Beiträge zur Chemie des Phosphors. 136 [1]. 31P-Kernresonanzspektren und Struktur der 1,3-Dihalogen-1,2,3-tri-tert-butyltriphosphane X(t-BuP)3X,X = Cl,Br, I

Contributions to the Chemistry of Phosphorus. 136. ³¹P-N.M.R. Spectra and Structure of 1,3-Dihalogen-1,2,3-tri-tert-butyltriphosphanes X(t-BuP)₃X, X = Cl, Br, I The 1,3-dihalogen-1,2,3-tri-tert-butyltriphosphanes (t-BuP)₃Cl₂ ( 1 ), (t-BuP)₃Br₂ ( 2 ), and (t-BuP)₃I₂ ( 3 ), which are formed in the halogenating ring cleavage of tri-tert-butyl-cyclotriphosphane, (t-BuP)₃, by halogens or halogen compounds, favour the erythro, threo configuration by steric reasons. However, the erythro, erythro configurated diastereomer, whose stability depends on the size of the halogen substituents and on the rate of inversion at the phosphorus atoms, is formed initially. The reaction of the erythro, erythro and erythro, threo configurated diastereomers of 1–3 with lithium aluminium hydride leads stereospecifically to the threo, threo and threo, erythro configurated diastereomers of 1,2,3-tri-tert-butyltriphosphane, H₂(t-BuP)₃ ( 4 ), respectively.     

Beiträge zur Chemie des Phosphors. 104. Synthese und Eigenschaften von 1,3-Dihalogen-1,2,3-tritert-butyltriphosphanen (t-BuP)3X2, X = Cl,Br, I

Contributions to the Chemistry of Phosphorus. 104. Synthesis and Properties of 1,3-Dihalogen-1,2,3-tri-tert-butyltriphosphanes (t-BuP)₃X₂, X = Cl, Br, I The halogenating ring-cleavage of tri-tert-butyl-cyclotriphosphane, (t-BuP)₃, by iodine, bromine or phosphorus(V)bromide as well as phosphorus(V)chloride leads to the first 1,3-dihalogen-1,2,3-triorganyltriphosphanes (t-BuP)₃I₂ ( 1 ), (t-BuP)₃Br₂ ( 2 ), and (t-BuP)₃Cl₂ ( 3 ). The 1,2-dihalogen-1,2-di-tert-butyldiphosphanes (t-BuP)₂I₂ ( 4 ), (t-BuP)₂Br₂ ( 6 ), and (t-BuP)₂Cl₂ ( 9 ) as well as the dihalogen-tert-butylphosphanes t-BuPI₂ ( 5 ), t-BuPBr₂ ( 7 ), and t-BuPCl₂ ( 10 ) are formed as by-products. Moreover, the reaction of (t-BuP)₃ with PBr₅ leads to 1-bromo-2,3,4-tri-tert-butyl-cyclo-tetraphosphane, (t-BuP)₃(PBr) ( 8 ). The compounds 1 and 3 could be isolated in a pure state and were characterized in all details. 3 is a reMarkably stable open-chain triphosphane.     

Beiträge zur Chemie des Phosphors. 224. Zur Thermolyse von 1,2-Di-tert-butyldiphosphan, 1,2,3-Tri-tert-butyltriphosphan und Tetra-tert-butylcyclotetraphosphan

Contributions to the Chemistry of Phosphorus. 224. On the Thermolysis of 1,2-Di-tert-butyldiphosphane, 1,2,3-Tri-tert-butyltriphosphane, and Tetra-tert-butylcyclotetraphosphane On disproportionation of 1,2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H (1) , 1,2,3-tri-tert-butyltriphosphane, H₂(t-BuP)₃ (2) , is formed which reacts further at temperatures above 100°C to give 1-(tert-butylphosphino)-2,3,4-tri-tert-butylcyclotetraphosphan, P₅(t-Bu)₄H (4) . Compound 4 reacts with 1 or 2 with lengthening of the P-sidechain to furnish the corresponding 1-(1,2-di-tert-butyldiphosphino)-2,3,4-tri-tert-butylcyclotetraphosphane, P₆(t-Bu)₅H (5) . At temperatures above 170°C, 5 disproportionates into the tetra-tert-butylcyclotetraphosphane, (t-BuP)₄ (3) which is stable up to about 200°C, and the bicyclo[3.1.0]hexaphosphane P₆(t-Bu)₄ from which the polycyclophosphanes P₉(t-Bu)₃ and P₈(t-Bu)₆ arise during the further course of the thermolysis. These products are finally converted through even more phosphorus-rich and more highly condensed t-butylcyclophosphanes into elemental phosphorus. In each reaction step, varying amounts of the monophosphane derivatives t-BuPH₂, (t-Bu)₂PH, and (t-Bu)₃P are formed. The proposed course of the reaction is further substantiated by the pyrolysis products of pure 2 and 3 .     

Beiträge zur Chemie des Phosphors. 129. Synthese und Eigenschaften der Phospha-germa-cyclobutane (t-BuP)2(GePh2)2 und (t-BuP)3GePh2

Contributions to the Chemistry of Phosphorus. 129. Synthesis and Properties of the Phospha-germa-cyclobutanes (t-BuP)₂(GePh₂)₂ and (t-BuP)₃GePh₂ The phospha-germa-cyclobutanes 1,2-di-tert-butyl-3,3,4,4-tetraphenyl-1,2-diphospha-3,4-digerma-cyclob utane, (t-BuP)₂(GePh₂)₂ ( 1 ), and 1,2,3-tri-tert-butyl-4,4-diphenyl-1,2,3-tri-phospha-4-germa-cyclobutan e, (t-BuP)₃GePh₂ ( 2 ), are obtained as main-products of the cyclocondensation of K(t-Bu)P? P(t-Bu)K with Ph₂GeCl₂ under certain reaction conditions. 1 and 2 could be isolated in the pure state and were clearly characterized as the first four-membered P₂Ge₂ and P₃Ge heterocycles, respectively.     

Beiträge zur Chemie des Phosphors. 142. P6(t-Bu)5H – das erste Cyclotetraphosphan mit P2-Seitenkette

Contributions to the Chemistry of Phosphorus. 142. P₆(t-Bu)₅H – the First Cyclotetraphosphane with a P₂ Side Chain The thermolysis of 1, 2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H, leads to formation of the hitherto unknown hexaphosphane P₆(t-Bu)₅H ( 1 ). In the first instance the iso-P₅H₅ derivative P₅(t-Bu)₄H [3] is formed, which reacts further with H₂(t-BuP)₂ or H₂(t-BuP)₃ yielding 1 . Compound 1 has been isolated in the pure state and structurally characterized as 1-(1,2-di-tert-butyldiphosphino)-2, 3, 4-tri-tert-butyl-cyclotetraphosphane, i. e. as a four-membered ring compound with a P₂ side chain. Due to the chirality of the P atoms in the side chain, 1 exists as a mixture of two configurational isomers, the threo-and the erythro-form.     

Beiträge zur Chemie des Phosphors. 122. 1,2,3,4-Tetra-tert-butyl-tetraphosphan,H(PBut)–(PBut)2–(PBut)H – ein stabiles kettenförmiges Tetraphosphan

Contributions to the Chemistry of Phosphorus. 122. 1,2,3,4-Tetra-tert-butyltetraphosphane, H(PBu^t)—(PBu^t)₂—(PBu^t)H — a Stable Chain-type Tetraphosphane The alcoholysis of 1,2,3,4-tetra-tert-butyl-1,4-bis(trimethylsilyl)-tetraphosphane, (Me₃Si)₂(PBu^t)₄, yields the hitherto unknown title compound 1 , which is the first stable partially substituted derivative of n-tetraphosphane(6), n-P₄H₆. 1 can also be obtained in the reaction of 1,4-dipotassium-1,2,3,4-tetra-tert-butyl-tetraphosphide, K₂(PBu^t)₄, with tert-butylchloride. In solution 1 forms the three diastereomers 1d (threo/d,l/threo), 1f (erythro/threo/threo), and 1b (erythro/d,l/erythro) in a ratio of about 10:5:1. Their correlation to the ³¹P-NMR spectroscopically observed spin systems results from the preferred trans arrangement of neighbouring tert-butyl groups as well as from the dependence of the ¹J(PP) coupling constant on dihedral angles and from the ³J(PP) long range coupling constant. The configuration and conformation of the existent isomers is determined by the all-trans arrangement of the tert-butyl groups and by the tendency of vicinal free electron pairs to assume a gauche conformation.     

Beiträge zur Chemie des Phosphors. 152. Funktionalisierte Cyclotriphosphane des Typs (t-BuP)2PX (X = K,SiMe3, SnMe3, Cl,Br, PCl2, P(t-Bu)Cl,P(t-Bu)I)

Contributions to the Chemistry of Phosphorus. 152. Functionalized Cyclotriphosphanes of the Type (t-BuP)₂PX (X = K, SiMe₃, SnMe₃, Cl, Br, PCl₂, P(t-Bu)Cl, P(t-Bu)I) Functionalized cyclotriphosphanes of the type (t-BuP)₂PX with electropositive or electronegative substituents X have been prepared on various synthetic routes: KP(t-BuP)₂ ( 1 ) can be obtained in 50–55 per cent purity by reacting (t-BuP)₄ or (t-BuP)₃ with potassium. Reaction of 1 with Me₃SiCl or Me₃SnCl leads to the cyclotriphosphanes (t-BuP)₂PSiMe₃ ( 2 ) and (t-BuP)₂PSnMe₃ ( 3 ), respectively; the cyclocondensation of Cl(t-Bu)P? P(t-Bu)Cl with P(SnMe₃)₃, however, is more convenient for the preparation of 3 . In a similar way the halogenated compounds (t-BuP)₂PCl ( 4 ) and (t-BuP)₂PBr ( 5 ) can be obtained from Me₃Sn(t-Bu)P? P(t-Bu)SnMe₃ ( 6 ) and PX₃ (X = Cl, Br). The phosphino-substituted cyclotriphosphanes (t-BuP)₂P? PCl₂ ( 7 ), (t-BuP)₂P? P(t-Bu)Cl ( 8 ), and (t-BuP)₂P? P(t-Bu)I ( 9 ) are accessible by the reaction of 3 with PCl₃ and t-BuPX₂ (X = Cl, I), respectively. 2–9 could be obtained free from phosphorus-containing by-products and were ³¹P-NMR spectroscopically characterized as compounds with a cyclic P₃ skeleton.     

Beiträge zur Chemie des Phosphors. 128. Synthese des Diphosphastanna-cyclopropans (t-BuP)2Sn(t-Bu)2

Contributions to the Chemistry of Phosphorus. 128. Synthesis of the Diphosphastanna-cyclopropane (t-BuP)₂Sn(t-Bu)₂ The first three-membered P₂Sn heterocycle, 1,2,3,3-tetra-tert-butyl-1,2,3-diphosphastanna-cyclopropane (1,2,3,3-tetra-tert-butyl-1,2,3-diphosphastannirane) ( 1 ), has been synthesized by [2+1] cyclocondensation of K(t-Bu)P—P(t-Bu)K with (t-Bu)₂SnCl₂. 1 is stable at room temperature. Besides, (t-BuP)₂[Sn(t-Bu)₂]₂ ( 2 ), (t-BuP)₄Sn(t-Bu)₂ ( 3 ), and (t-BuP)₄ are formed. In the reaction with Et₂SnCl₂, the six-membered ring compound [(t-BuP)₂SnEt₂]₂ ( 4 ) is the main-product; the four- and five-membered cyclostannaphosphanes (t-BuP)₃SnEt₂ ( 5 ) and (t-BuP)₃(SnEt₂)₂ ( 6 ) are also formed. 1 could be isolated in the pure state and has been unambiguously characterized as a three-membered heterocycle with a P₂Sn skeleton. The ³¹P-NMR parameters of the other new cyclostannaphosphanes 2–6 are reported.     

Beiträge zur Chemie des Phosphors. 138. P5(t-Bu)4H – das erste Derivat von iso-P5H5

Contributions to the Chemistry of Phosphorus. 138. P₅(t-Bu)₄H — the First Derivative of iso-P₅H₅ The thermolysis of 1,2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H, yields under suitable conditions the compound P₅(t-Bu)₄H ( 1 ) as the main product. Besides, the tert-butylphosphanes t-BuPH₂, P₆(t-Bu)₅H ( 2 ), H₂(t-BuP)₃, and (t-BuP)₄ are formed. 1 has been isolated in the pure state and structurally characterized as 1-(tert-butylphosphino)-2,3,4-tri-tert-butyl-cyclotetraphosphane. Hence, compound 1 is a derivative of iso-P₅H₅ with a branched phosphorus skeleton built up by a four-membered ring and a phosphorus side chain.     

Beiträge zur Chemie des Phosphors. 101. Synthese und Eigenschaften von Diphosphaboriranen (t-BuP)2BNR2 und (t-BuP)2BNR1R2

Contributions to the Chemistry of Phosphorus. 101 Synthesis and Properties of Diphosphaboriranes (t-BuP)₂BNR₂ and (t-BuP)₂BNR¹R² The reaction of K(t-Bu)P? P(t-Bu)K with diorganylaminodichloroboranes under suitable conditions leads to the new 1,2-di-tert-butyl-3-diorganylamino-1,2,3-diphosphaboriranes (-1,2-diphospha-3-boracyclopropanes) (t-BuP)₂BNR₂ ( 2 , 7 ) and (t-BuP)₂BNR¹R² ( 3 — 6 ), respectively. The P₂B three-membered heterocycles 2 — 5 can be isolated in good yields. They are relatively stable against dimerization to the corresponding phosphorus boron six-membered ring compounds with opposite boron atoms. The rate of dimerization depends on steric and electronic influences of the substituents at the three-membered ring. All NMR spectroscopic results are only consistent with a structure in which the B and N atoms show planar coordination and are connected by a partial double bond.     

Beiträge zur Chemie des Phosphors. 144. Synthese und Eigenschaften des Hexaphospha-3-germaspiro[2.4]heptans (t-BuP)2Ge(t-BuP)4

Contributions to the Chemistry of Phosphorus. 144. Synthesis and Properties of the Hexaphospha-3-germaspiro[2.4]heptane (t-BuP)₂Ge(t-BuP)₄ The cyclocondensation of K(t-Bu)P? P(t-Bu)K with germanium tetrachloride in the molar ratio of 2:1 yields the novel spirocyclic compound 1,2,4,5,6,7-hexa-tert-butyl-1,2,4,5,6,7-hexaphospha-3-germaspiro[2.4]heptane, (t-BuP)₂Ge(t-BuP)₄ ( 1 ). Besides considerable amounts of (t-BuP)₄ are formed and occasionally some (t-BuP)₃ can be found. 1 could be isolated in the pure state and has been NMR-spectroscopically characterized as a spirocyclic compound with a P₂GeP₄ skeleton.     

Beiträge zur Chemie des Phosphors. 123. Synthese und Eigenschaften der Diphosphagermirane (t-BuP)2GePh2 und (t-BuP)2GeEt2

Contributions to the Chemistry of Phosphorus. 123. Synthesis and Properties of the Diphosphagermiranes (t-BuP)₂GePh₂ and (t-BuP)₂GeEt₂ The first three-membered P₂Ge heterocycles, 1,2-di-tert-butyl-3, 3-diphenyl-1, 2, 3-diphosphagermirane, (t-BuP)₂GePh₂ (1) , and 1, 2-di-tert-butyl-3, 3-diethyl-1, 2, 3-diphosphagermirane, (t-BuP)₂GeEt₂ (2) , were synthesized by [2+1] cyclocondensation reactions of K(t-Bu)P—P(t-Bu)K with diphenylgermanium dichloride and diethylgermanium dichloride, respectively. The four-, five-, and six-membered cyclogermaphosphanes (t-BuP)₂(GePh₂)₂ (3) , (t-BuP)₃GeR₂ ( 6 R = Ph; 7 R = Et), (t-BuP)₄GePh₂ (5) and (t-BuP)₄(GePh₂)₂ (4) as well as (t-BuP)₄ are formed as by-products. The diphosphagermiranes 1 and 2 could be isolated in 93 and 100% purity, respectively, and were unambiguously characterized as compounds with a cyclic P₂Ge skeleton. The ³¹P-NMR parameters of the cyclogermaphosphanes 3—7 are reported.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 2. Die Kristall- und Molekülstruktur des Diphosphaborirans (t-BuP)2BNEt2

Structural Chemistry of Phosphorus-containing Chains and Rings. 2. Crystal and Molecular Structure of the Diphosphaborirane (t-BuP)₂BNEt₂ The three-membered P₂B-heterocycles 1,2-di-tert-butyl-3-diethylamino-1,2,3-diphosphaborirane, (t-BuP)₂BNEt₂, crystallizes triclinic in the space group P1 with a = 935.5 pm, b = 985.4 pm, c = 987.4 pm,α = 81.55°, β = 89.40°, γ =69.07°, and Z = 2 formula units. The main structural feature is a short B? N-bond length (138.2 pm) inside a plane P₂BN-group. The endocyclic bond angles are 54.0° on phosphorus and 72.0° on boron. The (average) bond lengths are P? P = 222.5 pm, P? C = 189.5 pm, P? B = 189.3 pm, B? N = 138.2 pm, N? C = 147.2 pm, C? C = 152.6 pm, and C? H = 98 pm. The geometry of the substituents ethyl and tert-butyl is quite normal.     

Lithiumhydridosilylamide R2(H)SiN(Li)R′ – Darstellung,Eigenschaften und Kristallstrukturen

Lithium Hydridosilylamides R₂(H)SiN(Li)R′ – Preparation, Properties, and Crystal Structures The hydridosilylamines R₂(H)SiNHR′ ( 1 a : R = CHMe₂, R′ = SiMe₃; 1 b : R = Ph, R′ = SiMe₃; 1 c : R = CMe₃, R′ = SiMe₃; 1 d : R = R′ = CMe₃) were prepared by coammonolysis of chlorosilanes R₂(H)SiCl with Me₃SiCl ( 1 a , 1 b ) as well as by reaction of (Me₃C)₂(H)SiNHLi with Me₃SiCl ( 1 c ) and Me₃CNHLi with (Me₃C)₂(H)SiCl ( 1 d ). Treatment of 1 a–1 d with n-butyllithium in equimolar ratio in n-hexane resulted in the corresponding lithiumhydridosilylamides R₂(H)SiN(Li)R′ 2 a–2 d , stable in boiling m-xylene. The amines and amides were characterized spectroscopically, and the crystal structures of 2 b–2 d were determined. The comparison of the Si–H stretching vibrations and ²⁹Si–¹H coupling constants indicates that the hydrogen atom of the Si–H group in the amides has a high hydride character. The amides are dimeric in the solid state, forming a planar four-membered Li₂N₂ ring. Strong (Si)H … Li interactions exist in 2 c and 2 d , may be considered as quasi tricyclic dimers. The ‘‘NSiHLi rings”︁”︁ are located on the same side of the central Li₂N₂ ring. In 2 b significant interactions occurs between one lithium atom and the phenyl substituents. Furthermore all three amides show CH₃ … Li contacts.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 1. Die KristallStruktur des Diphosphasilirans (t-BuP)2SiPh2

Structural Chemistry of Phosphorus-containing Chains and Rings. 1. Crystal Structure of the Diphosphasilirane (t-BuP)₂SiPh₂ The three-membered P₂Si-heterocycle 1, 2-di-tert-butyl-3, 3-diphenyl-1, 2, 3-diphosphasilirane (t-BuP)₂SiPh₂ crystallizes monoclinic in the space group P2₁ with a = 1041.2 pm, b = 882.3 pm, c = 1158.1 pm, β = 91.33° and Z = 2 formula units. A special structural feature is the regular triangle built up by two P and one Si. Therefore the endocyclic bond angle at Si is as low as 60°. The average bond lengths are P? P = 222.6 pm, P? Si = 222.5 pm, P? C = 190.8 pm, Si? C = 186.6 pm, (C? C )ph = 139.0 pm, ( C? C )_t-Bu = 151.7 pm. The geometry of the substituents phenyl and tert-butyl is quite normal, the last ones are slightly disordered.     

Zum Reaktionsverhalten lithiierter Aminosilane RR′ Si(H)N(Li)SiMe3

The Reaction Behaviour of Lithiated Aminosilanes RR′Si(H)N(Li)SiMe₃ The bis(trimethylsilyl)aminosubstituted silances RR′Si(H)N(SiMe₃)₂ 11 – 16 (R,R′ = Me, Me₃SiNH, (Me₃Si)₂N) are obtained by the reaction of the lithium silylamides RR′Si(H)N(Li)SiMe₃ 1 – 10 (R,R′ = Me₃SiNLi, Me, Me₃SiNH, (M₃Si)₂N) with chlorotrimethylsilane in the polar solvent tetrahydrofurane (THF). In the reaction of the lithium silylamides [(Me₃Si)₂N]₂(Me₃SiNLi)SiH 10 with chlorotrimethylsilane in THF the rearranged product 1,1,3-tris[bis(trimethylsilyl)amino]-3-methyl-1,3-disila-butane [(Me₃Si)₂N]₂Si(H)CH₂SiMe₂N(SiMe₃)₂ 17 is formed. The reaction of the lithium silyamides RR′ Si(H)N(Li)SiMe₃ 1 – 3 (1: R = R′ = Me; 2: R = Me, R′ = Me₃SiNH; 3: R = Me, R′ = Me₃SiNLi) with chlorotrimethylsilane in the nonpolar solvent n-hexane gives the cyclodisilazanes [RR′ Si? NSiMe₃]₂ 18 – 22 (R = Me, Me₃SiNH, (Me₃Si)₂N; R′ = Me, Me₃SiNH, (Me₃Si)₂N, N(SiMe₃)Si · Me(NHSiMe₃)₂) and trimethylsilane. The lithium silylamides 4 , 5 , 6 , 9 , 10 (4: R = R′ = Me₃SiNH; 5: R = Me₃SiNH, R′ = Me₃SiNLi; 6: R = R′ = Me₃SiNLi; 9: R = (Me₃Si)₂N, R ′ = Me₃SiNLi; 10: R = R′ = (Me₃Si)₂N) shows with chlorotrimethylsilane in n-hexane no reaction. The crystal structure of 17 and 21 are reported.     

Beiträge zur Chemie des Phosphors. 94. Tetraphenyl-cyclotetraphosphan, (PPh)4, und 1,2,3-Triphenyl-4-tert-butyl-cyclotetraphosphan, (PPh)3(PBut)

Contributions to the Chemistry of Phosphorus. 94. Tetraphenyl-cyclotetraphosphane, (PPh)₄, and 1,2,3-Triphenyl-4-tert-butyl-cyclotetraphosphane, (PPh)₃(PBu^t) The homocyclic four-membered phosphorus ring compounds tetraphenyl-cyclotetra-phosphane, (PPh)₄ ( 1 ), and l,2,3-triphenyl-4-tert-butyl-cyclotetraphosphane, (PPh)₃(PBu^t) ( 2 ), are obtained as main products by [3+l]-cyclocondensation of K(Ph)P? P(Ph)? P(Ph)K or Me₃Si(Ph)P? P(Ph)? P(Ph)SiMe₃ with PhPCl₂ or Bu^tPCl₂ respectively under suitable reaction conditions. At room temperature in solution 1 rearranges mostly to the oligomeric (PPh)₅, whereas 2 is remarkably stable. The ³¹P-NMR parameters of the mixed substituted four-membered ring compound 2 are reported and discussed.     

Beiträge zur Chemie des Phosphors. 106. Synthese und Eigenschaften des Diphosphacyclopropans (t-BuP)2CHMe

Contributions to the Chemistry of Phosphorus. 106. Synthesis and Properties of the Diphosphacyclopropane (t-BuP)₂CHMe The new 1,2-di-tert-butyl-3-methyl-1,2-diphosphacyclopropane (1,2-di-tert-butyl-3-methyl-diphosphirane), (t-BuP)₂CHMe ( 1 ), is obtained by reacting K(t-Bu)P? P(t-Bu)K with 1,1-dichloroethane under suitable conditions. 1 can be isolated by high vacuum distillation and is stable for months when stored under inert gas at room temperature. Particularly, no dimerization to the corresponding 1,2,4,5-tetraphosphacyclohexane takes place. The NMR parameters indicate an increase of the exocyclic bond angles compared to (t-BuP)₂CH₂. The signs of all CP coupling constants have been determined by spin tickling experiments. The ²J(CCP)-coupling of the methyl group at the ring carbon depends strongly on the dihedral angle.     

The Synthesis of tert‐Butyl(dichloromethyl)bis(trimethylsilyl)silane and (Dibromomethyl)ditert‐butyl(trimethylsilyl)silane and their Reactions with Organolithium Derivatives

tert‐Butyl(dichloromethyl)bis(trimethylsilyl)silane ( 4 ), prepared by the reaction of tert‐butylbis(trimethylsilyl)silane with trichloromethane and potassium tert‐butoxide, reacted with 2,4,6‐triisopropylphenyllithium (TipLi) (molar ratio 1 : 2) at room temperature to give (after hydrolytic workup) the silanol tBu(2,4,6‐iPr₃C₆H₂)Si(OH)–CH(SiMe₃)₂ ( 15 ). The formation of 15 is discussed as proceeding through the indefinitely stable silene tBu(2,4,6‐iPr₃C₆H₂)Si=C(SiMe₃)₂ ( 13 ), but attempts to isolate the compound failed. Treatment of (dibromomethyl)ditert‐butyl(trimethylsilyl)silane ( 7 ), made from tBu₂(Me₃Si)SiH, HCBr₃ and KOtBu, with methyllithium (1 : 3) at –78 °C afforded tBu₂MeSi–CHMeSiMe₃ ( 19 ); 7 and phenyllithium (1 : 3) under similar conditions gave tBu₂PhSi–CH₂SiMe₃ ( 20 ). The reaction paths leading to 15 , 19 and 20 are discussed. Reduction of 7 with lithium in THF produced the substituted ethylene tBu₂(Me₃Si)SiCH=CHSitBu₂SiMe₃ ( 21 ). For 21 the results of an X‐ray structural analysis are given.     

Synthesis and Structural Characterization of Some Novel Trialkylsilyl‐substituted Lithium Benzyl Complexes [Li(tmeda)][CHRSiMe2R′] (R = Ph, 3,5‐Me2C6H3; R′ = Me,tBu, Ph)

The reactions of PhCH₂SiMe₃ ( 1 ), PhCH₂SiMe₂^tBu ( 2 ), PhCH₂SiMe₂Ph ( 3 ), 3,5‐Me₂C₆H₃CH₂SiMe₃ ( 4 ), and 3,5‐Me₂C₆H₃CH₂SiMe₂^tBu ( 5 ) with ⁿBuLi in tetramethylethylenediamine (tmeda) afford the corresponding lithium complexes [Li(tmeda)][CHRSiMe₂R′] (R, R′ = Ph, Me ( 6 ), Ph, ^tBu ( 7 ), Ph, Ph ( 8 ), 3,5‐Me₂C₆H₃, Me ( 9 ), and 3,5‐Me₂C₆H₃, ^tBu ( 10 )), respectively. The new compounds 5 , 7 , 8 , 9 and 10 have been characterized by ¹H and ¹³C NMR spectroscopy, compounds 7 , 8 and 9 also by X‐ray structure analysis.