Preparations of cobalt-containing phosphines and reactions toward dicobalt octacarbonyl

Abstract

Treatments of bis(diphenylphosphino)methylene (dppm) bridged dicobalt complex, CO2(CO)(6)(mu-Ph2PCH2PPh2), with alkynes, Ph(2)PCequivalent toCR (2: R = CMe3; 3: R = SiMe3), at 60 degreesC in THF for 6 h gave alkyne-bridged complexes [(mu-Ph2PCH2PPh2)Co-2(CO)(4)][(mu-Ph(2)PCequivalent toR)] (4: R = CMe3; 5: R = SiMe3). Further reactions of 4 and 5 with Co-2(CO)(8) at 80 degreesC in toluene for 3 h resulted in the formations of unexpected tetra-cobalt clusters, [(mu-Ph2PCH2PPh2)(mu-PPh2)Co-4(CO)(7)(mu(4), mu(2)-CCR)] (6: R = CMe3; 7: R = SiMe3). All these compounds were characterized by spectroscopic means; 5, 6 and 7 were studied by X-ray diffraction methods as well. The structure of 6 (or 7) can be looked upon as a tetra-cobalt arachno cluster being coordinated with phosphine ligands and linked by organic moiety. (C) 2003 Elsevier B.V. All rights reserved.