Reaktionen von Trimethylsiloxychlorsilanen (Me3SiO)Me2−nPhnSiCl (n=0,1,2) mit Lithium—Bildung von Trimethylsiloxy-substituierten Silyl- und Disilanyllithiumver- bindungen sowie Di- und Trisilanen

Abstract

Abstract The trimethylsiloxychlorosilanes (Me 3 SiO)Me 2− n Ph n SiCl ( 1 : n = 0; 2 : n = 1; 3 : n = 2) were allowed to react with lithium metal in tetrahydrofuran (THF) and in a mixture of THF–diethylether– n -pentane in volume ratio 4:1:1 (Trapp mixture). The reaction of 1 with lithium metal in THF under refluxing leads to the homo-coupling product [(Me 3 SiO)Me 2 Si] 2 ( 4 ). A mixture of 1 and Me 3 SiCl in molar ratio 1:2 reacts with lithium metal in THF to give 4 and the cross-coupling product (Me 3 SiO)Me 2 SiSiMe 3 ( 7 ). The silyllithium derivatives Me 3 SiO(SiMePh) n Li ( 8 : n = 1; 9 : n = 2; 10 : n = 3) and Me 3 SiSiMePhLi ( 11 ) are formed in the reaction of 2 with lithium metal in THF at −78°C and in the Trapp mixture at −110°C. Main product in both cases is 9 . 8 – 11 are trapped by Me 3 SiCl and HMe 2 SiCl. The trapping products (Me 3 SiO)SiMePhSiMe 3 ( 13a ), Me 3 SiO(SiMePh) 2 SiMe 2 R ( 14a , 14b ; a : R=Me, b : R=H), Me 3 SiO(SiMePh) 3 SiMe 2 R ( 15a , 15b ) and Me 3 SiSiMePhSiMe 2 R ( 16a , 16b ) are obtained. The reaction of 3 with lithium metal like 2 produces the silyllithium derivatives Me 3 SiO(SiPh 2 ) n Li ( 18 : n = 1, 19 : n = 2) and Me 3 SiSiPh 2 Li ( 20 ), wich are trapped by Me 3 SiCl and HMe 2 SiCl to give the corresponding disilanes (Me 3 SiO)SiPh 2 SiMe 2 R ( 23a , 23b ) and trisilanes Me 3 SiO(SiPh 2 ) 2 SiMe 2 R ( 24a , 24b ) as well as Me 3 SiSiPh 2 SiMe 2 R ( 25a , 25b ). In addition to 18 , 19 and 20 LiSiPh 2 SiPh 2 Li ( 21 ) is formed in a small amount in the reaction of 3 with lithium metal at −78°C to afford tetrasilanes [RMe 2 SiPh 2 Si] 2 ( 26a , 26b ) after trapping by Me 3 SiCl and HMe 2 SiCl. The disilane (Me 3 SiO)SiMeR′SiMe 3 ( 17 ) (R′=3,4,5,6-tetrakis(trimethylsilyl)cyclohex-1-enyl) is produced by reaction of a mixture of 2 and Me 3 SiCl in molar ratio 1:6 with 6 equivalents of lithium at −78°C in THF. The reaction of a mixture of 3 and Me 3 SiCl in the molar ratio 1:10 with 11 equivalents of lithium under the same conditions gives (Me 3 SiO)SiR′ 2 SiMe 3 ( 27 ).