Preparation and X-ray analyses of siloxane-bridged acyclic and 8-membered cyclic phosphaethenes

Two Mes∗Pdouble bond; length as m-dashC (Mes∗ = 2,4,6-tri-t-butylphenyl) parts were successfully combined with one or two disiloxane chain(s) by the reaction of 2-silyl-1-phosphaethenyllithium with dichlorotetramethyldisiloxane, and the structures of bis(1-bromo-2-phosphaethenyl)disiloxane and 3,7-diphosphinidene-2,2,4,4,6,6,8,8-octamethyl-1,5-dioxa-2,4,6,8-tetrasilacyclooctane were characterized by spectroscopic analyses and X-ray crystallography.