Correlating Mossbauer and solution- and solid-state Sn-117 NMR data with X-ray diffraction structural data of triorganotin 2-[(E)-2-(2-hydroxy-5-methylphenyl)-1-diazenyl]benzoates

A series of R3SnO2CR' compounds, where R = Me (1), Et (2), Bu-n (3), Ph (4) , and cHex (5) and R'CO2 is the carboxylate residue of 2-[(E)-2-(2-hydroxy- 5-methylphenyl)-1-diazenyl]benzoic zoic acid, has been shown by multinuclea r magnetic resonance studies to be monomeric in solution. Crystallography s hows that monomeric four-coordinate species are found in the solid state fo r 4 and 5 but polymeric structures with five-coordinate tin atoms are found for 1-3. The different behavior is ascribed to the steric demands of the t in-bound substituents. A fair correlation is found between the difference i n Sn-117 chemical shift between the solution and solid states and the carbo nyl oxygen-tin distance of the compounds 1-5, only when the data of 4, R = Ph, are omitted. This indicates that the mesomeric effect of the phenyl gro up does not express its influence to the same extent in the solid and solut ion states, unlike the inductive effects. By contrast, a good correlation i ncluding 4 is found between the Mossbauer quadrupole splitting and the diff erence in Sn-117 chemical shift between the solution and solid states. This shows that the nature of the organic group on the tin atom contributes to similar extents to the values of the Sn-117 chemical shifts in solution and solid state, independently of the existence or not of mesomeric effects, a nd that the parallel behavior of QS and Sn-117 chemical shifts is geometry independent.