1.4-ADDITION OF 1.1.2.2-TETRACHLORODIMETHYLDISILANE TO 1.4-DIAZA-1.3-DIENES, SYNTHESIS AND MOLECULAR-STRUCTURE OF .6-DIMETHYL-2.5-DI-P-TOLYL-3.4-DIPHENYL-HEXA-3-ENE

Reaction of 1.1.2.2-tetrachlorodimethyldisilane (4) with 1.4-diazadien es like benzildianil (1), benzildi-p-tolil (2) and benzildi-p-anisil ( 3) leads to a 1.4-addition product of the disilane under cleavage of t he Si-Si bond (1a, 2a, 3a). The structure of 2a was determined by X-ra y crystallography (crystal data: monoclinic, P2(1)/n, a = 14.661(4), b = 12.283(2), c = 17.564(5) Angstrom, beta = 103.13 degrees, Z = 4, R = 0.0585 for 5992 independent reflections). Surprisingly, 2a was found to be in the cis-configuration with almost C-2 symmetry and a torsion angle of only 13 degrees. Owing to statistical disorder, some bond le ngths are not in the expected range.