Synthesis of platinum-mercury clusters and the molecular structure of Pt4(HgBr)2(μ-CO)4(PPh3)4

New platinum-mercury clusters, Pt₄(HgX)₂(μ-CO)₄(PR₃)₄ (X=Cl, Br, I, CF₃, or CCl₃; R=Ph or Et), were synthesized. The molecular and crystal structure of the Pt₄(HgBr)₂(μ-CO)₄(PPh₃)₄ cluster was established by X-ray structural analysis.     

A conformally invariant limit of the critical lattice Ising model

A detailed analysis of an expansion in powers of 1/N (N1) for the Hamiltonian and the transfer-matrix of the Ising chain consisting ofN sites is presented. A special attention is paid to a term proportional to 1/N closely related to the theory of free massless Majorana fermions. An effective Hamiltonian isomorphic to that in conformally invariant theory is derived. The eigenvectors of the Ising Hamiltonian are classified in the framework of conformal algebra representation theory. The momentum and the energy for these states are expressed through the central charge and conformal dimensions. A similar relation for the logarithms of the transfer-matrix eigenvalues is ascertained. These are complex-valued functions of a spectral parameter . A real part of such a function is shown to be proportional to sin , while an imaginary one - to cos. A direct geometrical interpretation of the lattice spectral parameter in the context of the conformally invariant theory for fermions inhabiting a torus is indicated. In other words, these fermions are represented as analytic anticommuting variables double (anti) periodic in a complex plane. The value of the spectral parameter coincides with an angle between these (anti) periods. A general scheme for the above expansion presumably suitable for a wide class of exactly solvable models is conjectured.     

Spin-adducts of η2-metallocomplexes of fullerene-60 with phosphoryl radicals

Using ESR spectroscopy, the reaction of P(O)(OPrⁱ)₂ phosphoryl radicals with C₆₀ML₂ (M=Pd, Pt) was studied and the spin-adducts formed were shown to be unstable under the reaction conditions. The ⁵-addition of Pt(PPh₃)₄ to the dimer of phosphorylfullerenyl radicals results in metal-containing dimers (RO)₂(O)PL₂MC₆₀-C₆₀ML₂P(O)(OR)₂, which dissociate when exposed to visible light to afford C₆₀ML₂P(O)(OR)₂ radicals; ML₂ in these complexes is located in different positions in relation to the radical center. As a result, the ESR spectra contain the superposition of at least five signals of radicals that differ in HFS constants andg-factors.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 938–940, May, 1994.The present work was supported by the Russian Foundation for Basic Research (Projects 93-03-18725 and 93-03-4101).     

X-ray study of the molecular structure of α-mercury and α-platinummercury derivatives of l-menthyl phenylacetate

The molecular structures of the L-menthyl ester of S-α-bromomercuriphenyl-acetic acid, diastereomer II, [α]²⁰_D ?18°, and of the related L-menthyl ester of α-bromobis(triphenylphosphine)platinummeruriphenylacetic acid, VI, have been investigated by the X-ray method. Insertion of L₂Pt carbenoid appears to occur into the HgBr bond in II and two phosphine ligands in the product VI occupy cis positions in a planar square around the platinum atom. The HgPt distance is 2.50 Å; there is intermolecular HgBr coordination in II, the distance being 3.23 Å.     

ESR spectra of products of oxidation of endometallofullerenes M@C82 (M = Y,La, Ce,Gd)

The ESR spectra of the products of oxidation of solutions and powders of Y@C₈₂ and La@C₈₂ with fuming sulfuric acid were studied. Based on the oxidation conditions and the sequence of spectral patterns, the spectra were attributed to the radical cations M@C₈₂ ⁿ⁺ (n = 2, 4), dimers M³⁺ ₂@C₁₆₄ ⁺, and polyendometallofullerenes.     

Spectrophotometric Determination of Ruthenium in Solutions of Nitroso and Sulfate Complexes Using Microwave Radiation

It has been shown that ruthenium can be determined in solutions of ammonium nitrosopentachlororuthenate (NH₄)₂[Ru(NO)Cl₅] with nitroso and aquachloro complexes present simultaneously by its reaction with 1,10-phenanthroline and in solutions of sulfate complexes using microwave radiation. It is found by molecular absorption and luminescence studies that the composition of the complex formed corresponds to ruthenium(II) tris-(1,10-phenanthrolinate) {[Ru(Phen)₃]²⁺}. The complexation time is decreased by several tens of times (down to 5 min) compared to conventional heating, and a 100% yield of the complex is achieved. In the presence of HCl, the conversion of nitroso species to aquachloro ruthenium complexes upon microwave irradiation is inefficient. It is found that, compared to [Ru₂OCl₁₀]^4–, [Ru(NO)Cl₅]^2– is more labile in the complexation reactions of ruthenium with 1,10-phenanthroline under microwave irradiation. Regardless of the concentration of H₂SO₄ (1.7–12 M) in the starting solutions, ruthenium sulfate complexes can be converted in a microwave field to more labile chloride complexes.     

Racemization as the stereochemical result of the solvolytic demercuration of optically active 1-(8-quinolyl)ethylmercuric bromide in methanol

Conclusions 1-(8-Quinolyl)ethylmercuric bromide undergoes racemization upon heating in methanol at reflux. This process was interpreted in terms of a radical mechanism for the solvolytic demercuration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 457–459, February, 1985.