Thoralf Gross

Geminal di(hypersilyl) compounds. The synthesis and structure of dimethylamino-bis[tris(trimethylsilyl)silyl]methane

Abstract Dimethylamino-bis[tris(trimethylsilyl)silyl]methane (5) is prepared by the reaction of tris(trimethylsilyl)silyllithium (1) with chloromethylene-dimethyliminium chloride. The proposed mechanism of the formation of 5, leading to the fixation of two bulky hypersilyl groups at one comparatively small carbon atom, is discussed. The structure of 5, elucidated by an X-ray crystal structure analysis, is characterized by tremendous distortions of the molecular skeleton due to the spatial demand of the two extended hemispherical (Me3Si)3Si groups, causing for example a central Si–C–Si angle of 132.6°.

Head-to-head versus head-to-tail dimerizations of transient silenes — the generation and dimerization behavior of 2-(2-dimethylaminoaryl)-1,1-bis(trimethylsilyl)silenes

Abstract The transient silenes (Me3Si)2SiCR1R2 (4: R1=H, R2=2-Me2N-5-Me–C6H3; 11: R1=Me, R2=2-Me2N–C6H4; 15: R1=3,5-Me2–C6H3, R2=2-Me2N–C6H4; 18: R1=Me, R2=2-Me2N-5-Me–C6H3) were generated following the mechanism of the sila-Peterson reaction. Thus, 4 was obtained by base-induced trimethylsilanol elimination from (2-dimethylamino-5-methylphenyl)tris(trimethylsilyl)silylmethanol (3). Addition of methyllithium or 3,5-dimethylphenyllithium, respectively, to the carbonyl group of 2-dimethylaminobenzoyl-tris(trimethylsilyl)silane (10) and subsequent elimination of Me3SiOLi led to 11 and 15, respectively. Similarly, (2-dimethylamino-5-methylbenzoyl)-tris(trimethylsilyl)silane (17) and MeLi gave 18. The silene 4 underwent a spontaneous head-to-tail cyclodimerization to give a 1,3-disilacyclobutane (5), whereas 11 afforded a linear head-to-head dimer (12). The dimerization rates of 15 and 18 proved to be slow, thus, under the conditions of the sila-Peterson reaction readdition products of eliminated trimethylsilanolate to the SiC bond of the silenes were obtained (16, 19). The structures of the compounds prepared were elucidated on the basis of comprehensive NMR and MS studies; for 5 also the results of an X-ray structural analysis are given. Possible reasons for the different behavior of the similarly structured silenes are discussed.

Geminal bis(hypersilyl) compounds — the synthesis and structure of bis(tris(trimethylsilyl)silyl)silanes

Protodesilylation of diphenylsilane with trifluoromethanesulfonic acid and subsequent reaction of the obtained bis(trifluoromethanesulfonyloxy)silane with tris(trimethylsilyl)silyllithium (1) (mola...

1,2-Di(hypersilyl)-ethylene — The unexpected result of the reaction of tris(trimethylsilyl) silyllithium with formic acid methyl ester

Tris(trimethylsilyl)silyllithium reacts with methyl formate in a molar ratio of 2:1 under formation of 1,2-bis[tris(trimethylsilyl)silyl]ethene (9). As reaction intermediates formyl-tris(trimethylsilyl)silane (5) and lithium bis[tris(trimethylsilyl)silyl]methoxide (6) were identified. 6 is quenched with water to give bis[tris(trimethylsilyl)silyl]methanol (7).