REACTION OF THE DINUCLEAR COBALT COMPLEX [CO-2(MU-PPH2CHCHC(O)CHCHPPH2)(CO)(4)] WITH 2-ELECTRON DONOR LIGANDS - THE STABILIZATION OF COBALT-ALKENE BONDS BY INCORPORATION OF ALKENES INTO A BRIDGING DIPHOSPHINE LIGAND

The thermal reaction of [Co-2{mu-PPh2CHCHC (O) CHCHPPh2} (CO)(4)] (2) with two-electron donor ligands, L, leads to the mono- and bis-substit uted complexes [Co{mu-PPh2CHCHC (O) CHCHPPh2} (CO)(3)(L)] (L = PPhMe2 (3a), PPh2H (3b), P(OMe)(3) (3c), (CNBu)-Bu-t (3d)) and [Co-2{mu-PPh2C HCHC (O) CHCHPPh2} (CO)(2)(L)(2)] (L = PPhMe2 (4a), PPh2H (4b), P(OMe) (3) (4c), (CNBu)-Bu-t (4d)), in which CO groups rather than bound alke nes have been displaced from the metal centres. Single crystal X-ray d iffraction has: been used to determine the structure of [Co-2{mu-PPh2C HCHC (O) CHCHPPh2} (CO)(2) (PPhMe2)(2)]. 0.25[C6H14] (4a) (which cryst allises in the monoclinic space group P2(1)/c with a = 15.932(2), b = 12.608(4), c = 23,847(3) Angstrom, beta = 98.87(3)degrees, Z = 4). (C) 1998 Elsevier Science S.A. All rights reserved.