Studies in the chemistry of bonds between metals: transition-metal carbonyl derivatives of thallium

Abstract

Thallium(I) tetracarbonylcobaltate has been prepared by metathesis of Na[Co(CO)₄] with thallium(I) salts in water, by metal exchange between Hg[Co(CO)₄]₂ and thallium metal, by reaction of thallium metal with dicobalt octacarbonyl, and by reduction of Tl[Co(CO)₄]₃ with thallium metal. Also prepared by metathesis reactions and isolated were the new compounds Tl[M(CO)₃(cp)](M = Cr, MO, and W; cp =η-cyclopentadienyl). Spectroscopic evidence is presented for the existence of Tl[Co(CO)₃PPh₃]{via Na[Co(CO)₃PPh₃] and thallium(I) acetate} and of Tl[Mn(CO)₅]{from [HMn(CO)₅] and thallium(I) ethoxide}. The stability of the thallium(I) compounds toward disproportionation decreases in the order Co(CO)₄ M(CO)₃(cp)(W > MO > Cr) > Co(CO)₃PPh₃≃ Mn(CO)₅ Fe(CO)₂(cp). The corresponding thallium(III) compounds have been characterized, except for Tl[Fe(CO)₂(cp)]₃ which readily decomposed to [Fe(CO)₂(cp)]₂, and thallium metal. Some of these, particularly Tl[Mn(CO)₅]₃, readily undergo light-promoted, reductive elimination to the corresponding thallium(I) compound. The reverse of this process has been demonstrated in some cases.