M. A. Fedotov

17O, 31P and 183W NMR spectra of paramagnetic complexes with the heteropolytungstate anion [Ln(PW11O39)2]11− and their co

Abstract Lanthanide complexes from La to Yb with [PW11O39]7− ligands were studied by 17O, 31P and 183W NMR methods. The complexes are

Role of protons in methyl phenyl sulfide oxidation with hydrogen peroxide catalyzed by Ti(IV)-monosubstituted heteropolytungstates

Acid tetrabutylammonium salts of Ti(IV)-monosubstituted heteropolytungstate, PW11TiO405−, show high catalytic acitivity in the oxidation of methyl phenyl sulfide with hydrogen peroxide, while the corresponding tetrabutylammonium salts containing no protons are poor catalysts for this reaction.

17O and 183W NMR diamagnetic and paramagnetic shifts in heterodecatungstates XW10O36− (X = Ln, Th, U) in aqueous solutions

Abstract Heterodecatungstates of the general formula X W 10 O 36 − where X = Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Th and U) have been studied by 17O and 183W NMR spectroscopy. It is shown that the structure of the heteropolyanions, where X occupies a centre of a square antiprism formed by two W5O18 ligands and which was determined in the crystalline state, is retained in aqueous solution. Completely resolved 17O and 183W NMR spectra for all atoms, even for the nearest oxygen atoms, have been recorded. From the analysis of the isotropic shifts, the contact and dipolar contributions have been estimated for all constituting atoms. The possible σ- and π-mechanisms of the spin transfer are considered. The negative spin density determines the dominant contact shift for the oxygen and tungsten nearest to X. The large pseudo-contact (ligand centred) contributions are estimated for the nearest oxygen and tungsten atoms. The positive spin density due to the σ-mechanism and large dipolar contribution gives rise to the observed chemical shift for the internal oxygen atom. The other oxygen atoms experience a mostly dipolar contribution with other terms probably cancelling each other. Temperature dependences of the chemical shifts are discussed. Copyright

Forms of Rh(III) in Nitric Acid Solutions

The forms of Rh(III) in nitric acid solutions are studied by 14N, 15N, 17O, and 103Rh NMR and electronic absorption spectra. At HNO3concentrations below 5 mol/l, rhodium mainly exists as low-nuclear oligomers with a bridging fragment Rh(μ-OH)(μ-ONO2)Rh; terminal positions of the central atoms are occupied by water molecules. It was found that the isotopic equilibrium 14NO–3/15NO–3of the bridging ligand sets in at an abnormally high rate, at which the isotopic exchange H217O/H216O of the terminal ligands also occurs in the dimers and trimers. The formation of low-nuclear oligomers is a common feature of Rh(III) complexes in aqueous solutions with ligand deficiency in the system. The possibility of isolating rhodium from nitric acid solutions using different methods is predicted.

Studies of the compositions of Pd(II) hydrolysis products

The characterization of the clusters formed on alkaline hydrolysis of [PdCl4]2− was performed using17O,23Na,35Cl,133Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)2]n·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.

Palladium(II), Copper(II), Iron(III), and Vanadium(V) Complexes with Heteropolyanion PW9O9–34: 31P, 183W, 51V NMR and IR Spectroscopy Studies

The formation of Pd(II)-containing and mixed Pd(II),Cu(II), Pd(II),Fe(III), and Pd(II),V(V) complexes with heteropolyanion PW9O9–34was studied using 31P, 183W, 51V NMR, visible UV and IR spectroscopy, and the differentiating dissolution methods. In an aqueous solution and at optimal pH (3.7), the monometallic complexes [Pd3(PW9O34)2]12–and [Pd3(PW9O34)2PdnOxHy]q–(nav= 3), the bimetallic complexes [Pd2Cu(PW9O34)2]12–, [Pd2Fe(PW9O34)2]11–, and [PdFe2(PW9O34)2]10–, and a mixture of the [Pd3(PW9O34)2PdnOxHy]q–(nav≈ 10) + [(VO)3(PW9O34)2]9–complexes are formed. The title complexes were isolated from solution as Cs+solid salts belonging to the same [M3(PW9O34)2] structural type.

The study of induced aquation of Rh(III) sulfate complexes

The processes of aquation of Rh(III) complexes in the presence of BaCl2 and Ba(ClO4)2 were studied by the 103RH and 17O NMR methods. In the first case, the final products were found to be the monomeric aqua chloride complexes, while in the second case, aqua hydroxo complexes were formed. The chloride ions present in the system significantly increase the process rate.

103Rh and 17O NMR study of oligomer rhodium(III) sulfates in aqueous solutions

By virtue of 103Rh-, 17O-NMR, electrophoresis in agarose gel, and pH-metry, we report on the formation of rhodium(III) sulfate complexes in aqueous solutions. At higher concentrations of sulfuric acid (above 3 M), more than 90% of metal was found to stay in the state of symmetric polynuclear complexes containing magnetically equivalent rhodium atoms. We also labeled the 103Rh-NMR chemical shifts for the complexes with 3, 4 and 6 metal atoms in the spectra.

Complexation of Rh(III) in diluted sulfuric acid solutions

Complex formation in a system Rh(III)-H2SO4-H2O was studied by the 103Rh and 17O NMR spectroscopy at room temperature. The formation of two interrelated systems of mononuclear and polynuclear complexes was established in the above solutions. The predominant species in the first system is a labile ionic pair {Rh(H2O)63+ SO42−}+, while in the second system, two inert binuclear complexes [Rh2(μ-SO4)2(H2O)8]2+ and [Rh2(μ-SO4)(μ-OH)(H2O)8]3+ prevail.

Synthesis properties and structure of binuclear anionic “Mo(V) hydroxide”, [Mo2O4(OH)4(H2O2]2−

Abstract The structure of “molybdenum(V) hydroxide” has been defined. The complex was obtained from MoO42−4 molybdate anion reduction with hydrazine-hydrate in aqueous solution. This compound is assigned the formula (N2H5)2[Mo2(μ-O)2(OH)4(H2O)2], dihydrazonium[di-μ-oxo-bis-(aquadihydroxooxomolybdate(V)]. The product similar in structure as that obtained on MoO2−4 reduction with NaBH4 and on (NH4)2MoOCl5 hydrolysis. Upon dissolving molybdenum(V) hydroxide in oxalic or tartaric acid solutions the diamagnetic complexes are obtained and characterized by means of IR, NMR and EXAFS spectroscopy.