A zwitterionic disilanylium from an unsymmetrical disilene.

The reaction of PhC(N t Bu) 2 SiSi(SiMe 3 ) 3 (1) with Me 3 SiCH 2 Cl afforded an unsymmetrical sp 2 -sp 3 disilene, 2, with concomitant elimination of Me 3 SiCl. The analogous reaction with PhC(N t Bu) 2 SiCl resulted in the oxidative addition of the C-Cl bond at the Si(II) atom (3). The reactions of 2 with sulfur and selenium led to compounds with SiE (ES (4) and Se (5)) double bonds. Tellurium reacted differently with 2 and furnished a zwitterionic compound, 6.