Ground- and Triplet Excited-State Properties Correlation: A Computational CASSCF/CASPT2 Approach Based on the Photodissociation of Allylsilanes
Φόρτωση...
Ημερομηνία
Συγγραφείς
Varras, P. C.
Zarkadis, A. K.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
American Chemical Society
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Journal of Physical Chemistry A
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
Excited-state properties, although extremely useful, are hardly accessible. One indirect way would be to derive them from relationships to ground-state properties which are usually more readily available. Herewith, we present quantitative correlations between triplet excited-state (T-1) properties (bond dissociation energy, D-0(T1), homolytic activation energy, E-a(T1), and rate constant, k(r)) and the ground-state bond dissociation energy (D-0), taking as an example the photodissociation of the C-Si bond of simple substituted allylsilanes CH2=CHC((RR2)-R-1)-SiH3 (R-1 and R-2 = H, Me, and Et). By applying the complete-active-space self-consistent field CASSCF(6,6) and CASPT2(6,6) quantum chemical methodologies, we have found that the consecutive introduction of Me/Et groups has little effect on the geometry and energy of the T-1 state; however, it reduces the magnitudes of D-0, D-0(T1) and E-a(T1). Moreover, these energetic parameters have been plotted giving good linear correlations: D-0(T1) = alpha(1) + beta(1) . D-0, E-a(T1) = alpha(2) + beta(2) . D-0(T1), and E-a(T1) = alpha(3) + beta(3) . D-0 (alpha and beta being constants), while k(r) correlates very well to E-a(T1). The key factor behind these useful correlations is the validity of the Evans-Polanyi-Semenov relation (second equation) and its extended form (third equation) applied for excited systems. Additionally, the unexpectedly high values obtained for E-a(T1) demonstrate a new application of the principle of nonperfect synchronization (PNS) in excited-state chemistry issues.
Περιγραφή
Λέξεις-κλειδιά
cis-trans isomerization, nonperfect synchronization, triphenylmethyl radicals, substituent constants, chemical-reactivity, activation-energies, perturbation-theory, bond, barriers, photochemistry
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000299985100013
http://pubs.acs.org/doi/pdfplus/10.1021/jp209583z
http://pubs.acs.org/doi/pdfplus/10.1021/jp209583z
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας