In order to gain a greater insight in the nature of the DǞSb transannular interaction in dibenzostibocines, a series of D(C 6 H 4 S) 2 SbHal complexes (D = S; Hal = Cl 1, Br 2, I 3; D = O, Hal = Cl 4) has been synthesised. X-ray structure determinations of complexes 1−4 reveal that the antimony atom is in a distorted ψ-bipyramidal geometry, acting as an acceptor atom. The eight-membered ring conformation in 1, 2 and 4 can be described as a twist-boat, while in 3 it is approaching C s symmetry. DFT calculations were carried out on 1 and 4.

The facile preparation of a C 4 -symmteric tetratriazolium salt and its subsequent metalation to generate a series of tetranuclear mesoionic carbene gold(I) complexes is presented. The complete structural characterization of the metallic carbenes and the benefits of cooperative catalysis in the processes of hydroamination and hydrohydrazination of terminal alkynes are discussed.

The anti-microbial properties of acetone extracts from Hibiscus sabdariffa calyces, fractions isolated by silica gel chromatography and hibiscus acid purified from some of these fractions and additionally identified by nuclear magnetic resonance spectroscopy, mid-infrared spectroscopy and X-ray diffraction, were studied against both multidrug-resistant Salmonella strains and pathogenic Escherichia coli bacteria. Gel diffusion was used to determine the anti-microbial effects. The mode of action of hibiscus acid was determined by crystal violet assay. Hibiscus acid and 17 of the 25 chromatographic fractions obtained, displayed an anti-microbial effect against all bacterial strains tested. Hibiscus acid showed a greater anti-microbial effect than the acetone extract against most of the bacteria strains, while chromatographic fractions IX–XIV exerted the greatest anti-microbial effect against all bacteria. The minimum inhibitory concentration of the acetone extract was 7 mg/mL, and the minimum bactericidal concentration was 10 mg/mL, while the corresponding values for hibiscus acid were 4–7 and 7 mg/mL, respectively. The results of the crystal violet assay indicate that hibiscus acid alters membrane permeability. Hibiscus acid is a potential alternative to control multidrug-resistant bacteria. Due to its ready availability and easy extraction from H. sabdariffa, hibiscus acid is potentially useful in the food industries.

Coordinative behavior of the di-(2-pyridyl)hydroxymethane (1) and di-(2-pyridyl)-2-pyridylsulfanylmethane (2) ligands towards Pd(II) and Pt(II) is described. The compounds 3-5 were characterized by IR, mass spectrometry and NMR spectroscopy. Crystal structures of [Pt{(C 5 H 4 N) 2 CH(OH)}Cl 2 ] 3 and [Pd{(C 5 H 4 N) 2 CH(2-C 5 H 4 NS)}Cl 2 ] 4 as DMSO solvates displayed the formation of neutral mononuclear complexes. In the complexes 3 and 4 is observed the formation of six-membered chelate rings. The local geometry of the metallic atoms can be described as square planar in the title complexes.

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