Structural study of bis(triorganotin(IV)) esters of 4-ketopimelic acid Jan Chalupa a , Karel Handlı ´r ˇ a , Ivana Cı ´sar ˇova ´ b , Robert Jira ´sko c , Jir ˇı ´ Brus d , Antonı ´n Lyc ˇka e , Ales ˇ Ru ˚z ˇic ˇka a, * , Jaroslav Holec ˇek a a Department of General and Inorganic, Faculty of Chemical Technology, University of Pardubice, Studentska ´ 95, CZ-532 10 Pardubice, Czech Republic b Charles University in Prague, Faculty of Natural Science, Hlavova 2030, 128 40 Praha 2, Czech Republic c Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska ´ 95, CZ-532 10 Pardubice, Czech Republic d Institute of Macromolecular Chemistry of Academy of Sciences of the Czech Republic, Heyrovsky ´ sq. 2, 162 06 Praha 6, Czech Republic e Research Institute for Organic Syntheses (VUOS), Rybitvı ´ 296, 532 18 Pardubice 20, Czech Republic Received 12 December 2005; received in revised form 26 January 2006; accepted 31 January 2006 Available online 7 March 2006 Abstract The set of six bis(triorganotin(IV)) esters of 4-ketopimelic acid was prepared. Their structures were studied using IR, NMR and X-ray crystallographic (cyclohexyl and ethyl derivatives) techniques both in solution and the solid state. Five of these compounds are polymeric in the solid state and depolymerise upon dissolving in non-coordinating and/or addition of coordinating solvent to monomeric species with four-coordinated tin atom or complexes with donor solvent with five-coordinated tin central atom. The tricyclohexyltin derivative is dimeric in the solid state and monomeric in solution. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Triorganotin(IV) esters; Ketopimelic acid; NMR; X-ray 1. Introduction There is a long-standing interest in chemistry of triorg- anotin(IV) carboxylates both in academia and industry, because of known catalytic and medical activity [1,2]. The structural motifs of these compounds are well estab- lished and studied by X-ray [3], Mo ¨ssbauer and CP MAS NMR techniques in the solid state, and mainly multinu- clear NMR techniques in solution [1]. The tin atom in these compounds can be four-coordinated (Fig. 1A) or five-coor- dinated with major occurrence in the solid state. In this case, the tin atom is surrounded by three carbon atoms originated from organyl groups and two oxygen atoms from one asymmetrically bidentate carboxylate (intramo- lecularly chelated – Fig. 1B) or two different carboxylate groups (intermolecularly bridging – Fig. 1C). The com- pounds where the intermolecularly bridging bond fashion is taking place form the polymeric networks in the solid state [3], which can be often fragmented into oligomeric or monomeric species in solution of various solvents [4]. Another structural motif in polymeric and/or chelate arrangement can be revealed when a further donor atom is implemented as a part of carboxylate ligand into the tin coordination sphere [3]. Only little is known about properties and structure of diesters of dicarboxylic acids. To the best of our knowl- edge, only six papers are related to the structure of triorg- anotin diesters of dicarboxylic acids [5] and certain others to the structure of mentioned esters adducts and complex compounds [6]. In our previous work, we have been interested in struc- ture of organotin carboxylates containing mainly one organotin fragment in solution of different solvents [4]. Now we would like to pay much more attention to systems where two or more non-equivalent organotin groups exist, caused by chemical or geometrical (sterical) non-equiva- lency or dynamic exchange and to study and compare such 0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2006.01.053 * Corresponding author. Tel.: +420 466037151; fax: +420 466037068. E-mail address: ales.ruzicka@upce.cz (A. Ru ˚z ˇic ˇka). www.elsevier.com/locate/jorganchem Journal of Organometallic Chemistry 691 (2006) 2631–2640