Spin-delocalization in mixed-valence binuclear cations of rhodium and iridium. A stable iridium(II) radical
Abstract
Oxidation of [Ir(cod)(µ-L)]2(cod = cyclo-octa-1,5-diene; L = pz or 4-Mepz, pzH = pyrazole) using NOBF4 affords cationic binuclear nitrosyl adducts [Ir2(cod)2(µ-L)2NO]BF4; by contrast similar reactions of [M(cod)(µ-L)]2(M = Rh or Ir; L = 3,5-Me2pz) yield binuclear cationic radicals [{M(cod)(µ-L)}2+·] BF4– which in e.s.r. spectra show hyperfine-coupling to both metals consistent with delocalized mixed-valence character.