STEREOCHEMICAL NONRIGIDITY IN A MACROCYCLIC VINYLSILOXANE-BASED TRIS(ALKENE)NICKEL(0) COMPLEX

A series of variable temperature saturation transfer NMR spectroscopic experiments show that the complex Me)(2)OSi(Me)(2)CH=CHSi(Me)(2)OSi(M e)(2)CH=Ch(2))] (1) undergoes slow chemical exchange with minor confor mers in benzene-d(6), at 298 K. The latter are proposed intermediates in an intramolecular process causing epimerization of the fused bicycl ic molecule to take place. The implications of these results for inter preting dynamic processes in the monocyclic complex [Pt(LL)(P(t)Bu(3)) ] and the Karstedt hydrosilylation catalyst [{Pt(LL)}(2)(mu-LL)] are d iscussed [LL = {Me(2)(CH2=CH)Si}O-2].