Conjugation effects and optical spectra of 1,2-diphosphole cycloadducts

Russian Chemical Bulletin - Quantum chemical calculations and a comparative analysis of Raman spectra of 3,4,5-triphenyl-1-propyl-1,2-diphosphole (1),...     

Molecular structure of (diethyldithiocarbomoyl)diphenylthiophosphinate

X-Ray study of (diethyldithiocarbomoyl)diphenylthiophosphinate was carried out. AZ-conformation of the diethyldithiocarbomoyl ligand, which results in a short nonvalent intramolecular P...S contact (3.315 Å), is realized in the molecule. Steric hindrances in the molecule increase the P-S-C bond angle to 106.39°.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1978–1980, October, 1995.The work was financially supported by the International Science Foundation (Gram RH1 000).     

Phosphorylation of pyridoxal azomethines. Synthesis of phosphorus containing azomethines and furopyridines

New O-phosphorylated pyridoxal derivatives have been synthesized through the reaction of azomethines with Р^V acid chlorides. 2-Chloro-2-thioxo-5,5-dimethyl-1,3,2-dioxaphosphinanes and diethylchlorothiophosphate have been employed as phosphorylating agents. Regardless of the nature of the phosphorylating agent, the reaction is regioselective at phenolic hydroxyl group. The structure of final products is determined by the nature of the substituent at the nitrogen atom. If R is alkyl or cycloalkyl group, the products of the reaction represent phosphorylated pyridoxal imines, whereas phosphorylated furopyridines are formed in the case R is aryl substituent.     

Study of the structures and photophysical properties of 1,3-diaza-5-phosphacyclohexanes using density functional theory and optical spectroscopy

Russian Chemical Bulletin - The steric and electronic structures of 1,3-diaza-5-phoaphacyclohexane with the pyridyl substituent at the phosphorus atom and a series of model...     

Force field,vibrational modes,and conformations for (t-BuO)3Sb AND (i-PrO)3Sb

By solving the inverse spectral problem for the (t-BuO)₃Sb molecule, we have obtained force constants for the Sb(OC)₃ fragments having the property of transferability. Rotation about the SbO bond weakly affects the frequencies of the skeletal vibrations of (RO)₃Sb molecules (R=t-Bu, i-Pr), while rotations of the propyl radicals about the OC bond lead to significant changes in the frequencies. In an equilibrium mixture of conformers of (i-PrO)₃Sb molecules, forms must be present with gauche orientation of the methine protons relative to the SbO bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2547–2551, November, 1989.     

IR and NMR spectra,intramolecular hydrogen bonding and conformations of para-tert-butyl-aminothiacalix[4]arene in solid state and chloroform solution

It is demonstrated that dissolution of aminothiacalix[4]arene in chloroform results in transformation of 1,3-alternate conformation, adopted in single-crystal and bulk polycrystalline solids, to the pinched-cone form. This conformer is stabilised by the intramolecular hydrogen bonds of two distal amino-groups acting as H-donors with another two amino moieties that appear as H-acceptors. The H-bonds cause quite small (ca. 10–20 cm^?1) red shift of the IR bands of the NH₂ stretching vibrations, which suggests rather weak NH?N hydrogen bonding. This latter is sufficient to stabilize the pinched-cone conformation in the chloroform solution, but the energy gap between the pinched-cone and other conformations is small, and solid-state intermolecular forces easily overcome it, leading to realisation of the 1,3-alternate conformer. The comparison of the DFT computed and experimental vibrational and NMR spectra demonstrates good quality of present quantum-chemical computations, allows complete interpretation of the spectra and reveals simple IR and NMR spectroscopic markers of the conformers of aminothiacalix[4]arenes.     

Anomalous temperature dependence of the intensity of the ΝP-H IR bands of dialkylphosphorous acids

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1709–1710, July, 1989.