Notes. Carbon-13 and phosphorus-31 nuclear magnetic resonance studies of the fluxional behaviour of the complexes [Fe 3 (CO) 10 {P(OMe) 3 } 2 ] and [Fe 3 (CO) 10 {P(OMe) 3 }{P(OPh) 3 }]

Variable-temperature 31P and 13C n.m.r. studies on the fluxional behaviour of the disubstituted derivatives [Fe3(CO)10{P(OMe)3}2] and [Fe3(CO)10{P(OMe)3}{P(OPh)3}] have uncovered the existence of several 1,2 isomers. Evidence is presented to suggest that phosphite ligand mobility plays a role in the isomerization processes at higher temperatures.