Steric Control over Molecular Structure and Supramolecular Association Exerted by Tin- and Ligand-Bound Groups in Diorganotin Carboxylates

Structural data (X-ray and solution and solid-state 119Sn NMR) show that skew-trapezoidal-bipyramidal diorganotin compounds of 2-quinaldate are invariably monomeric, owing to the
steric bulk of the carboxylate ligand. In contrast, most of the analogous compounds of
2-picolinate (2-pic) can increase their coordination number by polymerization or the
incorporation of solvent in their coordination sphere in the solid state. The exceptional
compound is tBu2Sn(2-pic)2 (3), for which no increase in coordination number is apparent,
a result that is correlated with the bulky tert-butyl groups. Thus, judicious choice of tin or
ligand substituents can be exploited to dictate coordination number and/or the degree of
supramolecular aggregation in the investigated systems.