Dicarboxylate rhodium complexes with diolefins and carbon monoxide

Article abstract of DOI:10.1016/S0277-5387(00)84508-8

Dinuclear rhodium complexes of the type [Rh₂(C₂O₄)(diolefin)₂] (diolefin)₂ 1,5-cyclooctadiene, 2,5-norbornadiene and tetrafluorobenzobarrelene) with bridging oxalate ligands have been obtained by reaction of [Rh(acac)(diolefin)] with oxalic acid (2: 1 mol ratio). The use of a 1 : 1 molar ratio affords [Rh(HC₂O₄)(COD)], that reacts with [Ir(acac)(COD)] yielding the heterodinuclear [(COD)Rh(C₂O₄)Ir(COD)] complex. Treatment of [Rh₂(C₂O₄)(diolefin)₂] complexes with phenanthroline type ligands leads to ionic complexes of formula [Rh(diolefin) (phen)][Rh(C₂O₄)(diolefin)]. Bubbling of carbon monoxide through solutions of the diolefin complexes leads to the formation of carbonylrhodium species of formula [Rh₂(C₂O₄)(CO)₂L₂] (L = CO, PPh₃ t-BuNC) or [Rh(CO)₂(phen)] - [Rh(C₂O₄)(CO)₂]. Other related malonate complexes are also described.