Interaction of phosphomolybdovanadium heteropolyacids with hydrazine hydrate studied by a calorimetric method

The heats of interaction of VO ₂ ⁺ and of heteropolyacids H_3+nPMo_12−nV_nO₄₀ (n=1,2,3,6) with N₂H₄ have been measured.

---

Измерены теплоты взаимодействия VO ₂ ⁺ и гетерополикислот H_3+nPMo_12−nV_nO₄₀ (n=1,2,3,6) с N₂H₄.

     

Mössbauer study of thermal decomposition of the [FeCp(SPh)CO]2 complex and its reaction with the surface of activated silica gel

Thermal decomposition of the [FeCp(SPh)CO]₂ complex and its reaction with the surface of activated silica gel were investigated by Mössbauer spectroscopy. A small amount of a complex with properties similar to ferrocene is separated in the first stage of thermal decomposition (120–130°C). The starting carbonyl complex totally disappears in the second stage (165–210°C), and two compounds are present among the products: a derivative of ferrocene and the final product, an x-ray amorphous, iron-containing structure with an ionic-covalent type of chemical bond (CB) and a 25 and 5 wt. % concentration of oxygen and sulfur, respectively. The Mössbauer parameters of this product and the compound formed in the reaction of [FeCp(SPh)CO]₂ with the surface of activated silica gel at 4.2–300 K are identical. The analysis of the data suggested that both structures are highly disperse clusters of iron oxide with the structure of an inverted spinel with superparamagnetic properties.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 771–778, April, 1991.We would like to thank Yu. B. Kopylovskii for assistance in processing the spectra with the MESLIN program.     

New Catalytic Reactions in the Presence of Mo-V-Phosphoric Heteropoly Acid Solutions

The possibility of performing new catalytic reactions in the presence of solutions of H _x+3PMo_12−x . V_xO₄₀ Mo-V-phosphoric heteropoly acids was examined.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 772–778.Original Russian Text Copyright © 2005 by Zhizhina, Simonova, Russkikh, Matveev.     

Kinetics of reduction of tungstovanadophosphoric heteropoly anions with VO2+ ions

The rate constants of interactions of PW_12-nV_nO₄₀ ^(3+n)– (n=1–4) heteropoly anions (HPAs) and various PW₁₀V₂O₄₀ ^–5 isomers with VO²⁺ were measured. The reactions occurred via formation of intermediate active complexes with V(IV) ions incorporated into the coordination sphere of HPA.

---

VO²⁺ PW_12-nV_nO₄₀ ^–(3+n) (n=1–4) PW₁₀V₂O₄₀ ^–5. , V(IV) .

     

Reactions of Aluminium Tribromide with Tetrakis(triphenylphosphine)nickel(0) and Tetrakis(triethylphosphite)nickel(0) Complexes

Reactions of aluminium tribromide with the Ni(0) phosphine and phosphite complexes are studied by EPR method. AlBr₃was found to cause the oxidation of the transition metal in the (PPh₃)₄Ni complex to the univalent state with the formation of the tetracoordinated (PPh₃)₃NiBr complex. With an excess of AlBr₃, the phosphine ligands are eliminated from the coordination sphere of Ni(I), and the coordinatively unsaturated complexes are destroyed to give the colloidal nickel. In the reaction of (P(OEt)₃)₄Ni with AlBr₃, Ni(0) is also oxidized to Ni(I), but the acido ligand is not eliminated even with a 15-fold excess of the Lewis acid. The activity of catalytic systems on the basis of the Ni(0) phosphine complexes and the Lewis acids in the low-molecular oligomerization reactions of olefines is determined by the cationic coordinatively unsaturated Ni(I) complexes formed in these systems.     

Oxidative coupling of alkylbenzenes to diaryls catalyzed by the palladium(II)-heteropolyacid system

Oxidative coupling of alkylbenzenes (benzene, toluene, o-xylene, durene) is shown to proceed in the presence of palladium salts and heteropolyacids under the action of oxygen with a high yield of diaryls. The addition of mercury salts and variation of the solvent affect the reaction rate and isomer composition of the products.

---

, (, , -, ) . .

     

Oxidative coupling of 5-membered heterocycles catalyzed by a Pd(II)-heteropolyacid system in dimethylformamide

Oxidative coupling of thiophene and 2-methylfuran to the corresponding dihetaryls in DMFA medium occurs in the presence of the homogeneous catalytic system Pd(II)-molybdovanodophosphoric heteropolyacid (HPA). The data obtained show that HPA may act as a reversible oxidant in polar aprotic media.

---

, Pd(II)- 2- . , .

     

Kinetics and mechanism of the wet oxidation of propene to acetone in the presence of Pd2+ ions and Mo-V-phosphoric heteropoly acids ?

Summary Oxidation of propene to acetone in water solutions in the presence of homogeneous catalysts (Pd²⁺ + HPA-x, where HPA-x = H_3+xPV_xMo_12-xO₄₀, x = 1-4) is studied. This reaction is shown to be of the 1st order with respect to C₃H₆ and of the 0.5th order with respect to Pd. The reaction rate does not depend on the concentration of HPA-x and acidity of the catalyst solution. The apparent activation energy of the reaction is 21 kJ/mol. A reaction mechanism is proposed.     

Catalytic oxidation of octene-1 in the presence of palladium(II) salts and heteropolyacids

In the presence of the catalytic system (PdSO₄+HPA), where HPA=H₉PMo₆V₆O₄₀, octene-1 is found to be selectively (95%) oxidized to octanone-2. The optimum concentration ratio for catalyst stability is [HPA]:[PdSO₄]=30–40. The substitution of PdCl₂ for PdSO₄ leads to the formation of all three isomeric octanones without decrease of the overall selectivity. Effective rate constants and the apparent activation energy have been determined in the temperature range from 60 to 80 °C.

---

(PdSO₄+), =H₉PMo₆V₆O₄₀, -1 ( 95%) -2. []:[PdSO₄]=30–40. PdSO₄ PdCl₂ . 60–80 °C.