Synthesis and characterization of poly(ethylene glycol) polymers functionalized by terminal tributyltin carboxylate moieties

Novel polymeric derivatives of various average molecular weights bearing tributyltin carboxylate moieties as terminal groups have been prepared by esterification with bis(tributyltin) oxide of the corresponding poly(ethylene glycol)s functionalized with dimethylenecarboxylic end groups. Low‐molecular‐weight compounds have also been synthesized, with the aim of investigating the influence of the polymeric chain on tin properties. As investigated by Sn NMR and Fourier transform infrared, the metal center appears to be completely tetracoordinated in chloroform solution at room temperature, whereas at low temperature, the tin atom undergoes a fast exchange between intramolecular pentacoordination with the ethereal oxygen atoms and the unassociated form. In the solid state, even at room temperature, all the polymeric products exhibit both tetracoordination and pentacoordination at tin, the latter achieved by interaction with both ethereal and carbonyl oxygens. The thermal behavior of the series of compounds indicates the presence of crystalline domains in the material, which can be ascribed either to intermolecular interactions at tin, giving rise to organometal aggregates, or to the formation of an ordered phase induced by the presence of the macromolecular chain, depending on the more or less elevated relative concentration of the organotin moieties in the sample. These findings are also confirmed by the X‐ray diffractions patterns of the investigated products. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3091–3104, 2005