Di- and tri-organotin(IV) complexes of the new bis(1-methyl-1H-imidazol-2-ylthio)acetate ligand and the decarboxylated analogues

Novel Organotin(IV) Schiff Base Complexes with Histidine Derivatives: Synthesis, Characterization, and Biological Activity

Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR (¹H, ¹³C  and ¹¹⁹Sn), as well as solid state ¹¹⁹Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive).

Bis(triphenylstannyl) thiophene-2,5-dicarboxylate

Mol­ecules of the title compound, [Sn₂(C₆H₅)₆(C₆H₂O₄S)], lie on inversion centres with the central thio­phene ring disordered equally over two orientations. The carboxyl­ate groups are approximately coplanar with the thio­phene ring [dihedral angle = 4.0 (1)°] and the Sn—O bond distance of 2.058 (4) Å is comparable to that in related organotin carboxyl­ates.