Noncovalent interactions in crowded olefinic radical cations Aim. To study the effect of electronic (α-and β-hyperconjugations) and steric (noncovalent interactions) factors on the structures of olefinic radical cations. Results and discussion. The effect of intramolecular dispersion interactions on the structures of crowded alkenes in the neutral and ionized forms has been studied at the density functional theory (DFT) level with and without dispersion corrections included, as well as at the MP2 theory level with medium size basis sets. The results obtained are compared to the available experimental data. An excellent agreement has been found between the experimental and MP2/DFT-computed geometries of sesquihomoadamantene, adamantylidene adamantane, bis-2,2,5,5-tetramethylcyclopentylidene, bis-D 3-homocub-4-ylidene, and bis-C S-homocub-8-ylidene in the neutral and ionized forms. The experimental ionization potentials are better reproduced with the DFT-methods. Experimental part. The structure and composition of compounds were proved by the methods of 1 H and 13 C NMR-spectroscopy, and GC-MS-analysis. Elemental analysis was performed for the compounds obtained. Conclusions. The twisting of the olefinic moieties in the sesquihomoadamantene and adamantylidene adamantane radical cations is determined by the balance between the σ-π-hyperconjugation and residual oneelectron π-bonding and is close to that of the prototypical ethylene radical cation (29°). The twisting reaches 55° for the bis-2,2,5,5-tetramethylcyclopentylidene radical cation due to substantial steric repulsions between methyl groups. At the same time, the ionized states of bis-D 3-homocub-4-ylidene and bis-C S-homocub-8-ylidene retain their planarity due to β-CC-hyperconjugation and intramolecular dispersion attractions.

P-Stereogenic diamondoid phosphines Despite diamondoid phosphines have found many synthetic applications and are even available commercially the chemistry of chiral diamondoid phosphines remains largely unexplored. Aim. To develop the convenient preparative method for the preparation of sterically-congested P-stereogenic secondary diamodoidyl phosphines as potential organocatalysts and ligands in the asymmetric synthesis. Results and discussion. A convenient method for the synthesis of P-stereogenic diamondoid phosphines with high yields through the phosphorylation of hydroxydiamondoids in trifluoroacetic acid followed by the reduction of the corresponding asymmetric chlorophosphonates has been proposed. The secondary phosphines obtained form stable complexes with borane that can be used to separate diamondoid phosphines into enantiomers. Experimental part. The experimental procedures for the preparation of 1-and 4-diamantyl-1-adamantyland phenylphosphines were developed; the structures of new compounds were confirmed by NMR and HRMS spectral data. Conclusions. A number of P-stereogenic mixed diamondoidylaryl phosphines and the secondary phosphines containing exclusively diamondoid substituents has been prepared. A degree of steric bulkiness is determined by the combination of diamondoid substituents around a phosphorus atom where 1-diamantyl derivatives are the most sterically-congested. The compounds obtained are potential ligands in asymmetric catalysis.