Steric Parameters of Conformationally Flexible Ligands from X-ray Structural Data. 1. P(OR)3 Ligands in Equivalent Ligand Environments

The complexes [Mo(η 5 -C 5 H 5 )(CO) 2 (L)I] (L = P(OMe) 3, P(OEt) 3, P(O i Pr) 3, P(O i Bu) 3, P(O n Pn) 3 ) were prepared and characterized by X-ray crystallography. Crystallographic cone (θ C ) and solid (Ω C ) angles for the phosphite ligands were calculated from the ligand conformations in the crystal structures and compared with the available literature data. The steric data are shown to be influenced by the surrounding ligand environment. The effects of the ligand conformation on the steric measurements are discussed, and the results applied to the analysis of equilibrium cis − trans isomer ratios in [Mo(η 5 -C 5 H 5 )(CO) 2 (L)I].