Syntheses and Crystal Structures of Two Diethyltin Complexes of N-Salicylidene-α-amino Acid

Two novel diethyltin(IV) complexes of N-salicylidenevaline (H2L1) and N-Salicylidenetryptophan (H2L2), Et2SnL1 1 and Et2SnL2 2, were synthesized and characterized by elemental analysis, IR, H-1 NMR and X-ray single-crystal diffraction analysis. Complex 1 belongs to the trigonal system, space group R-3 with a = b = 19.2730(5), c = 23.6890(13) angstrom, V = 7620.4(5) angstrom(3), Z = 6, D-c = 1.553 g/cm(3), mu = 1.518 mm(-1), F(000) = 3600, R = 0.0238 and wR = 0.0636. Complex 2 is of monoclinic system, space group P2(1)/c with a = 13.7550(8), b = 11.5425(7), c = 12.7876(7) angstrom, beta = 93.585(1)degrees, V = 2026.3(2) angstrom(3), Z = 4, D-c = 1.548 g/cm(3), mu = 1.286 mm(-1), F(000) = 976, R = 0.0298 and wR = 0.0722. Complex 1 is a cyclic trimer with a macrocyclic 12-membered ring structure formed by the bidentate bridging coordination of carboxylate group to tin atoms. The tin atom is six-coordinated in a distorted octahedral geometry. In complex 2, the distorted trigonal bipyramidal Et2SnL2 units are linked into polymeric chains by the weak Sn center dot center dot center dot O interaction involving Sn and the carbonyl O of an adjacent ligand, and the chains are further connected by intermolecular N-H center dot center dot center dot O hydrogen bonds to form a two-dimensional supramolecular structure.