STRUCTURAL CHEMISTRY OF ORGANOTIN CARBOXYLATES .7. SYNTHESIS OF TRIORGANOSTANNATE ESTERS OF DICARBOXYLIC-ACIDS - CRYSTAL-STRUCTURE OF DICYCLOHEXYLAMMONIUM 2,6-PYRIDINEDICARBOXYLATOTRIBUTYLSTANNATE

The dicyclohexylammonium 2,6-pyridinedicarboxylatotriorganostannates, [(c-C6H11)2NH2]-[R3Sn((O2C)2C5H3N)], (R = n-C4H9, C6H5) have been prepared from di-c-hexylamine, 2,6-pyridinedi-carboxylic acid and bis(tributyltin)oxide (R = n-C4H9) or triphenyltin hydroxide (R = C6H5). On the basis of Mossbauer quadrupole splittings the tin atoms are assigned five-coordinate geometries. An X-ray analysis of the R = n-butyl compound shows that the structure is polymeric with neighbouring triorganotin centres being linked by dicarboxylate ligands. Each carboxylate moiety is involved in coordination to a Sn atom via one O atom only which has the result that the Sn atoms are five-coordinate and exist in trigonal bipyramidal geometries with the O atoms in axial positions; Sn-O(1) 2.31(1), Sn-O(3') 2.26(1) angstrom and O(1)-Sn-O(3') 173.2(6)-degrees. The pyridine N atom is not involved in coordination to tin.