Stable Carbenes as Structural Components of Partially Saturated Sulfur-Containing Heterocycles

Recently, an unusual elongation of the C-S bond was observed experimentally for some sulfur-containing heterocycles. Using a superior ab initio (SCS-MP2/cc-pVTZ) level of theory, we showed that the phenomenon can be explained by a contribution of a donor–acceptor adduct of a carbene with an unsaturated ligand. One may achieve further elongation of the C-S bond, eventually turning it to a coordinate one, by increasing the stability of each part of the system as, e.g., in the utmost case of spiro adducts with Arduengo carbenes. The effect of carbene stability was quantified by employing the isodesmic reactions of carbene exchange

Stable Carbenes as Structural Components of Partially Saturated Sulfur-Containing Heterocycles

Recently, an unusual elongation of the C-S bond was observed experimentally for some sulfur-containing heterocycles. Using a superior ab initio (SCS-MP2/cc-pVTZ) level of theory, we showed that the phenomenon can be explained by a contribution of a donor–acceptor adduct of a carbene with an unsaturated ligand. One may achieve further elongation of the C-S bond, eventually turning it to a coordinate one, by increasing the stability of each part of the system as, e.g., in the utmost case of spiro adducts with Arduengo carbenes. The effect of carbene stability was quantified by employing the isodesmic reactions of carbene exchange

Stable Carbenes as Structural Components of Partially Saturated Sulfur-Containing Heterocycles

Recently, an unusual elongation of the C-S bond was observed experimentally for some sulfur-containing heterocycles. Using a superior ab initio (SCS-MP2/cc-pVTZ) level of theory, we showed that the phenomenon can be explained by a contribution of a donor-acceptor adduct of a carbene with an unsaturated ligand. One may achieve further elongation of the C-S bond, eventually turning it to a coordinate one, by increasing the stability of each part of the system as, e.g., in the utmost case of spiro adducts with Arduengo carbenes. The effect of carbene stability was quantified by employing the isodesmic reactions of carbene exchange.Peer reviewe

Photochromic resorcin[4]arenes: stabilization of intramolecular anthracene dimers in solution

Schäfer C, Rozhenko AB, Mattay J. Photochromic resorcin[4]arenes: stabilization of intramolecular anthracene dimers in solution. Photochemical & Photobiological Sciences. 2009;8(8):1187-1194.Several resorcin[4]arenes functionalized with two anthracene units on opposite sides of the upper rim of the macrocycle were synthesized. We investigated the potentially photochromic properties of these systems, with the main focus on the intramolecular [4+4] cycloaddition of the anthracenes and its reversibility by thermal ring opening. Whereas compound 9 proved to be a switchable host system (by irradiation and temperature, T-type photochromic substances), compounds 10-12 formed intramolecular photodimers upon irradiation, which are only stable at low temperature. The reopening occurred immediately at room temperature and was followed by UV/VIS spectroscopy. Further investigations showed that the cyclodimer of 11 can be stabilized significantly by sodium cations due to crown ether-like complexation. Additionally, quantum chemical calculations were performed to evaluate the different behaviour

Reduction of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with sodium sulfide: Synthesis of fluoro-containing sulfur-rich heterocycles

Fesun IM, Rozhenko AB, Timoshenko VM. Reduction of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with sodium sulfide: Synthesis of fluoro-containing sulfur-rich heterocycles. JOURNAL OF FLUORINE CHEMISTRY. 2006;127(6):774-779.Treatment of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with 2 equivalents of sodium sulfide gives after acidification 3,4-difluoro-2-mercapto-1,6,6a gimel(4)-trithiapentalene, which can be further reduced by sodium sulfide to 3,5-difluoro-4-mercapto-thiopyran-2-thione. (c) 2006 Elsevier B.V. All rights reserved

Synthesis of a new photoresponsive molecular carcerand

Sahu SN, Rozhenko AB, Eberhard J, Mattay J. Synthesis of a new photoresponsive molecular carcerand. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY. 2016;331:165-174.The synthesis of a covalently bonded new photoresponsive molecular capsule formed from two resorcin [4]arene cavitands by fourfold ether linkages using azobenzene subunits is reported. The new molecular capsule undergoes trans to cis isomerization upon irradiation with 365 nm light and can be reversed back from cis to trans form by means of exposure to visible light (530 nm) in benzene solution. The photo-switchable behaviour was also investigated by H-1 NMR spectroscopy which further substantiated the UV-vis experiment. The quantum chemical calculations both at PM6 as well as at the DFT (B97-D) level of approximation for various stereoisomers starting from all-trans to all-cis indicated an increasing flexibility of these molecular capsules. (C) 2016 Elsevier B.V. All rights reserved

Synthesis and Some Chemical Properties of a 1,2 lambda(3)sigma(3)-Thiaphosphirane

Turcheniuk KV, Rozhenko AB, Shevchenko IV. Synthesis and Some Chemical Properties of a 1,2 lambda(3)sigma(3)-Thiaphosphirane. European Journal of Inorganic Chemistry. 2011;2011(11):1762-1767.A rare example of the addition of sulfur to a phosphaalkene double bond leading to 1,2 lambda(3),sigma(3)-thiaphosphirane 4 is described. The relative accessibility of this compound has allowed the study of some of the chemical properties of the thiaphosphirane ring. The thermodynamic stability of 1,2 lambda(3),s(3)-thiaphosphiranes compared with lambda(5),sigma(3)-phosphoranes has been studied by DFT calculations

Photodissociation of methyl iodide embedded in a host-guest complex: A full dimensional (189D) quantum dynamics study of CH[sub 3]I@resorc[4]arene

Westermann T, Brodbeck R, Rozhenko AB, Schoeller W, Manthe U. Photodissociation of methyl iodide embedded in a host-guest complex: A full dimensional (189D) quantum dynamics study of CH[sub 3]I@resorc[4]arene. The Journal of Chemical Physics. 2011;135(18): 184102

Asymmetric induction in thia-Diels-Alder reactions of chiral polyfluoroalkylthionocarboxylates

Timoshenko VM, Siry SA, Rozhenko AB, Shermolovich YG. Asymmetric induction in thia-Diels-Alder reactions of chiral polyfluoroalkylthionocarboxylates. JOURNAL OF FLUORINE CHEMISTRY. 2010;131(2):172-183.A series of chiral S- or O-alkyl thionoesters have been synthesized by treatment of trifluorothioacetyl- or 2,2,3,3-tetrafluorothiopropionyl chloride with corresponding thiols or alcohols. The thia-Diels-Alder reaction of the thionoesters with symmetrical 1,3-dienes proceeds with diastereoselectivity up to 60%. Structures of cycloaddition products and corresponding transition states have been studied at the DFT level of approximation. The experimentally observed diastereomeric excess has been referred to differences in activation energies of transition states, preceding formation of the diastereomeric cycloaducts. (C) 2009 Elsevier B.V. All rights reserved

Anion-pi interactions in adducts of anionic guests with octahydroxy-pyridine[4]arene: theoretical and experimental elucidation

Rozhenko AB, Schoeller W, Letzel MC, Decker B, Mattay J. Anion-pi interactions in adducts of anionic guests with octahydroxy-pyridine[4]arene: theoretical and experimental elucidation. New Journal Of Chemistry. 2013;37(2):356-365.A theoretical investigation has been carried out at the DFT ( B3LYP, RI-BP86, RI-B97-D) and RI-MP2 levels of approximation for octahydroxy-pyridine[4]arene and a series of its adducts with anions (BF4-, PF6-, NO3-, CH3COO- and CF3COO-) and ammonium cations (NH4+). The encapsulated complexes ( two hosts to one guest molecule) are predicted to be more stable in the gas phase than the corresponding 1 : 1 adducts. Calculations using Grimme's B97-D functional have provided relative energies, which agree well with those derived at the RI-MP2 level of theory. By taking solvent effects into account using the COSMO routine, the formation of the anionic adducts is significantly less favourable. Complexes of octahydroxy-pyridine[4]arene with the ammonium cation seem to be unstable in solution. The most promising complexes of octahydroxy-pyridine[4]arene with BF4- and PF6- have been studied experimentally. Only formation of 1 : 1 anionic adducts has been detected using electrospray ionization mass spectrometry. Probably, in the 1 : 1 complexes the coordinated anion still interacts with a counterion. The excess of anionic guests used in the experiment and the conditions in the ESI source of the mass spectrometer have been considered another possible reason for shifting the equilibrium towards the 1 : 1 aggregates