| Abstract |
Reactions of (n)Bu(2)SnCl(L(1)) (1), where L(1) = acid residue of 5-[(E)-2-(4-methoxyphenyl)-1-diazenyl]quinolin-8-ol, with various substituted benzoic acids in refluxing toluene, in the presence of triethylamine, yielded dimeric mixed ligand di-n-butyltin(IV) complexes of composition [(n)Bu(2)Sn(L(1))(L(2-6))](2) where L(2) = benzene carboxylate (2), L(3) = 2-[(E)-2-(2-hydroxy-5-methylphenyl)-1-diazenyl]benzoate (3), L(4) = 5-[(E)-2-(4-methylphenyl)-1-diazenyl]-2-hydroxybenzoate (4), L(5) = 2-\(E)-4-hydroxy-3-[(E)-4-chlorophenyliminomethyl]-phenyldiazenyl\be nzoate (5) and L(6) = 2-[(E)-(3-formyl-4-hydroxyphenyl)-diazenyl]benzoate (6). All complexes (1-6) have been characterized by elemental analyses, IR, (1)H, (13)C and (117)Sn NMR and (119)Sn Mossbauer spectroscopy and their structures were determined by X-ray crystallography, complemented by (117)Sn CP-MAS NMR spectroscopy studies in the solid state. The crystal structure of 1 reveals a distorted trigonal bipyramidal coordination geometry around the Sn-atom where the Cl- and N-atoms of ligand L(1) occupy the axial positions. In complexes 2- 5, the molecules are centrosymmetric dimers in which the Sn-atoms are connected by asymmetric mu-O bridges through the quinoline O-atom to give an Sn(2)O(2) core. The differences in the Sn-O bond lengths within the bridge range from 0.28 to 0.48 angstrom, with the longer of the Sn-O distances being in the range 2.56-2.68 angstrom and the most symmetrical bridge being in 5. The carboxylate group is almost symmetrically bidentate coordinated to the tin atom in 5 (Sn-O distances of 2.327(2) and 2.441(2) angstrom), unlike the other complexes in which the distance of the carboxylate carbonyl O-atom from the tin atom is in the range 2.92-3.03 angstrom. The structure of 5 displays a more regular pentagonal bipyramidal coordination geometry about each tin atom than in 2-4. In contrast, the centrosymmetric dimeric structure of 6 involves asymmetric carboxylate bridges, resulting in a different Sn(2)C(2)O(4) motif. The Sn-O bond lengths in the bridge differ by about 0.6 angstrom, with the longer distance involving the carboxylate carbonyl O-atom (2.683(2) and 2.798(2) angstrom for two molecules in the asymmetric unit). The carboxylate carbonyl O-atom has a second, even longer intramolecular contact to the Sn-atom to which the carboxylate group is primarily coordinated, with these Sn center dot center dot center dot O distances being as high as 3.085(2) and 2.898(2) angstrom. If the secondary interactions are considered, all the di-n-butyl-tin(IV) complexes (2-6) display a distorted pentagonal bipyramidal arrangement about each tin atom in which the n-butyl groups occupy the axial positions. (C) 2009 Elsevier B. V. All rights reserved. |
