Carbonyl halides of the Group VIII transition metals. V. Halocarbonyl derivatives of ruthenium(III) and ruthenium(II)

Abstract

Formic acid in the appropriate hydrohalic acid both carbonylates and reduces ruthenium trihalides, but the nature of the products isolated depends upon the identity of the halogen. In the chloro system the first product is the pentachloro-carbonylruthenate(III) ion, [Ru(CO)Cl₅]^2-, and this is then reduced to the tetra- chlorocarbonylaquoruthenate(II) ion, [Ru(CO)(H₂O)Cl₄]^2-. More prolonged reaction gives [Ru(CO)₂Cl₄]^2- and the ultimate product is [Ru(CO)₃Cl₃]-.     In the bromo system there was no evidence for the formation of an aquo-ruthenium(II) species and the iodo system was even more simple as only [Ru(CO)₂I₄]^2- and [Ru(CO)₃I₃]^- were observed.     The direct reaction between carbon monoxide and RuX₃ in methanol produces compounds of the type Ru(CO)X₃ (X = Cl, Br) and the corresponding anions [Ru(CO)X₅]^- have been isolated and characterized.     In all cases the halocarbonyl anions could be isolated by the addition of suitable cations to the solutions. In most cases the parent halocarbonyls themselves were isolated by evaporation of the reaction solution without the addition of cations.