Part I. Analysis of (nu)(CO) infrared spectra has shown that Na('+) cation interacts specifically with the CO group trans to substituent ligands in LV(CO)(,5)('-) (L = PPh(,3), P(OPh)(,3), P(n-Bu)(,3) and CNMe). Such site selectivity was predicted on the basis of asymmetric electron distribution in such anions as reflected in calculated Cotton-Kraihanzel CO stretching force constants. The Et(,4)N('+) cation was also found to form a close interaction with LV(CO)(,5)('-) however the specific geometrical form could not be discerned. P-donor ligand substitution reactions of PV(CO)(,5)('-) were found to follow a dissociative mechanism. Vanadium-phosphorus bond cleavage was counterion dependent with the tightly interacting Na('+) promoting faster dissociation rates Part II. Analysis of the acidolysis reactions of MoH(,4)(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2) by AlCl(,3) and HBF(,4) has shown that abstraction of a hydride ligand results in unstable MoH(,3)(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2)('+) and MoH(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2)('+) intermediates which readily react with CO. Acidolysis of HMo((pi)-C(,3)H(,5))(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2) apparently results only in the HMo(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2)('+) intermediate The transfer of the highly sterically constrained proton in HMo(CO)(,2)(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2)('+) to various bases was examined. Some correlation between the steric requirements of the deprotonating agent and the rate of reaction was found. The molecular structure of {HMo(CO)(,2)(Ph(,2)PCH(,2)CH(,2)PPh(,2))(,2)('+)AlCl(,4)('-) was determined by x-ray diffraction methods to assist in understanding the degree of steric congestion about the hydride ligand