Calculations of magnetic shielding for the tin nucleus in a series of tetra-organotin compounds using density functional theory

Density functional theory calculations have been carried out for the isotropic shielding of the tin nucleus in the reference compound tetramethyltin, using a variety of approaches involving geometry variations, different functionals and different basis sets (both on the tin and on the ligands), though without relativity effects. The calculations were then extended to a series of tetra-organotin compounds. The effects of varying ligand chain-length, substitution at the alpha and beta positions, and bond order for compounds of the type Me3SnR were investigated. Variations of shielding with ligand R in symmetrical compounds of the type SnR4 were also studied. Results are compared to experimental data. The TZV basis for tin, combined with the 6-311G family of sets for the ligands and the B3LYP functional, were found to be the optimum choices.