Reactivity of a phosphinito-bridged Pt-I-Pt-I complex with nucleophiles: Substitution versus addition

摘要

As a result of the strong electrophilic character of the Pt bound to O, the phosphinito-bridged Pt-I complex [(PHCy2)Pt(mu-PCy2){kappa P-2, O-mu-P(O)Cy-2}Pt(PHCy2)](Pt-Pt) (1) undergoes attack at the O-bound Pt atom by molecules such as di- and tricyclohexylphosphane, dicyclohexylphosphane oxide, and dicyclohexylphosphane sulfide. Thus, reaction of 1 with PHCy2 gives the symmetric Pt-I dimer [(PHCy2)Pt(mu-PCy2)](2)(Pt-Pt) (2), while the hydrido-bridged complex syn-[(PHCy2)[kappa P-P(O)Cy-2[Pt(mu-PCy2)(mu-H)Pt(PHCy2){kappa P-P(O)Cy-2}](Pt-Pt) (4) is obtained from reaction of 1 with P(O)HCy2; the thiophosphinito complex [(PHCy2)Pt(mu-PCy2){kappa P-2,S-mu-P(S)Cy-2}Pt(PHCy2)](Pt-Pt) (8) forms selectively in reaction of 1 with P(S)HCy2. For comparison, the reaction with PCy3 results only in ligand substitution, affording [(PCy3)Pt(mu-PCy2){kappa P-2,O-mu-P(O)Cy-2)Pt(PHCy2)](Pt-Pt) (5). DFT studies confirmed the remarkable electrophilicity of the oxygen-bound Pt and shed light on the nature of the metal-metal bond in Pt dimers.