Synthesis, structure, and reactivity of siloxides and germyloxides of iron(II) and cobalt(II)

Abstract

Iron and cobalt siloxides and germyloxides [(Me3Si)3SiO]2M (M = Fe (1), Co (2)), (Me5Si2O)2Fe (3), (Pri3SiO)2M (M = Fe (4), Co (5)), (Pri3GeO)2Fe (6), (Ph3SiO)2Fe (7), (Me3SiO)2Fe (8), (Pri3GeO)2Fe(bpy) (9), and [(Me3Si)2NFe(μ-OSi2Me5)2]2Fe·C6H6 (10) were synthesized by the reactions of metal silylamides [(Me3Si)2N]2M (M = Fe, Co) with the corresponding silanols or triisopropylgermanol. The reaction of pentamethyldisilanol with iron(ii) silylamide affords either polymeric complex 3 or coordination oligomer 10, depending on the ratio of the reactants. The structures of complexes 9 and 10 were established by X-ray diffraction analysis. The interaction of the prepared compounds with carbon oxides was studied. Low-coordination cobalt siloxide is the only among all prepared compounds that absorbs CO (2 mol) at room temperature and under 1 atm to form an unstable cluster. Compounds 1, 2, and 4—8 react with CO2 to form carbonate complexes, and their reactivity decreases with a decrease in the electron-donating ability of the substituents at the central atom: (Me3Si)3SiO > Pri3GeO ≈ Pri3SiO > Me3SiO ≫ Ph3SiO.