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