Stereochemical nonrigidity has been observed in the Pt(0) complex [Pt{
(eta-ViMe2Si)201(P(t)Bu3)] (1a) by NMR spectroscopy. The activation pa
rameters have been measured by DNMR3 analysis of the spectra over a ra
nge of temperatures. It is concluded that the vinylsiloxane ligand is
undergoing a facile dissociation-reassociation process, although a rel
ated nondissociative mode involving a rotation about the alkene C-C ax
is cannot be completely dismissed.