A 3D Coordination Network Built from CuII4Cl3(H2O)2 Linear Clusters and Tetrapyridyl Tetrahedral Silane Ligands: Reversible Iodine Uptake and Friedel–Crafts Alkylation Reactions

Abstract

A novel three-dimensional coordination network 1 in a new 4,5,6-connected topology (4,5,6T115) built from linear CuII4Cl3(H2O)2 clusters and tetrahedral tetrakis(3-pyridyl)vinylsilane ligands is reported. Utilizing a similar tetrahedral ligand, tetrakis(3-pyridyl)ethylsilane, a different framework 2 having CuII2Cl(H2O)2 clusters is obtained in tcs topology. The activated sample of 1 shows an excellent and reversible uptake of I2 in solid as well as in solution phases owing to the presence of uncoordinated chloride ions and electron rich vinylic groups in it. The I2 uptake studies on the anion-exchanged samples, of bromide, iodide, and nitrate ions, show a progressive decrease in the adsorption capacity with the sample containing uncoordinated Cl– ion showing a maximum uptake of 48.5% and the one with the NO3– ions exhibiting the lowest uptake of 24.0%. These observations suggest that the halide counterions interact better with I2 in comparison with nitrate ions and the better I2 uptake in the presence of Cl– ions over the other two halides is due to its smaller size that offers a larger surface area for adsorption. Also, both these compounds were shown to be useful catalysts for the solvent-free syntheses of bis(indolyl)methanes via Friedel–Crafts alkylation reaction.