Synthesis, characterization and solution studies on heteronuclear iron–copper clusters containing diphosphine ligands: crystal structure of the dicluster [{Fe 2(μ-CO)(CO) 6(μ-PPh 2)Cu} 2(dppp)

Abstract

Treatment of dichloromethane solutions of the di-iron compound [NEt 4][Fe 2(CO) 6(μ-CO)(μ-PPh 2)] with one equivalent of [Cu(NCCH 3) 4]BF 4 at low temperatures, followed by the addition of half of an equivalent of diphosphine ligand (diphosphine=bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane), produces high yields of the mixed-metal dicluster compounds [{Fe 2(μ-CO)(CO) 6(μ-PPh 2)Cu} 2(diphosphine)]. The molecular structure of the dppp derivative has been determined by X-ray crystallography. For a 1:1:1 molar ratio of the reagents, complex mixtures have been obtained and studied by variable-temperature 31P-NMR spectroscopy.