title: The role of spin-orbit coupling in the photolysis of methylcobalamin.
abstract: The photolysis of the methylcobalamin cofactor (MeCbl) in its base-off form was investigated by considering the extent of spin-orbit coupling (SOC). Triplet Co-C photodissociation pathways previously invoked at the density functional theory level using Landau-Zener theory were further validated with ab initio calculations that combine SOC based on multi-state second order perturbation theory. It was determined that SOC is feasible between singlet and triplet states at elongated Co-C distances, leading to photodissociation from the state having dominant σ(dz(2)) character, by either direct coupling with the lowest singlet states or by crossing with SOC mixed triplets.
authors.affiliation: Department of Chemistry, Advanced Materials Engineering and Modelling Group, Wroclaw University of Technology, 50-370 Wroclaw, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Andruniów
authors.affiliation: Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Lodowski
authors.affiliation: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, USA.
authors.forename: Brady D
authors.initials: BD
authors.lastname: Garabato
authors.affiliation: Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Jaworska
authors.affiliation: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, USA.
authors.forename: Pawel M
authors.initials: PM
authors.lastname: Kozlowski
mesh_terms: D010782:Photolysis; D011789:Quantum Theory; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: C019476:mecobalamin; D014805:Vitamin B 12