Thermal substitution reactions of the heterodinuclear complex CpFe(CO)2Co(CO)4 with phosphorus ligands

Abstract

Abstract The thermal reactions of CpFe(CO) 2 Co(CO) 4 with phosphorus ligands (L = P( n -Bu) 3 , P( c -Hx) 3 , PPh 3 , P(OPh) 3 , PMePh 2 ) lead to formation of both ionic disproportionation products, [CpFe(CO) 2 L] + [Co(CO) 4 ] − , via a radical chain path, and neutral monosubstitution products, CpFe(CO) 2 Co(CO) 3 L, via a CO-dissociative pathway. Reaction with PPh( o -CH 3 Ph) 2 results in forming only the monosubstituted product and no reactions were observed with the two bulkiest ligands, P( o -CH 3 Ph) 3 and P(C 6 F 5 ) 3 . The slow CO-dissociative pathway is always in effect in these reactions, and the product distribution is therefore determined by the rate of radical chain process. The steric and electronic requirements on the ligand for the radical chain process to dominate are much milder than that for other homodinuclear and heterodinuclear complexes that have been studied.