FACILE ONE-STEP SYNTHESIS OF THE COLBALT(III) AND NICKEL(III) TERTIARY ARSINE COMPLEXES [MI(3)(ASME(3))(2)] (M=CO OR NI) DIRECTLY FROM THE POWDERED ELEMENTAL METALS

Diiodotrimethylarsine, Me(3)AsI(2), was treated with cobalt or nickel metal powder to give the metal(III) complex, [MI(3)(AsMe(3))(2)]. In t he case of cobalt, a metal(II) complex, [AsMe(3)I][Co-3(AsMe(3))], was also produced, whereas for the nickel reaction only the nickel(III) c omplex, [NiI3(AsMe(3))(2)], was formed in quantitative yield. The only other product from the reactions was diiodine, which was detected spe ctrophotometrically. Both complexes have been crystallographically cha racterised and found to be isostructural, consisting of a metal(III) a tom with three equatorial iodide ligands capped by two trimethylarsine ligands. These complexes are unique examples of X-ray structural char acterisation of compounds of this stoichiometry. Conventional wisdom w ould not have expected the 'soft' ligands I- and AsMe(3) to bind to th e relatively hard metal(III) centre.