Syntheses and spectroscopic studies of new cobalt(I) complexes

Abstract

The new Co(I) complexes [Me3SnCo(CO)aL] (L = PPh3, P(OPh)a, AsPh3) are prepared by reductively cleaving the dimers [Co(CO)3L]2 on a sodium amalgam, followed by the addition of Me3SnCl. A synthetic procedure is developed to prepare and purify these compounds on a large scale. A previous report that [Co(CO)3AsPh3]2 cannot be reductively cleaved without decomposition is proved wrong. The new products prove sufficiently stable to enable them to be studied by ir, nmr (1H, 13C{1H}, 31p{1H}, 119 Sn{1H}) and mass spectroscopy. The compounds [Me3SnCo(CO)aL] (L = PPh3, P(OPh)3, AsPh3) are shown to be non-susceptible towards nucleophilic substitution. Attempted displacement of a carbonyl ligand by an isocyanide ligand (using an excess of the latter) after treatment with the labilising agent Me3NO, leads to a variety of products of which only the major one can be identified as tra11,9-Co(CNR)aL2][PF 6] (R - t-Bu, Ph, 2,6-dimethylphenyl; L = PPh3, P(OPh)3, AsPh3). Except for the case where R = t-Bu, L = PPh3, the products are extremely unstable oils and cannot be characterised properly.