Fast reactions at planar four-co-ordinate complexes. Part I. Nucleophilicity towards palladium(II) complexes
Abstract
Rates of nucleophilic substitution reactions (i)[L = PPrn3, AsEt3, or piperidine, C5H11N; Y–= Cl–, N3–, Br–, I–, SCN–, or (NH2)2CS] have been measured in methanol at 25 °C. A set of nucleophilic reactivity constants, trans-[PdL2(NO2)2]+ Y–→trans-[PdL2(NO2)Y]+ NO2–(i)nPd0= log (k2[MeOH]/k1), have been calculated, k1 and k2 referring to rate constants for the solvolytic path and for direct nucleophilic attack on the complex trans-[Pd(PPrn3)2(NO2)2]. All the complexes studied obey the linear free-energy relation log k2=snPd0+ log k1, where s is a nucleophilic discrimination factor. The nPd0 sequence resembles that already found for platinum(II) complexes.