TY - JOUR
T1 - Controllable Electron Transfer in Mixed-Valence Bridged Norbornylogous Compounds
T2 - Ab Initio Calculation Combined with a Parametric Model and Through-Bond and Through-Space Interpretation
AU - Zilberg, Shmuel
AU - Stekolshik, Yaniv
AU - Palii, Andrew
AU - Tsukerblat, Boris
N1 - Funding Information:
The work was in part (quantum-chemical analysis of mixed-valence bridged norbornylogous compounds) performed with financial support from the Russian Science Foundation (project No. 20-13-00374) and in part (parametric modeling of the localization–delocalization phenomenon) with financial support from the Ministry of Science and Higher Education of the Russian Federation (state assignment no AAAA-A19-119092390079-8).
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/5
Y1 - 2022/5
N2 - In the context of a computationally guided approach to the controllable electron transfer in mixed-valence (MV) systems, in this article, we study the electron transfer (ET) in the series of oxidized norbornadiene C7H8 (I) and its polycyclic derivatives, C12H12 (II), C17H16, (III), C27H24 (IV), and C32H28 (V), with variable lengths of the bridge connecting redox sites. The work combines an ab initio CASSCF evaluation of the electronic structure of systems I-V with the parametric description in the framework of the biorbital two-mode vibronic model. The model involves coupling with the "breathing"mode and intercenter vibration modulating the distances between the redox fragments. The ab initio calculations were performed for two types of optimized structures of I-V: (a) charge-localized global minimum (Cs) and (b) symmetric configuration (C2v) with the delocalized charge. This allows one to estimate the potential barrier separating charge-localized configurations as well as vibronic coupling parameters and the electron transfer integral. Along with the adiabatic approach, the quantum-mechanical analysis of the vibronic levels has been applied to precisely estimate the quantum effect of tunneling splitting. We estimate the "through-space"and "through-bond"contributions to the parameters interrelated with the charge transfer (CT). The through-space effect proves to be a major factor of ET at a short distance between the redox centers, whereas the through-bond contribution is dominant at a long distance. Vibronic coupling under the condition of through-space ET leads to the localization of the positive charge on the -chromophore, while the through-bond component of ET results in compensating σ-shifts and subsequent charge delocalization over the bridge. The limitations of the parametric approach were discussed in the context of the two components contributing to the ET. Particularly, the bridge polarization in the course of through-bond ET proves to be beyond the basis of the employed parametric model.
AB - In the context of a computationally guided approach to the controllable electron transfer in mixed-valence (MV) systems, in this article, we study the electron transfer (ET) in the series of oxidized norbornadiene C7H8 (I) and its polycyclic derivatives, C12H12 (II), C17H16, (III), C27H24 (IV), and C32H28 (V), with variable lengths of the bridge connecting redox sites. The work combines an ab initio CASSCF evaluation of the electronic structure of systems I-V with the parametric description in the framework of the biorbital two-mode vibronic model. The model involves coupling with the "breathing"mode and intercenter vibration modulating the distances between the redox fragments. The ab initio calculations were performed for two types of optimized structures of I-V: (a) charge-localized global minimum (Cs) and (b) symmetric configuration (C2v) with the delocalized charge. This allows one to estimate the potential barrier separating charge-localized configurations as well as vibronic coupling parameters and the electron transfer integral. Along with the adiabatic approach, the quantum-mechanical analysis of the vibronic levels has been applied to precisely estimate the quantum effect of tunneling splitting. We estimate the "through-space"and "through-bond"contributions to the parameters interrelated with the charge transfer (CT). The through-space effect proves to be a major factor of ET at a short distance between the redox centers, whereas the through-bond contribution is dominant at a long distance. Vibronic coupling under the condition of through-space ET leads to the localization of the positive charge on the -chromophore, while the through-bond component of ET results in compensating σ-shifts and subsequent charge delocalization over the bridge. The limitations of the parametric approach were discussed in the context of the two components contributing to the ET. Particularly, the bridge polarization in the course of through-bond ET proves to be beyond the basis of the employed parametric model.
UR - http://www.scopus.com/inward/record.url?scp=85130735370&partnerID=8YFLogxK
U2 - 10.1021/acs.jpca.1c09637
DO - 10.1021/acs.jpca.1c09637
M3 - Article
C2 - 35537213
AN - SCOPUS:85130735370
SN - 1089-5639
VL - 126
SP - 2855
EP - 2878
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 19
ER -