Three water-soluble ruthenium(III) compounds, Y[cis-RuCl 2 (pic) 2 ]⋅nH 2 O (where pic = picolinate anion, Y = H(Hpic) 2 + (1), H 2 pic + (2) or K + (3), n = 2, 1.5 and 2.5, respectively), were synthesized and their X-ray structures determined. Compound 1 was fully characterized both as solid and in aqueous solution by elemental analysis, magnetic susceptibility measurements, EPR, IR and UV-Vis spectroscopy, cyclic voltammetry, microwave plasma atomic emission and mass spectrometry, capillary electrophoresis and chromatographic methods. It was shown that the coordination geometry around the low spin (S = ½) Ru III center is distorted octahedral with the chloride ligands in a cis configuration. Furthermore, all the measurements showed that the structures in the solid state and solution are absolutely identical with the cis-[RuCl 2 (pic) 2 ] − anion being inert in aqueous solution. Microbial studies showed that 1 exerts a strong inhibition on the growth and increased mortality level of the bacterial strains -E. coli, Pseudomonas sp., Sarcina sp., Micrococcus sp., Serratia sp., Bacillus cereus, B. subtilis and yeastSaccharomyces cerevisiae.

The crystal structures of [Ru(terpy)(bipy)Cl]Cl·2HO and [Ru(terpy)(en)Cl]Cl·3HO, where terpy = 2,2':6',2''-terpyridine, bipy = 2,2'-bipyridine and en = ethylenediamine, were determined and compared to the structure of the complexes in solution obtained by multi-nuclear NMR spectroscopy in DMSO as a solvent. In aqueous solution, both chlorido complexes aquate fully to the corresponding aqua complexes, viz. [Ru(terpy)(bipy)(HO)] and [Ru(terpy)(en)(HO)], within ca. 2 h and ca. 2 min at 37 °C, respectively. The spontaneous aquation reactions can only be suppressed by chloride concentrations as high as 2 to 4 M, i.e. concentrations much higher than that found in human blood. The corresponding aqua complexes are characterized by pK values of ca. 10 and 11, respectively, which suggest a more labile coordinated water molecule in the case of the [Ru(terpy)(en)(HO)] complex. Substitution reactions of the aqua complexes with chloride, cyanide and thiourea show that the [Ru(terpy)(en)(HO)] complex is 30-60 times more labile than the [Ru(terpy)(bipy)(HO)] complex at 25 °C. Water exchange reactions for both complexes were studied by O-NMR and DFT calculations (B3LYP(CPCM)/def2tzvp//B3LYP/def2svp and ωB97XD(CPCM)/def2tzvp//B3LYP/def2svp). Thermal and pressure activation parameters for the water exchange and ligand substitution reactions support the operation of an associative interchange (I) process. The difference in reactivity between these complexes can be accounted for in terms of π-back bonding effects of the terpy and bipy ligands and steric hindrance on the bipy complex. Consequences for eventual biological application of the chlorido complexes are discussed.

Food industry effluents are considered a potential alternative for methanol when seeking external carbon sources to enhance denitrification in municipal wastewater treatment plants (WWTPs). The aim of this study was to determine the immediate effects of dosing different carbon sources on the denitrification capability of process biomass from the Wschod WWTP in Gdansk (northern Poland). Five carbon sources, including settled wastewater, methanol, and three industrial effluents (distillery, brewery, and fish-pickling process) were tested in two kinds of batch experiments. The acclimation period of biomass to methanol also was investigated in bench-scale systems. During the conventional batch experiments, with the industrial effluents, the observed nitrate utilization rates (NURs) ranged from 2.4 to 6.0 g N/(kg VSS?h), which were only slightly lower than the rates associated with the use of the readily biodegradable fraction in the municipal (settled) wastewater [4.6 to 7.8 g N/(kg VSS?h)]. The conventional NURs observed with methanol and non-acclimated process biomass were low [i.e., 0.4 to 1.5 g N/(kg VSS?h)], and a minimum 2-week acclimation period of biomass to methanol in the bench-scale systems was needed to reach the level of 4.0 g N/(kg VSS?h). In other experiments, dosing the distillery and fish-pickling effluents at the beginning of the anoxic phase (preceded by the anaerobic phase) resulted in considerably higher (over 20%) NURs compared with the same experiments with the other carbon sources. Water Environ. Res., 81, 896 (2009).

[RuII(edta)(L)]2–, where edta4– =ethylenediaminetetraacetate; L = pyrazine (pz) and H2O, can reduce molecular oxygen sequentially to hydrogen peroxide and further to water by involving both outer-sphere and inner-sphere electron transfer processes.