Synthesis of three-co-ordinate mono-, bis-, and tris-olefin complexes of platinum with dimethyl or diethyl fumarate, dimethyl maleate, or maleic anhydride ligands

Abstract

Bis(cyclo-octa-1,5-diene)platinum, [Pt(cod)₂], reacts with dimethyl or diethyl fumarate (dmf or def) or maleic anhydride (ma) to give the complexes [Pt(cod)(olefin)](olefin = dmf, def, or ma). Dimethyl or diethyl maleate (dmm or dem) yield the fumarate complexes [Pt(cod)(olefin)](dmf or def). In the presence of 1 mol equivalent of Bu^tNC or PPh₃, complexes of the type [PtL(olefin)₂](L = CNBu^t or PPh₃; olefin = dmf, def, dmm, or ma) are produced. With an excess of Bu^tNC the complexes [Pt(CNBu^t)₂(olefin)] are formed. The latter species can also be obtained from the triplatinum complex [Pt₃(CNBu^t)₆] and the respective olefin. Addition of tricyclohexylphosphine to [Pt(CNBu^t)(dmf)₂] gives [Pt(CNBu^t)(dmf){P(C₆H₁₁)₃}]. The tris(olefin) complexes [Pt(C₂H₄)(olefin)₂](olefin = dmf or dmm) and [Pt(olefin)₃](olefin = dmf or def) are formed by treating [Pt(C₂H₄)₃] with the respective olefin. Tetra-alkylammonium halides react with a mixture of [Pt(cod)(dmf)] and dmf to give ionic complexes [NR₄][PtX(dmf)₂](X = Cl, Br, or I). Protonation of [Pt(cod)(dmf)] with trifluoroacetic acid gives selectively the platinum(II)σ-bonded complex [Pt{CH(CO₂Me)CH₂(CO₂Me)}(O₂CCF₃)(cod)].