Cobalt carbonyl derivatives phosphine complexes

The use of Co2(CO)g as a hydrogenation catalyst in the absence of CO generally results in decomposition to metal. Phosphine derivatives of cobalt carbonyl complexes, which are more robust hydrogenation catalysts, will be discussed next. 

In addition to the release of carbon monoxide, transition metal carbonyl complexes have also found applications in anticancer chemotherapy [212], radiolabelling [213-216], and as photosensitisers. The cobalt complex shown in Fig. 14 a demonstrates a higher anticancer activity than cis-platin in certain mammary tiunor cells Hnes [217,218]. Complexes such as Tc-99m(I)(CO)3(OH2)3 along with hydroxymethyl phosphine derivatives [219] and the cyclopentadienyl complex shown in Fig. 14b have useful radiopharmaceutical applications, in diagnosis, using Tc, as the metal centre, and in therapy based on Re and Re isotopes [220]. 

The mass of this work lies beyond the scope of this review, but a few prominent points may be cited. In most cases, treatment of either an alkyl or an acyl tetracarbonyl cobalt complex with triphenylphosphine gives only the acyl derivative, [Co(COR)(CO)3P(C6H5)3] (304, 306). The reactions of acyl, allyl, and hydridocobalt tetracarbonyl or acetylenedicobalt hexa-carbonyl complexes with phosphines are first order in the cobalt complex, so a dissociation mechanism prevails (64, 65, 66). However, the reaction between [Co(CO)3NO] and P(C6H5)3 is second order (66). 

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