Synthesis, characterization, crystal structures and in vitro antimicrobial activities of triorganotin(IV) complexes of azo-dicarboxylates

•Triorganotin(IV) complexes of azo-dicarboxylates have been synthesized and characterized.•NMR studies of the complexes indicate 4-coordinate quasi-tetrahedral structure in solution.•Crystal structures of complexes 1 and 3 show polymeric structures in solid state.•In vitro antimicrobial studies of the complexes show moderate activity.

Triorganotin(IV) complexes (R = n-butyl, phenyl and methyl) of azo-dicarboxylates were synthesized by reacting bis-tri-n-butyltin(IV) oxide with (E)-5-((2-carboxyphenyl)diazenyl)-2-hydroxy benzoic acid (L1HH′) [compound 1] and tri-organotin(IV) chlorides [R = Ph, Me] with either sodium salt of (E)-5-((2-carboxyphenyl)diazenyl)-2-hydroxy benzoic acid (L1Na) [compounds 2 and 3] or sodium salt of (E)-5-((4-carboxyphenyl)diazenyl)-2-hydroxy benzoic acid (L2Na) [compounds 4 and 5]. The complexes were characterized by elemental analysis, UV, IR and NMR-spectroscopy. NMR studies of the triorganotin(IV) complexes indicate that the complexes adopt 4-coordinate quasi tetrahedral geometry in solution state. The structures of complexes 1 and 3 in solid state were characterized by X-ray crystallography. The crystal structure analyses show that the complexes have polymeric structures with distorted trigonal bipyramidal geometry around tin atoms. Classical intra-molecular hydrogen bonds O—H⋯O have been observed in both the complexes. In-vitro antimicrobial activities of the complexes were also screened against various microbes and found to be effective.

Graphical abstractTri-organotin(IV) complexes [Bu3SnL1(1), Ph3SnL1(2), Me3SnL1(3), Ph3SnL2(4) and Me3SnL2(5)] have been synthesized using either azo-dicarboxylic acids [(E)-5-((2-carboxyphenyl)diazenyl)-2-hydroxy benzoic acid] (L1HH′) or its sodium salt (L1Na) or sodium salt of [(E)-5-((4-carboxyphenyl)diazenyl)-2-hydroxy benzoic acid] (L2Na). NMR studies indicate that the complexes adopt 4-coordinate quasi-tetrahedral geometry around tin atom in solution state. X-ray crystal studies of complex 1 and 3 shows trigonal bipyramidal polymeric structures in solid state. Complex 1 and 4 exhibit better antifungal and antibacterial activities than complex 3 and their corresponding ligands.Figure optionsDownload full-size imageDownload as PowerPoint slide