Easy obtention of tin(II) complexes by using semicarbazones in their hydrochloride forms

Abstract

The 2-benzoylpyridine-semicarbazone and 2-benzoylpyridine-N-4-phenylsemicarbazone can be prepared in their hydrochloride forms, having good solubility in water and/or methanol. We have used these compounds, named [H2L]Cl] and [H2LPh]Cl, as pre-ligands in reactions with SnCl2·2H2O in pure water or water/methanol mixtures. Four SnII coordination compounds were obtained and structurally analyzed by single-crystal X-ray diffraction: [Sn(HL)Cl][SnCl3] (1), [Sn(HL)(NCS)2] (2), [Sn(HLPh)Cl2] (3) and [Sn(HLPh)(NCS)2] (4). The 5s2 electron pair of SnII produced a clear gap in all compounds, which was fulfilled by tetrel bonds. The Sn‒Cl or Sn‒S tetrel bonds generated the pseudo-polymeric structures of 1 and 2, and the pseudo-dimeric structures of 3 and 4. Hydrogen bonds arranged the pseudo-polymers and pseudo-dimers into two-dimensional nets. Spectroscopic techniques, thermogravimetric analysis, and powder X-ray diffraction complemented the characterization of the compounds. Polymorphism was found for 3. Antimicrobial activity against bacterial and mycobacterial strains was evaluated. MIC values of 0.0976‒3.125 mM against M. abscessus, M. massiliense and M. fortuitum were obtained for compounds 1‒4.