@article{ShainyanSuslovaTranDinhPhienetal.2018, author = {Shainyan, Bagrat A. and Suslova, Elena N. and Tran Dinh Phien, and Shlykov, Sergey A. and Kleinpeter, Erich}, title = {Synthesis, conformational preferences in gas and solution, and molecular gear rotation in 1-(dimethylamino)-1-phenyl-1-silacyclohexane by gas phase electron diffraction (GED), LT NMR and theoretical calculations}, series = {Tetrahedron}, volume = {74}, journal = {Tetrahedron}, number = {32}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2018.06.023}, pages = {4299 -- 4307}, year = {2018}, abstract = {1-(Dimethylamino)-1-phenyl-1-silacyclohexane 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED), low temperature C-13 NMR spectroscopy and quantum-chemical calculations. The predominance of the 1-Ph-ax conformer (1-Ph-eq:1-Ph-ax ratio of 20:80\%, Delta G degrees (317 K) = -0.87 kcal/mol) in the gas phase is close to the theoretically estimated conformational equilibrium. In solution, low temperature NMR spectroscopy showed analyzable decoalescence of C-ipso and C(1,5) carbon signals in C-13 NMR spectra at 103 K. Opposite to the gas state in the freon solution employed (CD2Cl2/CHFCl2/CHFCl2 = 1:1:3), which is still liquid at 100 K, the 1-Ph-eq conformer was found to be the preferred one [(1-Ph-eq: 1-Ph-ax = 77\%: 23\%, K = 77/23 = 2.8; -Delta G degrees = -RT In K (at 103 K) = 0.44 +/- 0.1 kcal/mol]. When comparing 1 with 1-phenyl-1-(X)silacylohexanes (X = H, Me, OMe, F, Cl), studied so far, the trend of predominance of the Ph-ax conformer in the gas phase and of the Ph-eq conformer in solution is confirmed.}, language = {en} } @article{LindicSinhaMattssonetal.2022, author = {Lindic, Tilen and Sinha, Shreya and Mattsson, Stefan and Paulus, Beate}, title = {Prediction of a model crystal structure for Ni2F5 by first-principles calculations}, series = {Zeitschrift f{\"u}r Naturforschung : B, Chemical sciences}, volume = {77}, journal = {Zeitschrift f{\"u}r Naturforschung : B, Chemical sciences}, number = {6}, publisher = {De Gruyter}, address = {Berlin}, issn = {0932-0776}, doi = {10.1515/znb-2022-0072}, pages = {469 -- 473}, year = {2022}, abstract = {Electrochemical fluorination in anhydrous HF, also known as the Simons process, is a widely used industrial method for fluorination of organic compounds. Its mechanism, being not so well understood, has long been debated and is believed to involve higher valent nickel fluorides formed on the nickel-plated anode during the process. One of these is speculated to be Ni2F5, which was previously reported in the literature and assigned via infrared spectroscopy, but its crystal structure is not yet known. We have identified known crystal structures of compounds with similar stoichiometries as Ni2F5 and utilized them as a starting point for our periodic DFT investigations, applying the PBE+U method. Ni2F5 as the most stable polymorph was found to be of the same crystal structure as another mixed valent fluoride, Cr2F5. The calculated lattice parameters are a = 7.24 angstrom, b = 7.40 angstrom, c = 7.08 angstrom and beta = 118.9 degrees with an antiferromagnetic ordering of the nickel magnetic moments.}, language = {en} } @article{KirpichenkoShainyanKleinpeteretal.2018, author = {Kirpichenko, Svetlana and Shainyan, Bagrat A. and Kleinpeter, Erich and Shlykov, Sergey A. and Tran Dinh Phien, and Albanov, Alexander}, title = {Synthesis of 3-fluoro-3-methyl-3-silatetrahydropyran and its conformational preferences in gas and solution by GED, NMR and theoretical calculations}, series = {Tetrahedron}, volume = {74}, journal = {Tetrahedron}, number = {15}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2018.02.055}, pages = {1859 -- 1867}, year = {2018}, abstract = {The 3,3-disubstitued 3-silaheterocyclohexane with an electronegative substituent at silicon, 3-fluoro-3-methyl-3-silatetrahydropyran 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED) and low temperature C-13 and F-19 NMR spectroscopy. Quantum-chemical calculations were carried out both for the isolated species and Hcomplexes in gas and in polar medium. The predominance of the 1-FeqMeax conformer (1-F-eq:1-F-ax ratio of 65:35, Delta G degrees = 0.37 kcal/mol) determined from GED is close to the theoretically estimated conformational equilibrium, especially at the DFT level. In solution, low temperature NMR spectroscopy showed no decoalescence of the signals in C-13 (down to 95 K) and F-19 NMR spectra (down to 123 K). However, the calculated F-19 chemical shift of -173.6 ppm for the 1-FeqMeax conformer practically coincides with the experimentally observed value (-173 to -175 ppm) as distinct from that for the 1-FaxMeeq conformer (-188.8 ppm), suggesting compound 1 to be anancomeric in solution, in compliance with its theoretical and experimental preference in the gas phase.}, language = {en} }