Reactions of the anionic phenylphosphinidene cluster [Os3-(µ-H)(µ-PPh)(CO)10]– and its phenylphosphido isomer [Os3-(µ-PHPh)(CO)10]– with electrophiles. Crystal structures of [Os3H(µ-PMePh)(CO)10] and [{Os3H(PPh)(CO)10}2Hg]

Abstract

Deprotonation of [Os₃H(µ-PHPh)(CO)₁₀]3 gives the anion [Os₃H(µ-PPh)(CO)₁₀]^–4 containing a nucleophilic phosphorus centre which reacts with H⁺ to regenerate cluster 3 with the Ph group exo to the Os(CO)₄ group as in the starting material. However, Mel reacts with anion 4 at the most accessible side of the µ-PPh ligand to give [Os₃H(µ-PMePh)(CO)₁₀]6(X-ray structure reported) which has the Ph group endo and the Me group exo to the Os(CO)₄ group. Anion 4 reacts with [AuCl(PMe₂Ph)] to give [Os₃H(µ-PhPAuPMe₂Ph)(CO)₁₀]8(Ph probably endo) but the thermally generated isomer of 4, [Os₃(µ-PHPh)(CO)₁₀]^–5, reacts by the attack of gold at osmium atoms to give [Os₃(µ-AuPMe₂Ph)(µ-PHPh)(CO)₁₀]9(Ph probably endo) which is isomeric with 8. Compounds with P-Hg bonds are formed by the reaction of 4 with [HgCl(R)](R = Et, PhCH₂ or ferrocenyl) or with HgX₂(X = Cl, Br or I). The X-ray structure of the Hg-bridged product, [{Os₃H(PPh)(CO)₁₀}₂Hg], formed from anion 4 and HgX₂ or [Fe(C₅H₅)(C₅H₄HgCl)], is described. Although the co-ordination of the Hg atom is closely linear [P-Hg-P 171.8(2)°], there are fairly close approaches of O atoms of axial CO ligands to this atom (Hg ⋯ O 2.88 and 2.85 Å). The conformations of the two µ₃-PPh groups are different.