The crystal and molecular structures of R2Sn(O2CR(1))(2): R = tBu, Ph; (-O2CR1) = 2-[(E)-2-(2-hydroxy-5-methylphenyl)diazenyl]benzoate

The crystal. and molecular structures of two compounds of the general formu la R2Sn(O2CR1)(2) are reported where R = tBu and Ph, and (RCO2-)-C-1 is the anion derived from 2-[(E) -2-(2-hydroxy-5-methylphenyl)- 1-diazenyl]benzoi c acid. For the R = tBu compound, the tin atom exists in a skew-trapezoidal bipyramidal geometry in which the trapezoidal plane is defined by two asym metrically chelating carboxylate ligands and the organic residues lie over the weaker Sn-O interactions. A similar coordination geometry is found in t he R = Ph compound which was isolated as a di-chloroform solvate. The chlor oform molecules exert an influence on the molecular geometry in that a conf ormational change in the carboxylate ligand is induced in order to facilita te the formation of intermolecular hydrogen bonds. Systematic variations in the Sn-ligand parameters in these and related compounds are correlated wit h the varying Lewis acidity at the tin centers.