Structural characterization of dimethyl‐ and di‐n‐butyltin(IV) 2,3‐pyridinedicarboxylate in solution and in the solid state

Abstract

AbstractPotassium 2,3‐pyridinedicarboxylate (K2pdc) has been reacted with dimethyl‐ and di‐n‐butyltin(IV) dichloride to give complexes with polymeric structures: [Me2Sn‐µ2‐pdc]n (1) and [nBu2Sn‐µ2‐pdc]n (2). IR, NMR (1H, 119Sn) spectroscopic and X‐ray crystallographic studies of 1 and 2 proved the expected 1:1 stoichiometric composition of the complexes. In solution compounds 1 and 2 have either cyclooligomeric or polymeric structures with a coordination number of 7 for the tin atoms. In polar solvents rapid exchange reactions of coordinated solvent molecules take place at the tin centers. In the solid state, polymeric helicoidal structures are found, in which one solvent molecule is coordinated to each tin atom. For 1 the DMSO adduct was characterized and, interestingly, in the case of 2 two different solid‐state structures having very similar three‐dimensional structures and crystal lattice parameters, but different solvent molecules coordinated to the tin atoms (H2O and MeOH), could be isolated. The solid‐state structures of 1‐DMSO, 2‐H2O and 2‐MeOH differ in the number of units required for a complete turn of the helix (two for 1‐DMSO, three for 2‐H2O and 2‐MeOH), which may be explained by the different steric requirements of the organic substituents at the tin centers (R = Me for 1‐DMSO, R = nBu for 2‐H2O and 2‐MeOH) and the fact that different solvent molecules are coordinated to them. In all three cases the crystal lattices contain small voids that are filled with either the backbones of the coordinated solvent molecules and/or disordered, uncoordinated solvent molecules. Copyright © 2005 John Wiley & Sons, Ltd.