Komplexchemie at P-reicher Phosphane und Silylphosphane. VI. Bildung und Struktur der Chromcarbonylkomplexe des Tris(trimethylsilyl) heptaphosphanortricyclans (Me3Si)3P7

Formation and Structures of Chromium Carbonyl Complexes of Tris(trimethylsily)heptanortricyclane (Me₃Si)₃P₇ (Me₃Si)₃P₇ 1 reacts with one equivalent of Cr(Co)₅THF 2 to give the yellow (Me₃Si)₃P₇[Cr(Co)₅] 4. The Cr(Co)₅group is attached to a P^e atom. Yellow (Me₃Si)₃P₇[Cr(CO)₅]₂ 5 is obtained either from reacting 1 with two equivalents of 2 , or from 4 with one equivalent of 2. One Cr(CO)₅ groups in 5 is coordinated to a P^e atom, the other one to a P,^b atom. Similarly, Yellow (Me₃Si)₃P₇[Cr(CO)₅]₃ 6 results from reacting 5 with one equivalent of 2 . Two Cr(CO)₅ groups in 6 are linked to P^b atoms, and the third one either to a P^e or the P^a atom (assignment not completely clear). Derivatives containing a P^e bridge appear in reactions of 1 with higher amounts of 2 . Such, 5 forms mixtures of the red compounds (Me₃Si)₃P₇ × [Cr(CO)₅]₂[Cr(CO)₄] 8 and (Me₃Si)₃P₇[Cr(CO)₅] × [Cr(CO)₄] 9 , and even preferably 9 with four equivalents of 2 . In 8 , one Cr(CO)₅ group is attached to that p^e atom which is not engaged in the Cr(CO)₄ bridge, and the second to one of the P^b atoms directly adjacent to the bridge. The additional Cr(CO)₅ group in 9 is coordinated to the remaining P^b atom directly adjacent to the bridge. In reactions of 5 with even higher amounts of 2 , four Cr(CO)₅ groups and one Cr(CO)₄ bridge attach to the basic P₇ skeleton to from the less stable Me₃P₇[Cr(CO)₅]₄[Cr(CO)₄]. (Me₃Si)₃P₇ 1 reacts considerably slower with Cr(CO)₅THF 2 than R₃P₇ (R = Et, iPr). Cr(CO)₄NBD 3 reacts with 1 , but it was not possible to isolate (Me₃Si)₃P₇[Cr(CO)₄]. However, 4 with 3 forms (Me₃Si)₃P₇[Cr(CO)₅][Cr(CO)₄] 7 , and 5 with 3 yields (Me₃Si)₃P₇[Cr(CO)₅]₂[Cr(CO)₄] 8 . The structures of 4 , 5 , 7 , 8 or 9 are quite analogous to those of the derivatives of Et₃P₇ but there exist significant differences in stability and reactivity. While Et₃P₇[Cr(CO)₅]₂ in solution rearranges to give the stable Et₃P₇[Cr(CO)₅][Cr(CO)₄], the analogous (Me₃Si)₃P₇[Cr(CO)₅][Cr(CO)₄] 7 is not stable and is not obtained from (Me₃Si)₃P₇[Cr(CO)₅]₂ 5 . Et₃P₇[Cr(CO)5]₃ can just be detected spectroscopically and rearranges easily to give Et₃P₇[Cr(CO)₅]₂ [Cr(CO)₄] whereas (Me₃Si)₃P₇[Cr(CO)₅]₃ 6 can be isolated. These differences are caused by the greater steric requirements of Me₃Si groups. The formation of a P^e–Cr(CO)₄–P^e bridge, e.g., requires a Me₃Si group in 1 to switch from the s to the as position. Whereas many of the complex compounds of R₃P₇ (R = Et, iPr) crystallize easily, the analogous derivatives of (Me₃Si)₃P₇ did not yield crystals. The structures of the products were assigned by evaluating the coordination shift in their ₃₁P NMR spectra and by comparision of these spectra with those of such derivatives of Et₃P₇ which previously had been investigated by single crystal structure determinations.     

Komplexchemie P-reicher Phosphane und Silylphosphane. VII. Carbonylkomplexe des Heptaphosphans(3) iPr2(Me3Si)P7

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. VII Carbonyl Complexes of the Heptaphosphane(3) iPr₂(Me₃Si)P₇ From the reaction of iPr₂(Me₃Si)P₇ 1 with one equivalent of Cr(CO)₅THF the yellow products iPr₂(H)P₇[Cr(CO)₅] 2 and iPr₂(Me₃Si)P₇[Cr(CO)₅] 3 were isolated by column chromatography on silicagel. The P? H group in 2 results from a cleavage of the P? SiMe₃ bond during chromatography. The Cr(CO)₅ group in 2 is linked to an iPr? P^e atom, in 3 to the Me₃Si? P^e atom of the P₇ skeleton. The substituents do not force the formation of a single isomer; nevertheless 3 ist considerably favoured as compared to 2 . From the reaction of 1 with 2 equivalents of Cr(CO)₅THF the yellow iPr₂(H)P₇[Cr(CO)₅]₂ 4 was isolated bearing one Cr(CO)₅ group at an iPr? P^e atom, the other one at a P^b atom of the P₇ skeleton. Compound 3 yields with Cr(CO)₄NBD the red iPr₂(Me₃Si)P₇[Cr(CO)₅][Cr(CO)₄] 5 . Three isomers of 5 appear. Two P^e atoms of 5 are bridged by the Cr(CO)₄ group, the third P^e atom is linked to the Cr(CO)₅ ligand. iPr₂(H)P₇[Fe(CO)₄] was isolated from the reaction of 1 with Fe₂(CO)₉. ³¹P NMR and MS data are reported.     

[t-Bu2P]3P7 und (t-Bu2Sb)3P7 sowie Untersuchungen zur Bildung von Heptaphosphanen(3) mit PMe2-, PF2- und P(CF3)2-Gruppen

[t-Bu₂P]₃P₇ and (t-Bu₂Sb)₃P₇, as well as Investigations on the Formation of Heptaphosphanes (3) Containing PMe₂, PF₂, and P(CF₃)₂ Groups Tris(di-tert-butylphospha)heptaphosphanortricyclane (t-Bu₂P)₃P₇ 1 obtained by reacting Li₃P₇ · 3 DME with t-Bu₂PF forms yellow crystals. (t-Bu₂Sb)₃P₇ 2 produced similarly from t-Bu₂SbCl and Li₃P₇ · 3 DME didn't form crystals; it decomposes in a solution of toluene above ?10°C. Both compounds were identified by their ³¹P{¹H} NMR spectra, and 1 also by elemental analysis and single crystal structure determination (space group) P2₁/a, a = 1 712.0(9) pm, b = 1 105.1(7) pm, c = 1 854.0(10) pm, β = 94.96(4)°, Z = 4 formula units in the elementary cell). Attempts to synthesize (Me₂P)₃P₇ 3 , (F₂P)₃P₇ 4 and [(F₃C)₂P]₃P₇ 5 failed as dialkylchlorophosphanes as Me₂PCl e. g. with Li₃P₇ · 3 DME react under Li/Cl exchange, dialkylfluorophosphanes (except t-Bu₂PF) disproportionate, and neither PF₃ nor (F₃C)₂PBr with Li₃P₇ · 3 DME give the desired products 4 or 5 , resp.     

Reaktionen des tBu(Me3Si)P?P(Li)?P(tBu)2 mit CH3Cl und 1,2-Dibromethan

Reactions of tBu(Me₃Si)P? P(Li)? P(tBu)₂ with CH₃Cl and 1,2-Dibromoethane tBu(Me₃Si)P? P(Li)? P(tBu)₂ · 0.95 THF 1 with CH₃Cl (?70°C) yields tBu(Me₃Si)P? P = P(Me)(tBu)₂ 2 at ?70°C, with 1,2-Dibromoethane tBu(Me₃Si)P? PBr? P(tBu)₂ 3 (main product) and tBu(Me₃Si)P? P?P(Br)tBu₂ 4. 3 eliminates Me₃SiBr yielding the cyclotetraphosphane {tBuP? P[P(tBu)₂]}₂ 5 .     

Kristallstruktur des Lithium‐Trimethylsilanolats [Li7(OSiMe3)7(THF)]

The lithium silanolate LiOSiMe₃ is accessible from the reaction of Me₃SiOSiMe₃ with LiMe in tetrahydrofuran. Single crystals of [Li₇(OSiMe₃)₇(THF)] were obtained from toluene at 25 °C. The structure of [Li₇(OSiMe₃)₇(THF)] (C2/c) features a capped trigonal antiprismatic arrangement of seven Li atoms. The Li atoms in [Li₇(OSiMe₃)₇(THF)] are μ₃‐bridged by seven O atoms of the silanolate ligand.     

Zur Synthese der Heptaphospha-nortricyclane R3P7R = Et,i-Pr,n-Bu,i-Bu,SiH2Me,SiH3, Et2P–SiMe2

Concerning the Synthesis of the Heptaphospha-nortricyclanes R₃P₇ R = Et, i-Pr, n-Bu, i-Bu, SiH₂Me, SiH₃, Et₂P—SiMe₂ The preparative access to the compounds Et₃P₇ 1 ,i-Pr₃P₇ 2 ,n-Bu₃P₇ 3 ,i-Bu₃P₇ 4 , (H₃Si)₃P₇ 5 , (MeH₂Si)₃P₇ 6 , and (Et₂P—SiMe₂)₃P₆ 7 through the reaction of Li₃P₇ · 3 DME with either EtBr, i-PrBr, n-BuBr, H₃SiI, MeSiH₂Br or Et₂P—Sime₂Cl, respectively, is described. At 20°C the compounds 1 to 4 are yellow-greenish, viscid liquids (viscosity increases with the size of R), which are well soluble in ethers and non-polar solvents. 5 forms colorless crystals, which (similar to those of 6 ) decompose, when exposed to sunlight. 6 and 7 are generated quantitatively, these compounds, however, cannot be isolated undecomposed. While the formation of 1 occurs quantitatively via the red intermediate Li₂EtP₇, it is possible to isolate Li(i-Pr)₂P₇ from the residue of the reaction leading to i-Pr₃P₇. This Li-phosphide is said to cause the formation of higher, P-rich phosphanes like i-Pr₃P₉. Treatment of Li₃P₇ with (Me₃C)₃SiBr does not yield [(Me₃C)₃Si]₃P₇. The ratio R₃P₇(sym.): R₃P₇(asym.) — being 1:3 in Et₃P₇ or Me₃P₇-shifts with increasing size of R, favouring the symmetrical isomer. There are no hints for the formation of an asymmetrical isomer in (H₃Si)₃P₇ — as already known from (Me₃Si)₃P₇, where an asymmetric isomer does not exist either.     

Komplexchemie P-reicher Phosphane und Silylphosphane. XI [1]. Bildung,Reaktionen und Strukturen von Chromcarbonylkomplexen aus Reaktionen von Li(THF)2[η2-(tBu2P)2P] mit Cr(CO)5 · THF und Cr(CO)4 · NBD

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. XI. Formation, Reactions, and Structures of Chromium Carbonyl Complexes from Reactions of Li(THF)₂[η₂-(^tBu₂P)₂P] with Cr(CO)₅ · THF and Cr(CO)₄ · NBD Reactions of Li(THF)₂[η²-(^tBu₂P)₂P] 1 with Cr(CO)₅ · THF yield Li(THF)₂Et₂O[Cr(CO)₄{η²-(^tBu₂P)₂P}η¹-Cr(CO)₅] 2 and the compounds [Cr(CO)₄{η²-(^tBu₂P)₂PH}] 3 , [Cr(CO)₅{η¹-(^tBu₂P)₂PH}] 4 , (^tBu₂P)₂PH 5 and ^tBu₂PH · Cr(CO)₅ 6 . The formation of 3, 4, 5 and 6 is due to byproducts coming from the synthesis of 1. 2 reacts with CH₃COOH under formation of 3 . After addition of 12-crown-4 1 with NBD · Cr(CO)₄ in THF forms Li(12-crown-4)₂[Cr(CO)₄-{η²-(^tBu₂P)₂P}] 7 (yellow crystals). 7 reacts with CH₃COOH to 3 – which regenerates 7 with LiBu – with Cr(CO)₅THF to compound 2 , with NBD · Cr(CO)₄ in THF to 2 and 3 (ratio 1 : 1). With EtBr, 7 forms [Cr(CO)₄{η²-(^tBu₂P)₂PEt}] 8 , and [Cr(CO)₄{η²-(^tBu₂P)₂PBr}] 9 with BrCH₂? CH₂Br. The compounds were characterized by means of ¹H, ¹³C, ³¹P, ⁷Li NMR spectroscopy, IR spectroscopy, elementary analysis, mass spectra, and 2, 3 and 4 additionally by means of X-ray diffraction analysis. 2 crystallizes in the space group P1 with 2 formula units in the elementary cell; a = 10.137(9), b = 15.295(12), c = 15.897(14) Å; α = 101.82(7), β = 91.65(7), γ = 98.99(7)°; 3 crystallizes in the space group P2_t/n with 4 molecules in the elementary unit; a = 11.914(6), b = 15.217(10), c = 14.534(10) Å; α = 90, β = 103.56(5), γ = 90°. 4 : space group P1 with 2 molecules in the elementary unit; a = 8.844(4), b = 12.291(6), c = 14.411(7) Å, α = 66.55(2), β = 89.27(2), γ = 71.44(2)°.     

Synthese,Charakterisierung und Struktur von P7(t-Bu3Si)3 („Tris(supersilyl)heptaphosphan(3)”︁)

Synthesis, Characterization, and Structure of P₇(t-Bu₃Si)₃ (?Tris(supersilyl)heptaphosphane(3)”? Tris(tri-tert-butylsilyl)heptaphosphanortricyclane P₇(t-Bu₃Si)₃ 1 is obtained from the reaction of (t-Bu)₃Si? Si(t-Bu)₃ with white phosphorus and forms colorless to pale yellow thermostable crystals. 1 is identified by the complete analysis of its ³¹P{¹H} NMR spectrum (A[MX]₃ spin system) as well as by a single crystal structure determination (space group Pca2₁, a = 170.76(2)pm, b = 131.14(3)pm, c = 426.61(5)pm, α = β = γ= 90°, Z = 8 formula units in the elementary cell). The steric demand of the (t-Bu)₃Si-Groups causes an increase of the exocyclic bond angles at the equatorial phosphorus atoms P^e, while it does not particularly influence the P₇-skeleton. Chlorine (r.t.) and bromine (70°C) degrade the P₇-cage of 1 with formation of PX₃ and (t-Bu)₃SiX (X = Cl, Br).     

Reaktionen von (tBu)2P?PP(Br)tBu2 mit LiP(SiMe3)2, LiPMe2 und LiMe,LitBu, LinBu

Reactions of (tBu)₂P? P?P(Br)tBu₂ with LiP(SiMe₃)₂, LiPMe₂ and LiMe, LitBu and LinBu The reactions of (tBu)₂P? P?P(Br)tBu₂ 1 with LiP(SiMe₃)₂ 2 yield (Me₃Si)₂P? P(SiMe₃)₂ 4 and P[P(tBu)₂]₂P(SiMe₃)₂ 5 , whereas 1 with LiPMe₂ 2 yields P₂Me₄ 6 and P[(tBu)₂]₂PMe₂ 7 . 1 with LiMe yields the ylid tBu₂P? P?P(Me)tBu₂ (main product) and [tBu₂P]₂PMe 15 . In the reaction of 1 with tBuLi [tBu₂P]₂PH 11 is the main product and also tBuP? P?P(R)tBu₂ 21 is formed. The reaction of 1 with nBuLi leads to [tBu₂P]₂PnBu 17 (main product) and tBu₂P? P?P(nBu)tBu₂ 22 (secondary product).     

Phosphinophosphiniden-Phosphorane tBu2P?P = P(R)tBu2 aus Li(THF)2[η2-(tBu2P)2P] und Alkylhalogeniden

The Phosphinophosphinidene-phosphoranes ^tBu₂P? P = P(R)^tBu₂ from Li(THF)₂[η²-(^tBu₂P)₂P] and Alkyl Halides We report the formation of ^tBu₂P? P = P(R)^tBu₂ a and (^tBu₂)₂PR b (with R = Me, Et, ⁿPr, ⁱPr, ⁿBu, PhCH₂, H₂C = CH? CH₂ and CF₃) reactions of Li(THF)₂[η²-(^tBu₂P)₂P] 2 with MeCl, MeI, EtCl, EtBr, ⁿPrCl, ⁿPrBr, ⁱPrCl, ⁿBuBr, PhCH₂Cl, H₂C = CH? CH₂Cl or CF₃Br. In THF solutions the ylidic compounds a predominate, whereas in pentane the corresponding triphosphanes b are preferrably formed. With ClCH₂? CH = CH₂ only b is produced; CF₃Br however yields both ^tBu₂P? P = P(Br)^tBu₂ and ^tBu₂P? P = P(CF₃)^tBu₂, but no b . The ratio of a:b is influenced by the reaction temperature, too. The compounds ^tBu₂P? P = P(Et)^tBu₂ 4a and (^tBu₂P)₂PEt 4 b , e. g., are produced in a ratio of 4:3 at ?70°C in THF, and 1:1 at 20°C; whereas 1:1 is obtained at ?70°C in pentane, and 1:2 at 20°C. Neither ^tBuCl nor H₂C = CHCl react with 2 . The compounds a decompose thermally or under UV irradiation forming ^tBu₂PR and the cyclophosphanes (^tBu₂P)_nP_n.     

Synthese eines Titana-Oxacyclohexanringes durch kontrollierte Ringöffnung von Tetrahydrofuran. Kristallstrukturen von [Ti(CH2)4O{Me2Si(NBut)2}]2, [TiCl{Me2Si(NBut)2}]3(μ3-O)(μ3-Cl) und [Li2(THF)3{Me2Si(NBut)2}]

Synthesis of a Titana-Oxacyclohexane Ring by Controlled Ring Opening of Tetrahydrofurane. Crystal Structures of [Ti(CH₂)₄O{Me₂Si(NBu^t)₂}]₂, [TiCl{Me₂Si(NBu^t)₂}]₃(μ₃-O)(μ₃-Cl), and [Li₂(THF)₃{Me₂Si(NBu^t)₂}] [TiCl₃(THF)₃] reacts with [(Bu^tNLi)₂SiMe₂]₂ in diethyl ether at –35 °C under redox disproportionation and formation of the yellow titana(IV)-oxacyclohexane complex [Ti(CH₂)₄O{Me₂Si(NBu^t)₂}]₂. According to the crystal structure analysis the titanium atoms are linked to form centrosymmetric dimers via the oxygen atoms of the Ti(CH₂)₄O six-membered rings, which are in chair conformation. Along with the nitrogen atoms of the chelating [Me₂Si(NBu^t)₂]^2– ligands the titanium atoms obtain a distorted trigonal-bipyramidal surrounding. While [TiCl{Me₂Si(NBu^t)₂}]₃(μ₃-O)(μ₃-Cl) with a cluster-like structure is obtained as a by-product. According to the crystal structure analysis of [Li₂(THF)₃ · {Me₂Si(NBu^t)₂}], which is involved in the synthesis reaction, the two lithium atoms are connected with both the nitrogen atoms of the t-butyl amide groups and bridged via an oxygen atom of one of the THF molecules.     

Bildung siliciumorganischer Verbindungen. 110. Reaktionen von (Cl3Si)2CCl2, seiner Si-methylierten Derivate,von (Cl3Si)2CHCl, (Cl3Si)2C(Cl)Me und Me2CCl2 mit Silicium (Cu-Kat.)

Formation of Organosilicon Compounds. 110. Reactions of (Cl₃Si)₂CCl₂ and its Si-methylated Derivatives as well as of (Cl₃Si)₂CHCl, (Cl₃Si)₂C(Cl)Me and Me₂CCl₂ with Silicon (Cu cat.) The reactions of (Cl₃Si)₂CCl₂ 1 , its Si-methylated derivatives (Me₃Si)₂CCl₂ 8 , Me₃Si? CCl₂? SiMe₂Cl 9 , (ClMe₂Si)₂CCl₂ 10 , Me₃Si? CCl₂? SiMeCl₂ 11 , Cl₂MeSi? CCl₂? SiCl₃ 12 as well as of (Cl₃Si)₂CHCl 38 , (Cl₃Si)₂CClMe 39 and of Me₂CCl₂ with Si (Cu cat.) in a fluid bed reactor ( 38 and 39 also in a stirred solid bedreactor) arc presented. While (Cl₃Si)₂CCl₂ 1 yields C(SiCl₃)₄ 2 the 1,1,3,3-tetrachloro-2,2,4,4-tetrakis(trichlorsilyl)-1,3-disilacyclobutane Si₆C₂Cl₁₆ 3 and the related C-spiro linked disilacyclobutanes Si₈C₃Cl₂₀ 4 , Si₁₀C₄Cl₂₄ 5 , Si₁₂C₅Cl₂₈ 6 , Si₁₄C₆Cl₃₂ 7 this type of compounds is not obtained starting from the Si-methylated derivatives 8, 9, 10, 11 They Produce a number of variously Si-chlorinated and -methylated tetrasila- and trisilamethanes. However, Cl₂MeSi? CCl₂? SiCl₃ 12 forms besides of Si-chlorinated trisilamethanes also the disilacyclobutanes Si₆C₂Cl₁₅Me 34 and cis- and trans Si₆C₂Cl₁₄Me₂ 35 as well as the spiro-linked disilacyclobutanes Si₈C₃Cl₁₉Me 36 , Si₈C₃Cl₁₈Me₂ 37 . (Cl₃Si)₂CHCl 38 mainly yields HC(SiCl₃)₃ 31 and also the disilacyclobutanes cis- and trans-(Cl₃Si)HC(SiCl₂)₂CH(SiCl₃) 41 and (Cl₃Si)₂C(SiCl₂)₂CH(SiCl₃) 45 the 1,3,5-trisilacyclohexane [Cl₃Si(H)C? SiCl₂]₃ 44 as well as [(Cl₃Si)₂CH]₂SiCl₂, and (Cl₃Si)₂CClMe 39 mainly yields (Cl₃Si)₂C?CH₂and (Cl₃Si)₂besides of HC(SiCl₃)₃, MeC(SiCl₃)₃and (Cl₃Si)₃C? SiCl₂Me.,. Me₂CCl₂ 59 mainly yields Me(Cl)C?CH₂, Me₂CHCl and HCl₂Si? CMe₂? SiCl₃, besides of Me₂C(SiCl₃)₂ and Me₂C(SiCl₂H)₂ Compound 3 crystallizes triclinically in the space group P1 (Nr. 2) mit a = 900,3, b = 914,0, c = 855,3 pm, α = 116,45°, β = 101,44°, γ = 95,86° and one molecule per unit cell. Compound 4 crystallizes monoclinically in thc space group C2/c (no. 15) with a = 3158.3,b = I 103.7, c = 2037.4 pm, β = 1 16.62° and 8 molecules pcr unit cell. The disilacyclobutane ring of compound 3 is plane, showing a mean distance of d (Si-C) =19 1.8 pm and the usual deformations of endocyclic angles: α_Si = 94,2°> 85,8° = α_C.The spiro-linked disilacyclobutane rings of compound 4 are slightly folded by a mean angle of (19.0°). Their mean distances were found to be d (Si? C) = 190.4 pm relating to the central carbon atom and 192.0 pm to the outer ones, respectively. The deformations of endocyclic angles: α_Si = 93,9°> 84,4° = α_C are comparable to those of compound 3.     

Zur Bildung cyclischer Silylphosphane Umsetzung von Li-Phosphiden mit R2SiCl2 (R = Me,Et, t-Bu)

Formation of Cyclic Silylphosphanes. Reaction of Li-Phosphides with R₂SiCl₂ (R? Me, Et, t-Bu) The reaction of Me₂SiCl₂ with Li-phosphides (mixture of LiPH₂, Li₂PH) leads to the formation of Me₂Si(PH₂)Cl 1 , Me₂Si(PH₂)₂ 2 , H₂P? SiMe₂? PH? SiMe₂Cl 3 , (H₂P? SiMe₂)₂PH 4 , (HP? SiMe₂)₃ 6 , 5 , 7 , 8 , 9 , 10 , 40 . Excess of phosphides in Et₂O – as well as excess of LiPH₂ – favourably forms 10 . Li₂PH (virtually free of Li₃P and LiPH₂) is obtained by reaction of LiPH₂ · DME with LiBu; Li₃P by reaction of PH₃ with LiBu in toluene. Isomerization by Li/H migration determines the course of reaction of the PH-bearing compounds with Li-phosphides. With Me₂SiCl₂ Li₃P mainly generates compound 10 . The reaction of the Li-phosphides with Et₂SiCl₂ mainly leads to (HP? SiEt₂)₃ 18 and (HP? SiEt₂)₂ 17 as well as to Et₂Si(PH₂)Cl 11 , Et₂Si(PH₂)₂ 12 , (ClEt₂Si)₂PH 13 , H₂P? SiEt₂? PH? SiEt₂Cl 14 , (H₂P? SiEt₂)₂PH 15 and 16 . In the reaction with LiPH₂ · DME the same compounds are obtained and isomerization by Li/H migration (formation of PH₃) already begins at ?70°C. In toluene ClEt₂Si? P(SiEt₂)₂P? SiEt₂Cl is additionally formed. Derivatives of 9, 10, 40 are not observed. The reaction of (t-Bu)₂SiCl₂ with LiPH₂ leads to HP[Si(t-Bu)₂]₂PH 20 (yield 76%) and formation of PH₃, the reaction with Li₂PH to 20 (54%) besides HP[Si(t-Bu)₂]₂PLi 21 .     

A Novel Divalent Ytterbium Complex Supported by a Bridged Diamide Ligand: Synthesis and Structure of [{Me2Si(NPh)2Yb(THF)2}(μ3‐Cl)(μ4‐Cl){Li(THF)}2]2·2THF

The reaction of anhydrous YbCl₃ with 1 equiv. of Li₂Me₂Si(NPh)₂ in THF, after workup, yielded a ytterbium(III) chloride [{Me₂Si(NPh)₂Yb}(μ₂‐Cl)(TMEDA)]₂·3PhMe ( 1 ) (TMEDA=tetramethylethanediamine). The same reaction followed by treatment with Na‐K alloy afforded a new ytterbium(II) complex supported by a bridged diamide with four coordinated LiCl molecules, [{Me₂Si(NPh)₂Yb(THF)₂}(μ₃‐Cl)(μ₄‐Cl){Li(THF)}₂]₂·2THF ( 2 ) in high yield. Both complexes were structurally characterized by X‐ray analysis to be dimers. Complex 1 was a chlorine‐bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me₂Si(NPh)₂Yb(THF)₂]‐(μ₃‐Cl)[Li(THF)]₂ moieties were connected with each other by two μ₄‐Cl bridges to form a "chair‐form" framework.     

Synthese der Silatetraphospholane (tBuP)4SiMe2, (tBuP)4SiCl2 und (tBuP)4Si(Cl)SiCl3 Molekül- und Kristallstruktur von (tBuP)4SiCl2

Synthesis of the Silatetraphospholanes (tBuP)₄SiMe₂, (tBuP)₄SiCl₂, and (tBuP)₄Si(Cl)SiCl₃ Molecular and Crystal Structure of (tBuP)₄SiCl₂ The reaction of the diphosphide K₂[(tBuP)₄] 7 with the halogenosilanes Me₂SiCl₂, SiCl₄ or Si₂Cl₆ in a molar ratio of 1:1 leads via a [4 + 1]-cyclocondensation reaction to the silatetraphospholanes (tBuP)₄SiMe₂ 1,1-dimethyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 1 , (tBuP)₄SiCl₂, 1,1-dichloro-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 2 , and (tBuP)₄Si(Cl)SiCl₃, 1-chloro-1-trichlorsilyl-1-sila-2,3,4,5-tetra-t-butyl-2,3,4,5-tetraphospholane, 3 , respectively, with the 5-membered P₄Si ring system. The reaction leading to 1 is accompanied with the formation of the by-product Me₂(Cl)-Si–(tBuP)₄–Si(Cl)Me₂ 1a (5:1), which has a chain structure. On warming to 100°C 1a decomposes to 1 and Me₂SiCl₂. The compounds 2 and 3 do not react further with an excess of 7 due to strong steric shielding of the ring Si atoms by the t-butyl groups. 1, 2 and 3 could be obtained in a pure form and characterized NMR spectroscopically; 2 was also characterized by a single crystal structure analysis. 1a was identified by NMR spectroscopy only.     

Kettenverlängerung am P2(SiMe3)4 durch Reaktion mit LiBu

Extension of the Chain Length of P₂(SiMe₃)₄ by Reaction with LiBu The first steps of the reaction of P₂(SiMe₃)₄ 1 with LiBu in THF, which finally yields Li₃P₇ among other P-rich phosphides while P(SiMe₃)₃ and LiP(SiMe₃)₂ are simultaneously split off, were investigated by means of ³¹P-NMR spectroscopy. At ?20°C first of all one Si? P bond is cleaved generating Li(Me₃Si)P? P(SiMe₃)₂ 2 as well as BuSiMe₃. Subsequently 2 forms Li(Me₃Si)P? P(SiMe₃)? P(SiMe₃)₂ 5 and LiP(SiMe₃)₂ 4 in equimolar ratios. This clearly demonstrates that both compounds are generated in one single reaction step. This behaviour is caused by the different basicity of the respective P-atoms in 2 , which necessarily results in a multicentered mechanism.     

Über den Einfluß der Substituenten im (R3Si)2(P–Si)R2Cl auf Bildung und Eigenschaften der Hexasila-tetraphosphadantane und deren 31P-NMR-Spektren

The Effect of the Substituents in (R₃Si)₂P–SiR₂Cl on the Formation and the Properties of the Hexasilatetraphospha-adamantanes and their ³¹P-NMR Spectra The thermolysis of (Me₃Si)₂P–SiEt₂Cl 4 at 300°C leads to the silylphosphanes with adamantane structure (Et₂Si)_x(Me₂Si)_6–x (x = 0–6), aside of (Me₃Si)₃P, (Et₂MeSi) (Me₃Si)₂P, (Et₂MeSi)₂(Me₃Si)P and Me₃SiCl, Et₂SiCl, Et₂MeSiCl. Due to the different positions of the Et₂Si-bridges in the adamantane cage the compounds featuring x = 2–4, form isomers. The thermolysis of (Me₃Si)₂P–SiEtMeCl 14 occurs analogously and leads to the adamantanes (EtMeSi)_x (Me₂Si)_6–xP₄ (x = 0–6). The introduction of the SiEtMe group causes the existence of chiralic isomers of the compounds featuring x = 2–6. From (Et₃Si)₂P–SiEt₂Cl 24 (Et₂Si)₆P₄ is obtained. The thermolyses of (Me₃Si)₂P–SiPh₂Cl 25 and [(Me₃Si)P–SiPh₂]₂ do not enable the formation of adamantanes with SiPh₂-bridges. They rather lead to Me- and Ph-substituted trisilylphosphanes. The syntheses of the starting compounds 4, 14, 24 , and 25 are reported. The ³¹P-NMR spectra of silylphosphanes with adamantane structure show, that the linear increase of the ³¹P-chemical shift values as dependent on the rising number of Et groups, which is observed in partially Et-substituted methyltrisilylphosphanes, allows the prediction of the δ³¹P values of the specific P atoms in an adamantane cage, heeding both the position and the direction of the SiEt groups in the particular molecule.     

Komplexchemie P-reicher Phosphane und Silylphosphane. X [1] Zum Einfluß der Komplexierung auf die Reaktivität des [(Me3Si)2P]2PH

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. X. The Influence of the Formation of Complex Compounds on the Reactivity of [(Me₃Si)₂P]₂PH Whereas [(Me₃Si)₂P]₂PH 1 by BuLi is attacked at the PH group to give [(Me₃Si)₂P]₂PLi 2 , the related chromium carbonyl complex (Me₃Si)P^IV ? ²P^IV(H) ? ³P^III(Si? Me₃)₂ · Cr(CO)₄ 3 with BuLi yields Li(Me₃Si)¹P^IV ? ²P^IV(H) ? ³P^III(SiMe₃)₂ · Cr(CO)₄ 4 by cleaving a Si? P bond at the chromium substituted ¹P atom. Dissolved in ether, 4 is stable for a longer time, while under comparable conditions 2 forms Li₃P₇ which is not obtained from 4 . MeOH in 3 cleaves selectively the Me₃Si groups from the complex substituted P atom yielding (Me₃Si)(H)¹P^IV ? ²P^IV(H) ? ³P^III(SiMe₃)₂ · Cr(CO)₄ 5 and HP^IV ? ²P^IV(H) ? ³P^III(SiMe₃)₂Cr(CO)₄ 6. 5 and 6 seem to be stable in contrast to the uncoordinated triphosphanes which are not known.     

Untersuchungen zur Reaktionsfähigkeit der höheren Silylphosphane (me3Si)4P2, [(me3Si)2P]2PH, [(me3Si)2P]2P–Sime3 und (me3Si)3P7

Investigations Concerning the Reactivity of the Higher Silylphosphanes (me₃Si)₄P₂, [(me₃Si)₂P]₂PH, [(me₃Si)₂P]₂P—Sime₃, and (me₃Si)₃P₇ The reaction of (me₃Si)₂P? P(Sime₃)₂ 1 in ether solutions (THF, monoglyme) with t-buLi (me ? CH₃; t-bu ? (CH₃)₃C) yields (me₃Si)₃P, (me₃Si)₂PLi and Li₃P₇ via (me₃Si)₂P? P(Li) (Sime₃) 4 . Already at ?40° (me₃Si)₃P₂Li 4 decomposes yielding (me₃Si)₂PLi, Li₃P₇ and (me₃Si)₃P. The metallation of (me₃Si)₃P₂H with t-buLi leads to the same results. t-buLi with [(me₃Si)₂P]₂PH 2 in pentane forms [(me₃Si)₂P]₂PLi, which reacts on with meCl or me₃SiCl to [(me₃Si)₂P]₂Pme or [(me₃Si)₂P]₂PSime₃, resp. On addition of monoglyme to a suspension of [(me₃Si)₂P]₂PLi in pentane, or by treating [(me₃Si)₂P]₂PH in ethers with t-buLi (me₃Si)₂PLi, Li₃P₇, (me₃Si)₃P, are formed. The same compounds are generated by reacting [(me₃Si)₂P]₂P—Sime₃ in ethers with t-buLi. The metallation of (me₃Si)₃P₇ in ethers with t-buLi yields (me₃Si)₂PLi, (me₃Si)₃P, (t-bu)₃P₄?(Sime₃), Li₃P₇ and a red solid. The formation of (me₃Si)₂P₇Li is the first step of this reaction.     

New methodology for the introduction of sulfur into organic molecules : Synthesis of anhydrous Li2S,Li2S2 and LiSr species by lithium triethylborohydride reduction of elemental sulfur and disulfides

Anhydrous THF solutions of Li₂S or Li₂S₂ (or chemically equivalent species) are rapidly and quantitatively formed by the reaction of common yellow sulfur with appropriate stoichiometries of commercially available LiEt₃BH. Only volatile by-products H₂ and Et₃B are produced; however, the Et₃B probably associates with the anionic sulfur species generated. Subsequent reaction with electrophiles (alkylating agents or acylating agents) affords sulfide or disulfide derivatives in high yields. In several cases, literature procedures are substantially improved. Disulfides are cleaved to lithium mercaptides by LiEt₃BH. Subsequent addition of electrophiles affords unsymmetrical sulfides. Trisulfides and tetrasulfides can also be prepared by LiEt₃BH reduction of S_g, but only in low yield.