Synthesis, Spectral, Biological and Theoretical Investigation of Some New Sn (IV) Complexes with Schiff Base Ligands Containing NNOS Coordination Sphere

New tin (IV) complexes of empirical formula, [Cl2 Me2 Sn(H2 L)1-3], where ((H2 L)1-3: Methyl-2- {[1-methyl-2-(2-hydroxy-3-methoxyphenyl)methylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate [H2cd3OMesalMeen], Methyl-2-{[1-methyl-2-(2-hydroxy-4 methoxyphenyl)methylidynenitrilo]ethyl}amino-1-cyclopentenedithiocar-boxylate, [H2 cd4OMesalMeen], Methyl-2-{[1-methyl-2-(2-hydroxy-5-methoxyphenyl) methylidynenitrilo]ethyl}amino-1- cyclopentenedithiocarboxylate, H2 cd5OMesalMeen]) have been prepared and fully characterized by a variety of physico-chemical techniques. Spectroscopic data suggest that in three complexes the Schiff base ligand is coordinated through oxygen. The Schiff base ligands and their Sn (IV) complexes were tested against two pathogenic bacteria (Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria). All the complexes exhibit higher antibacterial activity than the free ligands. Computation analyses at the level of DFT with Becke’s three parameter hybrid methods were performed to study the geometrics, electronic structures; HOMO- LUMO energy gap, dipole moment and its calculated vibrational frequencies were investigated. An excellent agreement between the experimental and calculated results obtained from the two spectra methods.