1-Metallacyclopropene Complexes and η¹-Vinyl Complexes Containing the Cp*W(NO) Fragment

The solid-state molecular structure of Cp*W(NO)(CH 2 SiMe 3 )(η 2 -CPhCH 2 ) reveals that the vinyl ligand in this complex exists in a distorted form in the solid state that cannot be readily described by either of the classic η 1 -vinyl or 1-metallacyclopropene limiting structures, by comparison to other crystallographically characterized vinyl complexes reported in the literature. However, the NMR parameters for the CPhCH 2 fragment in this complex are characteristic of those of a 1-metallacyclopropene unit. In addition to these studies, a series of vinyl-containing species of the general formulas Cp*W(NO)(η 2 -CPhCH 2 )(X) and Cp*W(NO)(η 1 -CPh CH 2 )(LX) (X = Cl, OTf; LX = O 2 CPh, NH t Bu, (PPh 3 )(H)) has been prepared, and the solid-state metrical parameters and solution NMR spectroscopic properties of these complexes have been examined and compared to those of other vinyl-containing complexes reported in the literature. It has been found that the nature of the tungsten−vinyl interaction in these compounds is dependent upon the donor strength of the one-electron (1e) X or 3e LX donor ligands that are also present in the tungsten coordination sphere.