Nickel(ii) N-heterocyclic carbene complexes as efficient catalysts for the Suzuki—Miyaura reaction

Russian Chemical Bulletin - Catalytic activity of nickel(ii) and palladium(ii) N-heterocyclic carbene (NHC) complexes derived from imidazole, benzimidazole, and 1,2,4-triazole was comparatively...     

Methods of the Lagrangian and Hamiltonian Mechanics in Aeroacoustics Problems

Acoustical Physics - It is well known that a sound source related to nonstationary motion of vortices at small Mach numbers can be obtained in the incompressible inviscid fluid approximation. In...     

On the limit shape of elements of an arithmetic semigroup with an exponentially growing counting function of basis elements

We consider an arithmetic semigroup with exponential growth of the counting function of abstract primes. The Bose–Einstein statistics provides the most probable mean occupation numbers in the sense that large deviations of a sum of occupation numbers from the corresponding sum for the Bose–Einstein statistics have small probabilities. The probabilities of large deviations are estimated.     

Dimroth rearrangement “thiadiazole-triazole”: synthesis and exploration of 3-sulfanyl-1,2,4-triazolium salts as NHC-proligands

Russian Chemical Bulletin - The reaction of 1,4-disubstituted thiosemicarbazides with N,N-dimethylformamide dimethyl acetal afforded 1,4-disubstituted 1,2,4-triazolium-3-thiolates. Heating of the...     

1,1,2,2-Tetramethyl-3-trimethylsilyl-1,2-disilacyclobutane: synthesis and spontaneous polymerization

Gas-phase dehalogenation of 1,2-bis[chloro(dimethyl)silyl]-2-trimethylsilylethane with alkali metals gave 1,1,2,2-tetramethyl-3-trimethylsilyl-1,2-disilacyclobutane (3). Its spontaneous ring-opening polymerization at room temperature afforded an amorphous linear polymer with T _g = ?8.9°C, M _w = 3.47·10⁵–3.85·10⁵, and M _w /M _n = 2.43—2.86. According to spectroscopic data (IR and ¹H, ¹³C, and ²⁹Si NMR), the backbone of the polymer consists of alternating monomer units joined in the “head-to-tail” ([Me₂SiCH(SiMe₃)CH₂SiMe₂SiMe₂CH-(SiMe₃)CH₂SiMe₂]) and “head-to-head” ways ([Me₂SiCH₂CH(SiMe₃)SiMe₂SiMe₂CH-(SiMe₃)CH₂SiMe₂]).     

Gas phase reaction of dichlorogermylene with the chlorine-substituted ethylenes

Gas phase reaction of dichlorogermylenes formed in the systems GeCl₄-Si₂Cl₆ or Ge-GeCl₄ with 1,2-dichloroethylene and trichloroethylene was studied. It is shown that:GeCl₂ inserts into the C-Cl bond of 1,2-dichloroethylene and forms the derivatives with one or two trichlorogermyl groups. A specific feature of the reaction of:GeCl₂ with trichloroethylene was found. In this reaction the formation of only monosubstituted compounds like 1,1-dichloro-2-trichlorogermylethylene and 1,2-dichloro-1-trichlorogermylethylene takes place. The rule established is valid in general also for the reaction of trichloroethylene with dichlorosilylene, another analog of carbene. Reactions taking place in the course of synthesis of organochlorogermanes are considered.     

Quantum chemical calculations of NMR chemical shifts of organic molecules: XI. Conformational and relativistic effects on the 31P and 77Se chemical shifts of phosphine selenides

Conformational and relativistic effects on the ³¹P and ⁷⁷Se chemical shifts of phosphine selenides were analyzed in terms of the ZORA-GIAO-B1PW91/TZP approach. The effect of conformation of phosphine selenides related to internal rotation about the single P-C bonds was found to be insignificant, while the contribution of relativistic spin-orbit interaction to the calculated values of ⁷⁷Se chemical shifts did not exceed 10 ppm. On the other hand, relativistic effects arising from magnetic shielding of the phosphorus nucleus in the P=Se fragment by selenium are fairly strong (25–30 ppm), which indicates the necessity of including the contribution of relativistic spin-orbit interaction in the calculation of ³¹P chemical shifts in phosphine selenides.     

Formation of the Heavy Isotope $${}^{\boldsymbol{6}}$$ He upon Stopped Pion Absorption by Nuclei

Physics of Atomic Nuclei - A survey of experimental results on the level structure in the heavy helium isotope $${}^{6}$$ He that were obtained in reactions induced by stopped pion absorption in...