Synthesis, characterization, crystal structures and electrochemical studies of organotin(IV) carboxylates

Four new organotin(IV) compounds [Me3SnL] (1), {[Me2SnL]2O}2 (2), Bu2SnL2 (3) and [Bu3SnL] (4), where L = O2C(C2H5)CCHC6H4F have been synthesized by refluxing the corresponding organotin(IV) chlorides with sodium (E)-2-(2-fluorobenzylidene) butanoate (NaL) in dry toluene except 2 for which Me2SnO was refluxed with (E)-2-(2-fluorobenzylidene) butanoic acid (LH) in the same solvent. NaL and all the compounds were characterized by FT-IR, 1H NMR and 13C NMR spectroscopy. NaL and compounds 1 and 2 were also characterized by X-ray single crystal analysis which confirmed a linear polymeric structure for compound 1 and a stannoxane for 2. The structural analyses have shown a bridging behavior of the ligand in trimethyl- and tributyl-, chelating as well as bridging behavior in dimethyl- and a chelating bidentate mode of coordination in dibutyltin(IV) compound which is also confirmed from the crystal analysis for compounds 1 and 2. Cyclic voltammetry was used to evaluate the electrochemical, kinetic and thermodynamic parameters for the electron transfer processes of compounds 1–4. Predominantly adsorption controlled redox processes were exhibited by the slope of log ipvs. −log v plots. The values of the diffusion coefficient (Do) indicated the role of solvent in the mobility of the electro-active species to some extent but the overall rate of the redox process was typical of the adsorption controlled process and could not be explained on the basis of solvation effects. The values of formal potential and charge transfer coefficient were also calculated.