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(PPh₃)][PF₆] (1) results in clean formation of [(PP(H)P)Pt(SPh)][PF₆] (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)(PPh₃)][PF₆] (R = Ph (4), Me (5)). HCl addition to 1 cleanly generates [(PP(H)P)PtCl][PF₆] (6^PF6PF6PF6). 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).