P,C,P-Pincer complexes of ruthenium based on ruthenocene and pentamethylruthenocene

The first ruthenocene- and pentamethylruthenocene-based ruthenium pincer complexes, RuCl(CO)[{2,5-(Bu^t ₂PCH₂)₂C₅H₂}Ru(C₅H₅)] and RuCl(CO)[{2,5-(Bu^t ₂PCH₂)₂C₅H₂}Ru-(C₅Me₅)], were synthesized by cyclometallation of {1,3-(Bu^t ₂PCH₂)₂C₅H₂}Ru(C₅H₅) and {1,3-(Bu^t ₂PCH₂)₂C₅H₂}Ru(C₅Me₅), respectively, with RuCl₂(DMSO)₄ in 2-methoxyethanol and characterized by ¹H and ³¹P{¹H} NMR spectroscopy, and X-ray diffraction.     

A graphic model for calculating the properties of alkylsilanes, based on the additivity of energy contributions

A 18-constant additive scheme for calculating the physicochemical properties of alkylsilanes is obtained, based on the transferability of subgraphs in molecular graphs of the homologic SiC _n H_{2n + 4} series of alkylsilanes. The model considers multiple nonvalence interactions through no more than one atom and pair nonvalence interactions through no more than three skeletal atoms along a molecular chain. A linear dependence is established within the classification of the structural elements in a molecule. The enthalpies of formation Δ_f H° (g, 298 K) for alkylsilanes SiC _n H_{2n + 4} not studied experimentally were calculated numerically by considering different approximations.     

Efficient catalytic systems based on paramagnetic closo-ruthenacarboranes for the controlled synthesis of polymers

Novel catalytic systems were proposed for controlled radical polymerization of vinyl monomers. These systems are based on the paramagnetic (17-electron) closo-complex, namely, 3,3-(dppb)-3-Cl-closo-3,1,2-RuC₂B₉H₁₁ (1, dppb is 1,4-bis(diphenylphosphino)butane) and its mono(P-phenylene)- and di(P,P-ortho-phenylene)cycloboronated derivatives, namely, (R = H, n = 10 (2); R = Me, n = 8 (3)) and (4). With the polymerization of methyl methacrylate as an example, the effect of the steric hindrances in complexes 1?C4 on the synthesis and molecular-weight characteristics of the resulting polymers was analyzed. In the presence of aliphatic amines, the polymerization rate increases substantially and the catalyst concentration can be lowered without losing control of the process. The structure of 17-electron complex 3 in the solid state and its paramagnetic nature were confirmed by X-ray diffraction and ESR spectroscopy.     

On the acoustic nature of a microwave echo in silicate glasses

The results on the magnetic field dependence of the intensity of a microwave echo in silicate glasses containing paramagnetic impurities are used to construct a model of the formation of an echo as a super-position of an acoustic electron spin echo of the system of paramagnetic impurities and a polarization echo of the ensemble of quartz microcrystals present in the glass. Representing microcrystals in the glass as an ensemble of acoustic oscillators makes it possible to explain the anomalous low-temperature specific heat of glasses without invoking the model of localized two-level tunneling centers. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 11, 812–816 (10 December 1998)     

Q-balls in the Wick–Cutkosky model

In the present paper Q-ball solutions in the Wick–Cutkosky model are examined in detail. A remarkable feature of the Wick–Cutkosky model is that it admits analytical treatment for the most part of the analysis of Q-balls, which allows one to use this simple model to demonstrate some peculiar properties of Q-balls. In particular, a method for estimating the binding energy of a Q-ball is proposed. This method is tested on the Wick–Cutkosky model taking into account the well-known results obtained for this model earlier.     

A Model of Solid-Phase Synthesis in Binary Powder Mixtures with Allowance for Caking

Russian Journal of Physical Chemistry A - A mathematical model of solid-phase chemical synthesis in a binary powder mixture is constructed and studied with allowance for the shrinking of the...     

Is there the radion in the RS2 model?

We analyse the physical boundary conditions at infinity for metric fluctuations and gauge functions in the RS2 model with matter on the brane. We argue that due to these boundary conditions the radion field cannot be gauged out in this case. Thus, it represents a physical degree of freedom of the model.     

Drift effects on geodesic acoustic modes

We present a fluid model for geodesic acoustic modes including diamagnetic effects due to inhomogeneous plasma density and temperature. Effects of ion parallel viscosity (pressure anisotropy), which allows to recover exactly the adiabatic index obtained in kinetic theory are considered. We show that diamagnetic effects lead to the positive up-shift of the GAM frequency and appearance of the second (lower frequency) branch related to the drift frequency. The latter is a result of modification of the degenerate (zero frequency) zonal flow branch which acquires a finite frequency or becomes unstable in regions of high temperature gradients.