@article{KarnaGreinEngelsetal.1989,
  author    = {Karna, S. and Grein, F. and Engels, Bernd and Peyerimhoff, S.D.},
  title     = {The hyperfine coupling constants of \(^{19}\)F\(_2\)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58817},
  year      = {1989},
  abstract  = {The isotropic (a\(_{iso}\)) and dipolar (A\(_{dip}\)) hyperfine coupling constants of 19F2 were obtained from MRD-CI wave functions using a variety of basis sets. In series I, increasing numbers of d functions were added to a 5s4p contracted Huzinaga!Dunning basis. In series II, the 5s3p basis set was uncontracted in several steps until 9s5p was reached, to which were added from one to three d-polarization functions. Cl parameters (selectioo threshoids and the number of reference coofiguratioos) were also varied. A study of the R dependence of aiso and Adip was perfonned. The best values obtained at R\(_e\) are 260 G for a\(_{iso}\) and 308 G for A\(_{dip}\)• compared with experimental values of about 280 G for a;10 and 320 G for A\(_{dip}\)·},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{FunkenEngelsPeyerimhoffetal.1990,
  author    = {Funken, K. and Engels, Bernd and Peyerimhoff, S.D. and Grein, F.},
  title     = {Study of the hyperfine coupling constants of the moleculs NH<sub>2</sub>, NHD and ND<sub>2</sub>},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58875},
  year      = {1990},
  abstract  = {In the present paper we c:alculate tbe magnetic hyperfine couplina constants (hfcc) ai.ID and A11 of the ground states of the isotopes NH2, NHD and ND2 using truncated MR..CI methods. Differences from other theoretical methocls and shortoominp of the truncated Cl approach in calculating tlj10 are studied. Polarization effects wbich detennirae ailo. as weU as a simple model to describe the dipolar hfcc's, are discussed. All results are in. excellent aareement with experimental data. lt is shown that ab initio methods are able to obtain reliable values for otf-diaaonal values of A41 which are difficult to measure experimentaDy.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{EngelsPericReuteretal.1992,
  author    = {Engels, Bernd and Peric, M. and Reuter, W. and Peyerimhoff, S.D. and Grein, F.},
  title     = {Study of the hyperfine coupling constants \(^{14}\)N and \(^1\)H) of the NH\(_2\) molecule in the X\(^2\)B\(_1\) ground state and the A\(^2\)A\(_1\) excited state},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58937},
  year      = {1992},
  abstract  = {The hyperfine coupling constants (hfcc) A\(_{iso}\) and A\(_{ij}\) are calculated for the atoms of NH\(_2\) in its, two lowest-lying electronk states at various molecular geometries by means of the ab initio multireference configuration interaction .method. The vibronically averaged values of the hfccs for the K = 0 and 1 levels in \(^{14}\)N \(^1\)H\(_2\) in the energy range up to 20 000 cm\(^{-1}\) are computed. Polarization elfects which determine A\(_{iso}\) as well as a simple model to describe the dipolar hfccs are discussed. All resrilts are in excellent agreement with experimental data.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{EngelsPeyerimhoff1988,
  author    = {Engels, Bernd and Peyerimhoff, S.D.},
  title     = {Study of the 1s and 2s shell contributions to the isotropic hyperfine coupling constant in nitrogen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58793},
  year      = {1988},
  abstract  = {The istropic part of the hyperfine coupling constant is investigated by means of multireference configuration interaction calculations employing Gaussian basis sets. A detailed study of the 1s and 2s spin polarisation in the nitrogen atom and the NH molecule shows that the structure of the lower-energy space of the unoccupied orbitals is essential for the results. A contraction of the Gaussian basis is possible without loss of accuracy if enough flexibility is retained to describe the main features of the original space of unoccupied functions. Higher than double excitations are found to be non-negligible for the description of α\(_{iso}\).},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{EngelsPeyerimhoff1989,
  author    = {Engels, Bernd and Peyerimhoff, S.D.},
  title     = {Study of orbital transformations in configurational interaction calculation of hyperfine coupling in nitrogen and CH molecule},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58847},
  year      = {1989},
  abstract  = {Multi-reference configuration interaction calculations employing various orbital transformations are undertaken to obtain the isotropic hyperfine coupling constant a\(_{iso\) in nitrogen and a\(_{iso\) (H) in the CH molecule. The natural orbital (NO) basis is found to be more effective than the simple RHF-MO basis; the most obvious is a basis of spin natural orbitals (SNO). It is found that a\(_{iso\) is approached from opposite sides in the NO and 2s shell SNO basis if the CI expansion is increased. Both results are within a few percent of the full CI Iimit for the nitrogen atorn (in the given AO basis) and the experimental value for Hin the CH radical. Various features ofthe SNO are discussed.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{Engels1993,
  author    = {Engels, Bernd},
  title     = {Study of influences of various excitation classes on ab initio calculated isotropic hyperfine coupling constants},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58973},
  year      = {1993},
  abstract  = {Reliable prediction of the isotropic hyperfine coupling constant A\(_{iso}\) is still a difficult task for ab initio calculations. Strang dependence on the method employed for its ca1culation has been found. Within a CI ansatz A\(_{iso}\) is considerably affected by the excitation classes taken into account within the CI calculation. In the present work the influence of various excitation classes on A\(_{iso}\) is examined. Calculations including all single, double, triple and a large part of the quadruple excitations are performed and the individual effects of the excitation classes are studied. It is found that the surprisingly good agreement found for S-CI treatments is due to large error cancellations. The importance of higher than double excitations arises from their indirect influence on the single excitations.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{WeiserCuiDewhurstetal.2023,
  author    = {Weiser, Jonas and Cui, Jingjing and Dewhurst, Rian D. and Braunschweig, Holger and Engels, Bernd and Fantuzzi, Felipe},
  title     = {Structure and bonding of proximity-enforced main-group dimers stabilized by a rigid naphthyridine diimine ligand},
  series = {Journal of Computational Chemistry},
  volume    = {44},
  journal   = {Journal of Computational Chemistry},
  number    = {3},
  doi       = {10.1002/jcc.26994},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312586},
  pages     = {456 -- 467},
  year      = {2023},
  abstract  = {The development of ligands capable of effectively stabilizing highly reactive main-group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity-enforced group 13-15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8-naphthyridine (napy) core. We show that the redox-active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element-element interaction modes, the latter ranging from isolated, element-centered lone pairs (e.g., E = Si, Ge) to cases where through-space π bonds (E = Pb), element-element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI-E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy-based ligands in main-group chemistry.},
  language  = {en}
}
@article{RangFantuzziArrowsmithetal.2021,
  author    = {Rang, Maximilian and Fantuzzi, Felipe and Arrowsmith, Merle and Krummenacher, Ivo and Beck, Eva and Witte, Robert and Matler, Alexander and Rempel, Anna and Bischof, Tobias and Radacki, Krzysztof and Engels, Bernd and Braunschweig, Holger},
  title     = {Reduktion und Umlagerung eines Bor(I)-Carbonylkomplexes},
  series = {Angewandte Chemie},
  volume    = {133},
  journal   = {Angewandte Chemie},
  number    = {6},
  doi       = {10.1002/ange.202014167},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224409},
  pages     = {3000 -- 3005},
  year      = {2021},
  abstract  = {Bei der Einelektronenreduktion eines durch eine cyclisches (Alkyl)(amino)carben (CAAC) stabilisierten Arylborylen-Carbonylkomplexes erfolgt die Bildung eines dimeren Borylketyl-Radikalanions, bedingt durch eine intramolekulare Arylmigration zum CO Kohlenstoffatom. Computergest{\"u}tzte Analyse liefert Hinweise auf eine radikalanionische [(CAAC)B(CO)Ar]\(^{.-}\) Zwischenstufe. Weiterf{\"u}hrende Reduktion des entstandenen Komplexes liefert ein hoch nukleophiles (Boranyliden)methanolat.},
  language  = {de}
}
@article{DietschreitWagnerLeetal.2020,
  author    = {Dietschreit, Johannes C. B. and Wagner, Annika and Le, T. Anh and Klein, Philipp and Schindelin, Hermann and Opatz, Till and Engels, Bernd and Hellmich, Ute A. and Ochsenfeld, Christian},
  title     = {Predicting \(^{19}\)F NMR Chemical Shifts: A Combined Computational and Experimental Study of a Trypanosomal Oxidoreductase-Inhibitor Complex},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  number    = {31},
  doi       = {10.1002/anie.202000539},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214879},
  pages     = {12669 -- 12673},
  year      = {2020},
  abstract  = {The absence of fluorine from most biomolecules renders it an excellent probe for NMR spectroscopy to monitor inhibitor-protein interactions. However, predicting the binding mode of a fluorinated ligand from a chemical shift (or vice versa) has been challenging due to the high electron density of the fluorine atom. Nonetheless, reliable \(^{19}\)F chemical-shift predictions to deduce ligand-binding modes hold great potential for in silico drug design. Herein, we present a systematic QM/MM study to predict the \(^{19}\)F NMR chemical shifts of a covalently bound fluorinated inhibitor to the essential oxidoreductase tryparedoxin (Tpx) from African trypanosomes, the causative agent of African sleeping sickness. We include many protein-inhibitor conformations as well as monomeric and dimeric inhibitor-protein complexes, thus rendering it the largest computational study on chemical shifts of \(^{19}\)F nuclei in a biological context to date. Our predicted shifts agree well with those obtained experimentally and pave the way for future work in this area.},
  language  = {en}
}
@article{MetropoulosEngelsPeyerimhoff1993,
  author    = {Metropoulos, B. and Engels, Bernd and Peyerimhoff, S.D.},
  title     = {On the chemi-ionization reaction O + CH ----> HCO\(^+\)+ e\(^-\). Coollinear O-CH Approach},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58963},
  year      = {1993},
  abstract  = {We have investigated theoretically the importance of the O(\(^3\)P)+CH(a\(^4\sum^-\)) and the O(\(^3\)P)+CH(X\(^2\Pi\)) channels in the collinear chemi-ionization reaction O+CH->HCO\(^+\) +e\(^-\). We have found that both channels may lead to chemi-ionization via favorable Franck-Condon overlaps with the states ofthe ionic species.},
  subject      = {Organische Chemie},
  language  = {en}
}