Diphosphine complexes of iridium(I), palladium(II), and platinum(II)

Abstract

Diphosphines Ph₂P[CH₂]_nPPh₂(n= 1–4) form novel trans-carbonyl complexes of Ir^I of stoicheiometry[{Ir(CO)Cl(diphosphine)}_m] in which the diphosphine (n= 1,3, or 4) bridges the metal atoms. Contrary to a previous postulate, the complex of Ph₂P[CH₂]₂PPh₂ is [Ir(CO){Ph₂P(CH₂)₂PPh₂}₂][Ir(CO)₂Cl₂]. The diphosphine complexes of Pd^II and Pt^II, some of which are described for the first time, are each of cis geometry. In each case Ph₂P[CH₂]₂PPh₂ chelates the metal and the complex is mononuclear, but Ph₂P[CH₂]₄PPh₂ bridges metal atoms of trinuclesr complexes. The diphosphine Ph₂P[CH₂]₃PPh₂ chelates Pd^II but forms a bridaed complex of Pt^II. Bridging by a diphosphine ligand occurs when the angle PMP which would be sub-tended by a chelating ligand exceeds 90°.