Odd-Number Cyclo[n]Carbons Sustaining Alternating Aromaticity
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Odd-Number Cyclo[n]Carbons Sustaining Alternating Aromaticity. / Baryshnikov, Glib V.; Valiev, Rashid R.; Valiulina, Lenara I.; Kurtsevich, Alexandr E.; Kurten, Theo; Sundholm, Dage; Pittelkow, Michael; Zhang, Jinglai; Agren, Hans.
I: Journal of Physical Chemistry A, Bind 126, Nr. 16, 2022, s. 2445-2452.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Odd-Number Cyclo[n]Carbons Sustaining Alternating Aromaticity
AU - Baryshnikov, Glib V.
AU - Valiev, Rashid R.
AU - Valiulina, Lenara I.
AU - Kurtsevich, Alexandr E.
AU - Kurten, Theo
AU - Sundholm, Dage
AU - Pittelkow, Michael
AU - Zhang, Jinglai
AU - Agren, Hans
PY - 2022
Y1 - 2022
N2 - Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.
AB - Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.
KW - MOLECULAR-ORBITAL METHODS
KW - ALL-CARBOATOMIC RING
KW - DENSITY FUNCTIONALS
KW - CARBON CLUSTERS
KW - ELECTRONIC-STRUCTURE
KW - BASIS-SETS
KW - THERMOCHEMISTRY
KW - TRANSITION
KW - GENERATION
KW - DESIGN
U2 - 10.1021/acs.jpca.1c08507
DO - 10.1021/acs.jpca.1c08507
M3 - Journal article
C2 - 35420813
VL - 126
SP - 2445
EP - 2452
JO - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
JF - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
SN - 1089-5639
IS - 16
ER -
ID: 313865770