M(cup)n complexes have been prepared (M = Cu, Ni, Fe, Co, Mn, or Zn ; n=2, M-=Fe ; n=3 cupH = cupferron) and structures have been proposed on the basis of spectroscopic, thermal and magnetic techniques. Their behaviour towards the Lewis bases pyridine, triphenyl- phosphine and hydroxylamine has been investigated. All of the M(cup)2 complexes, except when M = Zn or Fe, affords adducts on reaction with pyridine, whereas the complex Fe(cup)3 underwent an internal redox reaction. Internal redox behaviour was also observed when the complexes Cu(cup)2 and Fe(cup)3 were treated with triphenylphosphine. On the basis of the nature of the products arising from these reactions and from a kinetic study of the reaction of Cu(cup) with the phosphine, mechanistic proposals have been made
