The electronic structure and energetics of V+-benzene half-sandwiches of different multiplicities: Comparative multireference and single-reference theoretical studyстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Multireference complete active space self-consistent field CASSCF and multiconfigurational
quasidegenerate perturbation theory MCQDPT and single-reference ab initio Møller–Plesset
second order perturbation theory MP2 and coupled clusters with singles, doubles and noniterative
triples CCSDT and density functional theory PBE and B3LYP electronic structure calculations
of VC6H6+ half-sandwich in the states of different multiplicities are described and compared.
Detailed analyses of the geometries and electronic structures of the all found states are given;
adiabatic and diabatic dissociation energies are estimated. The lowest electronic state of VC6H6+
half-sandwich was found to be the quintet 5B2 state with a slightly deformed
upside-down-boat-shaped benzene ring and d4 configuration of V atom, followed by a triplet 3A2
state lying about 4 kcal/mol above. The lowest singlet state 1A1d4 lies much 28 kcal/mol
higher. MCQDPT calculated adiabatic dissociation energy 53.6 kcal/mol for the lowest 5B2d4
state agrees well with the current 56.4 54.4 kcal/mol experimental estimate, giving a preference to
the lower one. Compared to MCQDPT, B3LYP hybrid exchange-correlation functional provides the
best results, while CCSDT performs usually worse. Gradient-corrected PBE calculations tend to
systematically overestimate metal-benzene binding in the row quintettripletsinglet.