Pairwise ligand exchange reactions in tetrahedral and pseudo-tetrahedral transition metal complexes

Ligand exchange reactions between various transition-metal complexes of the form [Mo(Q)2X2], [M(Q)CpX2] and [Mo(Q)2CpX], where Q and X are di-anionic and mono-anionic ligands, respectively, and M is Nb or Ta, have been studied. The formal electron count at the metal, and also the steric and electronic properties of the supporting ligands, are found to influence exchange rates, while ligand steric and electronic properties affect equilibrium constants.