S. G. Feng

Geometric features of d4 metal dicarbonyl monomers with cis-π-donor ligands

Abstract Molecular orbital descriptions for five closely related cis -dicarbonyl tungsten(II) d b4 model complexes are presented. The idealized compounds considered are [H 3 W(CO) 2 (SH) 2− , [H 3 W(CO) 2 (OH) 2− , [H 3 W(CO) 2 (NH 2 )] 2− , [H 3 W(CO) 2 (NMe 2 )] 2− , and [H 3 W(CO) 2 (HCCH)] − . These five compounds were chosen to reveal the interplay between the OCWCO bond angle and the orientation of a cis single-faced π-donor ligand, and the conclusions are based on Extended Huckel calculations. These compounds display similar orientations for the π-donor ligand with respect to the OCWCO angle, and each π-donor ligand encounters a barrier to rotation around the tungsten-ligand axis. Coordinates for the computer model [H 3 (CO) 2 W(HCCH) − were based on the results of a single-crystal x-ray diffraction study of [Tp′W(CO) 2 (PhCCMe)][BPh 4 ] (Tp′= tris (3,5-dimethylpyrazolyl) borate) that is reported here.