SYNTHESIS AND STRUCTURE OF DI-N-BUTYLTIN PYRIDINE-2-PHOSPHONATE-6-CARBOXYLATE

The crystal structure of di-n-butyltin pyridine-2-phosphonate-6-carbox ylate, [C14H24NO6PSn](2), features centrosymmetric dimers disposed abo ut a central Sn2O2 core. The phosphonate carboxylate dianion is mu(2)- tetradentate, coordinating one tin atom via one of the phosphonate oxy gen atoms, the pyridine nitrogen atom, and one of the carboxylate oxyg en atoms; the latter atom also coordinates the second tin atom of the dimer. The remaining positions in the seven-coordinate, distorted pent agonal bipyramidal geometry are occupied by a water molecule and two n -butyl groups that occupy axial positions. The lattice is stabilized b y hydrogen-bonding contacts leading to an arrangement of parallel, ort hogonally related chains of dimeric units. In methanol solution, the d imer is involved in a dissociation equilibrium that is fast on the NMR time scale.