Chiral P,N-bidentate N-pyrrolylphophines as ligands with remarkable electronic properties

Previously unknown chiral P,N-bidentate N-pyrrolylphosphines and their chelate complexes [Rh(η²-P,N)(CO)Cl] and [Pd(Allyl)(η²-P,N)]BF₄ were synthesized by phosphorylation of (E,1R,2R,3R,5S)-2-[(2,6,6-trimethylbicyclo[3.1.1]heptyl-3-)iminomethyl]-1H-pyrrole. The composition and structures of the novel compounds were determined by the ¹H, ¹³C, and ³¹P NMR, IR, mass spectrometry (electrospray), and elemental analysis methods. N-pyrrolylphosphines were found to have unusual electronic properties, being simultaneously more strong π-acids and σ-bases as compared to phosphites.     

Factoring linear partial differential operators and the Darboux method for integrating nonlinear partial differential equations

Using a new definition of the generalized factorization of linear partial differential operators, we discuss possible generalizations of the Darboux integrability of nonlinear partial differential equations. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 122, No. 1, pp. 144–160, January, 1999.     

New oxazoline-containing phosphoramidite ligand for palladium-catalyzed asymmetric allylic sulfonylation

New chiral oxazoline-containing phosphoramidite was synthesized and its complex formation with rhodium(i) and palladium(ii) was examined. The new ligand is a highly efficient chiral inductor (ee up to 92%) in palladium-catalyzed asymmetric sulfonylation of 1,3-diphenylallyl acetate with sodium p-toluenesulfinate.     

Effect of Thermal Treatment on the Structure and Properties of Hydroxyapatite

X-ray diffraction analysis and transmission electron microscopy were used to demonstrate that hydroxyapatite produced by the precipitation method is a powder composed of anisometric particles with longitudinal size of 70–100 nm and transverse size of 7–9 nm. The particles are constituted by crystallites with longitudinal sizes of 22–24 nm and transverse sizes of 8–10 nm. At a temperature of 600°C, the crystallite sizes grow, and the volume porosity and specific surface area decrease. Synthetic hydroxyapatite has a low thermal stability as compared with hydroxyapatite of biological origin.     

Two-channel scheme for dark matter particle detection based on a low-temperature magnetic calorimeter

Problems of dark matter (DM) particle detection are briefly reviewed. An original two-channel scheme for direct detection of cosmic DM particles is proposed. This scheme is based on a superlow-temperature calorimeter which includes a nuclear spin system whose magnetic response is measured by a quantum interferometer (SQUID). Low threshold and the capability for efficiently suppressing the recoil-electron background are the most important advantages of the proposed scheme. They make it possible to detect DM particles in the range of extremely low recoil energies and carry out direct DM search with high sensitivity.     

Results of the Monte Carlo simulation of the LORD experiment with allowance made for the antenna system parameters and galactic noise effect

The results of the Monte Carlo simulation of the LORD experiment are presented for two types of antenna systems with various parameters. The effect of possible polarization mismatch and galactic noise “percolation” are taken into consideration.     

A study of the oxidation of titanium hydride powder by measurements of its electrical resistance

The oxidation of titanium hydride powder by air oxygen and the influence of oxidation conditions on the degree of oxidation of hydride particles, specific gas content in the powder, and kinetics of its thermal decomposition were studied. The resistometry method was used to determine the effective activation energy of oxidation of titanium hydride by air oxygen. The content of the surface nonconducting phase formed by titanium oxide and oxohydride films under various oxidation conditions was estimated.     

Platinum and rhodium complexes with isoleucinol-based bi- and tricyclic hydrophosphoranes

The complex formation of bi- and tricyclic hydrophosphorane derivatives of isoleucinol with [Pt(COD)Cl₂], [Rh(CO)₂Cl]₂, and [Rh(THF)₂(COD)]⁺BF₄ ^– (COD is cycloocta-1,5-diene) was investigated. In all cases, bicyclic hydrospirophosphorane selectively forms the metal chelates [M(²-PN)(X)Cl] (M = Pt, X = Cl; M = Rh, X = CO) and [Rh(²-PN)(COD)]⁺BF₄ ^–. («» denotes the residue of the hydrospirophosphorane ligand, which does not contain the P and N atoms). In addition, tricyclic hydrophosphorane (L) generates the phosphoranide complexes [Pt(¹-L)(COD)Cl]⁺Y^– (Y = Cl or BF₄). The structures of the new compounds were established by IR spectroscopy, ³¹P, ¹³C, ¹H, ²H, ¹¹B, ¹⁹F, and ¹⁹⁵Pt NMR spectroscopy, and plasma-desorption and electrospray ionization mass spectrometry. The possible mechanism of coordination of hydrophosphoranes is discussed.