Reaktionen des [(me3Si)2P]2PLi mit Chlorphosphanen

Reactions of [(me₃Si)₂P]₂PLi with Chlorophosphanes [(me₃Si)₂P]₂PLi 1 with (C₆H₅)₂PCl yields only a small amount of the expected [(me₃Si)₂P]₂P–P(C₆H₅)₂ 2 ; the main products are (me₃Si)₂P–P(C₆H₅)₂ 3 and (C₆H₅)₂P–P(C₆H₅)₂ 4 besides some (me₃Si)₃P 5 and (C₆H₅)₂P–Sime₃ 6. 3 and 4 result from the metallation of (C₆H₅)₂PCl by 1 t-buPCl₂ and 1 form the P₃-ring (me₃Si)(me₃C)P₃[P(Sime₃)₂] 9 as main product besides some [(me₃Si)₂P]₂P–Sime₃ 7 and 5. 9 is afforded by elimination of me₃SiCl, from the initially formed unstable [(me₃Si)₂P]₂P–P(Cl)Cme₃ 10 . Similarly 1 and PCl₃ yield mainly the P₃-ring (me₃Si)(Cl)P₃ · [P(Sime₃)₂] 11 due to elimination of me₃SiCl from [(me₃Si)₂P]₂P–PCl₂.     

Zur Bildung von Disilylphosphino-Element-Verbindungen des C,Si, P

The Formation of Disilylphosphino-Element Compounds of C, Si, P The reactions of (me₃Si)₂PLi · OR₂ a (OR₂ = 1 monoglyme or 2 THF; me = CH₃) with CH₃Cl, CH₂Cl₂, ClCH₂CH₂Cl and ClCH₂? C₆H₅ give the compounds (me₃Si)₂Pme, (me₃Si)₂P? CH₂? P(Sime₃)₂, (me₃Si)₂P? CH₂CH₂Cl, (me₃Si)₂P? CH₂CH₂? P(Sime₃)₂ and (me₃Si)₂P? CH₂C₆H₅ respectively. In the same manner a reacts with me₂SiCl₂ in a molar ratio 1:1 to (me₃Si)₂P? Sime₂Cl and in a molar ratio 2:1 to (me₃Si)₂P? Sime₂? P(Sime₃)₂ b . The compound b decomposes to [me₃SiP? Sime₂]₂ and (me₃Si)₃P at 220°C. In the reactions of a with ClP(C₆H₅)₂ and ClPme₂ the compounds (me₃Si)₂P? P(C₆H₅)₂ and (me₃Si)₂P? Pme₂, respectively, are obtained. a reacts with HgCl₂ to (me₃Si)₂P? P(Sime₃)₂. (me₃Si)₃P can be cleaved with ClP(C₆H₅)₂ and ClPme₂ yielding (me₃Si)₂P? P(C₆H₅)₂ and (me₃Si)₂P? Pme₂, respectively. The ¹H- and ³¹P-n.m.r. and mass spectroscopic data are reported.     

Bildung siliciumorganischer Verbindungen. 85 [1]. Bildung,Reaktionen und Struktur des 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butans

me₃Si? CCl₂?Sime₂Cl (me ? CH₃) läßt sich mit n-buLi (bu ? C₄H₉) bei–100°C (Lösungsmittel THF/Äther) in me₃Si? CCl(Li)? Sime₂Cl a überführen. das mit meJ me₃Si? CClme? Sime₂Cl bildet. Wird a in Abwesenheit eines Abfangreagenzes langsam erwärmt, so bildet sich unter Abspaltung von LiCl (Cl aus der SiCl-Gruppe) über eine reaktive Zwischenstufe des Bicyclobutans b . Die Struktur von b ist durch NMR-Untersuchung, Röntgenstrukturanalyse und Abbaureaktionen gesichert. Mit HBr bzw. CH₃OH werden die Si? C-Bindungen der Dreiringe in b gespalten, so daß sich me₃Si? CH₂? C(Sime₂X)₂Sime₃ (X ? Br, OCH₃) bildet. Formation of Organosilicon Compounds. 85. Formation, Reactions, and Structure of 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butane me₃Si? CCl₂? Sime₂Cl (me ? CH₃) with n-buLi (bu ? C₄H₉) at –100°C (solvent: THF/ether) yields me₃Si? CCl(Li)? Sime₂Cl a , which forms me₃Si? CClme? Sime₂Cl with meI. By warming a slowly in absence of any trapping reagent the bicyclobutane b is obtained via a reactive intermediate under elimination of LiCl (Cl from the SiCl group). The structure of b is established by nmr investigations, X-ray structure determination and chemical derivatisation.     

Monolithinierte Silylphosphane

Monolithium Silylphosphanes We report a convenient method for preparation of (me₃Si)₂PLi-etherates (me = CH₃) using the cleavage of (me₃Si)₃P with butyllithium. If monoglyme is used as a solvent the reaction occurs at ?40°C according to equation If other ethers are applied the crystalline adducts (me₃Si)₂PLi · 1 triglyme, (me₃Si)₂PLi · 2 THF are formed. In the presence of less polar solvents e.g. dioxane or diethylether the cleavage reaction occurs on heating only; in nonpolar solvents e.g. toluene or pentane no cleavage is observed. In monoglyme (me₃Si)₃P undergoes a cleavage reaction at ?40°C with butyllithium, at ?20°C with methyllithium, with LiPHme and LiP(C₂H₅)₂ at 0°C forming (me₃Si)₂PLi · 1 monoglyme. The reaction of (me₃Si)₂PH with butyllithium in cyclopentane gives (me₃Si)₂PLi which is free of any coordinated ether. (me₃Si)₂PH and meLi react at ?40°C in (C₂H₅)₂O as a solvent yieling (me₃Si)₂PLi · 0.5 (C₂H₅)₂O.     

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.     

Bildung siliciumorganischer Verbindungen. XXXI. Synthese des Brme2Si?CH2?Sime2?CC?Sime2?CH2-Sime2Br und dessen Abbau mit HBr

The synthesis of C₆H₅me₂Si? CH₂? Sime₂? C?C? Sime₂? CH₂? Sime₂C₆H₅ (a) is described, which forms Brme₂Si? CH₂? Sime₂? C?C? Sime₂? CH₂-Sime₂Br(b) with HBr. The reaction of (b) with HBr (1–4 moles at ?78°C) yields Brme₂Si? CH₂? Sime₂Br, as well as 1,2-dibromo-ethane (main products) and Brme₂Si? CH₂/? Sime₂CH = CHBr, Brme₂Si? CH₂? Sime₂CH₂? CHBr₂.     

Bildung siliciumorganischer Verbindungen. 74. Synthese und NMR-Spektren von Si-methylierten und -chlorierten 2,2-Dichloro-1,3-disilapropanen und 2-Methyl-2-chloro-1,3-disilapropanen

Formation of Organosilicon Compounds. 74. Synthesis and NMR-Spectra of Si-methylated and -chlorinated 2,2-Dichloro-1,3-disilapropanes and 2-Methyl-2-chloro-1,3-disilapropanes The compounds me₃Si? CCl₂? Sime_nCl_3?n (n = 1–3; me = CH₃) are synthesized by reaction of me₃Si? CCl₂Li (formed from me₃Si? CCl₂H with n-buLi, bu = butyl) with the appropriate methylchlorosilanes. The compounds Clme₂Si? CCl₂? Sime_nCl_3?n are obtained by analogous reactions of (C₆H₅)me₂Si? CCl₂Li, cleavage of the Si-phenyl group with bromine and conversion of the Si? Br to the Si? Cl group with HCl in PCl₃. The 2-methyl-2-chloro-1,3-disilapropanes are synthesized by lithination of the CCl₂ group of 2,2-dichloro-1,3-disilapropanes, followed by reaction with meI. (Clme₂Si)₂CmeCl is obtained from (C₆H₅me₂Si)₂CCl₂ by reaction with n-buLi to (C₆H₅me₂Si)₂ CClLi, which forms (C₆H₅me₂Si)CClme with meI. Cleavage with bromine to (Brme₂Si)₂CClme and reaction with HCl/PCl₃ leads to the expected compound. The influence of the substitution on the ¹H, ¹³C and ²⁹Si NMR spectra is investigated.     

Bildung siliciumorganischer Verbindungen. LVI. Reaktionen Si- und C-chlorierter 1,3,5-Trisilapentane mit CH3MgCl

Formation of Organosilicon Compounds. LVI. Reactions of Si- and C-Chlorinated 1,3,5-Trisilapentanes with CH₃MgCl (Cl₃Si? CCl₂)₂SiCl₂ (1) reacts with an excess of meMgCl (me = CH₃) forming me₃Si? C?C? Sime₃ (2), Sime₄, H₂C?C(Sime₃)[CH(Sime₃)₂] (3) as main products and (me₃Si)₂C? CH(Sime₃) and as by-products. The cleavage reaction of (1) to (2) and (3) does not occur when the meMgCl-concentration is lowered. The reaction is started by the formation of a GRIGNARD reagent at a CCl-group in compound (1). Cl₃Si? CCl₂? SiCl₂? CH₂? SiCl₃ forms with ; me₃Si? CCl₂? SiCl₂? CHCl? SiCl₃ forms (me₃Si)₂C?CH(Sime₃). A reaction sequence is given.     

Bildung siliciumorganischer Verbindungen. 89. Selektive Photobromierung von Si-methylierten Carbosilanen

Formation of Organosilicon Compounds. 89. Selective Photobromination of Si-methylated Carbosilanes A selective photobromination of the C atoms in the skeleton of Si-methylated carbosilanes is reported. (me₃Si? CH₂)₂Sime₂ reacts to me₃Si? CBr₂? Sime₂? CH₂? Sime₃ in good yields (me = CH₃); the second CH₂ group is considerably slower brominated. Photobromination of (me₂Si? CH₂)₃ consecutively yields a and b . Also from (me₂Si? CH₂)₄ the derivative with one CBr₂ group is accessible. Bromination of tertiary CH groups is highly preferred; this is shown by the selective formation of c . The C-bromination of SiBr-substituted carbosilanes is significantly more difficult; nevertheless (Brme₂Si)₂CH₂ selectively forms (Brme₂Si)₂CBr₂. Brme₂Si? CH₂? Sime₂? CH₂? Sime₃ forms Brme₂Si? CH₂? Sime₂? CBr₂? Sime₃, i. e., only the CH₂ group non-adjacent to SiBr is attacked. The formation of CHBr groups could not be detected. Higher temperatures and longer reaction times increase the formation of polymers.     

Bildung und Eigenschaften von Li2P7R (R = Si(CH3)3, CH3, C(CH3)3)

Formation and Properties of Li₂P₇R (R = Si(CH₃)₃, CH₃, C(CH₃)₃) The reaction of P₇(Sime₃)₃ with Li₃P₇ in the molar ratio of 2:1 yields LiP₇(Sime₃)₂, and in the molar ratio of 1:2 Li₂P₇Sime₃ is formed. Li₂P₇me and Li₂P₇Cme₃ (me = CH₃) are obtained by reaction of white phosphorus with Lime, or LiCme₃, respectively [2]. The compounds Li₂P₇R (R = Sime₃, Cme₃, me) show typical valence tautomerism, as established by ³¹P-n.m.r. spectroscopy at various temperatures. Also LiP(Sime₃)₂ transforms P₇(Sime₃)₃ to yield Li₂P₇Sime₃ but in this reaction considerable cleavage of P? P bonds occurs, too.     

Bildung siliciumorganischer Verbindungen. LVIII. Die Synthese eines Carbosilans mit Propellan-Struktur

Formation of Organosilicon Compounds. LVIII. Synthesis of a Carbosilane with Propellane Structure 1 (· ? C resp. CH₂; x ? Si(CH₃)₂ resp. Si) is formed by a coupling reaction of BrSi(CH₂? Sime₂? CH₂? Sime₂Br)₃ 2 with CCl₄ and Li. The reaction of C₆H₅me₂Si? CH₂Li with Clme₂Si? CH₂Br leads to C₆H₅me₂Si? CH₂? Sime₂? CH₂Br. Metallation with lithium and succeeding reaction with Cl₃SiC₆H₅ produces compound C₆H₅Si(CH₂? Sime₂? CH₂? Sime₂C₆H₅)₃, which than forms 2 by cleavage with bromine.     

Bildung und Reaktionen silylierter Triphosphane

Formation and Reactions of Silylated Triphosphanes Silylated triphosphanes, containing primary P(SiMe₃)₂, P(SiMe₃)CMe₃, or P(SiMe₃) Me endgroups and secondary =PCl, =PH, =PLi, =PSiMe₃, or =PCMe₃ groups were prepared by firstly reacting PCl₃ with P(SiMe₃)₂R (R = CMe₃, Me) and subsequently by substituting the diphosphanes R(Me₃Si)P—PCl₂ with LiP(SiMe₃)R′ (R′ = SiMe₃, CMe₃, Me) Such triphosphanes, containing both =PCI and =PSiMe₃ groups decompose at room temperature. Stable products, however, were isolated after immediately derivating the 2-chloro-triphosphanes at ? 78°C with LiCMe₃. Among the competing reactions:

• 1 =PC1 substitution yielding the =PCMe, group.
• 2 Cl/Li exchange forming the phosphides =PLi and Ne,CCl,
• 3 consecutive reactions of the phosphides, producing the =PH derivatives -L iso-butene + LiCl with Me₃CCI, or the =PSiMe₃ derivatives with Me₃SiCl, respectively,

the formation of secondary =PI1 groups is favored by sterically requiring groups, –SiMe, or -CMe ₃ , at the primary P atoms; whereas Me groups enable the substitution of the secondary P atoms by SiMe ₃ or CMe ₃ . Pure 2-Li-triphosphides were readily obtained from the =PH derivatives with LiBu in n-pentane. In ethers these phosphides eliminate (Me ₃ Si) ₃ P, LiP(SiMe ₃ ) ₂ , or (Me ₃ C)P(SiMe ₃ ) ₂ , yielding P-rich compounds in a complex reaction sequence. For instance, Li ₃ P ₇ is generated as main-product from [(Me ₃ Si) ₂ P] ₂ PLi, the cyclotetraphosphane P ₄ (CMe ₃ ) ₃ SiMe ₃ from (Me ₃ Si) ₂ P-P(Li)-P(SiMe ₃ )CMe ₃ , and the cyclic pentaphosphide LiP ₅ (CMe ₃ ) ₄ from [(Me ₃ C)(Me ₃ Si)P] ₂ PLi.     

Bildung siliciumorganischer Verbindungen. 67. Untersuchungen zur metallorganischen Synthese Si-methylierter und C-chlorierter Carbosilane über Chlorcarbenoide

Formation of Organosilicon Compounds. 67. Studies of Metallorganic Synthesis of Si-methylated and C-chlorinated Carbosilanes Using Chlorocarbenoids Synthesis and reactions of C₆H₅me₂Si? CCl₂H (A), (H₅C₆me₂Si)₂CCl₂ (B), and me₂Si(CCl₂H)₂ (C) were investigated in order to find conditions for the synthesis of C-functional carbosilanes via chlorocarbenoids. (A) and (B) react with n-butyl-Li(buLi) (?100°C/THF/ether/pentane) yielding H₅C₆me₂Si? CCl₂Li and (H₅C₆me₂Si)CClLi, respectively. These lithium reagents form (B) and(H₅C₆me₂Si)₃CCl with H₅C₆me₂SiCl. In the reaction of (H₅C₆me₂Si)₃CCl with lithium (H₅C₆me₂Si)₃CLi (D) is obtained. (D) forms with H₂O/HCl the compound (H₅C₆me₂Si)₃CH which is cleaved by HBr yielding (Brme₂Si)₃CH. (C) gives LiCCl₂? Sime₂(CCl₂H) with buLi (molar ratio 1:1) in a low temperature reaction. Clme₂Si? CCl₂? Sime₂(CCl₂H) is formed in the reaction of LiCCl₂? Sime₂? CCl₂H with Sime₂CCl₂ (yield >90%). Reacting (C) and buLi (1:3) and treating this solution with Sime₂CI₂ gives (ClSime₂)₂C?CH Sime₂Cl (>85%) via a monosilacyclopropane intermediate. In the inverse reaction, if (C) is added to buLi, (HCCl₂)me₂SiC?Sime₂(CCl₂H) is one of the isolated reaction products. If buLi is added to (C) (2:l) and this solution is treated with Sime₃Cl, compounds me₃Si? CCL₂? Sime₂? CCL₂H, me₃Si? CClH? Sime₂(CCl₂H), (me₃Si? CC1₂)₂Sime₂, me₃Si? CHCI? Sime₂? CC1₂? Sime₃ are isolated. The same products were obtained in the reaction of me₃Si? CCl₂? Sime₂? CCl₂H with buLi and me₃SiCl.     

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.     

Cyclische Diazastannylene. XIX. Zur Reaktion eines Bis(amino)germylens, -stannylens und -plumbylens mit Phosphortrichlorid und 2, 3-Dimethyl-1, 3-butadien

Cyclic Diazastannylenes. XIX. Reaction of a Bis(amino)germylene, -stannylene, and -plumbylene with Phosphorus Trichloride and 2, 3-Dimethyl-1, 3-butadiene The cyclic bis(amino)germylene 1 reacts with PCl₃ by a threefold insertion into the P? Cl bonds and forms [Me₂Si(N^tBu)₂Ge(Cl)]₃P( 4 ). 4 crystallizes in the triclinic space group P1 with cell dimensions: a = 1955.2(9), b = 1378.3(6), c = 1074.3(5) pm, α = 90.4(1), β = 121.6(1), γ = 97.9(1)° and Z = 2. X-ray structure analysis was used to show, that the molecule 4 has approximately C_3h point symmetry. All germanium, chlorine, and silicon atoms are quite accurately situated in a plane, perpendicular to which the GeN₂Si-rings are erected. The only heavy atom which disturbs the mirror symmetry is the phosphorus, which is on the top of a flat pyramide (Ge? P? Ge = 115.0°). Important bond lengths (mean values) are: Ge? P = 231.0(4), Ge? N = 182.4(7), Ge? Cl = 217.9(2) and Si? N = 173.6(7) pm. The unusual nearly planar coordination of the phosphorus atom can be explained by the particular steric requirements of the substituents. PCl₃ oxidizes the tin atom in the bis(amino)stannylene 2 by the formation of Me₂Si(N^tBu)₂SnCl₂ ( 5 ); as additional product originates an amorphous solid of analytical composition (PCl)_n. In contrast to 1 and 2 the lead atom     

Untersuchungen zur Metallierung der Cyclophosphane P4(Cme3)3(Sime3), P4(Cme3)2(Sime3)2, P4(Sime3)4

Investigations Concerning the Metallation of the Cyclotetraphosphanes P₄(Cme₃)₃(Sime₃), P₄(Cme₃)₂(Sime₃)₂, and P₄(Sime₃)₄ The reaction of white phosphorus with LiCme₃ and me₃SiCl yields P₄(Sime₃)(Cme₃)₃ 1 . With n-buLi this crystalline cyclotetraphosphane forms the crystalline LiP₄(Cme₃)₃. In the same manner, n-buLi, with trans-P₄(Sime₃)₂(Cme₃)₂ 2 to yields LiP₄(Sime₃)(Cme₃)₂, which in contrast to LiP₄(Cme₃)₃ decomposes within a few hours yielding P(Sime₃)₂n-bu 6 , P(Sime₃)₃ 8 , LiP(Sime₃)₂ 9 and also the cyclic compounds P₄(Sime₃)(Cme₃)₃ 10 , LiP₄(Cme₃)₃ 11 and LiP₃(Cme₃)₂ 12 . The composition of the product mixture depends on the molar ratio of 2 to LiC₄H₉. At a molar ratio of 1:1 11 and 12 are not jet observed. At molar ratios of 1:1.5 and 1:2 P(Sime₃)₃ is not found. The amount of 11 and 12 grows with increasing concentration of n-buLi. On addition of n-buLi the solution of P₄(Sime₃)₄ immediately turns red. Li₃P₇ and Li₂P₇(Sime₃) (among others) are formed so fast that the first intermediates in the lithiation sequence so far could not be elucidated. These results demonstrate clearly that replacement of two me₃Si groups in P₄(Sime₃)₄ by two me₃C groups excludes the rearrangement of LiP₄(Sime₃)(Cme₃)₂ to a P₇-molecule.     

Die Strukturen der Heptahetero-Nortricyclene P7(Sime3)3 und P4(Sime2)3

The Structures of the Heptahetero-Nortricyclenes P₇(Sime₃)₃ and P₄(Sime₂)₃ Tris(trimethylsilyl)heptaphospha-nortricyclene P₇(Sime₃)₃ 1 and Hexamethyl-trisila-tetraphospha-nortricyclene P₄Si₃me₆ 2 are structural analogons to the hetero-nortricyclenes P and P₄S₃. 1 crystallizes in the space group P2₁ with a = 965.7 pm, b = 1746.5 pm, c = 693.3 pm, β = 99.61° and Z = 2 formula units. In the P₇ system tge P? P bond lengths differ functionally, namely 221.4 pm in the three-membered ring, 219.2 pm at the ring atoms and 217.9 pm at the bridgehead atom. The P? Si and Si? C bond lengths are 228.8 pm and 187.8 pm respectively. 2 crystallizes in the space group R3 with a_R = 1129.3 pm, α_R = 50.01° (hexagonal axes: a = 954.7 pm, c = 2956.9 pm) and Z = 2 formula units. In the P₄Si₃ systems the bond lengths are P? P = 220.2 pm, P? Si = 228.3 pm and 224.7 pm (to the bridgehead atom). The Si? C bond lengths are 187.3 pm. The structures are discussed with related compounds.     

Gasphasen-Reaktionen. 92. Thermische HCl-Abspaltung aus Alkyldichlorphosphanen (H3C/H)3C?PCl2 zu Phosphaalkenen (H3C/H)2CPCl und Phosphaalkinen (H3C/H)C≡P

Gasphase Reactions. 92 Thermal Elimination of HCl from Alkyldichlorophosphanes (H₃C/H)₃C? PCl₂ to Phosphaalkenes (H₃C/H)₂C?PCl and Phosphaalkines (H₃C/H)C≡P The alkyldichlorophosphanes H₃C? PCl₂, ClH₂? PCl₂, (H₃C)H₂C? PCl₂ and (H₃C)₂HC? PCl₂ split off HCl on heating in a gasflow under reduced pressure. PE spectroscopic gas analysis proves that under these conditions the short-lived phosphaalkenes H₂C?PCl, (H₃C)H₂C?PCl and – catalyzed by [MgCl₂? MgO/SiO₂]_∞ – (H₃C)₂C?PCl as well as the phosphaalkines HC≡P and (H₃C)C≡P are formed, all of which can be isolated by low temperature condensation. Based on the PES ionization patterns recorded and on the MNDO calculations for their assignment, the π_CP multiple bonds are discussed. The presumable pathway of the HCl elimination is rationalized for (H₃C)H₂C? PCl₂ by an approximate MNDO energy hypersurface.     

Bildung siliciumorganischer Verbindungen. 98. Umsetzung silylierter Phosphorylide mit PCl3

Formation of Organosilicon Compounds. 98. Reaction of Silylated Phosphorus Ylides with PCl₃ The reaction of Si-substituted phosphorus ylides as Me₂Si(CH₂? SiMe₂)₂C?PMe₃Br 1 , Cl₂Si(CH₂? SiCl₂)₂C?PMe₂Cl 2 , and (Cl₃Si)₂C?PMe₂Cl 3 with PCl₃ yields (Cl₂P)₂C?PMe₂Cl 5 by chlorinating cleavage of the Si-ylid-C bond. Besides 5 also (ClMe₂SiCH₂)₂SiMe₂, (Cl₃SiCH₂)₂SiCl₂, resp. SiCl₄ result from the reaction of 1, 2 and 3 with PCl₃. (Cl₂P)₂C?PMe₂Cl forms colourless crystals, mp. 84°C.     

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.