Eleonora A. Ishmaeva

Conformational analysis of 1,4-heterophosphinanes

Structure of 1,4-heterophosphinanes in solution was studied by the methods of dipole moments, Kerr effect, molecular mechanics, and density functional theory calculations. It was determined that chair conformation with an equatorial orientation of the exocyclic phenyl substituent is preferred for 1,4-heterophosphinanes independent of the second heteroatom in six-membered phosphorus heterocycle (oxygen, sulfur or silicon), and the coordination state of the phosphorus atom (σ3P or σ4P).

Mechanism of the hydrolysis reactions of 1-hydroxysilatrane and 1-hydroxygermatrane, 2,2-dihydroxysilocane and 2,2-dihydroxygermocane

GRAPHICAL ABSTRACT ABSTRACT The mechanism of the hydrolysis reactions of 2,2-dihydroxysilocane, 2,2-dihydroxygermocane, 1-hydroxysilatrane, and 1-hydroxygermatrane was studied by the density functional theory method. According to the quantum chemical calculations, the reactions of hydrolysis for 2,2-dihydroxysilocane and 2,2-dihydroxygermocane are characterized by the lower values of activation energy than for 1-hydroxysilatrane and 1-hydroxygermatrane. The ring configurations of the hydrolysis products are stable due to the presence of transannular interaction N→X (X = Si, Ge) and intramolecular hydrogen bond in their molecules.

Conformational Analysis of 2-Chloro-N-[2-((Diphenylphosphoryl)Methyl)Phenyl]-Acetamide and 2-Chloro-N-[2-((Diphenylthiophosphoryl)Methyl)Phenyl]Acetamide

GRAPHICAL ABSTRACT Abstract The polarities of 2-chloro-N-(2-((diphenylphosphoryl)methyl)phenyl)acetamide and 2-chloro-N-(2-((diphenylthiophosphoryl)methyl)phenyl)acetamide were determined, and conformational analysis of these was carried out by the method of dipole moments and quantum chemical calculations. The formation of intramolecular hydrogen bond Р˭O…НN or Р˭S…НN in these acetamides is possible.

Polarity and Conformational Analysis of Secondary Phosphine Selenides

Abstract The polarities of bis(2-phenylethyl) and bis(2-phenylpropyl) phosphine selenides were determined and conformational analysis of these phosphine selenides was carried out by the method of dipole moments, IR spectroscopy, and quantum chemical calculations. They exist as an equilibrium of several conformers, and the preferred conformers have gauche orientation of the P = Se and Csp3 – Csp3 bonds. GRAPHICAL ABSTRACT

Conformational Analysis of 1,3,2-Dioxaphospholane and Pyrocatehine Phosphite with Oc(O)Cf3 Exocyclic Substituents

Abstract Conformational analysis of 1,3,2-dioxaphospholane-2-yl-2,2,2-trifluoroacetate and 4,5-benzo-1,3,2-dioxaphosphole-2-yl-2,2,2-trifluoroacetate was carried out by dipole moment method and quantum chemical calculations (DFT B3LYP/6-31G*). GRAPHICAL ABSTRACT

Theoretical Conformational Analysis of Cyclic Organophosphorus and Organosilicon Compounds

Abstract The structure of some six- and eight-membered phosphorus and silicon heterocycles was established by the method of dipole moments and density functional theory calculations. There are two necessary conditions for the feasibility of the transannular interaction in these heterocycles: (1) the favorable disposition of the donor and acceptor centers in a molecule and (2) the presence of the substituents with the considerable polarizing effect at the heteroatom.

Polarity and Structure of Silatranes with Planar Fragments

The structure of silatranes N[CH 2 (RMeC 6 H 2 )O] 3 SiR 1 with planar fragments in six-membered semi-rings was established by the methods of dipole moments and density functional theory calculations. They are endo-structures with transannular interaction N → Si in which the oxygen atoms located adjacent to the silicon participate besides the nitrogen and silicon atoms.

Experimental and Theoretical Conformational Analysis of Methylene- and Cyanophosphines and Their Oxides

The structure of a great number of methylenephosphine oxides 1-11 and cyanophosphines and their oxides 12-18 was studied by semiempirical PM3 and ab initio RHF/6-31G** calculations. Obtained results are in good agreement with experimental data (dipole moments, Kerr effect, IR spectroscopy). In 12-18 the contribution of interactions of CN group or Ph ring with lone pair of electrons (LPE) of the P atom, d-orbitals of the P atom, or P=O group is absent.

Phosphorus Compounds in Lower Coordination States Electrical Properties and Features of Structure

Abstract PI and PII-derivatives have been investigated by electrical and electrooptical methods for the determination of the main parameters of multiple phosphorus bonds, polarity and polarizability, and on their basis spatial and electronic structure of these compounds has been studied. Experimental data on polarity and polarizability of phosphaalkynes P=CR, phosphaalkenes R1 P=CR2R3, phosphyenes, diphosphenes, arsa- and stibaphosphenes R1P=ER2 (E = N, PI As, Sb) have been obtained. Polarities of P=C, P=C and P=E bonds have been determined. Multiple P=C and P=N bonds have considerable anisotropy of polarizability.

Polarity and structure of derivatives of bis(2-phenylethyl)selenophosphinic acid

Abstract Conformational analysis of derivatives of bis(2-phenylethyl)selenophosphinic acid was carried out by the method of dipole moments and density functional theory calculations. The conformations of the examined compounds fit into the overall conformational picture for the PIV compounds: these derivatives exist as conformational equilibrium of non-eclipsed gauche and trans forms with propeller arrangement of the substituents relative to the P=Se bond. We stipulate that the eclipsed cis orientation of substituent may be caused by the formation of H-contact.