Volume 49, Issue 12

Thin film CuGaSe 2 solar cells were prepared from the elements using electrochemical deposition of Ga from an alkaline bath. Sputtered copper layers with a small gallium content (Cu 0.86 Ga 0.14 ) on Mo/soda-lime glass served as a substrate. Subsequent reactive annealing of the thus created Cu/Ga precursor layer with selenium vapour yielded CuGaSe 2 . Chalcopyrite phase formation was studied with XRD, micro-Raman spectroscopy, SEM-EDX and Auger electron spectroscopy. It was concluded from these measurements that the binary phases Cu 2 Se and Ga 2 Se 3 are generated prior to the formation of the favoured CuGaSe 2 phase. Complete solar cell structures were fabricated by chemical bath deposition of CdS and chemical vapour deposition of ZnO onto the CuGaSe 2 absorber layer. Promising 3.2% efficiency with U oc = 542 mV, I sc = 12.0 mA/cm 2 and FF = 0.49 were achieved, proving that electrochemical gallium deposition from an aqueous bath can contribute to the efficient thin film processing of chalcopyrite solar cells.

Facile large-scale synthesis of the benzyl-dibromo-phosphines RPBr 2 (R = C 6 H 5 CH 2 , 3,5-Me 2 C 6 H 3 CH 2 , 2-BrC 6 H 4 CH 2 ) is accomplished by the photochemical reaction of toluene, mesitylene, and 2-bromotoluene, respectively, with PBr 3 in the absence of solvent. If the reactions are carried out up to 50% completion the amount of by-products formed is remark­ ably low, rarely exceeding 10% of the total amount of products formed. The selectivity of the photoreaction may be improved up to 98% if it is carried out in a modified Soxhlet apparatus which allows the predominant irradiation of only the starting materials. The appar­ ent limitations imposed by the low turnovers required to achieve good product selectivity are by far outweighed by the large amounts of desired products formed in a short period of time and by the easy recovery of unreacted starting material by distillation. Thus in the case of 2-BrC 6 H 4 CH 2 PBr 2 , in a typical run 94 g (261 mmol) of product may be isolated after 2.5 h of irradiation of 970 mmol of 2-BrC 6 H 5 CH 3 and 1.39 mol of PBr 3 . In this case the turnover is 32%. the isolated yield 27%, and the by-product 2-methylphenyl-dibromo-phosphine only amounts to less than 2%. The benzyl-dibromo-phosphines are easily methylated with two equivalents of MeMgCl to give the respective benzyl-dimethyl-phosphines in 79-93% yield. Tertiary benzylphosphines MePRR′ (R = 2-BrC 6 H 4 CH 2 , R′ = Me 3 SiCH 2 ; R = R′ = 2-BrC 6 H 4 CH 2 ) are obtained in easy one-pot syntheses by consecutive reactions of 2-BrC 6 H 4 CH 2 PBr 2 with Me 3 SiCH 2 MgCl and MeMgCl, and with 2-BrC 6 H 4 CH 2 MgBr and MeMgCl, respectively.

Bis(N,N-diethyl-N′-benzoylselenoureato)lead(II) has been prepared and characterized by single-crystal structure analysis. Pb(C 12 H 15 N 2 OSe)2 crystallizes in the non-centrosymmetric orthorhombic space group Iba2. The cell parameters are a = 13.206(3), b = 20.542(4), c = 10.089(2) A and Z = 4. R = 0.025. The direction of the polar axis was determined unambig­ uously. Pb(II) is bidentally coordinated to two N,N-diethyl-N′-benzoylselenourea molecules. The coordination polyhedron is a distorted pseudo-trigonal bi-pyramid with one equatorial position occupied by an electron lone-pair. The Pb-Se and Pb-O bond lengths are 2.876(1) and 2.444(4) Å, respectively. In the crystal lattice, each Pb atom also shows interactions with two Se atoms of a neighboring molecule. The Pb-Se distance of that interaction is 3.643 Å.

[Me 4 N] 2 [Mn(SPh)Cl 3 ] (1) was obtained by reaction of MnCl 2 ·4H 2 O with one equivalent of NaSPh from methanolic solutions in the presence of [Me 4 N]Cl. Under similar conditions the compound [Et 4 N] 2 [Mn(SPh) 3 Cl] (2) waso isolated using [Et 4 N] + cations. Crystal data: 1: a = 9.425(3), b = 11.903(3)t c -19.073(4) Å, space group P 2 1 cn, Z = 4; 2: a = 14.420(7), b = 13.834(8), c = 17.918(10) Å, β = 90.69(4)°, space group P2 1 /c, Z = 4. The structures were refined to R = 0.0839 (1) and 0.0328 (2), respectively. Besides the dianion [Mn(SPh) 3 Cl] 2- (6), crystals of 2 contain traces of [Mn(SPh) 2 Cl 2 ] 2- (7) distributed over 3.8% of the anion positions. The existence of [Mn(SPh)Cl 3 ] 2- (5), 6 and 7 under similar conditions is interpreted in terms of ligand exchange solution equilibria. Within these mononuclear anions, the central metal/sulfur/halide cores show distorted tetrahedral stereochemistries. The reaction of MnCl 2 with NaSPh (molar ratio 1:3) in hot mixtures of acetonitrile and DMF leads to [Mn 2 (SPh) 6 ] 2- (8), which can be isolated as crystalline [Ph 4 P] 2 [Mn 2 (SPh) 6 ] (3) with a = 13.383(2), b = 13.565(2), c = 20.438(4) Å, β = 106.41(1)°, space group P2 1 /c, Z = 2. The final refinement converged to R = 0.0380. 8 consists of two edge-sharing MnS 4 tetrahedra showing structural similarities with other tetrahedral complexes of the type [M 2 (SR) 6 ] 2- . According to magnetochemical studies, the manganese atoms are antiferromagnetically coupled with J=-18.6(2) cm -1 . Reaction of 3:2:1 molar ratio mixtures of NaSPh/MnBr 2 /[Et 4 N]Br in hot acetonitrile leads to [Et 4 N] 2 [Mn 4 (SPh) 6 Br 4 ] (4) which crystallizes with a = 14.109(3), b = 27.556(5), c = 16.194(4) Å, β = 95.35(2)°, space group P 2 1 /n, Z=4. The structure was refined to R = 0.0583. This compound is also available by reaction of [Et 4 N] 2 [Mn(SPh) 4 ] with MnBr 2 in a molar ratio of 3:5. The anion [Mn 4 (SPh) 6 Br 4 ] 2- (9) contains a central {Mn 4 S 6 Br 4 } core which exhibits an adamantane-like structure: A Mn 4 tetrahedron is inscribed into a S 6 octahedron with the S atoms bridging the edges of the Mn 4 tetrahedron. Terminally bonded Br atoms complete the tetrahedral coordination spheres of the manganese atoms and thus form an outer Br 4 tetrahedron. As a result, the symmetry of the central core comes close to T d . The observed distortion is attributed to intramolecular repulsions of the organic residues. Selected properties of compounds 1-4 are reported.

Chiral thiolate complexes [Cp(NO)(Ph 3 P)ReSCH 2 R] (R=Ph, 4-C 6 H 4 Cl, 4-C 6 H 4 OMe, H, Me) are obtained from [Cp(NO)(Ph 3 P)ReCH 3 ] by acid cleavage in the presence of thiol and subsequent deprotonation. Small amounts of (chloromethyl)thioether complexes [Cp(NO)(Ph 3 P)ReS(CH 2 Cl)CH 2 R]BF 4 are formed when dichloromethane is used as a sol­ vent in this reaction. Hydride abstraction using [Ph 3 C]PF 6 converts the thiolate complexes into ionic thioaldehyde complexes [Cp(NO)(Ph 3 P)Re(η 2 -S=CHR)]PF 6 . These are obtained as pure (RR,SS)-diastereomers as shown spectroscopically and by X-ray structure determination of [Cp(NO)(Ph 3 P)Re(η 2 -S=CHPh)]PF 6 . Crystals are monoclinic, space group I2/a (No. 15), a = 25.877(3), b = 18.785(2), c = 13.768(1) Å , β = 104.93(1)°, Z -8.

η 3 -Phosphinoketene complexes of tungsten Cp(CO)ClW [η 3 -P(Ph 2 )-C(R)=C=O] (R=Me, Ph) react with hydrogen chloride under protonation of the ketene oxygen atom converting the ketene into a new cyclobutenol system. The products have been characterized by 1 H, 13 C, 31 P NMR. IR and mass spectra. 1-Carbonyl-1,1-dichloro-1-(η 5 -cyclopentadienyl)-2,2-di-phenyl-3-methyl-1-wolframa-2-phospha-3-buten-4-ol crystallized in the monoclinic space group P2 1 /n with a = 9.046(2), b = 7.369(1), c = 30.266(2) Å, β = 96.63(3)° and Z = 4.

Reactions of [Cp*IrCl 2 ] 2 (Cp*=η 3 -C 5 Me 5 ) with [MgC 4 H 6 ·2 THF] n at low temperature give [Cp*Ir(η 4 -C 4 H 6 )] together with [Cp*Ir(η 3 -C 4 H 7 )R] compounds, the latter being formed via C-H activation of solvent molecules RH (RH = benzene, toluene, anisole, thiophene, furane, N-methylpyrrole, pentane, cyclohexane. THF). In the case of pyrrole, C-N -activation occurs. The ratio of syn and anti isomers of the 1-methylallyl complexes as well as the sites of C-H activation of RH were investigated by NMR spectrometry. An enantiomorphous crystal of [Cp*Ir(η 3 -C 4 H 7 )C 6 Hs] was characterized by X-ray diffraction analysis which reveals trigonal planar coordination at the Ir atom and an exo, syn conformation of the 1-methylallyl ligand. A mechanism of the reaction which involves 16-electron intermediates is discussed. The corresponding system [Cp*RhCl 2 ] 2 /butadienemagnesium/RH gives only [Cp*Rh(η 4 -C 4 H 6 )], and no C-H activation is observed.

The synthesis of triphenyltelluroniumsulfide (Ph 3 TeS) 4 is described together with a NMR-spectroscopic characterization. The structure of the title compound was determined by single crystal X-ray diffraction. Crystals of triphenyltelluroniumsulfide are triclinic (space group P1) with the cell parameters a = 1178.0(3) pm. b = 1295.8(6) pm. c = 1298.7(4) pm, α = 77.67(3)°, β = 82.18(2)°, γ = 66.00(2)° (V = 1766(1) × 10 6 pm 3 ) and Z = 2. The compound appears to form a step-like structure of two [Ph 3 TeS] 2 units and crystallizes with two molecules of CH 2 Cl 2 per unit cell.

Two routes for the preparation of sterically demanding phosphinoesters RR′P(CH 2 ) n CO 2 Me (n=1,2 or 3) and RR′P(CH 2 ) n CO 2 Et (n=1 or 2) have been developed: (1) reaction of trimethyl-silyl phosphines RR′PSiMe 3 (R=R′=/Pr. rBu) with ω-chloroalkylesters, and (2) hydrophos- phination of secondary phosphines HP(R)Ph (R = Me, Et. Pr. iPr, iBu) with unsaturated carboxylic esters. From iPr 2 PCH 2 CO 2 Me (3) and iPr 2 PCH 2 CO 2 Et (4), a variety of rhodium(I) and rhodium(III) complexes, mainly with alkyne and vinylidene ligands, have been prepared. Compound [RhCl(C 8 H 14 ) 2 ]2 (19) reacts with four equiv. of 3 to give [RhCl(iPr 2 PCH 2 CO 2 Me) 2 ] (20) which on further treatment with CO affords the carbonyl complex trans-[RhCl(CO)(iPr′>PCH 2 CO 2 Me) 2 ] (21). The related ethylene derivative trans-[RhCl(C 2 H 4 )(iPr 2 PCH 2 CO 2 Me) 2 ] (23) is obtained from [RhCl(C 2 H 4 ) 2 ] 2 (22) and 3. Compound 20 reacts with H 2 and HCl by oxidative addition to yield [RhHXCl(iPr 2 PCH 2 CO 2 Me) 2 ] (24, 25) and with RC≡CR′ to give the alkyne complexes trans-[RhCl(RC≡CR′)(iPr 2 PCH 2 CO 2 Me) 2 ] (26-28). The analogous compounds trans- RhCl(HC≡CR)(iPr 2 PCH 2 CO 2 Me) 2 ] (29, 30), equally prepared from 20 and HC≡CR, both rearrange thermally and photochemically to produce the vinylidene isomers trans-[RhCl(=C=CHR)(iPr 2 PCH 2 CO 2 Me) 2 ] (31, 32). In contrast, propyne reacts with 20 to give the allene complex trans-[RhCl(CH 2 =C=CH 2 )(iPr 2 PCH 2 CO 2 Me) 2 ] (33). The synthesis of [RhCl(iPr 2 PCH 2 CO 2 Et) 2 ] (34) and the corresponding alkyne and vinylidene adducts 35 and 36, obtained with HC≡CCO 2 Me as the substrate, is also described.

The benzo-bridged, heterocyclic compounds [E(Cl)S 2 -1,2]C 6 H 2 [4,5-S 2 E(Cl)] (E = P (1), As (2), Sb (3), Bi (4)) have been obtained as air-stable solids from the reaction of ECl 3 with 1.2.4.5-(HS) 4 C 6 H 2 in diethyl ether. 1-4 are insoluble in common solvents and have been characterized mainly by elemental analyses and their infrared and mass spectra.

2,3,5,6-Tetrakis(isopropylidene)-1,4-dimethyl-1,4-diboracyclohexane (1c) is formed in 66% yield from 3,4-bis(chloromethylboryl)-2,5-dimethyl-2,4-hexadiene (4a) and (Me 2 C=CLi) 2 . Surprisingly, 1,4-dichloro-2,3,5,6-tetrakis(isopropylidene)-1,4-diboracyclohexane (1d) is obtained in 38% yield, when tetrabutyltin and 3,4-bis(dichloroboryl)-2,5-dimethyl-2,4-hexadiene (4b) are heated. Reactions of 1,2-bis(chloromethylboryl)ethane derivatives 5a, b with (Me 2 C=CLi) 2 lead to the 2,3-bis(isopropylidene)-1,4-diboracyclohexanes 6a, b in 41 and 35% yield. The irradiation of 6a, b and 1c,d with ultraviolet light induces an antarafacial [1,5]-Hshift which leads to the formation of the diboracyclohexenes 7a, b and 8a, b, as indicated by NMR studies. On further irradiation 8a, b rearrange to form the corresponding nido-C 4 B 2 carboranes 9a, b. The constitutions of the compounds are derived from spectroscopic data and are proven by X-ray structure analyses of 1c, d, e.

6,6-Dimethylfulvene reacts with Co(C 2 H 4 )(PMe 3 ) 3 to give a diamagnetic dicobalt complex containing a novel bis (η 5 ,η 2 )-chelating hydrocarbon ligand which is a tetramer of 6,6-dimethylfulvene. C,C-coupling via radicals induces multiple chirality in the ligand and the structurally characterized stereoisomer adopts a (S,R,R,S) configuration (m eso form).

Eightfold functionalized octasilsesquioxanes (R 8 Si 8 O 12 ) are synthesized using the hydrosilylation method. Different types of groups R, consisting of an (-O-SiMe 2 (CH 2 ) 2 ) spacer unit and various terminal units (-CH 2 (C 2 Me)B 10 H 10 , - C 5 H 3 MeMn(CO) 3 , -SiMe 2 C 5 H 4 FeC 5 H 5 , -SiMe 2 Cl, -SiMeCl 2 , -Si(OEt) 3 ) have been introduced. The hydrosilylation products have been characterized by 1 H, 13 C, 29 Si NMR and infrared spectroscopy and elemental analysis. The redox properties of the ferrocenyl substituted compound have been studied by cyclovoltammetry.

The metallophosphaalkene (η 5 -C 5 Me 5 )(CO) 2 Fe-P=C(NMe 2 ) 2 (1) was converted into the stable metallated 1-phospha-1,3-butadiene, (η 5 -C 5 Me 5 )(CO) 2 Fe-P=C(E)-=C(NMe 2 ) 2 5a) and the [3+2]-cycloadduct (4a) by treatment with the alkyne E-C≡C-E (E=CÒ 2 Me). A similar reaction of 1 with Me-C≡C-E (E = CQ 2 Me) resulted in the formation of the 1,2-dihydrophosphete (6). The cycloadduct (4c) was the sole tractable product from the reaction of 1 with the alkyne Ph-C≡C-C(0)tBu. The compounds 4a-c, 5 a, b and 6 have been characterized by elemental analysis as well as by spectroscopic data (IR, 1 H, 13 C, 31 P NMR, MS). The molecular structures of 4a, 5a and 6 have been determined by single crystal X-ray analysis.

Hexacarbonyl-μ-η 5:5 -fulvalene-dimolybdenum (1) reacts photochemically with allene to η 2 -allene-pentacarbonyl-μ-η 5:5 -fulvalene-dimolybdenum (2), μ-η 2:2 -allene-tetracarbonyl- μ-η 5:5 -fulvalene-dimolybdenum (4), and dicarbonyl-μ-η 5:5 -fulvalene-μ-η 1:2:3 -2-methylene- 4-penten-1,4-diyl-dimolybdenum (5). Complex 2 rearranges readily at room temperature to pentacarbonyl-μ-η 1:3 -2-propen-1,2-diyl-μ-η 5:5 -fulvalene-dimolybdenum (3). Upon UV irradiation 4 yields with an excess of allene μ-η 2:2 -Allene-pentacarbonyl-μ-η 5:5 -fulvalene-dimolyb-denum (2) shows a hindered rotation of the allene ligand with an energy barrier of ⊿G # 303 = 53.3 ± 2 kJ/mol. Hexacarbonyl-μ-η 5:5 -bis(cyclopentadiendiyl)methane-dimolybdenum (6) reacts with allene to μ-η 2:2 -ailene-tetracarbonyl-μ-η 5:5 -bis(cyclopentadiendiyl)methane- dimolybdenum (7) and octacarbonyl-bis{μ-η 5:5:1 -(cyclopentadiendiyl-cyclopentadientriyl)-methanejdihydrido-tetramolybdenum (8). For μ-η 2:2 -allene-tetracarbonyl-μ-η 5:5 -fulvalene-dimolybdenum (4) and 7 a hindered ligand movement was detected, by which the bridging allene ligand changes from one the side of the molecule to the other. The activation barriers of these pseudo rotations were determined for 4 with ⊿G # 303 = 57.4 ± 2 kJ/mol and for 7 with ⊿G # 293 = 63.4 ± 2 kJ/mol. Hexacarbonyl-μ-η 5:5 -fulvalene-ditungsten, hexacarbonyl-μ-η 5 -bis(cyclopentadiendiyl)ethane-dimolybdenum and hexacarbonyl-μ-η 5:5 -bis(cyclopen- tadiendiyl)propane-dimolybdenum form no stable photoproducts with allene.

(Cyclopentadiene pentayl)pentakis[(1,4-phenylene)alkanones] C 5 H(C 6 H 4 C(0)R-4) 5 (R=CH 3 (1a), C 3 H 7 (1b), C 5 H 7 (1c), C 7 H 15 (1d)) react with N 2 H 4 (H 2 O)/KOH or Et 3 SiH/ CF 3 COOH to yield the oxygen free ligands C 5 H(C 6 H 4 CH 2 R-4) 5 (2a, 2b, 2c and 2d), which after reaction with NaNH 2 give the corresponding sodium salts Na[C 5 (C 6 H 4 CH 2 R-4) 5 ] (3a, 3b, 3c and 3d). The sodium salts Na[C 5 (C 6 H 4 C(O)R-4) 5 ] (R=CH3 (4a), C 5 H 11 (4c) and 3a react with InCl to give In[C 5 (C 6 H 4 C(O)R-4) 5 ] (5a, 5c) and In[C 5 (C 6 H 4 CH 2 R-4) 5 ] (6a). 2a, 2b, 2c and 2d react with TlOC 2 H 5 yielding Tl[C 5 (C 6 H 4 CH 2 R-4) 5 ] (7a, 7b, 7c and 7d). The 1 H and 13 C NMR spectra of the new compounds are reported and discussed.

The diuretic sulfonamides furosemid (H 2 Fur) and hydrochlorothiazid (H 2 Hyt) were used as ligands in zinc complexes. Spectroscopic data indicate that in [(HFur)Zn(H 2 O) 2 ]ClO 4 and (HFur) 2 Zn the furosemid ligand is bound to zinc via its carboxylate and amine functions while (Fur)Zn(NH 3 ) 2 is a coordination polymer with Zn-carboxylate and Zn-sulfonimide coordination. A structure determination shows (Hyt)Zn(NH 3 ) 2 to be a coordination polymer as well, with both deprotonated sulfonamide functions forming Zn-N bonds.

The Pd-catalyzed oxidative coupling reaction of methyl o-toluate gives, in the presence of a Pd/1,10-phenanthroline(phen)/Cu catalyst, exclusively, the para-linked biphenyldicarboxylates 1, 2, and 3. On the other hand, the meta-linked biphenyldicarboxylates 4 and 5, were predominantly formed in a catalyst system of Pd/2,4-pentanedione(acacH)/Cu, and under similar conditions 6 and 7 were also obtained from the coupling reaction of methyl m-toluate and methyl p-toluate, respectively. A reaction scheme has been proposed.

The oxidation of E-1,2-di-tert-butyl-1,2-dimesityl disilene (1) in benzene by gaseous dioxygen to give 2 and 3 has been studied at various temperatures and with rapid or slow addition of oxygen. The effect of various additives (amines, phosphines, THF) on the product distribution was also investigated. Ab initio MO calculations were carried out on the oxidation of H 2 Si=SiH 2 with triplet oxygen. These led to a proposed reaction mechanism for the oxidation of 1, in which the initial intermediate is a disileneperoxy biradical 6′, which can close to give 2 or react with another molecule of disilene to give ultimately 3.

The exo/endo[4+2]-cycloadducts of Cl 2 Si=CHCH 2 t Bu and cyclopentadiene 1 are transformed into the Si-dimethoxy- and chloro-methyl-substituted derivatives 2 and 4. In the case of the 2-silabicyclo[2.2.1] compounds 2 (R 1 = R 2 = OCH 3 ), 3 (R 1 = R 2 = CH 3 ) and 4 (R 1 = Cl; R 2 = CH 3 ) the allyl cleavage with HCl/ether gives the ring opened products 8, 9, and 10 in good yields. The reaction can also be carried out with HBr/ether. In 1 the cleavage of the allyl-silicon bond is disfavoured due to the two chlorine atoms at silicon. Instead HCl adds to the C=C double bond and stereospecifically gives the exo-6-chloro-2,2-dichloro-3-exo/endo-neopentyl-2-silabicyclo[2.2.1]heptanes 5. When the stronger acid CF 3 SO 3 H is used no addition to the double bond is observed but only the allyl cleavage takes place to give the triflate 7. The ring opened cyclopentene compounds can be reduced by LiAlH 4 to give the corresponding Si-H-compounds 19 and 20. Intramolecular hydrosilylation of 19 leads to the exo/endo-2,2-dimethyl-3-neopentyl-2-silabicyclo[2.2.1]heptanes 21 and so the former bicyclic structure is regenerated.

The new partially organylsubstituted polycyclophosphanes P 7 Pr i 4 H, iso-P 7 Pr i 4 H, P 8 Pr i 5 H, P 9 Pr i 4 H, and P 10 Pr i 5 H have been obtained by reaction of Pr i PCl 2 with PCl 3 and magnesium and subsequent chromatographic work-up of the crude reaction product containing isopro-pylphosphorus magnesium compounds. According to 31 P NMR spectroscopic investigations, P 7 Pr i 4 H is 7-hydrogen-2,3,5,6-tetraisopropylbicyclo[2.2.1]heptaphosphane, iso-P 7 Pr i 4 H is hydrogen tetraisopropylbicyclo[2.2.1]heptaphosphane, P 8 Pr i 5 H is hydrogen pentaisopropylbicyclo[3.3.0]octaphosphane (two constitutional isomers), P 9 Pr i 4 H is hydrogen tetraisopropyltricyclo[3.3.1.0 3,7 ]nonaphosphane (two configurational isomers), and P 10 Pr i 5 H is 10-hydrogen-3,4,5,8,9-pentaisopropyltricyclo[5.2.1.0 2,6 ]decaphosphane (two configurational isomers).

Reaction of (1) in CH 2 Cl 2 with benzimidazole yields . The salt [4] + BPh 4 - has been prepared in THF by metathesis of [4] + Cl - with NaBPh 4 . Deprotonation of the cationic ring in [4] + BPh 4 - was accomplished using 1,8-diazabicyclo[5.4.0 1,7 ]undec-7-ene and resulted in the six-membered carbacyclophosphazene (6). Treating 1 with 8 -hydroxyquinoline in CH 2 Cl 2 yields the octahedral cis-complex = 8-oxyquinolinate group). The com pounds [4] + BPh 4 - , 6 and 7 are characterized by their IR, Raman, 31 P{ 1 H} NMR, 13 C{ 1 H} NMR, 1 H NMR and mass spectra. Crystals suitable for X-ray structure analyses have been obtained for [4] + BPh 4 - and 7×0.5 CH 2 Cl 2 . The colourless plates of [4] + BPh 4 - crystallize in the triclinic space group P1̄, with the lattice constants a = 1172.7(3), b = 1326.2(3), c = 1806.1(6) pm; α = 100.79(2), β = 103.71(3), γ = 108.18(2)°. The black blocks of 7×0.5 CH 2 Cl 2 crystallize in the monoclinic space group P 2 1 /c with the lattice constants a = 1159.0(10), b = 2008.9(10), c = 2034.6(12) pm; β = 105.86(5)°.

The structure of the chlorophosphazenes used as catalyst for the polycondensation of siloxanoles to various high molecular weight silicone polymers in the industrial scale has been determined as [PCl 3 =N(-PCl 2 =N) x -PCl 3 ] + [PCl 6 ] - . mainly with x=1 and x=2. For better un­ derstanding of the catalytic mechanism, the reaction behaviour of these ionic phosphazenes with water and siloxanes has been studied. Thereby three further types of phosphazenes have been synthesized: PCl 3 =N(-PCl 2 =N) x -PCl 2 =O,HO-PCl 2 =N(-PCl 2 =N) x -PCl 2 =O and siloxy derivatives of the latter ≡Si-O-PCl 2 =N(-PCl 2 =N) x -PCl 2 =O. Although several P-Cl bonds could be attacked by the nucleophiles, the reactions were found to be extremely selective and the products were obtained in very high yields. Finally relations between phosphazene structure and catalytic activity have been ascertained to find the optimal catalyst structure.

Complexes of the types R 3 Pb-Fe(CO) 2 Cp [R=Me (a). Et (1b), i Pr (lc), i Bu (Id)]. R 2 Pb[Fe(CO) 2 Cp] 2 [R=Me (2a), Et (2b)], i Pr 2 (Br)Pb-Fe(CO) 2 Cp (3c) and [R 2 PbFe(CO) 4 ] 2 [R=Me (4a), Et (4b). i Pr (4c)], as well as the spiro-complexes Pb[Fe(CO) 4 PbR 2 ] 2 [R = Me (5a). Et (5b). i Pr (5c)] and Pb[Fe(CO) 4 ] 4 (6) were studied by multinuclear magnetic resonance spectroscopy ( 1 H. 13 C, 207 Pb NMR). For the first time, coupling constants 1 J( 207 Pb 57 Fe) were determined, covering a range between 33.5 (6) and 117 Hz (4a). The magnitude of the geminal coupling constants ∣ 2 J( 207 Pb 207 Pb) ∣ in the spiro-compounds 5 decreases from 1090.0 Hz (5a) to 377.0 Hz (5c). The signs of the coupling constants n J( 207 Pb 13 C (R) ) (n = 1, 2) and n J( 207 Pb 1 H (R) ) (n = 2, 3) were determined by various 2D NMR experiments. Among all known Pb(IV) compounds the lowest 207 Pb nuclear magnetic shielding was found in Pb[Fe(CO) 4 ] 4 (6): δ 207 Pb +3586.6. According to the single crystal X-ray structure determination of 4b (orthorhombic; space group Pbca; a = 967.4, b = 1367.7, c = 1772.4 pm), the Pb 2 Fe 2 ring is planar with bond angles FePbFe = 102.8° and PbFePb = 77.2°, and there is a relatively short transannular distance of 340.8 pm between the two lead atoms.

It is shown that the introduction of sterically demanding ligands in lanthanoid metal complexes can depend more on the precise composition of the lanthanoid precursor than on the size of the new ligand. Thus, tris(r-butyl)methanol (“rmojt-H”) does not react with the amides Ln[N(SiMe 3 ) 2 ] 3 of the “late” (small) lanthanoid metals. However, fast and clean reactions occur with the sterically less demanding derivatives Ln[N(SiHMe 2 ) 2 ] 3 , with new homoleptic complexes Ln(tritox) 3 (Ln = Y, Nd) being formed with practically all metals of this group of elements. The molecular and crystal structures of some lanthanoid amides and alkoxides are described.

LiCH(PMe 2 ) 2 reacts with SiCl 4 or with PhR 2 SiCl (R = Me, Ph) via the carbanion to give silyl substituted phosphino methanes; Cl 2 Si[CH(PMe 2 ) 2 ] 2 (3) or PhR 2 Si[CH(PMe 2 ) 2 ] (4) (R = Me) and (5) (R = Ph), respectively. 4 and 5 are deprotonated by n BuLi to give trimeric {Li[C(PMe 2 ) 2 (SiMe 2 Ph)]} 3 (6) and in the precence of TMEDA. monomeric {Li[C(PMe 2 ) 2 (SiMe 2 Ph)]·TMEDA (7) or {Li[C(PMe 2 ) 2 (SiPh 3 )]} · TMEDA (8), respectively. {Li[C(PMe 2 )(SiMe 3 ) 2 ]} 2 ·TMEDA reacts with R 2 SiCl 2 (R = Me. Cl) via both the carbanion, thus generating a tetraheteroatom substituted methane moiety and, in a second substitution step, via phosphorus, thus generating an ylidic moiety. The obtained compounds (Me 3 Si) 2 (PMe 2 )C-SiR 2 -PMe 2 =C(SiMe 3 ) 2 (9) (R = Me) and (10) (R = Cl) are structurally characterized by X-ray crystallography as well as compounds 3, 5, 6 and 7. The observed variations in bond lengths and angles are explained to be mainly due to steric congestion. The ambidentate nature of phosphinomethanides thus clearly can be influenced by the nature of their carbanion substituents.

The crystal structure of [P(C 6 H 5 ) 4 ][B 6 H 6 I] has been determined by single crystal X-ray diffraction analysis; triclinic, space group P1 with a = 7.5137(9), b = 12.623(2), c = 13.6363(13) Å, α = 87.787(13)°, β = 83.836(13)°, γ = 88.156(10)°. The additional H atom could be refined with B-H distances of 1.13 to 1.31 A above one of the facettes of the B 6 octahedron opposite to the I substituent.

In the synthesis of oligophosphane ligands containing the neopentyl framework, the electrophilic activation of an OH group in com pounds of the type R′CH 2 C(CH 2 OH)(CH 2 PR 2 ) 2 is a serious problem which may be overcome by BH 3 protection of the intrinsically nucleophilic phosphane groups. It is shown that the hydroxy group of HOCH 2 C(CH 2 PPh 2 )3 (1) may be mesylated to yield MsOCH 2 C(CH 2 PPh 2 BH 3 ) 3 (3) after protection of 1 as its BH 3 derivative (2).

The di-tert-butyl peroxide-initiated reactions of triethyl- and tri-n-propylsilane with bis-(vinyldim ethylsilyl) compounds, CH 2 =CH(CH 3 ) 2 SiXSi(CH 3 ) 2 CH=CH 2 (X-O,CH 2 , NH,NCH 3 and NSiMe 3 ) resulted in hydrosilylation-cyclization to give mixtures of trialkylsilylm ethyl-substituted disilacyclohexanes and trialkylsilylm ethyl-substituted disilacyclopentanes. The ratio of six-membered to five-membered ring products obtained is dependent on the linking group X and decreased in the order X=O>CH 2 >NH>NCH 3 . For X = NSiMe 3 only a mixture of the cis and trans isomers of the five-membered ring product was obtained.