CRYSTAL-STRUCTURE AND REACTIVITY OF [CU(DMPE)2][CU(CO(CO)4)2] (DMPE = 1,2-BIS(DIMETHYLPHOSPHINO)ETHANE) - STAGGERED AND ECLIPSED CONFORMATIONS OF [(CO)4COCUCO(CO)4]- ANIONS

The reaction of NaCo(CO)4 with 1,2-bis(dimethylphosphino)ethane (dmpe) and CuCl in dichloromethane solution gave pale yellow, air-sensitive [Cu(dmpe)2] [Cu(Co(CO)4)2], which has been characterized by X-ray crystallography at room temperature. The crystals are monoclinic, space group C2/c, with unit cell dimensions a = 18.437 (5) Å,b = 9.880 (2) Å, c = 38.109 (9) Å, β = 102.07 (2)°, V = 6788 (3) Å3, Z = 8, and RwF = 6.02%. The anions [(CO)4CoCuCo(CO)4]− are monomers with staggered and eclipsed forms existing simultaneously in the unit cell. The staggered form adopts a linear conformation around copper, whereas in the eclipsed form the Co-Cu-Co bond angle is slightly less than 180°. Reaction of 2 equiv of the ligand dppe (1,2-bis(diphenylphosphino)ethane) with [Cu(Co(CO)4)2]− at −78 °C instantly affords the Co(CO)4− anion and Cu(dppe)2+, indicative of a highly labile Cu-Co bond. © 1990, American Chemical Society. All rights reserved.