Preparation of Ni- or Pt-Containing Cyclic Esters by Oxidative Addition of Cyclic Carboxylic Anhydrides and Their Properties

Metal containing cyclic ester complexes, (Remark: Graphics omitted.)(L=1,2-bis(diphenylphosphino)ethane (dpe) or 2,2′-bipyridine (bpy); R1, R2=H or CH3) and (Remark: Graphics omitted.) (L=tricyclohexylphosphine (PCy3) or dpe; n=1 or 2), have been prepared by oxidative addition of cyclic carboxylic anhydrides to zero-valent metal complexes. These complexes have been characterized by elemental analysis and spectroscopies (IR as well as 1H-, 13C{1H}-, and 31P{1H}-NMR) and chemical reactivities. Rate of the oxidative addition of succinic anhydride to Ni(bpy)(cod) (cod=1,5-cyclooctadiene) is expressed by a second order rate equation, R=k[Ni(bpy)(cod)][succinic anhydride], and temperature dependence of k gives the activation energy of 68 kJ mol−1. The reaction of methylsuccinic anhydride with Ni(cod)2 in the presence of tertiary phosphine or bpy affords two isomers, (Remark: Graphics omitted.) and (Remark: Graphics omitted.), corresponding to two modes of C–O bond cleavage in methylsuccinic anhydride promoted by Ni; dependence of the ratio between the two isomers on the kind of ligand added and reaction conditions has been examined.