Calculation of the 119Sn isomer shifts in complexes of tin tetrachloride with organic ligands

The CNDO/2 method in a sp-valence basis has been used to calculate the electronic structure of tin tetrachloride and four complexes of tin tetrachloride with organic ligands. The calculation has given the theoretical values of the 119Sn isomer shifts, which have been compared with the experimental values. It has been shown that the decrease in the isomer shift taking place on complex formation is due to the decrease in the 5s electron density on the tin atom. For complexes of the type SnCl4L2, a correlation is observed between the isomer shifts and the ionization potentials of the donor molecule, indicating an increase in the isomer shift with increase in the strength of the donor - acceptor interaction