Reaction rates for the alkylation of Mn(CO)(dppm)(2)CN (dppm = PPh2CH2PPh2), Mn(CO)(2)(tripod)CN [tripod = (PPh2CH2)(3)CCH3], Re(CO)(3)(dppm)CN, (eta(6)-C6Me6)Mn(CO)(2)CN, CpFe(dppe)CN (dppe = PPh2CH2CH2PPh2), CpRu(dppe)CN, and CpRu(CO)(PPh3)CN with methyl 4-nitrobenzenesulfonate (MeONs) to produce complexes of the type [LnM-CNMe](+) (-)ONs were investigated in 1,2-dichloroethane (DCE) at 30.0 degrees C. The reactions are first order in both the complex and the alkylating agent, which is consistent with a mechanism that involves nucleophilic attack of the cyanide nitrogen on the methyl of the MeONs. The second-order rate constants (k(2)) correlate approximately with the stretching frequency of the cyanide ligand nu(CN) in the complexes. There is a somewhat better correlation between nu(CN) of the CNCH3 ligands in the products and k(2). There is also a good correlation between the rate constant (k(2)) and the calculated force constant (k(CO)) for the nu(CO) vibrational mode of the analogous [LnM-CO](+) complex. These correlations appear to be useful for predicting nucleophilicitics of metal cyanide complexes of different metals, in different oxidation states, and with ligands exhibiting a range of electronic and steric properties.