Does type of phosphine affect rotational barrier of vinylidene in the complexes OsHCl(Cdouble bond; length as m-dashCH2)(L)2 (L = phosphine)?

Density functional molecular orbital calculations at the BP86 level were performed to investigate rotational barrier of vinylidene ligand in the model complexes OsHCl(Cdouble bond; length as m-dashCH2)(L)2 (L = PMe3, PH3, PF3). Results of calculations indicate that the rotational barrier increases with the increasing π-accepting ability of phosphine. This result has been explained on the basis of the extent of π-interaction between metal and vinylidene ligand in the complexes.