µ3-Oxotrimetal acetato-complexes of chromium, manganese, iron, cobalt, rhodium, and iridium

Abstract

New pyridine- and β-picoline-containing oxo-centred complex ions [M₃ ^IIIO(CO₂Me)₆L₃]⁺, M = Cr, Mn, Fe, Co, Rh, and Ir, L = py and β-pic, were synthesised and their redox behaviour studied electrochemically. There is evidence for reduced species in which the oxo-centred triangular structure is maintained in the case of the Mn, Fe, and Co complexes but these could not be isolated. For iridium, complexes [Ir₃ ^III,III,IVO(CO²Me)₆L₃]⁺² in which the metal atom is in the mean oxidation state 3⅓ have also been characterised and shown to undergo reduction to the Ir^III species. Attempts to prepare oxo-centred complexes of Cu, Ag, Ni, Pd, Pt, and Mo were unsuccessful. The cobalt complex ion [Co₃O(CO₂Me)₆L₃]⁺ appears to be different from the other oxo-centred ions and a structure with both bridging and chelate acetato-groups is proposed.