Substitution in Carbonyls Replacement of other Ligands

The conversion of /ranj-[IrX(CO)L2], where L = PMe2Ph or AsMc2Ph, in the presence of an excess of L, into the five-co-ordinate species [Ir(CO)L4]+X is thought to occur through the five-co-ordinate neutral 

Triphenylphosphine reacts with the manganese-silicon bonded compound (6) by reductive elimination  

Compounds FeX(NO)2L, where L = a phosphine or a phosphite, react with further quantities of L to produce Fe(NO)aL2 by a second-order process. The mechanism of this unusual reaction, which is both a substitution and a redox reaction, appears to be rapidly established preequilibration with the extra molecule of L, followed by rate-determining loss of X from the five-co-ordinate intermediate.  

Reactions of R NX with [(arene)M(CO)3] (M = Cr, Mo, or W X = F, Cl, Br, I, OH, SCN, N3, or OEt) lead rapidly to products of general formula [R4N]3[(C0)3MX3M(C0)3]. Promotion of this type of ionic reaction may explain why these complexes serve as catalysts in Friedel-Crafts reactions. Solvent appears to facilitate the substitution of Cl in the photolysis of [(A -C6H5)Fe(CO)2Cl] at 400 nm in DMSO or pyridine.  

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