Steric and Electronic Influences in Os3(CO)11(PR3) Structures

Abstract

The structures of Os3(CO)11(PR3) with R = F, OPh, Et, p-C6H4Me, o-C6H4Me, p-C6H4(CF3) and C6H11, and with PR3 = P(OCH2)3CMe have been determined. The Os-Os bond lengths in these compounds are compared to the Os-Os lengths for the other structures of Os3(CO)11(PR3) clusters reported in the literature. In most cases, the Os-Os bond length remote from the P ligand [range, 2.8666(4)-2.9044(4) Å] and that in the pseudo-trans position [range, 2.8712(5)-2.900(1) Å] show little variation as the steric and electronic properties of the P ligand are varied. The Os-Os length cis to PR3 shows more variation [range, 2.879(1)-2.9429(4) Å] and is sensitive to both the size and the σ-donor/π-acceptor properties of the PR3 ligand: larger or better donor PR3 ligands cause an increase in the Os-Os bond length. The Os-P distances [range, 2.15(2)-2.478(1) Å] show a similar dependence on the steric and electronic properties of the PR3 ligand.