Intramolecular cyclization of ω‐haloalkylsubstituted thiophosphorylacetonitriles: Synthesis and stereochemistry of 3‐cyano‐2‐oxo‐1,2‐thiaphosphacyclanes

Intramolecular S‐alkylation in a series of ω‐haloalkyl‐substituted thiophosphorylacetonitriles 5–7 presents an effective synthetic route to the hitherto unknown 3‐cyano‐2‐oxo‐1,2‐thiaphospholanes 14 and thiaphosphinanes 15 . The compounds were obtained as a mixture of cis‐ and trans‐isomers that were resolved to individual stereoisomers in most cases. For some of them, X‐ray diffraction analysis has been performed. It was shown that ³¹P NMR spectroscopy can be used to assign the stereochemistry of 3‐cyano‐2‐oxo‐1,2‐thiaphosphacyclanes. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:1–21, 2002; DOI 10.1002/hc.1101     

Isotope effects in α-PdH(D) as an instrument for diagnosing bulk defects

Protium and deuterium sorption in the α-phase region is studied for highly defective palladium electrodeposits fabricated under controllable potentiostatic modes, particularly in the region of concentrated hydride formation. An anomalously high hydrogen content is observed for these samples in both α- and β-hydrides. On the basis of coulometry in the course of anodic hydrogen extraction, the non-linear sorption isotherms are plotted and their specific features are considered under an assumption of simultaneous equilibrium sorption of hydrogen by several types of lattice positions with a certain degree of defectiveness. Less defective palladium samples deposited in the absence of bulk hydridization are studied for comparison. The approach is proposed to estimate the fraction of defective regions. The procedure of analyzing the low-pressure limit is used for the first time for determining the specific values of the isotope effect, and also H and D Sievert's constants. The isotope effect is demonstrated to be extremely sensitive to the type of defectiveness. Electronic Publication     

A new approach in small-angle neutron scattering: A method of triple isotopic substitutions

A new method is proposed for studying the structure and mutual arrangement of selected components in multicomponent particles. Here the difference between the scattering curve of a solution containing two types of structurally identical particles (differing only in the degree of deuteration) and the scattering curve of a solution containing particles of a third type (deuterated to an intermediate degree) is considered. This difference scattering curve differs only by a numerical multiplier from the “vacuum” scattering curve of the particle in which the scattering density is equal to the difference between the scattering densities of the particles of the first and second types. This means that any particle component which is deuterated (protonated) to the same degree in the particles of three different types does not contribute to the difference scattering curve and, consequently, is “invisible” for neutrons. The difference scattering curve depends neither on the isotopic content of the solvent nor on the inter-particle interference and particle association. Possible applications of this method are discussed.     

Stereoselective electrocatalytic transformation of malonate and alkylidenecyanoacetates into (E)-3-substituted 2-cyanocyclopropane-1,1,2-tricarboxylates

Electrolysis of malonate and alkylidenecyanoacetates in alcohols in an undivided cell in the presence of NaBr results in stereoselective formation of (E)-3-substituted 2-cyanocyclopropane-1,1,2-tricarboxylates in 75-90% yields.     

Spectral analysis and crystal structure of a new mononuclear copper(II) complex of 3-aminopyridine

A new Cu(II)-complex of 3-aminopyridine, [CuCl(3-AP)₄][Cu(3-AP)₄(H₂O)]Cl₃ · 2H₂O (1), containing two contrasting complex cations has been synthesized and structurally characterized by single crystal X-ray diffraction and solid-state linear-dichroic infrared (IR-LD) spectral analysis. In both cations four 3-AP molecules coordinate the Cu(II) atom in a monodentate fashion through their endocyclic (N_py) nitrogens, thereby generating a square-planar coordination geometry for the CuN₄ chromophor. Perpendicular to the N₄ plane, the metal ion is coordinated by a chloride anion in the first cation and a water ligand in the second cation. One of three additional water molecules of crystallization occupies the vacant octahedral site of the second cation and participates in a weak Cu···OH₂ interaction. An IR-LD spectral analysis of the samples, oriented as a suspension in a nematic liquid crystal confirmed the crystallographic data and the retention of the pyridine ring aromatic character after coordination. The presented results are additionally supported by UV, ¹H-NMR, EPR and MS analysis and by thermogravimetric and calorimetric data.     

Classification of polyhedral matroids

This paper establishes polyhedral properties of matroidal structures. Classical problems such as enumeration and classification of polyhedra matroids, the characterization of face complexes, the metric properties of graphs of polymatroids are considered. Supported by DAAD and Belarussian Fundamental Science Fund     

Asymptotics of Solutions of Difference Equations with Variable Coefficients

Linear difference equations in a Hilbert space with coefficients depending on the number n of the equation are considered. It is assumed that the coefficients differ from constant ones by a finite sum of exponentially vanishing terms as n → ∞. An asymptotic formula for solutions as n → ∞ is obtained. The coefficients in the asymptotic expansion are expressed as linear functionals on the space of sequences in the terms on the right-hand side.     

On the failure of hyperbolicity in elasticity

The failure of hyperbolicity leading to the instability as an ill-posedness of the Cauchy problem is investigated for elasticity. The criteria for that instability are derived in terms of the potential energy as a function of the strain invariants. The theory is illustrated by examples.     

A unified model description of mobile and localized adsorption: I. MFA with nonadditive lateral interactions — an application to disordered adsorbed monolayer on a structureless substrate

A simple model is used to treat mobile adsorption on a structureless substrate. The influence of temperature on the state of motion of adsorbed particles is described by means of an interpolation formula used earlier in the theory of hindered rotation, whereas the influence of the nearest-neighbour potential with varying degree of coverage is accounted for in terms of a “free area”, available for individual particle motion, for which a simple analytical expression, based on an harmonic oscillator approximation, is obtained. An irregularity in the long range order of the adsorbed monolayer is introduced in terms of “varying distances”, resp. of varying energy bonds between the particles in dependence of the number of nearest neighbours actually present in the first coordination sphere of each particle (nonadditivity of the bonds).