Homobimetallic complexes containing Sn(IV) with acetylene dicarboxylic acid: their syntheses and structural interpretation by spectroscopic, semi-empirical, and DFT techniques

Homobimetallic carboxylates with general formulae (R3Sn)(2)L (where R = Me, n-Bu, Ph and L=acetylene dicarboxylate dianion) have been synthesized by refluxing disodium salt of acetylene dicarboxylic acid with triorganotin chlorides in 1 : 2 (L : M) molar ratio in methanol under reflux. These complexes have been characterized by elemental analyses, FTIR, and multinuclear NMR (H-1, C-13) spectroscopies. DFT calculations have been performed for structural elucidation and results were compared with semi-empirical data. FTIR data indicate bidentate chelation of the ligand with tin and the complexes exhibit five-coordinate geometry in the solid state. Such coordination behavior is also supported by DFT and semi-empirical studies. NMR data confirm four-coordinate geometry in solution.