6 H 4 , M = Mn (5b), M = Re (6b); n = 1, X = 1,2-C 6 H 4 , M = Mn (8a), M = Re (9a); n = 2, X = 1,2-C 6 H 4 , M = Mn (8b), M = Re (9b)] are obtained by the reaction of the bistriflates X[(CH 2 )„-CH 2 -OSO 2 CF 3 ] 2 [X = 1,4-C 6 H 4 , n = 1 (la), n = 2 (lb); X = 1,3-C 6 H 4 , n = 1 (4a), n = 2 (4b); X = 1,2-C 6 H 4 , n = 1 (7a), n = 2 (7b)] with the carbonyl metalates [M(CO) 5 ]- (M = Mn, Re) in THF and dimethyl ether, respectively. According to an X-ray structural analysis 8a crystallizes in the triclinic space group P1̅ with Ζ = 2. Depending on the solvent, the reaction of 7 a with [Mn(CO)5]~ affords also the cyclic carbene complex 10a. The behavior of the manganese compounds toward CO has been investigated exemplarily in the case of 8a and leads to the diacyl complex 1,2-C 6 H 4 [CH 2 CH 2 C(O)Mn(CO) 5 ] 2 (11). Upon reaction with Na 2 CO 3 /CH 3 OH 11 is converted to give the corresponding diester 1,2-C 6 H 4 [CH 2 CH 2 C(O)OCH 3 ] 2 (12).

The molecular complex PdCl 2 [P(OSiMe 3 ) 3 ] 2 was obtained both as cis- (la) and trans- (lb) isomer from palladium(II) chloride with the equivalent amount of tris(trimethylsilyl)phosphite in a THF suspension at room temperature. With excess P(OSiMe 3 ) 3 the complex {PdCI[PO(OSiMe 3 ) 2 ][P(OSiMe 3 ) 3 ] 2 } (2) is formed with elimination of trimethylchlorosilane. By partial hydrolysis the anionic binuclear palladium complex (NMe 2 H 2 ) 2 {Pd 2 Cl 4 [P 4 O 5 (OSiMe 3 ) 4 ]} (3) is generated from palladium(II) chloride and excess P(OSiMe 3 ) 3 in THF in the presence of dimethylamine. All complexes form colourless, moisture-sensitive crystals, which were characterized by X-ray structure determinations. 1a: Space group C2/c, Z = 4,2973 observed unique reflections, R = 0.044. Lattice dimensions at —80°C: a =1052.9(2), b =1675.3(5), c = 2240.1(7) pm, β = 99.88(2)°. The compound has a molecular structure with cis-arrangement of the P(OSiMe 3 ) 3 groups with Pd—P bond lengths of 222.9 pm. 1b: Space group P1̄, Z = 1, 3796 observed unique reflections, R = 0.053. Lattice dimensions at-70°C: a = 959.5(2), b = 998.3(2), c =1162.6(2) pm, α=86.99(3)°, β = 81.63(3)°, γ = 62.91(3)°. The compound has a molecular structure with trans-arrangement of the P(OSiMe 3 ) 3 groups with Pd—P bond lengths of 230.4 pm. 2: Space group P2 1 2 1 2 1 , Z = 4,4444 observed unique reflections, R = 0.055. Lattice dimensions at —70°C: a =1050.0(2), b = 2090.5(3), c = 2357.8(6) pm. The complex has a molecular structure with trans-arrangement of the P(OSiMe 3 ) 3 groups with Pd — P bond lengths of 233.6 and 232.1 pm. The Pd—P bond length of the [PO(OSiMe 3 ) 2 ]- ligand is 224.8 pm. 3: Space group P1̄, Z = 2,4762 observed unique reflections, R = 0.071. Lattice dimensions at —80°C: a = 1169.3(6), b = 1299.6(6), c = 1641.7(12) pm, α = 69.19(4)°, β = 87.37(5)°, γ = 80.01(4)°. In the dimeric anion {Pd 2 Cl 4 [P 4 O 5 (OSiMe 3 ) 4 ]} 2 - the two cis-PdCl 2 units are bridged by the four phosphorus atoms of the [P 4 O 5 (OSiMe 3 3 ) 4 ] 2- ligand with average Pd— P bond lengths of 221.5 pm.

The reaction of tris(chlorodimethylsilyl)methane HC(SiMe 2 Cl) 3 (1) with dry ammonia in hexane leads to the tris(disilazane) molecule HC(Me 2 SiNHSiMe 2 ) 3 CH (3) in satisfactory yields. According to its 1 H, 13 C, and 29 Si NMR spectra this bicyclic cage-molecule exhibits virtual (time-averaged) D 3h symmetry. In the crystal (rhombohedral, space group R3) the manxane-type structure has a crystallographic three-fold axis, but the structure obeys only D 3d symmetry to a good approximation, owing to a disrotatory twist of the two Si 3 triangles against each other. The crystals of compound 3 are isomorphous with those of the analogous tris(disiloxane) 2.

In MeOH/THF solution, Fe(II) ions and the tetradentate thioether-thiolate ′S 4 ′ 2- ([1,2-Bis(2-mercaptophenylthio)ethane(2-)]) slowly form the tetrameric [Fe(′S 4 ′)] 4 1. The crystal structure of 1 · THF • 2 MeOH was determined by X-ray structure analysis. Chiral 1 crystallizes as a pair of enantiomers each of which consist of four homochiral [Fe(′S 4 ′)] fragments bridged via μ 2 - and µ 3 -S(thiolato) donors; stereochemical aspects of the enantiospecific tetramerization of [Fe(′S 4 ′)] fragments are discussed. In strong polar solvents such as dimethylformamide, dissociation of [Fe(′S 4 ′)] 4 into [Fe(′S 4 ′)] 2 fragments is indicated by the formation of [Fe(CO)(′S 4 ′)] 2 upon reaction with CO.

Tripod ligands CH 3 C(CH 2 PR 2 )(CH 2 PR′ 2 )(CH 2 PR″ 2 ), 6(a—e), with three different donor groups are obtained from CH 3 C(CH 2 Cl)(CH 2 Br)(CH 2 OSO 2 CF 3 ), 3, by successive replacement of the three different leaving groups. 3 itself is easily accessible from CH 3 C(CH 2 OH) 3 in a few simple steps. The general applicability of this strategy is demonstrated by the preparation of five different ligands 6(a—e). For one specific example (6 a) the coordination behaviour is examplified by the synthesis of its Mo(CO) 3 derivative: CH 3 C(CH 2 P(Ph) 2 )(CH 2 P(3-Tol) 2 )(CH 2 P(4-Tol) 2 )• Mo(CO) 3 (7). All compounds, including their intermediates CH 3 C(CH 2 Cl)(CH 2 Br)(CH 2 PR 2 ), 4(a—c), and CH 3 C(CH 2 PR 2 )(CH 2 PR ′2 )(CH 2 C1), 5(a— c), have been obtained in an analytically pure state and fully characterized by their spectroscopic data. The methods developed lend themselves to the almost deliberate shaping of tripod metal templates.