“…688 Brought [216,220], frans-1,4-dimethyl-1,2,4,5-tetraphenyl-3,6-bis(trimethylsilyl)-1,4-disilacyclohexa-2,5-diene 131 [218] and frans-1,2,3,4,5,6-hexamethyl-1,4-bis(trimethylsilyl)-1,4-disilacyclohexa-2,5-diene 132 [219] has a nearly planar conformation with a slight deformation towards a chair form. Unlike all above-mentioned 1,4-disilacyclohexa-2,5-dienes the molecules of the c/'s-isomer 132 [219] and 1,1,4-trimethyl-3,6-diphenyl-2,4,5-tris(trimethylsilyl)-1,4-disilacyclohexa-2,5-diene 133 [217] are distorted from planarity to yield a boat conformation with silicon atoms deviating from the plane by 0.…”