Dodecatungstocobaltate and Sn (IV)-Substituted Polyoxometalate: Preparation, Characterization and Catalytic Performances in Solventless Synthesis of Bis(indolyl)methanes

Electrophilic substitution reaction of indole with various aldehydes and cyclohexanone were carried out in the presence of electron-transfer (K5CoW12O40.3H2O) and green Lewis acid ([(n-C4H9)4N]3 PMo2W9(Sn4+.H2O)O39) catalysts. These catalysts were characterized by N2-adsorption measurements, FT-IR, UV-Vis, 31P NMR, TGA, cyclic voltammetry and elemental analysis. Mechanisms for their catalytic activity are proposed. Both of these catalysts can be recovered and reused.Keywords: Dodecatungstocobaltate, Sn (IV)-substituted polyoxometalate, bis(indolyl)methanes, electrophilic substitution, solvent-freecondition