Studies on metal carboxylates. 12. Reactions of molybdenum(II), rhodium(II), and rhenium(III) acetates with gaseous hydrogen chloride and hydrogen bromide

Article abstract of DOI:10.1021/ic50163a042

Molybdenum(II) acetate (Mo₂(O₂CCH₃)₄) reacts with gaseous hydrogen chloride and hydrogen bromide at 300°C to afford the phases β-MoX₂, where X = Cl or Br. Reaction of these halides with pyridine and monodentate tertiary phosphines to produce metal-metal bonded dimers of the type Mo₂X₄L₄ suggests that they are best formulated as [Mo₂X₄]_n and are accordingly the parent halides of haloanions Mo₂X₈^4-. In contrast to this behavior, the rhenium(III) acetates, Re₂-(O₂CCH₃)₄X₂, where X = Cl or Br, react with HCl and HBr to yield the trinuclear halides Re₃X₉. This is the first instance where a dinuclear rhenium halide containing a quadruple metal-metal bond has been converted to a trinuclear cluster. The related reaction of dinuclear rhodium(II) acetate with HCl and HBr differs from those involving Mo₂(O₂CCH₃)₄ and Re₂(O₂CCH₃)₄X₂ in that disproportionation to RhX₃ and rhodium metal occurs.