Intramolecular electron transfer in mixed-valence complexes [(NH3)5Ru-L-Ru(NH3)5]5+ (L = N2, pyz, pym, 4,4′-bipy, bpa)

The dynamics of the intramolecular electron transfer from Ru(II) to Ru(III) in binuclear mixedvalence complexes [(NH₃)₅Ru-L- Ru(NH₃)₅]⁵⁺ (L = N₂,pyz, bipy, pym, bpa) is analyzed by the semiempirical CINDO +CI method. Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 579–590, July–August, 1998.     

Quantum chemical study of the magnetic properties and electronic structure of the Creutz-Taube ion [(NH3)5Ru-pyz-Ru(NH3)5]5+

A method is developed of calculating the g-tensor from the results of quantum chemical calculations by semiempirical methods in a many-electron approximation. Calculations are performed for the g-tensors of the ruthenium complexes [(NH₃)₅Ru-pyz-Ru(NH₃)₅]⁵⁺ and [NH ₃Ru-pyz]³⁺. A comparison between the experimental and calculated g-factors of the Creutz-Taube ion [(NH₃)₅Ru-pyz-Ru(NH₃)₅]⁵⁺ allows one to conclude that the electronic structure of this ion is localized.     

Electronic structure, spectrum, and intramolecular electron transfer model of [(NH3)5Ru-(4,4’-bipy)-Ru(NH3)5]5+

The electronic structure of the ground and excited states of the binuclear mixed-valence complex [Ru(NH₃)₅]₂(4,4’-bipy)⁵⁺ is calculated by the semiempirical INDO + CI method, and an electronic spectrum assignment is given. A theoretical model of electron transfer between the Ru(II) and Ru(III) metal centers is constructed on the basis of many-electron wave functions. The dependence of the electron transfer characteristics on the angles between the planes of the pyridine rings and also between the pyridine rings and the planes of cis(NH₃)-Ru-cis(NH₃) is analyzed. Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 3, pp. 447–456, May–June, 1997.     

Electronic structure and spin bonds in the [(NH3)5Cr-O-Cr(NH3)5]4+ complex

The electronic structure of the lowest singlet, triplet, quintet, and septet states of the binuclear complex [Cr(NH₃)₅]₂O⁴⁺ are calculated by the semiempirical MC SCF method in the INDO approximation. Schemes of spin coupling of Cr-O-Cr in these states are analyzed. Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 3, pp. 457–464, May–June, 1997.     

Asymmetric salt effects on anion/cation reactions: A comparative study of the [Fe(CN)6]4− + [Co(NH3)5pz]3+ and [Ru(NH3)5pz]2+ + [Co(C2O4)3]3− reactions

The kinetics of electron transfer reactions between [Fe(CN)₆]^4? and [Co(NH₃)₅pz]³⁺ and between [Ru(NH₃)₅pz]²⁺ and [Co(C₂O₄)₃]^3? was studied in concentrated salt solutions (Na₂SO₄, LiNO₃, and Ca(NO₃)₂). An analysis of the experimental kinetic data, k_obs, permits us to obtain the true (unimolecular) electron transfer rate constants corresponding to the true electron transfer process (precursor complex → successor complex), k_et. The variations of both, k_obs and k_et, with salt concentrations are opposite for these reactions. These opposite tendencies can be rationalized by using the Marcus–Hush treatment for electron transfer reactions. The conclusion is that the negative salt effect found for the first reaction ([Fe(CN)₆]^4? + [Co(NH₃)₅pz]³⁺) is due to the increase of the reaction and reorganization free energies when the concentration of salt increases. In the case of the second reaction ([Ru(NH₃)₅pz]²⁺ + [Co(C₂O₄)₃]^3?), the positive salt effect observed is caused by the fact that the driving force becomes more favorable when the concentration of salt increases. Thus, it is shown that for anion/cation electron transfer reactions the kinetic salt effect depends on the charge sign of the oxidant (and the reductant). © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 37: 81–89, 2005     

Quantum-Chemical Study of the Electronic Structure of the Complex Ions [Ru(NH3)5pyz]2 + and [Ru(CN)5pyz]3 - in Solution

The hydration shell of the complex ions [Ru(NH₃)₅pyz]^{2 +} and [Ru(CN)₅pyz]^{3 -} was simulated on the basis of ab initio Hartree-Fock calculations in the supermolecular approximation, within the framework of the multicavity polarizable continuum model. In calculations of the spectral characteristics of complexes with a pronounced nonuniformity of electron density distribution, it is primarily necessary to take into account the shift of energy levels of particular fragments under the action of the electrostatic potential produced by the solvation surrounding. Consideration of the charge transfer between the complex and the outer-sphere water molecules has no significant effect on the calculated electronic spectrum; the transferred electron density is below 1e.     

Synthese und Kristallstrukturen von NH4[Si(NH3)F5] und [Si(NH3)2F4]

Synthesis and Crystal Structures of NH₄[Si(NH₃)F₅] and [Si(NH₃)₂F₄] Single crystals of NH₄[Si(NH₃)F₅] and [Si(NH₃)₂F₄] are obtained by reaction of silicon powder with NH₄HF₂ in sealed Monel ampoules at 400°C. NH₄[Si(NH₃)F₅] crystallizes with the tetragonal space group P4/n (no. 85) with a = 614.91(7) pm, c = 721.01(8) pm, Z = 2. Characteristic for the structure is the anionic octahedron [Si(NH₃)F₅]^?. Si(NH₃)₂F₄ crystallizes with the monoclinic space group P2₁/c (no. 14) with a = 506.9(1) pm, b = 728.0(1) pm, c = 675.9(1), β = 93,21(2)°, Z = 2. Trans-[Si(NH₃)₂F₄] molecules are characteristic for this structure.     

Binding Study of the [Ru(NH3)5pz]2+ Complex to Bile Anion Aggregates through Kinetic Measurements

The electron transfer reaction between [Ru(NH₃)₅pz]²⁺ and [Co(C₂O₄)₃]^3? was studied in the presence of monomers and aggregates of bile salts (sodium deoxycholate, sodium taurodeoxycholate, and sodium glycocholate) at 298.2 ± 0.1 K. The results show a decreasing rate constant with the successive addition of bile salts. To rationalize the trends of the reaction rate on the [bile salts], two models were used. One of them takes into account the aggregation feature by considering a stepwise self‐association between monomers, whereas the other assumes the formation of a critical micellar concentration. Binding constants between [Ru(NH₃)₅pz]²⁺ species and deoxycholate or taurodeoxycholate aggregates were higher than that for glycocholate aggregates. These results are consistent with the way in which the monomers are added to form the bile anion aggregates.     

X-ray diffraction study of [Ru(NH3)5Cl][ReCl6] and [Ru(NH3)5Cl]2[ReCl6]Cl2 and their thermolysis products. Crystal-chemical analysis of the Ru-Re system

Binary complex salts [Ru(NH₃)₅Cl][ReCl₆] and [Ru(NH₃)₅Cl]₂[ReCl₆]Cl₂ were synthesized and characterized. An X-ray diffraction analysis showed that they were isostructural with the previously obtained isoformula salts [Rh(NH₃)₅Cl][OsCl₆] and [Ir(NH₃)₅Cl]₂[PtCl₆]Cl₂, respectively. Thermolysis of these compounds under hydrogen and helium was studied. According to X-ray phase analysis data, bimetallic solid solutions Ru_0.67Re_0.33 and Ru_0.50Re_0.50 were the final products of thermolysis. Their unit cell parameters correspond to the characteristics of alloys with similar compositions. Original Russian Text Copyright ? 2009 by S. A. Martynova, K. V. Yusenko, I. V. Korolkov, I. A. Baidina, and S. V. Korenev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 126–132, January–February, 2009.     

Synthesis,spectroscopic characterization and X-ray single crystal structures of trans-bis[4-methoxyphenyl (3-methylbutyl) dithiophosphinato] nickel(II) and bis [4-methoxyphenyl (3-methylbutyl) dithiophosphinato]cobalt(II) complexes

Thionation of 3-methylbutylmagnesium bromide with Lawesson’s Reagent (LR) gave 4-methoxyphenyl (3-methylbutyl)dithiophosphinic acid (DTPA), and the latter was converted to the ammonium salt (NH₄L = Ammonium 4-methoxyphenyl (3-methylbutyl) dithiophosphinate). The complex, trans–bis[4-methoxyphenyl(3–methylbutyl) dithiophosphinato] nickel(II) [NiL₂], was prepared by the reaction of NH₄L with NiCl₂.6H₂O in EtOH. Bis [4-methoxyphenyl (3-methylbutyl) dithiophosphinato]cobalt(II) [(CoL₂)₂] was also prepared in the same way. The structures of the complexes have been characterized by elemental analysis, FTIR, ¹H, ¹³C, ³¹P NMR and X-ray diffraction. The single crystal X-ray structures of [NiL₂] and [(CoL₂)₂] show that the nickel complex is square planar while the cobalt counterpart has tetrahedral coordination with a dimeric structure. Bond lengths, angles, torsion angles and dihedral angles are correlated to the structures and also compared with the literature data on similar compounds.     

Synthesis, properties, and thermal decomposition products of [Ru(NH3)5Cl][PtCl6] and [Ru(NH3)5Cl]2[PtCl6]Cl2

The double complex salts [Ru(NH₃)₅Cl][PtCl₆] (I) and [Ru(NH₃)₅Cl]₂[PtCl₆]Cl₂ (II) were synthesized and studied by X-ray diffraction. They were found to be isostructural to the previously synthesized [Rh(NH₃)₅Cl][OsCl₆] and [Ir(NH₃)₅Cl]₂[PtCl₆]Cl₂. The thermolysis of the complexes in the atmosphere of hydrogen and helium was studied by the powder X-ray diffraction analysis. The product of the salt I thermolysis is a single-phase solid solution Ru_0.5Pt_0.5 (a = 3.857(3) ?), the thermolysis of salt II results in a double-phase metallic powder. Original Russian Text ? S.A. Martynova, K.V. Yusenko, I.V. Korol’kov, S.A. Gromilov, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 7, pp. 541–545.     

Double complex salts [M(NH3)5Cl][M′Br4] (M = Rh, Ir, Co, Cr, Ru; M′ = Pt, Pd): Synthesis, x-ray diffraction characterization, and thermal properties

Double complex salts (DCSs) with [M(NH₃)₅Cl]²⁺ (M = Rh, Ir, Co, Cr, Ru) cations and [PtBr₄]^2? anions were prepared in high yields. The salts were two-phase mixtures of the anhydrous and monohydro DCSs. Anhydrous analogues containing [PdBr₄]^2? anions with M = Cr or Ru were synthesized. All the compounds were characterized using a set of physicochemical methods. The crystal structure of chloropentaamminechromium(III) tetrabromopalladate(II) was solved: space group Pnma, Z = 4, a = 17.068(2) Å, b = 8.315(12) Å, c = 9.653(14) Å. The [M(NH₃)₅Cl][M′X₄] (M = Rh, Ir, Co, Cr, Ru; M′ = Pd, Pt; X = Cl, Br) compounds were shown to be isostructural. The [M(NH₃)₅Cl][PtBr₄] · H₂O monohydrates are isostructural to the [M(NH₃)₅Cl][PdCl₄] · H₂O monohydrates (space group P2₁/c, z = 4). The properties of the compounds were comparatively analyzed. The tendencies of the thermal stability of the complexes were elucidated. The thermolysis products of the double complex salts obtained under a helium or hydrogen atmosphere were studied.     

Semiempirical calculations of the electronic spectra of organometallic compounds: Estimation of solvent and counterion effects

The electronic spectra of the [Ru(NH₃)₅pz]²⁺, [Ru(NH₃)₅pz]³⁺, and [Ru(CN)₅pz]³⁻ complexes are calculated by the CI INDO method. The effect of solvation on the spectra is considered in a point charge approximation and in terms of the parametric model of a charged sphere enveloping the metal fragment. Interrelation of these approaches is discussed. Data on the molecular electrostatic potentials created by the complexes are presented to substantiate the models. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 603–618, July–August, 1996. Translated by I. Izvekova     

Thermal decomposition of the [Pt(NH3)4]2+ complex in NaX zeolite

The effect of the calcination procedure on the decomposition of the [Pt(NH₃)₄]²⁺ complex in a cesium-containing NaX zeolite was studied by thermal decomposition accompanied by mass spectrometry and diffuse reflectance spectroscopy, as well as electron paramagnetic resonance and infrared spectroscopy. The decomposition of the complex took place in two steps. Under oxygen, the [Pt(NH₃)₄]²⁺ complex was first converted into the [Pt(NH₃)₂]²⁺ complex in the first step, with predominant nitrogen release. In the second step, corresponding to the decomposition of the remaining two amine ligands, NO was also formed and adsorbed. Oxygen paramagnetic species were also observed. Under He, the decomposition also occurred in two steps with H₂ release.     

Complexation of the [Rh(NH3)5H2O]3+ ion in aqueous solutions of H3PO4 based on 31P NMR data

The kinetics of the reaction between the [Rh(NH₃)₅H₂O]³⁺ ion and H₃PO₄ was studied by ³¹P NMR at 323?C343 K (E _a = 100.9 ± 0.3 kJ/mol, lnA = 35.7 ± 0.1). An empirical dependence of the ³¹P chemical shift on the equilibrium pH was found. The acid dissociation constants of the coordinated H₂PO ₄ ^? (3.9) and H PO ₄ ^2? ions (9.1) were estimated. The chemical shifts of the [Rh(NH₃)₅H₂PO₄]²⁺, [Rh(NH₃)₅HPO₄]⁺, and [Rh(NH₃)₅PO₄]⁰ complex ions were 8.38 ± 0.03, 10.76 ± 0.05, and 13.63 ± 0.05 ppm, respectively.     

Darstellung von [(C2H5)2NH2]3[PS3F]F und [(C2H5)2NH2]3[PS2SeF]F und Kristallstruktur der selenhaltigen Phase

Preparation of [(C₂H₅)₂NH₂]₃[PS₃F]F and [(C₂H₅)₂NH₂]₃ [PS₂SeF]F and Crystal structure of the Phase with Selenium The title compounds were prepared by reaction of diethylammon ium-trithiophosphite with fluoride ions (as diethylammonium fluoride) and sulfur and selenium, respectively. The crystal structure of the selenium containing phase was determined. It does not represent a phosphoranate with a [PS₂SeF₂]^3? anion, but a double salt of [PS₂SeF]^2? with F^?.     

Conformational analysis of the [(C5H4CR'R")2M]2+ dications (M=Ru, Os) as a tool for determining their onium or dicarbocation structure

The [(Me₂CC₅H₄)₂M]²⁺ and [(Me(H)CC₅H₄)₂M]²⁺ dications (M=Ru, Os) were generated and their precursors, dicarbinols, were synthesized.¹H NMR spectral analysis showed that the former dications have a dicarbocation structure. For the [(Me(H)CC₅H₄)₂M]²⁺ dications, the energies of both the onium and dicarbocation structures are close, and compounds of both types can be simultaneously observed in solution. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1522–1528, August, 1997.     

About the stability of Au(NH3) 4 3+ in aqueous solution

The transformations of Au(OH) ₄ ^? in aqueous solutions (T = 20°C, I = 1) containing NH₃ and NH ₄ ⁺ (pH 8.1–8.5) were studied. The most pronounced changes in the system occur in the range 0 > log [NH ₄ ⁺ ] > ?2.0 (c _Au = (1?10) × 10^?4 mol/L, the monitoring time was about two weeks). When log [NH ₄ ⁺ ] > 0, Au(NH₃) ₄ ³⁺ dominates together with the amido form Au(NH₃)₃NH ₂ ²⁺ ; when log [NH ₄ ⁺ ] < ?2.0, no changes in the spectra are observed, probably, because of the very low rate of the processes. As c _Au increases in the indicated range, the polymerization rate grows. The equilibrium constant for Au(NH₃)₃OH²⁺ + NH₃ = Au(NH₃) ₄ ³⁺ + OH is log $ K_{4 OH, NH_3 } The transformations of Au(OH)₄⁻ in aqueous solutions (T = 20°C, I = 1) containing NH₃ and NH₄⁺ (pH 8.1–8.5) were studied. The most pronounced changes in the system occur in the range 0 > log [NH₄⁺] > −2.0 (c _Au = (1−10) × 10⁻⁴ mol/L, the monitoring time was about two weeks). When log [NH₄⁺] > 0, Au(NH₃)₄³⁺ dominates together with the amido form Au(NH₃)₃NH₂²⁺; when log [NH₄⁺] < −2.0, no changes in the spectra are observed, probably, because of the very low rate of the processes. As c _Au increases in the indicated range, the polymerization rate grows. The equilibrium constant for Au(NH₃)₃OH²⁺ + NH₃ = Au(NH₃)₄³⁺ + OH is log = −4.2 ± 0.3. This constant was used together with other constants, taking into account possible ligand effects, to estimate the formation constant of Au(NH₃)₄³⁺: logβ₄ = 47 ± 1, E _3/0 = 0.64 ± 0.02 V, log = −8.5 ± 1 (substitution of 4 NH₃ for 4 OH⁻ in Au(OH)₄⁻), log = 17.5 ± 1 (substitution of 4NH₃ for 4Cl⁻ in AuCl₄⁻). Original Russian Text ? I.V. Mironov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 4, pp. 711–715.     

Stability of [Co(NH3)6]3+ in nitrobenzene saturated with water

From extraction measurements, the individual extraction constant of the hexamminecobalt (III) cation, [Co(NH₃)₆]³⁺, in water-nitrobenzene system has been determined . Further, using known thermodynamic parameters and general relations, the stability constant of the complex [Co(NH₃)₆]³⁺ in nitrobenzene saturated with water was evaluated for 25 °C in the form log _nb{[Co(NH₃)₆]3+}=54.1.     

Crystal structure of [Pd(NH3)4][Rh(NH3)(NO2)5]

An XRD analysis is used to study the single crystal of [Pd(NH₃)₄][Rh(NH₃)(NO₂)₅] double complex salt at T = 150(2) K. Crystallographic characteristics are as follows: a = 7.6458(5) ?, b = 9.8813(6) ?, c = 9.5788(7) ?, β = 109.469(2)°, V = 682.30(8) ?³, P2₁/m space group, Z = 2, d _x = 2.553 g/cm³. The geometry of the complex [Rh(NH₃)(NO₂)₅]²⁻ anion is described for the first time: Rh-N(NO₂) distances are 2.020(4)–2.060(3) ?, Rh-N(NH₃) 2.074(4) ?, N(NO₂)-Rh-N(NH₃) trans-angle is 178.8(2)°.