Preparation of 6,6-diarylfulvene complexes of rhodium(I) and their reaction with dioxygen

Abstract

Complexes [RhL2]+[L = P(OPh)3 or L2= cyclo-octa-1,5-diene] react with 6,6-diarylfulvenes C5H4C(C6H4X-4)2 to yield products [Rh{C5H4C(C6H4X-4)2}L2]+ in which the fulvene is bound to the metal through the five-membered ring. Corresponding reactions with [Rh(CO)2]+ yield complexes [Rh{C5H4C(C6H4X-4)2}2]+ containing two fulvene ligands. Atmospheric oxidation of these complexes results in the linking of the exocyclic carbon atoms in the two fulvene ligands by a peroxide bridge. If the initial attack by O2 is on the metal, the subsequent rearrangement may be viewed either as a transfer of singlet oxygen from metal to ligands or as a nucleophilic attack by peroxide on the (probably somewhat positively charged) exocyclic carbon atoms of the fulvene ligands.