Das iso-Tetraphosphan P[P(SiMe3)Me]2[P(SiMe3)2]

H ? C Bond Cleavage in Ferrocene by Organylruthenium Complexes Cp*(Me₃P)₂RuCH₂CMe₃ ( 1 ) reacts at 85°C with ferrocene ( 2 ) by cleavage of one H? C bond in 2 to give CpFe[η⁵-C₅H₄Ru(PMe₃)₂Cp*] ( 3 ) (Cp = η⁵-C₅H₅; Cp* = η⁵-C₅Me₅) and neopentane. The ruthenium atom in 3 has a distorted tetrahedral geometry, the planar Cp ligands in the ferrocenyl fragment are eclipsed. Solutions of 3 in [D₆]benzene or [D₈]THF exhibit H? D exchange of the ferrocenyl protons. In the [D₈]THF molecule only the α-deuterium atoms are exchanged. Reaction pathways for this exchange are discussed.     

Das P(SiMe2)3P

P(SiMe₂)₃P Li₃P (produced from the elements) forms with Me₂SiCl₂ at 20°C in toluene the bicyclic compound P(SiMe₂)₃P 4 beside small amounts of ClMe₂Si? P(SiMe₂)₂P? SiMe₂Cl and traces of P₄(SiMe₂)₆ 7. 4 can be transformed into 7 by thermal treatment. With the formation of 4 the existence of a bicyclic silylphosphane is confirmed which has already been mentioned in connection with P(SiEt₂)₃P [1], but could not be proven until now.     

[Ge9{Si(SiMe3)3}2{Ge(SiMe3)3}]–: The Mixed Substituted Metalloid Germanium Cluster and the Intermetalloid Cluster [ZnGe18{Si(SiMe3)3}4{Ge(SiMe3)3}2]

The novel metalloid germanium cluster [Ge₉(Hyp)₂Hyp^Ge]^– ( 1 ) was synthesized, exhibiting two different bulky groups [Hyp = Si(SiMe₃)₃; Hyp^Ge = Ge(SiMe₃)₃]. Further reaction of 1 with ZnCl₂ gives the derivative [ZnGe₁₈(Hyp)₄(Hyp^Ge)₂] ( 2 ) in good yield, showing that the substitution of Si(SiMe₃)₃ by Ge(SiMe₃)₃ within a metalloid Ge₉R₃^– compound leads to a comparable reactivity. 1 and 2 are characterized by NMR spectroscopy, mass spectrometry ( 1 ) and single crystal structure analyses ( 2 ). 1 and 2 are the first metalloid germanium clusters bearing germyl groups.     

Metal-Free Oxidative Trifluoromethylthiolation of Terminal Alkynes with CF(3)SiMe(3) and Elemental Sulfur

A metal-free oxidative trifluoromethyl-thiolation of terminal alkynes using readily available CF(3)SiMe(3) and elemental sulfur at room temperature has been developed. This reaction provides an efficient and convenient method for the preparation of alkynyl trifluoromethyl sulfides bearing a wide range of functional groups. Preliminary investigation revealed that elemental sulfur instead of air acted as the oxidant.     

Synthesis and Crystal Structure of the two Lithium Hypersilylcuprates LiCu2[Si(SiMe3)3]3 and [Li7(OtBu)6][Cu2{Si(SiMe3)3}3]

The two hypersilylcuprates LiCu₂Hyp₃ ( 2 ) and [Li₇(O^tBu)₆][Cu₂Hyp₃] ( 3 ) (Hyp = Si(SiMe₃)₃) were synthesized by reactions of unsolvated lithium hypersilanide, LiHyp with hypersilylcopper and CuO^tBu, respectively. Both contain the novel A‐frame trihypersilyldicuprate anion [Cu₂Hyp₃]^–. In the former case a molecular compound is produced containing intimate ion pairs. In the latter case the cuprate anion and the unique large [Li₇(O^tBu)₆]⁺ cation form a salt‐like compound, only sparingly soluble in unpolar solvents. According to NBO analyses the bonding within the trihypersilyldicuprate moiety is best described by interaction of a bridging lewis‐basic hypersilanide anion with two lewis‐acidic hypersilyl copper fragments.     

Reactions between a sodium amide Na[N(SiMe3)R1] (R1 = SiMe3, SiMe2Ph or But) and a cyanoalkane RCN (R = Ad or Bu(t))

Reactions between sodium amides Na[N(SiMe3)R1] [R1 = SiMe3 (1), SiMe2Ph (2) or But (3)] and cyanoalkanes RCN (R = Ad or But) were investigated. In each case the nitrile adduct [Na{mu-N(SiMe3)2}(NCR)]2 [R = Ad (1a) or But (1b)], trans-[Na{mu-N(SiMe3)(SiMe2Ph)}(NCR)]2 [R = Ad (2a) or But (2b)], [(Na{mu-N(SiMe3)But})3(NCAd)3] (3a) or [(Na{mu-N(SiMe3)But})3(NCBut)n] [n = 3 (3b) or 2 (3c)] was isolated. The reaction of complexes 3a or 3b with benzene afforded the ketimido complex [Na{mu-N=C(Ad)(Ph)}]6.2C6H6 (4a) or [Na{mu-N=C(But)(Ph)}]6 (4b); the former was also prepared in more conventional fashion from NaPh and AdCN. The synthesis and structure of an analogue of complex 1a, [Li{mu-N(SiMe3)2}(NCAd)]2 (5a), is also presented. The compounds 1a, 1b, 2a, 2b, 3, 3b, 4a, 4b and 5a were characterised by X-ray diffraction.     

Preparation and characterization of arsine derivatives: X-ray crystal structures of As (SitBuMe2)3, As (SiMe3)2(SiPh3), Et3Ga · As(SiMe3)2(SiPh3), and As(SePh)3

As(Si¹BuMe₂)₃ (1) was prepared by the salt-elimination reaction between (Na/K)₃As and ¹BuMe₂SiCl. Mixing LiAs(SiMe₃)₂ with Ph₃SiCl (1:1) yielded As(SiMe₃)₂(SiPh₃) (2) in a good crystalline yield. Reaction of 2 (1:1) with Et₃Ga gave the expected Lewis acid-base adduct Et₃Ga · As(SiMe₃)₂(SiPh₃) (3). The 1:1 mole ratio reaction of In(SePh)₃ with As(SiMe₃)₃ resulted in a ligand redistribution around the indium and arsenic centers to afford As(SePh)₃ (4) in a low yield. The solid-state structures of 1–4 have been established by single-crystal X-ray analysis. Crystal data for 1, monoclinic space group P 2₁/c, with a = 11.112(2), b = 17.453(2), c = 14.199(2) Å, β = 114.89° for Z = 4; 2, orthorhombic space group P c2₁n, with a = 9.236(1), b = 16.612(2), c = 16.803(4) Å for Z = 4; 3, monoclinic space group P 2₁/c, with a = 16.799(1), b = 11.199(2), c = 19.413(3) Å, β = 112.22(1) for Z = 4; 4, trigonal space group R &3macr;, with a = 12.863(5), c = 18.96(1) Å for Z = 6. © 1996 John Wiley & Sons, Inc.     

Darstellung funktioneller Polysilane: Tris(chlordimethylsilyl)methylsilanMeSi(SiMe 2Cl)3

Tris(chlorodimethylsilyl)silane is prepared by halogen/methyl exchange usingMe ₃SiCl and AlCl₃. Its vibrational (Ir,Raman) and²⁹Si-NMR-spectra are discussed and compared with the spectra of Tetrakis(chlorodimethylsilyl)silane.

     

Preparation and Characterization of Halogen-Boron-Phosphorus Compounds. X-ray Crystal Structures of X(3)B.P(SiMe(3))(3) and [X(2)BP(SiMe(3))(2)](2) (X = Cl, Br)

The 1:1 mole ratio reactions of boron trihalides (BX(3)) with tris(trimethylsilyl)phosphine [P(SiMe(3))(3)] produced 1:1 Lewis acid/base adducts [X(3)B.P(SiMe(3))(3), X = Cl (1), Br (2), I (5)]. Analogous 1:1 mole ratio reactions of these boron trihalides with lithium bis(trimethylsilyl)phosphide [LiP(SiMe(3))(2)] produced dimeric boron-phosphorus ring compounds {[X(2)BP(SiMe(3))(2)](2), X = Br (3), Cl (4)}. X-ray crystallographic studies were successfully conducted on compounds 1-4. Compound 1 crystallized in the orthorhombic space group Pbca, with a = 13.420(3) ?, b = 17.044(5) ?, c = 21.731(7) ?, V = 4970.6(25) ?(3), and D(calc) = 1.229 g cm(-3) for Z = 8; the B-P bond length was 2.022(9) ?, Compound 2 crystallized in the orthorhombic space group Pbca, with a = 13.581(6) ?, b = 17.106(7) ?, c = 22.021(9) ?, V = 5116(4) ?(3), and D(calc) = 1.540 g cm(-3) for Z = 8; the B-P bond length was 2.00(2) ?. Compound 3 crystallized in the monoclinic space group P2(1)/n, with a = 9.063(5) ?, b = 16.391(8) ?, c = 9.331(4) ?, V = 1379.2(12) ?(3), and D(calc) = 1.676 g cm(-3) for Z = 2; the B-P bond length was 2.023(10) ?. Compound 4 crystallized in the monoclinic space group P2(1)/n, with a = 9.143(5) ?, b = 16.021(8) ?, c = 9.170(4) ?, V = 1342.2(11) ?(3), and D(calc) = 1.282 g cm(-3) for Z = 2; the B-P bond length was 2.025(3) ?. Thermal decomposition studies were performed on compounds 1-4, yielding colored powders with boron:phosphorus ratios greater than 1:1 and significant C and H contamination indicated by elemental analyses.     

Zur Bildung der Cyclotetraphosphane cis- und trans-P4(SiMe3)2(CMe3)2 bei der Umsetzung von (Me3C)PCl2 mit LiP(SiMe3)2 · 2 THF

Formation of the Cyclotetraphosphanes cis- und trans-P₄(SiMe₃)₂(CMe₃)₂ in the Reaction of (Me₃C)PCl₂ with LiP(SiMe₃)₂ · 2 THF The mechanism of the reaction of (Me₃C)PCl₂ 1 with LiP(SiMe₃)₂ · 2 THF 2 was investigated. With a mole ration of 1:1 at ?60°C quantitatively (Me₃C)(Cl)P? P(SiMe₃)₂ 3 is formed. This compound eliminates Me₃SiCl on warming to 20°C, yielding Me₃Si? P?P? CMe₃ 4 (can be trapped using 2,3-dimethyl-1,3-butadiene in a 4+2 cycloaddition), which dimerizes to produce the cyclotetraphosphanes cis-P₄(SiMe₃)₂(CMe₃)₂ 5 and trans-P₄(SiMe₃)₂(CMe₃)₂ 6 . Also with a mole ratio of 1:2 initially 3 is formed which remarkably slower reacts on to give [(Me₃Si)₂P]P₂P? CMe₃ 8 . Remaining LiP(SiMe₃)₂ cleaves one Si? P bond of 8 producing (Me₃)₂P? P(CMe₃)? P(SiMe₃)₂Li. Via a condensation to the pentaphosphide 10 and an elimination of LiP(SiMe₃)₂ from this intermediate, eventually trans-P₄(SiMe₃)₂(CMe₃)₂ 6 is obtained as the exclusive cyclotetra-phosphane product.     

Nucleophilic trifluoromethylation of cyclic imides using (trifluoromethyl)trimethylsilane CF3SiMe3

A variety of cyclic five-membered imides was trifluoromethylated in good to excellent chemical yields using (trifluoromethyl)trimethylsilane CF3SiMe3 under fluoride ion catalysis. The method was successfully applied to the stereoselective synthesis of trifluoromethylated bi- and tricyclic lactams which could serve as precursors for designed thrombin inhibitors.     

Reactions of LiE(SiMe(3))(3), E = Si, Ge: X-ray Crystal Structure of the Cyclotetrastannane [ClSnSi(SiMe(3))(3)](4)

Reaction of SnCl(2).dioxane with 2 equiv of Li(THF)(3)Si(SiMe(3))(3) in hexane afforded the cyclotetrastannane [(Me(3)Si)(3)SiSnCl](4) in reasonable yield. From pentane, the product crystallized as a red-orange disolvate in the P&onemacr; space group (triclinic) with a = 14.735(2) ?, b = 14.976(2) ?, c = 24.066(3) ?, alpha = 76.94 degrees, beta = 76.19 degrees, gamma = 62.11 degrees, V = 4517.5 ?(3), and Z = 2. The Sn(4) ring consisted of a slightly distorted, nonplanar (fold angle = 18.9 degrees ) rectangle with Sn-Sn distances of 2.8054(6), 2.8111(6), 2.9122(6), and 2.9146(6) ?. The pentane molecules were disordered. Selected mono- and dihalogermanes were treated with 1 equiv of Li(THF)(3)Si(SiMe(3))(3) or Li(THF)(2.5)Ge(SiMe(3))(3), affording (Me(3)Si)(3)EGe(CF(3))(3) (E = Si, Ge) and (Me(3)Si)(3)GeGeR(3) (R = Cl, CH(3), C(6)H(5)). Besides the monosubstitution product, the reaction of GeCl(4) with 1 equiv of Li(THF)(2.5)Ge(SiMe(3))(3) also gave a small amount of the linear tetragermane (Me(3)Si)(3)GeGeCl(2)GeCl(2)Ge(SiMe(3))(3). Good yields of the analogous phenyl derivative, (Me(3)Si)(3)GeGePh(2)GePh(2)Ge(SiMe(3))(3), were obtained by treating Ph(2)GeCl(2) with 2 equiv of the lithium-germyl reagent.     

Ge(9) {Si(SiMe(3) )(3) }(3) {SnPh(3) }]: A Tetrasubstituted and Neutral Deltahedral Nine-Atom Cluster

Reaching neutral territory: The title compound, the first tetrasubstituted deltahedral Zintl cluster, is no longer an ion (see picture; Ge?green, Si?purple, Sn?blue). It is a neutral molecule formed by a reaction of the trisilylated anion with Ph(3) SnCl.     

Unusual coordination modes of arylthiolates in Mo(eta(5)-SC(6)H(3)-2,6-(SiMe(3))(2))(eta(7)-SC(6)H(3)-2,6-(SiMe(3))(2))

Treatment of MoCl(3)(thf)(3) with LiSC(6)H(3)-2,6-(SiMe(3))(2) (LiSAr) resulted in formation of the pi-sandwiched bis-arylthiolato complex, Mo(eta(5)-SC(6)H(3)-2,6-(SiMe(3))(2))(eta(7)-SC(6)H(3)-2,6-(SiMe(3))(2)) (1), while the analogous reaction with LiSC(6)H(3)-2-Ph-6-SiMe(3) afforded the trithiolate complex Mo(SC(6)H(3)-2-Ph-6-SiMe(3))(3) (3). The acetonitrile adduct Mo(SAr)(2)(CH(3)CN)(3) (2) was isolated from the CH(3)CN solution of 1, in which one acetonitrile is coordinated to the metal center in an eta(2)-fashion. Structures of 1, 2, and 3 have been determined by X-ray diffraction.     

The nature of the anchimeric assistance by the acetoxy group in solvolysis of (Me3Si)2C(SiMe2)OCOMe) (SiMe2Cl)

Solvolysis of (Me₃Si)₂C(SiMe₂OCOMe)(SiMe₂Cl) in 3/2 v/v MeOH/dioxane at 35°C is ca. 11–14 times as fast as that of (Me₃Si)₂C(SiMe₂OMe)(SiMe₂Cl), which suggests that the anchimeric assistance by the acetoxy group is provided through the carbonyl oxygen.     

Bildung und Struktur des iso-Tetraphosphans P[P(SiMe3)Me]3

Formation and Structure of iso-Tetraphosphane P[P(SiMe₃)Me]₃ The reaction of MeP(SiMe₃)₂ with PCl₃ (molar ratio 3:1, ?78°C, n-pentane) yields by cleaving of the P? Si bond P[P(SiMe₃)Me]₃ 1 with Cl₂P? P(SiMe₃)Me and ClP[P(SiMe₃)Me]₂ as intermediates. The reaction rate decreases by the increase of phosphorylation. The last reaction step (formation of 1 ) occurs while warming up to room temperature. 1 forms colorless hexagonal crystals, melting point 65 ± 1°C. Tris(trimethylsilyl-methyl-phosphino)phosphane 1 crystallizes monoclinically in the space group Cc (No. 8) with Z = 8 formula units per unit cell. The molecules possess approximated C₃ symmetry and have (RRR) and (SSS) configurations, respectively. The bond distances d?(P? P) = 220.1 pm, d?(P? C) = 186.5 pm, and d?(P? Si) = 225.2 pm are normal and within the expected range of known distances. According to repulsive interactions between the non bonded electron pairs of the terminal P atoms and the protons of the methyl groups the angles at the central and terminal P atoms are enlarged to ? P P P = 105.1° and ? P P C = 106.9°, respectively.     

Dihaloheptasilanes X2Si[SiMe(SiMe3)2]2 as potential precursors for silylenes, disilenes and cyclotrisilanes

The synthesis of new dihaloheptasilanes X₂Si[SiMe(SiMe₃)₂]₂ (X=Cl: 2, Br: 3, I: 4) was performed by treating dihydridoheptasilane 1 (X=H) with CCl₄, HCBr₃ or HCI₃. Difluoroheptasilane 6 (X=F) was prepared from either diphenylheptasilane 5 (X=Ph), triflic acid (HOTf), and LiF with concomitant isolation of heptasilanes 7 (X₂=Ph and OTf), 8 (X₂=F and Ph), and 9 (X₂=F and OTf), or by halogen exchange from 2 using ZnF₂. Crystal structures of 2, 3, 4, and 5 are reported. The reduction of 2 with Li, Na or KC₈ resulted in the instantaneous formation of various cyclotrisilanes, while the reduction of 3 gave exclusively the unsymmetrical cyclotrisilane (E)-1-methyl-2,3,3-tris[methylbis(trimethylsilyl)silyl]-1,2-bis(trimethylsilyl)cyclotrisilane 10, which was characterized by X-ray crystallography. A mechanism for the formation of cyclotrisilanes via a silylsilylene-to-disilene rearrangement is proposed. Attempts to prepare the tetradekasilane [(Me₃Si)₂MeSi]₂SiH–SiH[SiMe(SiMe₃)₂]₂ (by reductive dehalogenation of either HClSi[SiMe(SiMe₃)₂]₂ 13 or HISi[SiMe(SiMe₃)₂]₂ 18), or the tetradekasilane [(Me₃Si)₂MeSi]₂SiPh–SiPh[SiMe(SiMe₃)₂]₂ (by reductive dehalogenation of either PhClSi[SiMe(SiMe₃)₂]₂ 14 or PhISi[SiMe(SiMe₃)₂]₂ 19) as precursors for the disilene [(Me₃Si)₂MeSi]₂Si=Si[SiMe(SiMe₃)₂]₂ failed. 14 was characterized by X-ray crystallography. All compounds described were also characterized by multinuclear NMR spectroscopy and elemental analysis.