Derivatives of bivalent germanium, tin, and lead. Part XIX. Reactions of bis(β-ketoenolato)tin(II) compounds with metal carbonyls: the octa-carbonyldicobalt system

Abstract

The reaction of bis(β-ketoenolato)tin(II) compounds, [SnX₂], with octacarbonyldicobalt in benzene at room temperature yields products of composition [{Co(CO)₄}₂SnX₂], [Co₂(CO)₇(SnX₂)], or [Co(CO)₄(SnX)] depending on the nature of the β-ketoenolato-residue X. Infrared data indicate that the β-ketoenolato-groups chelate tin in all cases, and also the presence of both terminal and bridging carbonyl groups in [Co₂(CO)₇(SnX₂)]. Tin-119m Mössbauer data for [{Co(CO)₄}₂SnX₂] are very similar to those of [Co₂(CO)₇(SnX₂)], which have the same structure as that determined for [{Co(CO)₄}₂Sn(pd)₂](pd = pentane-2,4-dronate), demonstrating that the tetra-carbonylcobalt groups occupy cis positions at octahedrally co-ordinated tin. The Mössbauer isomer shifts of [Co(CO)₄(SnX)] fall in the range 3.35–3.68 mm s^–1, above those of the corresponding [SnX₂] compounds, and structures involving [Co(CO)₄]^– anions co-ordinated to [SnX]⁺ cations via the carbonyl oxygen atom are proposed. The mechanisms of formation of the complexes are discussed.