Ligand substitution in [Fe2(CO)6(NO)(µ-PPh2)] and the isomerism of [Fe2(CO)4(PMe3)2(NO)(µ-PPh2)]

Abstract

Treatment of [NEt₄][Fe₂(CO)₆(µ-CO)(µ-PPh₂)] with NO⁺BF₄^– provided [Fe₂(CO)₆(NO)(µ-PPh₂)]1. Several phosphide-bridged diiron complexes, [Fe₂(CO)₅(PR₃)(NO)(µ-PPh₂)](R = Me 2, OMe 3 or Ph 4), [Fe₂(CO)₄L₂(NO)(µ-PPh₂)][L = PMe₃5, PEt₃6, PPh₃7, P(C₆H₄OMe-p)₃8, P(OMe)₃9, P(OEt)₃10, P(OPh)₃11, ½Ph₂PCH₂PPh₂12, ½Ph₂PP(CH₂)₃PPh₂13 or ½(η⁵-C₅H₄PPh₂)₂Fe 14] and [Fe₂(CO)₃{P(OMe)₃}₃(NO)(µ-PPh₂)]15, have been derived from ligand substitution in 1. These complexes exhibit structural versatility. Interconversion between two isomers of 5, 5b and 5c, has been established by variable-temperature ³¹P-{H} NMR, two-dimensional exchange spectroscopy and single-crystal structure determination.