A. B. Nikol'skii

Photochemistry of bridged symmetrical polypyridyl ruthenium(II) complexes

Abstract The photochemical behaviour of [RuL 2 (BL)X] + ( 1 ) and [L 2 XRu(BL)RuXL 2 ] 2+ ( 2 ) (L≡2,2′-bipyridyl (bpy), 1,10-phenanthroline(phen); BL≡4,4′-bipyridyl (4,4′bpy), pyrazine (pyz) and trans -1,2-bis(diphenylphosphino)ethylene (dppene); X≡Cl, NO 2 ) in acetonitrile and methanol solutions during steady state irradiation at λ = 450 nm was studied. Compounds 1 and 2 (L≡bpyX≡Cl) with both bridging and terminal dppene ligands were found to be photochemically inert. The irradiation of compounds 1 and 2 with BL≡pyz and 4,4′-bpy resulted in the formation of solvate complexes [RuL 2 (Solv)X] + ( 3 ) in both acetonitrile and methanol; however, the photolysis of 2 proceeded via a mixture (1:1) of 1 and 3 in the first step. The quantum yields of the processes under study are discussed in terms of the excited states.

Dirhodium(II) dicarboxylato complexes containing carbonyl and C-bonded methoxycarbonyl ligands

Abstract Oxidation of rhodium(I) carbonyl chloride, [Rh(CO) 2 Cl] 2 , with copper(II) acetate or isobutyrate in methanol solutions yields binuclear double carboxylato bridged rhodium(II) complexes with RhRh bonds, [Rh(μ-OOCRκO)(COOMeκC)(CO)(MeOH)] 2 , where R=CH 3 or i -C 3 H 7 . According to X-ray data, surrounding of each rhodium atom in these complexes is close to octahedral and consists of another rhodium atom, two oxygens of carboxylato ligands, terminal carbonyl group, C-bonded methoxycarbonyl ligand, and axial CH 3 OH. Methoxycarbonyl ligand is shown to originate from CO group of the parent [Rh(CO) 2 Cl] 2 and OCH 3 group of solvent. N- and P-donor ligands L ( p -CH 3 C 6 H 4 NH 2 , P(OPh) 3 , PPh 3 , PCy 3 ) readily replace the axial MeOH yielding [Rh(μ-OOCRκO)(COOMeκC)(CO)(L)] 2 . The X-ray data for the complex with R= i -C 3 H 7 , L=PPh 3 showed the same molecular outline as with L=MeOH. Electronic effects of axial ligands L on the spectral parameters of terminal carbonyl group are essentially the same as in the known series of rhodium(I) complexes (an increase of δ 13 C and a decrease of ν (CO) with strengthening of σ-donor and weakening of π-acceptor ability of L).

Solubility of d-elements salts in organic and aqueous-organic solvents: I. Copper, cobalt, and cadmium sulfates

Solubility at 25°C has been determined in the MSO4–H2O–Solv systems (M = Co, Cu, or Cd; Solv = dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, tetrahydrofuran, or dioxane) via the isothermal saturation method. Analysis of the solubility as function of the permittivity and donor power of solvents along with the information on the cations radius leads to the conclusion that ion–ion association dominates over solvation interactions in the studied systems.

Chemistry of Ruthenium Polypyridine Complexes: IV. Quantum-Chemical Simulation of the Effect of Solvation Shell on the Electronic Structure of Ru(II) Complexes with Nitrogen-containing Ligands

Ab initio quantum-chemical calculations of Ru(II) complexes have been fulfilled with consideration for solvation within the framework of the polarized continuum model. Energy levels of fragments of Ru(II) complexes with organic ligands are shifted relative to each other by electrostatic interactions with the solvation shells.

Solubility of d-element salts in organic and aqueous–organic solvents: II. Effect of halocomplex formation on solubility of cobalt bromide and chloride and nickel chloride

Solubility of salts in the systems MCl2–H2O–Solv (M = Co, Ni) and CoBr2–H2O–Solv (Solv = dimethyl sulfoxide, dimethyl formamide, and dimethyl acetamide) at 25°C was measured experimentally. Dominating species of cobalt and nickel halides existing in various concentration regions were identified by analysis of electron absorption spectra. It was shown that the major factor defining solubility is the interaction of halocomplexes of metal ions with solvent molecules.

Solubility of d-elements salts in organic and aqueous-organic solvents: III. Influence of intermolecular association on solubility of cadmium bromide and iodide

Solubility in the systems CdX2–H2O–Solv (X = Br, I; Solv = dimethyl sulfoxide, N,N-dimethyl acetamide, N,N-dimethyl formamide, and 1,4-dioxane) at 25°C was measured by the isothermal saturation method. A relation between the shape of the solubility isotherm and the structure of the binary solvent depending on its composition was found. Positions of solubility maxima and isotherms inflection points in the most cases correlate with destruction of intermolecular associates formed by solvent components.

Electronic structure and spectra of [Ru(NH3)5pyz]2+ and [(NH3)5Ru-pyz-Ru(NH3)5]4+

The electronic structure and spectra of [Ru(NH3)5pyz]2+ and [(NH3)5Ru-pyz-Ru(NH3)5]4+ are calculated by the INDO (CINDO-E/S) method. Changes in molecular orbitals, charge distributions, and bond order indices of the pyrazine molecule and [Ru(NH3)5pyz]2+ complex in the [(NH3)5Ru-pyz-Ru(NH3)5]4+ binuclear complex are analyzed.

Solubility of salts of d-elements in organic and water-organic solvents: V. Inner-sphere chalcogen S–S contacts in the [Ni(DMSO)4(H2O)2]Cl2 solvate

It was proved by the IR spectroscopy that the first coordination sphere of nickel cations in the NiCl2·2DMSO·9H2O, NiCl2·5DMSO·4H2O, and NiCl2·4DMSO·2H2O compounds contains dimethyl sulfoxide and water ligands. According to X-ray structural analysis, in crystals of the NiCl2·4DMSO·2H2O compound, noncovalent contacts between sulfur atoms of neighboring dimethyl sulfoxide molecules are realized in the inner sphere of the complex.

Solubility of d-elements salts in organic and aqueous-organic solvents: IV. Solubility of cadmium chloride

Solubility of cadmium chloride at 25°C in four ternary systems containing mixed water-organic solvents was measured by the isothermal saturation method. Dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and 1,4-dioxane were used as organic components. In all systems the organic component addition provides a salting-out effect within the whole range of the binary solvent compositions.

Solubility of Copper(II) Chloride in Mixed Organic Oxygen-Containing Solvents

Solubility of copper(II) chloride at 25°C in binary organic solvents consisting of dimethyl sulfoxide, N,N-dimethylacetamide, and 1,4-dioxane was determined by the isothermal saturation method. The shape of solubility isotherms for all ternary systems under study is connected with the structural type of formed copper chloride solvates, the composition of which is defined by the solvent donor number. Solvates crystallize predominantly, where the metal ion coordinates molecules of the solvent with a greater donor power. The temperature increase in the system CuCl2–dimethylacetamide–dioxane up to 50°C leads to the formation of the cluster compound [Cu4Cl6O(DMA)4]; its structure was determined by the X-ray structural analysis method.