The synthesis and structural characterization of a series of pentacoordinate diorganotin(IV) N-arylidene-α-amino acid complexes

Eight new diorganotin complexes formulated as R 2 Sn(OArCR″=NCHR′COO) were prepared and characterized by 1 H and 13 C NMR, IR, and elemental analysis. A single crystal X-ray diffraction study of the dibutyltin N-salicylidenevaline complex, Bu 2 Sn(OC 6 H 4 CH=NCH(i-Pr)COO), determines the molecular structure. The crystals are orthorhombic, space group P2 1 2 1 2 1 with a = 9.187(2) Å, b = 10.003(2) Å, c = 23.482(4) Å, V = 2157.8(6) Å 3 , Z = 4, and D c = 1.392 g cm −3 . The final discrepancy factors are R F = 0.040, and R w = 0.021 for 1131 significant reflections. The tin atom has a distorted trigonal bipyramidal coordination, with no short intermolecular contacts. The two axial SnO bonds of 2.078(10) and 2.151(8) Å and the equatorial SnN bond of 2.158(8) Å are among the shortest found in related complexes. The fact that the closest intermolecular SnO distance is 4.511(8) Å indicates a nonbridging carbonyl group.