Generation of a bridging ethenyl ligand at a di-iron centre via carbonphosphorus bond cleavage

Abstract

UV irradiation of [Fe 2(CO) 6(μ-CO)(μ-dppm)] ( 1) with diphenylvinylphosphine yields [Fe 2(CO) 5(μ-Ph 2PCHCH 2)(μ-dppm)] ( 2) in which the vinylphosphine acts as a bridging four electron donor ligand to the di-iron centre. Thermolysis of 2 results in carbonphosphorus bond cleavage giving the μ-alkenyl complex [Fe 2(CO) 4(μ-CHCH 2)(μ-PPh 2)(μ-dppm)] ( 3). The μ-ethenyl moiety in 3 is static at room temperature but at higher temperatures “windshield wiper” fluxionality is observed, a process conveniently monitored by 31P NMR spectroscopy.