@article{KleinpeterKoch2019,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Benzyne - an acetylene- or cumulene-like electronic structure?},
  series = {Tetrahedron},
  volume    = {75},
  journal   = {Tetrahedron},
  number    = {33},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2019.07.011},
  pages     = {4663 -- 4668},
  year      = {2019},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of benzyne 1 and analogues (benzene 2, 1,2,3-cyclohexatriene 3, cyclohexen-3-yne 4, cyclohexen-4-yne 5, cyclohexyne 6) have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values could be employed to compare the diatropic ring current effects of benzene and benzyne, and, when compared with the spatial magnetic properties of the analogues, to answer the question whether the benzyne electronic structure is more acetylene- or cumulene-like, supported by structural data and delta(C-13)/ppm values. (C) 2019 Published by Elsevier Ltd.},
  language  = {en}
}
@article{KleinpeterKoch2018,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Paramagnetic ring current effects in anti-aromatic structures subject to substitution/annelation quantified by spatial magnetic properties (TSNMRS)},
  series = {Tetrahedron},
  volume    = {74},
  journal   = {Tetrahedron},
  number    = {7},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2017.12.020},
  pages     = {700 -- 710},
  year      = {2018},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of the typically anti-aromatic cyclopentadienyl cation, cyclobutadiene, pentalene, s-indacene and of substituted/annelated analogues of the latter structures have been calculated using the CIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values were employed to visualize and quantify the dia(para) magnetic ring current effects in the studied compounds. The interplay of dia(para)magnetic ring current effects due to substitution/annelation caused by heavy exo-cyclic n,pi-electron delocalization can be qualified.},
  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}
}
@article{KleinpeterKoch2021,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Intramolecular carbene stabilization via 3c,2e bonding on basis of the magnetic criterion},
  series = {Tetrahedron : the international journal for the rapid publication of full original research papers and critical reviews in organic chemistry},
  volume    = {95},
  journal   = {Tetrahedron : the international journal for the rapid publication of full original research papers and critical reviews in organic chemistry},
  publisher = {Elsevier Science},
  address   = {Amsterdam},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2021.132357},
  pages     = {9},
  year      = {2021},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of bent cyclobutylcarbene 8, 1,2-diboretane-3-ylidene 9, and some carbene analogues of boron 14-18 as most intriguing examples of carbenes, which can be stabilized as homoaromatic systems with 3c,2e bonding, have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values (actually, ring current effect/anisotropy effects as measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the degree of present 3c,2e-homoaromaticity. Results are confirmed by geometry (bond angles and bond lengths) and spectroscopic data, the delta(B-11)/ppm data and the C-13 chemical shifts of the carbene electron-deficient centre.},
  language  = {en}
}
@article{KleinpeterKoch2021,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Quantification of sigma-acceptor and pi-donor stabilization in O, S and Hal analogues of N-heterocyclic carbenes (NHCs) on the magnetic criterion},
  series = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  volume    = {125},
  journal   = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory},
  number    = {33},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1089-5639},
  doi       = {10.1021/acs.jpca.1c05257},
  pages     = {7235 -- 7245},
  year      = {2021},
  abstract  = {The spatial magnetic properties, through-space NMR shieldings (TSNMRSs), of stable O, S and Hal analogues of N-heterocyclic carbenes (NHCs) have been calculated using the GIAO perturbation method employing the nucleus-independent chemical shift (NICS) concept and the results visualized as iso-chemical-shielding surfaces (ICSSs) of various sizes and directions. The TSNMRS values (actually the anisotropy effects measurable in H-1 NMR spectroscopy) are employed to qualify and quantify the position of the present mesomeric equilibria (carbenes <-> ylides). The results are confirmed by geometry (bond angles and bond lengths), IR spectra, UV spectra, and C-13 chemical shifts of the electron-deficient carbon centers.},
  language  = {en}
}
@article{KleinpeterHeydenreichKochetal.2017,
  author    = {Kleinpeter, Erich and Heydenreich, Matthias and Koch, Andreas and Krtitschka, Angela and Kr{\"u}ger, Tobias and Linker, Torsten},
  title     = {NMR spectroscopic conformational analysis of 4-methylene-cyclohexyl pivalateThe effect of sp(2) hybridization},
  series = {Magnetic resonance in chemistry},
  volume    = {55},
  journal   = {Magnetic resonance in chemistry},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0749-1581},
  doi       = {10.1002/mrc.4630},
  pages     = {1073 -- 1078},
  year      = {2017},
  abstract  = {The conformational equilibrium of the axial/equatorial conformers of 4-methylene-cyclohexyl pivalate is studied by dynamic NMR spectroscopy in a methylene chloride/freon mixture. At 153K, the ring interconversion gets slow on the nuclear magnetic resonance timescale, the conformational equilibrium (-G degrees) can be examined, and the barrier to ring interconversion (G(\#)) can be determined. The structural influence of sp(2) hybridization on both G degrees and G(\#) of the cyclohexyl moiety can be quantified.},
  language  = {en}
}
@article{Kleinpeter2008,
  author    = {Kleinpeter, Erich},
  title     = {Quantitative study and visualization of spherical 2(N + 1)2 homoaromaticity by through space NMR shieldings (TSNMRS)},
  doi       = {10.1016/j.theochem.2007.11.029},
  year      = {2008},
  abstract  = {The through space NMR shielding (TSNMRS) values of adamantane, the 2(N + 1)2 spherical (4c, 2e) homoaromatic compounds 1,3-dehydro-5,7-adamantandiyl dication (C10H122+) and 1,3-dehydro-5,7-cubandiyl dication (C8H42+), and the (6c, 8e) homoaromatic compound 2,2;,4,4;,6,6;,8,8;,10,10;-dehydroadamantane tetracation (C10H44+) have been ab initio calculated, employing the NICS concept, and visualized as iso-chemical shielding surfaces (ICSSs). TSNMRS values can be successfully employed to study both the endohedral and exohedral aromaticity/ antiaromaticity of the compounds studied.},
  language  = {en}
}
@article{KleinpeterKoch2008,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {Trisannelated benzenes - Aromatic molecules or 1,3,5-cyclohexatriene derivatives subjected to magnetic properties},
  doi       = {10.1016/j.theochem.2008.02.013},
  year      = {2008},
  abstract  = {The through space NMR shielding (TSNMRS) values of two tricyclobutabenzene (TCBB) derivatives 2, of the corresponding hexamethylene and hexaoxo TCBB derivatives 3, of [4n]annuleno[4n + 2]annulene 5 and of its tricyclobutadiene parent compound 4 have been ab initio calculated by the GIAO perturbation method employing the nucleus- independent chemical shift (NICS) concept of Paul von Ragu{\´e} Schleyer, and visualized as iso-chemical shielding surfaces (ICSS). TSNMRS values can be successfully employed to quantify and visualize the aromaticity of the central, and in 5 also of the terminal benzene ring moieties.},
  language  = {en}
}
@article{ShainyanUshakovTolstikovaetal.2008,
  author    = {Shainyan, Bagrat A. and Ushakov, Igor A. and Tolstikova, Ljudmila L. and Koch, Andreas and Kleinpeter, Erich},
  title     = {N-Trifyl substituted 1,4-diheterocyclohexanes{\`u}stereodynamics and the Perlin effect},
  year      = {2008},
  abstract  = {The stereodynamic behaviour of 1-(trifluoromethylsulfonyl)piperidine 1, 4-(trifluoromethylsulfonyl)morpholine 2, 1,4-bis(trifluoromethylsulfonyl)piperazine 3 and 4-(trifluoromethylsulfonyl)thiomorpholine 1,1-dioxide 4 was studied by low-temperature 1H, 13C and 19F NMR spectroscopies. In acetone solution, compounds 1, 2 and 4 were found to exist as mixtures of two conformers in the ratio of 4:1, 4:1 and 8:1, respectively, differing by orientation of the CF3 group with respect to the ring. Compound 3 exists as a mixture of three conformers in the ratio of 3:28:69 also differing by the orientation of the two CF3 groups. Unlike the previously studied N-trifyl substituted 1,3,5-triheterocyclohexanes, the preferred conformers of compound 1 and of 1,4-diheterocyclohexanes 2-4 are those with the CF3 group directed outward from the ring, which is caused by intramolecular interactions of the oxygen atoms of the CF3SO2N groups with the equatorial hydrogens in the ;-position. B3LYP/6-311+G(d,p) calculations of the energy, geometry and NMR parameters corroborate the experimental data. The calculated Perlin effects for all conformers of compounds 1-4 as well as those measured for the major conformers of compounds 3 and 4 were analyzed by the use of the NBO analysis.},
  language  = {en}
}
@article{BaranacStojanovicTatarKleinpeteretal.2008,
  author    = {Baranac-Stojanovic, Marija and Tatar, Jovanan and Kleinpeter, Erich and Markovic, Rade},
  title     = {High-Yield Synthesis of Substituted and Unsubstituted Pyridinium Salts Containing a 4-Oxothiazolidine Moiety},
  year      = {2008},
  abstract  = {A new series of unsubstituted and substituted pyridinium salts bearing a 4-oxothiazolidinyl moiety has been prepared by an efficient rearrangement of 2-(1-bromoalkylidene)thiazolidin-4-ones. The process in based on three steps, namely carbon-bromine cleavage, bromine transfer, and substitution, each induced by pyridine or its derivatives, acting as base and reactant.},
  language  = {en}
}