Thermodynamics and mechanism of oxidation of aqua(ethylenediaminetetraacetato)chromium(III) in ethanolwater solvents

Summary The kinetics of the oxidation of aqua(ethylenediaminetetraacetato)chromium(III) by periodate have been investigated in various ethanol: water mixtures in the 0–54 wt% ethanol range, at six different temperatures in the 15–40°C range. The effect of solvent on the rate and mechanism of the reaction has been studied and an innersphere mechanism for the reaction is proposed, consistent with the calculated activation parameters.     

Crystal structure of barium isothiocyanato(ethylenediaminetetraacetato)cobaltate(III)

All-Union Scientific-Research Institute for Chemical Reagents and Highly Pure Chemical Substances. M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 4, pp. 120–127, July–August, 1988.     

Polymeric aqua(nitrilotriacetato)erbium(III)

In the structure of the title compound, [Er(C₆H₆NO₆)(H₂O)]_n, the Er atoms are eight‐coordinated by one N atom and six O atoms from three symmetry‐related nitrilo­tri­acetate (NTA) ligands, and by one O atom of a water mol­ecule, adopting a distorted square‐antiprismatic geometry. The Er atoms are linked by the NTA ligands into layers, which are interconnected via O—H?O hydrogen bonds between the water mol­ecules and the carboxyl­ate O atoms. The asymmetric unit contains one Er atom, one NTA ligand and one water mol­ecule, all of which are located in general positions.     

Poly[[aqua(μ7‐ethylenediaminetetraacetato)dicadmium(II)] monohydrate]

The title compound, {[Cd₂(C₁₀H₁₂N₂O₈)(H₂O)]·H₂O}_n, consists of two crystallographically independent Cd^II cations, one ethylenediaminetetraacetate (edta) tetraanion, one coordinated water molecule and one solvent water molecule. The coordination of one of the Cd atoms, Cd1, is composed of five O atoms and two N atoms from two tetraanionic edta ligands in a distorted pentagonal–bipyramidal coordination geometry. The other Cd atom, Cd2, is six‐coordinated by five carboxylate O atoms from five edta ligands and one water molecule in a distorted octahedral geometry. Two neighbouring Cd1 atoms are bridged by a pair of carboxylate O atoms to form a centrosymmetric [Cd₂(edta)₂]⁴⁻ unit located on the inversion centre, which is further extended into a two‐dimensional layered structure through Cd2—O bonds. There are hydrogen bonds between the coordinated water molecules and carboxylate O atoms within the layer. The solvent water molecules occupy the space between the layers and interact with the host layers through O—H...O and C—H...O interactions.     

Solid-phase condensation of rhodium(III) aqua sulfates

Solid-phase condensation of rhodium(III) aqua sulfates yielding oligomeric rhodium(III) aqua sulfate complexes was revealed. The isothermal dehydration of rhodium(III) aqua sulfates under thermal diffusion conditions in the temperature range 100–130°C was studied, and effective rate constants and activation energies were determined. The solid phases of dehydration products were studied by X-ray powder diffraction and IR spectroscopy, and solutions of polymeric phases were studied by ¹⁰³Rh and ¹⁷O NMR, electronic absorption spectroscopy, chromatography, and electrophoresis.     

Oxygenation of a ruthenium(II) thiolate to a ruthenium(II) sulfinate proceeds via ruthenium(III)

Exposure of acetonitrile/methanol solutions of [PPN][Ru(DPPBT)3] [PPN = bis(triphenylphosphoranylidene); DPPBT = 2-diphenylphosphinobenzene thiolate] to oxygen initiates metal-centered oxidation, yielding the ruthenium(III) thiolate Ru(DPPBT)3. Ru(DPPBT)3 further reacts with oxygen, at sulfur, to give the ruthenium(III) sulfinate complex [Ru(DPPBT-O2)2(DPPBT)], which is reduced under ambient conditions to [PPN][Ru(DPPBT-O2)2(DPPBT)]. Ruthenium(II) sulfinate is the only product isolated from acetonitrile/methanol. Yellow crystals of [PPN][Ru(DPPBT-O2)2(DPPBT)] were obtained. Ruthenium(III) sulfinate was isolated as green prism-shaped crystals upon oxygenation of [PPN][Ru(DPPBT)3] in chlorobenzene/hexane. Electrochemical oxidation of ruthenium(II) sulfinate yields the ruthenium(III) derivative, which is rapidly reduced back to ruthenium(II) upon the addition of hydroxide.     

Reactions of ruthenium benzylidenes with H2O to give benzaldehyde and (aqua)ruthenium complex

The second generation of Grubbs type catalyst, (PCy₃)(H₂IMes)Cl₂RuCHPh (1) undergoes the Cl replacement with CH₃CN to give cationic ruthenium carbene complexes, [(RCN)₃(H₂IMes)RuCHPh](OTf)₂ (2, R = CH₃ (a), Ph (b)) in the presence of AgOTf. The reaction of 2a with H₂O in the presence of CH₃CN gives (aqua)ruthenium complex, [Ru(H₂IMes)(NCCH₃) ₄(H₂O)](OTf)₂ (3) and benzaldehyde. Benzaldehyde is also observed in the reaction of 1 with H₂O. Plausible reaction pathways are suggested for the degradation of ruthenium benzylidenes to give benzaldehyde on the basis of the isotope labeling experiments.     

Crystallochemical study of ruthenium(III) tris-dipivaloylmethanate

The structure of ruthenium(III) dipivaloylmethanate is determined by single crystal X-ray diffraction at temperature of 150 K. The crystallographic data for C₃₃H₅₇O₆Ru are as follows: a = 9.6119(11) Å, b = 17.4603(19) Å, c = 21.519(2) Å, β = 95.187(2)°, C2/c space group, V = 3596.7(7) ų, Z = 4, d_calc = = 1.202 g/cm³, R = 0.0642. The structure is molecular, the metal atom coordinates six oxygen atoms of three ligands of β-diketone. The Ru–O distances are in the range of 1.99 Å to2.03 Å. The complexes have a distorted single layer hexagonal packing with the Ru…Ru distances being 9.84 Å within the layer, and 10.93 Å between the layers.     

Kinetics and mechanism of ruthenium(III) and ruthenium(III)-EDTA catalyzed oxidation of cyclohexanol by molecular oxygen

The kinetics of the oxidation of cyclohexanol by molecular O₂ catalyzed by Ru(III) and Ru(III)-EDTA complexes has been investigated by oxygen absorption method in the pH range 1.75–3.00 at 30°C (=0.1M KNO₃) in a 11 ethanol-water medium. In both cases the reaction was found to be first order with respect to substrate and catalyst concentration. The rate was found to decrease with the decrease of pH in case of Ru(III)-EDTA complex. Ethanol is not oxidized under the reaction conditions. A possible mechanism for the catalytic oxidation of cyclohexanol is proposed.

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O₂, Ru(III) Ru(III)-EDTA, pH 1,75–3,00 30°C (=0,1M KNO₃) - (11). . pH Ru(III)-EDTA. . .

     

Studies on ruthenium(III), rhodium(III) and iridium(III) complexes of indazoles

Summary New complexes of the general formula M(L)₃Cl₃ and M(5-AInz)₂Cl₃ · n H₂O (where M = Ru^III, Rh^III and Ir^III; L = indazole and 5-nitroindazole; n=1–2) have been synthesized and characterised by elemental analysis, molar conductance, magnetic susceptibility and i.r. and electronic spectral measurements. All the complexes are covalent and apparently have an octahedral geometry. The ligands are monocoordinated through the pyrrole nitrogen. From the far i.r. spectra amer configuration has been assigned to the indazole and 5-nitroindazole complexes.