Conformational dependence of electronic spectra and zero-field splitting parameters in 2-naphthylphenylcarbene

Abstract

Quantum mechanical calculations using ab initio and semi-empirical methods have been camed out for elucidating the electronic structure and geometry of 2-naphthylphenylcarbene conformers. The Zlcis conformer has the lowest ground state triplet energy, the lowest triplet-triplet (To-TI) transition energy, as well as the largest zero-field splitting parameter D. A clear-cut relationship between the D value and the geometry is pointed out.Key words: carbenes, conformational isomerism, triplet-triplet transitions, CS-INDOJCI calculations, ZFS D parameters.Resume : Dans le but dlCtudier la structure Clectronique et la gComCtrie du 2-naphtylphCnyle carbbne, des calculs de chimie quantique (ab initio et semi-empiriques) ont Ct C rCalisCs sur diffkrents conformbres de ce carbttne. Le calcul montre que c'est le conformkre Z k i s qui prksente 1'Cnergie minimale dans son Ctat triplet fondamental, 1'Cnergie de transition triplet-triplet (To-T,) la plus faible ainsi que la valeur la plus ClevCe du paramtttre D de sCparation des sous-niveaux triplets en champ nul. Une relation simple reliant D et la gComCtrie est mise en Cvidence.

Second-order perturbation theory using correlated orbitals. II. A coupled MCSCF perturbation strategy for electronic spectra and its applications to ethylene, formaldehyde and vinylidene

“…[70]), spin-orbit couplings in the ab initio scheme [71] or zero-field splitting parameters in a semi-empirical framework [72]. It was furthermore recently extended to semiempirical electronic Hamiltonians (PPP or CS/ INDO), using zeroth-order spaces designed to deal with the optical spectra of large conjugated systems or related ions [73][74][75][76][77][78].…”