Synthesis, characterization and solution studies on heteronuclear iron-copper clusters containing diphosphine ligands: crystal structure of the dicluster [{Fe-2(mu-CO)(CO)(6)(mu-PPh2)Cu}(2)(dppp)]

Treatment of dichloromethane solutions of the di-iron compound [NEt4][Fe-2( CO)(6)(mu-CO)(mu-PPh2)] with one equivalent of [Cu(NCCH3)(4)]BF4 at low tem peratures, followed by the addition of half of an equivalent of diphosphine ligand (diphosphine = bis(diphenylphosphino)methane (dppm), bis(diphenylph osphino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bi s(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane), p roduces high yields of the mixed-metal dicluster compounds [(Fe-2(mu-CO)(CO )(6)(mu-PPh2)Cu)(2)(diphosphine)]. The molecular structure of the dppp deri vative has been determined by X-ray crystallography. For a 1:1:1 molar rati o of the reagents, complex mixtures have been obtained and studied by varia ble-temperature P-31-NMR spectroscopy. (C) 2000 Elsevier Science S.A. All r ights reserved.