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Structure of 1,3,2-diazaphosphinine heterocyclic system was studied using quantum chemical calculations and X-ray diffraction method for one derivative. It was found that two P–N single bonds were different in their nature: one of them turned out to be significantly shorter and stronger, whereas the other one is longer and more diffused. The found effect is strengthened by π-donor substituents. The effect was interpreted by equilibrium of Lewis structures and analyzing the charge distribution by the NBO approach. The observed effect can be considered as the special form of π-conjugation in the heterocycles with the phosphorus (V) atom included.

This article summarizes some of our investigations of compounds featuring the structural fragment P‒C‒P. Phosphorus atoms in different oxidation states and coordination numbers display different chemical behaviors. This may lead to unique chemical properties when they are bridged by a methylene group in a P‒CH2‒P system. For example, the PIII‒CH2‒PVunit is able to add different unsaturated compounds to give zwitterionic products with oppositely charged phosphorus atoms. In addition, the two hydrogen atoms in P‒CH2‒P may also take part in different transformations, resulting in the formation of carbodiphosphoranes or in the formation of a direct P-P bond to give three-membered ring diphosphiranes.

The reactions of 1,3-diphosphaphenalene 3 with sulfur, borane-tetrahydrofuran, and transition metal carbonyls are reported.

Isotropic C-13 nuclear magnetic shielding values (sigma(iso)) and corresponding chemical shift magnitudes (delta(C)) have been calculated for the large series of the thiocarbonyl compounds using DFT (RI-BP86 and B3LYP) and ab initio (RHF and MP2, with or without resolution of the identity approximation) levels of theory and different basis sets. As expected, the Hartree-Fock method and hybrid B3LYP approach essentially overestimate deshielding of the C=S carbon nuclei. The RI-BP86 level of approximation provides a noticeably better agreement with the experiment and can be used for calculations of the theoretical C-13 NMR spectra for the most classes of the thiocarbonyl compounds. Geometry optimizations and the nuclear magnetic shielding calculations using the MP2 level of theory provide the most reliable results. The resolution of the identity algorithm implemented into the TURBOMOLE program set does not affect the calculated sigma(iso) and delta C values compared to the strict MP2 nuclear magnetic shielding calculations (using the GAUSSIAN-03 program packet). A poor agreement with the experiment found in the case of the thiourea and thiosemicarbazide derivatives is referred to the different conformations of these species in the gas phase, solid state, and solution.

The reaction of potassium fluoride with the corresponding acid chlorides results in the formation of dialkylamido sulfoxylic acid fluorides Alk 2 N-S-F. Stereo- and regioselectivity of dimethylamido and diisopropylamido sulfoxylic acid fluorides addition reactions to the C,C double bond in cyclohexene, 3,4-dihydro-2H-pyrane, and vinyl ethyl ether has been investigated. This reaction is a convenient approach to the β -fluoroalkyl sulfenic acid derivatives.

An unusual P,P-disubstituted diphosphiranes was prepared and characterized by treatment of 1,8-bis[bis(di-alkylamino)phosphino]naphthalenes HCl followed by Me4NF.

A wide series of low-coordinated phosphorus (III) compounds including iminophosphines 1, two- 2 or mono-coordinated 3 phosphorus-containing cations, and anion 4, where Mes∗ = 2,4,6-tris-(tert-butyl)phenyl, has been investigated by 13C, 15N and 31P NMR spectroscopy. The spectral parameters obtained are considered in connection with the ab initio (6–31G∗) calculation data of the model compounds.