Dibutyltin derivatives of 4-hydroxy-2,6-pyridine-dicarboxylic (chelidamic) acid.: Crystal structures of bis[aquadibutyl(4-hydroxy-2,6-pyridinedicarboxylato)tin]•2[bis(dicyclohexylammonium)2,6-pyridinedicarboxylate] and dibutyl(4-hydroxy-2,6-pyridinedicarboxylato)tin

Bis[aquadibutyl(4-hydroxy-2,6-pyridinedicarboxylato)tin] . 2[bis(dicyclohexylammonium) 2,6-pyridine-dicarboxylate] crystallizes with the seven-coordinate tin atom in a trans-C2SnNO4 pentagonal bipyramidal [C-Sn-C 164.5(2)degrees] coordination environment. The tin atom is O,N,O-chelated by the 4-hydroxy-2,6-pyridinedicarboxylato dianion, and is datively bonded to a carboxyl oxygen end of the other half of the centrosymmetric bis[aquadibutyl(4-hydroxy-2,6-pyridinedinedicarboxylato)tin] moiety. The neutral moiety is hydrogen bonded to two bis(dicyclohexylammonium) 2,6-pyridinedicarboxylate ion-pairs, and adjacent bis [aquadibutyl(4-hydroxy-2,6-pyridinedicarboxylato)tin] . 2[bis(dicyclohexylammonium) 2,6-pyridinedicarboxylate] entities are linked by a short hydrogen bond [O-hydroxyl ... O-carbonyl 2.474(5) Angstrom] to form a ribbon running parallel to the a-axis. Dibutyl(4-hydroxy-2,6-pyridinedicarboxylato)tin is also O,N,O-chelated; the trans-C2SnNO4 pentagonal bipyramidal [C-Sn-C 152.0(1)degrees] coordination arises from O,O-bridging by the carboxyl -CO2 fragment of a neighboring molecule, the carboxylate bridge [Sn-O 2.733(2) Angstrom, 2.983(2) Angstrom] resulting in a three-dimensional network structure for the compound. The geometry is distorted towards a hexagonal bipyramid owing to a weak intermolecular [Sn ... O 3.652(1) Angstrom] contact.