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 A). The conformations of the two µ3-PPh groups are different.