INTRA-MOLECULAR COMPARISON OF THE PI-DONOR CAPABILITY OF OXO AND ORGANO-IMIDO LIGANDS - X-RAY CRYSTAL-STRUCTURES OF N-1-ADAMANTYLIMIDOTRIOXOOSMIUM AND BIS(N-TERT-BUTYLIMIDO)DIOXOOSMIUM

The structures of the two title compounds have been determined and refined to final weighted R values of 0.029 and 0.039, respectively. The monoimido derivative shows a nearly linear [171.4 (4)°] Os-N-C arrangement, while the bisimido complex possesses both a linear [178.9 (9)°] and a bent [155.1 (8)°] organoimido ligand. In these molecules the Os-N bond lengths are on average 0.02-0.03 Å shorter than the Os-O bonds. In contrast, for isostructural organoimido and oxo complexes, intermolecular comparison of Os-N and Os-O finds the latter to be shorter on average by 0.05 Å. The results are explained in terms of differences in Os-O and Os-N bond orders consistent with the higher electronegativity of oxygen vs. nitrogen. © 1979, American Chemical Society. All rights reserved.