TY - JOUR A1 - Reusch, Engelbert A1 - Holzmeier, Fabian A1 - Gerlach, Marius A1 - Fischer, Ingo A1 - Hemberger, Patrick T1 - Decomposition of Picolyl Radicals at High Temperature: A Mass Selective Threshold Photoelectron Spectroscopy Study JF - Chemistry - A European Journal N2 - The reaction products of the picolyl radicals at high temperature were characterized by mass‐selective threshold photoelectron spectroscopy in the gas phase. Aminomethylpyridines were pyrolyzed to initially produce picolyl radicals (m /z =92). At higher temperatures further thermal reaction products are generated in the pyrolysis reactor. All compounds were identified by mass‐selected threshold photoelectron spectroscopy and several hitherto unexplored reactive molecules were characterized. The mechanism for several dissociation pathways was outlined in computations. The spectrum of m /z =91, resulting from hydrogen loss of picolyl, shows four isomers, two ethynyl pyrroles with adiabatic ionization energies (IE\(_{ad}\)) of 7.99 eV (2‐ethynyl‐1H ‐pyrrole) and 8.12 eV (3‐ethynyl‐1H ‐pyrrole), and two cyclopentadiene carbonitriles with IE′s of 9.14 eV (cyclopenta‐1,3‐diene‐1‐carbonitrile) and 9.25 eV (cyclopenta‐1,4‐diene‐1‐carbonitrile). A second consecutive hydrogen loss forms the cyanocyclopentadienyl radical with IE′s of 9.07 eV (T\(_0\)) and 9.21 eV (S\(_1\)). This compound dissociates further to acetylene and the cyanopropynyl radical (IE=9.35 eV). Furthermore, the cyclopentadienyl radical, penta‐1,3‐diyne, cyclopentadiene and propargyl were identified in the spectra. Computations indicate that dissociation of picolyl proceeds initially via a resonance‐stabilized seven‐membered ring. KW - ionization energy KW - photoelectron spectroscopy KW - pyrolysis KW - radicals KW - synchrotron radiation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-208132 VL - 25 IS - 72 ER - TY - JOUR A1 - Schleier, Domenik A1 - Reusch, Engelbert A1 - Lummel, Lisa A1 - Hemberger, Patrick A1 - Fischer, Ingo T1 - Threshold photoelectron spectroscopy of IO and IOH JF - ChemPhysChem N2 - Iodine oxides appear as reactive intermediates in atmospheric chemistry. Here, we investigate IO and HOI by mass‐selective threshold photoelectron spectroscopy (ms‐TPES), using synchrotron radiation. IO and HOI are generated by photolyzing iodine in the presence of ozone. For both molecules, accurate ionization energies are determined, 9.71±0.02 eV for IO and 9.79±0.02 eV for HOI. The strong spin‐spin interaction in the 3Σ− ground state of IO+ leads to an energy splitting into the Ω=0 and Ω=±1 sublevels. Upon ionization, the I−O bond shortens significantly in both molecules; thus, a vibrational progression, assigned to the I−O stretch, is apparent in both spectra. KW - ionization potential KW - radicals KW - reactive intermediates KW - photolysis KW - synchrotron radiatoren Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204751 VL - 20 IS - 19 ER - TY - INPR A1 - Röder, Anja A1 - Petersen, Jens A1 - Issler, Kevin A1 - Fischer, Ingo A1 - Mitric, Roland A1 - Poisson, Lionel T1 - Exploring the Excited-State Dynamics of Hydrocarbon Radicals, Biradicals and Carbenes using Time-Resolved Photoelectron Spectroscopy and Field-Induced Surface Hopping Simulations T2 - The Journal of Physical Chemistry A N2 - Reactive hydrocarbon molecules like radicals, biradicals and carbenes are not only key players in combustion processes and interstellar and atmospheric chemistry, but some of them are also important intermediates in organic synthesis. These systems typically possess many low-lying, strongly coupled electronic states. After light absorption, this leads to rich photodynamics characterized by a complex interplay of nuclear and electronic motion, which is still not comprehensively understood and not easy to investigate both experimentally and theoretically. In order to elucidate trends and contribute to a more general understanding, we here review our recent work on excited-state dynamics of open-shell hydrocarbon species using time-resolved photoelectron spectroscopy and field-induced surface hopping simulations, and report new results on the excited-state dynamics of the tropyl and the 1-methylallyl radical. The different dynamics are compared, and the difficulties and future directions of time-resolved photoelectron spectroscopy and excited state dynamics simulations of open-shell hydrocarbon molecules are discussed. KW - Excited state dynamics KW - Hydrocarbon radicals KW - time-resolved photoelectron spectroscopy KW - field-induced surface hopping Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-198734 UR - https://doi.org/10.1021/acs.jpca.9b06346 N1 - This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of Physical Chemistry A, copyright © American Chemical Society after peer review. To access the final edited and published work see Journal of Physical Chemistry A 2019, 123, 50, 10643-10662. https://doi.org/10.1021/acs.jpca.9b06346. ER - TY - JOUR A1 - Ramler, Jacqueline A1 - Poater, Jordi A1 - Hirsch, Florian A1 - Ritschel, Benedikt A1 - Fischer, Ingo A1 - Bickelhaupt, F. Matthias A1 - Lichtenberg, Crispin T1 - Carbon monoxide insertion at a heavy p-block element: unprecedented formation of a cationic bismuth carbamoyl JF - Chemical Science N2 - Major advances in the chemistry of 5th and 6th row heavy p-block element compounds have recently uncovered intriguing reactivity patterns towards small molecules such as H\(_2\), CO\(_2\), and ethylene. However, well-defined, homogeneous insertion reactions with carbon monoxide, one of the benchmark substrates in this field, have not been reported to date. We demonstrate here, that a cationic bismuth amide undergoes facile insertion of CO into the Bi–N bond under mild conditions. This approach grants direct access to the first cationic bismuth carbamoyl species. Its characterization by NMR, IR, and UV/vis spectroscopy, elemental analysis, single-crystal X-ray analysis, cyclic voltammetry, and DFT calculations revealed intriguing properties, such as a reversible electron transfer at the bismuth center and an absorption feature at 353 nm ascribed to a transition involving σ- and π-type orbitals of the bismuth-carbamoyl functionality. A combined experimental and theoretical approach provided insight into the mechanism of CO insertion. The substrate scope could be extended to isonitriles. KW - carbon monoxide KW - p-block element Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-181627 VL - 10 ER -