Observations on trisoxalatometallate(III) complexes

Abstract

Crystallographic, spectroscopic, and thermogravimetric information on crystalline complexes of the stoicheiometry K₃[M(C₂O₄)₃],xH₂O is combined in an attempt to elucidate the role played by water in their structures. The complexes where M = Al, V, Cr, or Fe, and x= 3 are best formulated as involving the tris-chelated ion [M(C₂O₄)₃]^3–, whereas the complexes of formulae K₃[M(C₂O₄)₃], (n+½)H₂O, where n= 4 for M = Rh or Ir, and n= 3 for M = Co, differ. For the rhodium and iridium complexes the ½H₂O appears unique and is possibly constitutive, and the complex of cobalt is probably similar. Several features of the chemistry of trisoxalato-complexes are discussed.