Vibrational spectra of metal–metal bonded complexes of group VIII

Abstract

Studies have been made of the vibrational spectra of a number of binuclear complexes, viz. Fe₂(CO)₉, Co₂(CO)₈, K₈[Co₂(CN)₈], [Ni phen₃][Fe₂(CO)₈](phen = 1,10-phenanthroline), Co₂(CO)₆[P(OPh)₃]₂, K₄[Ni₂(CN)₆(CO)₂], K₄[Ni₂(CN)₆], K₆[Co₂(CN)₁₀], and [Co₂(CNMe)₁₀](ClO₄)₄. From these studies it is concluded that, in the solid state, all but the first two contain metal–metal bonds without bridging ligands. The idealised symmetries for the metal–metal bonded complexes are D_3d for [Fe₂(CO)₈]^2–, [Co₂(CN)₈]^8–, and Co₂(CO)₆[P(OPh)₃]₂; C_2h for [Ni₂(CN)₆(CO)₂]^4–; D_2h for [Ni₂(CN)₆]^4–; and D_4d for [Co₂(CN)₁₀]^6–. Spectra of trinuclear complexes with linear M–M′–M bonds, Hg[Fe(NO)(CO)₃]₂, and bent M–M′–M bonds (HgX)₂Fe(CO)₄ and SnCl₂[Co(CO)₄]₂ were studied, and also those of Rh₄(CO)₁₂ and Rh₆(CO)₁₆.