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

The trimethylsiloxychlorosilanes (Me3SiO)Me2−nPhnSiCl (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 [(Me3SiO)Me2Si]2 (4). A mixture of 1 and Me3SiCl in molar ratio 1:2 reacts with lithium metal in THF to give 4 and the cross-coupling product (Me3SiO)Me2SiSiMe3 (7). The silyllithium derivatives Me3SiO(SiMePh)nLi (8: n=1; 9: n=2; 10: n=3) and Me3SiSiMePhLi (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 Me3SiCl and HMe2SiCl. The trapping products (Me3SiO)SiMePhSiMe3 (13a), Me3SiO(SiMePh)2SiMe2R (14a, 14b; a: R=Me, b: R=H), Me3SiO(SiMePh)3SiMe2R (15a, 15b) and Me3SiSiMePhSiMe2R (16a, 16b) are obtained. The reaction of 3 with lithium metal like 2 produces the silyllithium derivatives Me3SiO(SiPh2)nLi (18: n=1, 19: n=2) and Me3SiSiPh2Li (20), wich are trapped by Me3SiCl and HMe2SiCl to give the corresponding disilanes (Me3SiO)SiPh2SiMe2R (23a, 23b) and trisilanes Me3SiO(SiPh2)2SiMe2R (24a, 24b) as well as Me3SiSiPh2SiMe2R (25a, 25b). In addition to 18, 19 and 20 LiSiPh2SiPh2Li (21) is formed in a small amount in the reaction of 3 with lithium metal at −78°C to afford tetrasilanes [RMe2SiPh2Si]2 (26a, 26b) after trapping by Me3SiCl and HMe2SiCl. The disilane (Me3SiO)SiMeR′SiMe3 (17) (R′=3,4,5,6-tetrakis(trimethylsilyl)cyclohex-1-enyl) is produced by reaction of a mixture of 2 and Me3SiCl in molar ratio 1:6 with 6 equivalents of lithium at −78°C in THF. The reaction of a mixture of 3 and Me3SiCl in the molar ratio 1:10 with 11 equivalents of lithium under the same conditions gives (Me3SiO)SiR′2SiMe3 (27).