Synthesis, spectroscopic characterization and X-ray structures of five-coordinate diorganotin(IV) complexes containing 5-hydroxypyrazoline derivatives as ligands

Four new diorganotin(IV) complexes have been prepared from R2SnCl2 (R = Me, Ph) with the ligands 5-hydroxy-3-metyl-5-phenyl-1-(S-benzildithiocarbazate)-pyrazoline (H2L1) and 5-hydroxy-3-methyl-5-phenyl-1-(2-thiophenecarboxylic)-pyrazoline (H2L2). The complexes were characterized by elemental analysis, IR, 1H, 13C, 119Sn NMR and Mössbauer spectroscopies. The complexes [Me2SnL1], [Ph2SnL1] and [Me2SnL2] were also studied by single crystal X-ray diffraction and the results showed that the Sn(IV) central atom of the complexes adopts a distorted trigonal bipyramidal (TBP) geometry with the N atom of the ONX-tridentate (X = O and S) ligand and two organic groups occupying equatorial sites. The C–Sn–C angles for [Me2Sn(L1)] and [Ph2Sn(L1)] were calculated using a correlation between 119Sn Mössbauer and X-ray crystallographic data based on the point-charge model. Theoretical calculations were performed with the B3LYP density functional employing 3–21G(*) and DZVP all electron basis sets showing good agreement with experimental findings. General and Sn(IV) specific IR harmonic frequency scale factors for both basis sets were obtained from comparison with selected experimental frequencies.