Neutral Cobalt Carbonyl Catalysts for the Equilibration between CO and P(OPh)3 Ligands in Carbonylcobaltates

The substitution reaction of [Co(CO)(4)](-) by P(OPh)(3) was investigated in THF tinder a CO atmosphere, the reaction consists of an equilibrium, which, in order to be established, needs [Co-2(CO)(6)(P(OPh)(3))(2)]. The catalysis by this neutral carbonyl is formally related to a previously reported case, where either [Co-2(CO)(8)] or [Co-4(CO)(12)] was found to be necessary for the (CO)-C-13 scrambling in [Co(CO)(4)](-). The kinetic analysis reported in this paper indicates, however, that the two CO labilizations differ in their mechanism-the substitution by P(OPh)(3) is ascribed to a disproportionation-synpro-portionation of [Co-2(CO)(6)(P(OPh)(3))(2)].