Preparation, characterization and kinetics of formation of some Schiff base chelates of Sn(II) and UO2(VI)

The synthesis, characterization and formation kinetics of Sn(II) and UO2(VI ) complexes of the nitrogen and oxygen donor ligands m-chlorophenylsalicyla ldimine (Hcps), m-nitrophenylsalicylaldimine (Hnps), m-methoxyphenylsalicyl aldimine (Hmps) and m-methylphenylsalicylaldimine (Hmsa) are reported. The structures of the free ligands and their Sn(II) and UO2(VI) complexes were determined by NMR, elemental analyses, IR and UV-Vis studies and magnetic s usceptibility measurements. Under pseudo-first order conditions, having an excess of the Schiff base present, the kinetics of complex formation of Sn( II) and UO2(VI) with a series of Schiff bases was studied spectrophotometri cally using the stopped-flow technique in methanol as solvent. The activati on parameters DeltaH(#) and DeltaS(#) for the formation reactions of the co mplexes studied in methanol are almost identical which supports the assumpt ion that the reactions have a common mechanism The reactions are considered to proceed through an associative mechanism.