LIGAND SUBSTITUTION IN [FE-2(CO)(6)(NO)(MU-PPH(2))] AND THE ISOMERISMOF [FE-2(CO)(4)(PME(3))(2)(NO)(MU-PPH(2))]

Treatment of [NEt(4)][Fe-2(CO)(6)(mu-CO)(mu-PPh(2))] with NO+BF4- prov ided [Fe-2(CO)(6)(NO)(mu-PPh(2))] 1. Several phosphide-bridged dii com plexes. [Fe-2(CO)(5)(PR(3))(NO)(mu-PPh(2))] (R = Me 2, OMe 3 or Ph 4), [Fe-2(CO)(4)L(2)(NO)(mu-PPh(2))] [L = PMe(3) 5, PEt(3) 6, PPh(3) 7, P (C(6)H(4)OMe-p)(3) 8, P(OMe)(3) 9, P(OEt)(3) 10, P(OPh)(3) 11, 1/2Ph(2 )PCH(2)PPh(2) 12, 1/2Ph(2)PP(CH2)(3)PPh(2) 13 or 1/2(eta(5)-C(5)H(4)PP h(2))(2)Fe 14] and [Fe-2(Co)(3)(P(CMe)(3)}(3)(NO)(mu-PPh(2))] 15, have been derived from ligand substitution in 1. These complexes exhibit s tructural versatility. Interconversion between two, isomers of 5, 5b a nd 5c. has been established by variable-temperature P-31-(H) NMR. two- dimensional exchange spectroscopy and single-crystal structure determi nation.