Heterolytic addition of E-H bonds across Pt-P bonds in Pt N-heterocyclic phosphenium/phosphido complexes

Abstract

The reactivity of E-H bonds (E = S, O, Cl) with Pt(ii) complexes ligated by an N-heterocyclic phosphido-containing diphosphine ligand have been investigated. Addition of PhSH to [(PPP)Pt(PPh 3)][PF 6 ] (1) results in clean formation of [(PP(H)P)Pt(SPh)][PF 6 ] (3), in which the substrate has added across the Pt-P NHP bond. Similar reactivity occurs when 1 is treated with ROH (R = Ph, Me), but in this case the O-H bond adds across the Pt-P bond in the opposite direction producing [(PP(OR)P)Pt(H)(PPh 3)][PF 6 ] (R = Ph (4), Me (5)). HCl addition to 1 cleanly generates [(PP(H)P)PtCl][PF 6 ] (6 PF6). The neutral Pt-NHP complex (PPP)PtCl (2) exhibits similar reactivity; however, in the presence of the nucleophilic Cl - anion, the (PP(OR)P)Pt(H)Cl species presumably generated via addition of ROH (R = Me, Et) undergoes an Arbuzov-like dealkylation reaction to exclusively form the N-heterocylic phosphinito species (PP(O)P)Pt(H) (7). © 2012 The Royal Society of Chemistry.