title: Threshold Ionization and Spin-Orbit Coupling of Ceracyclopropene Formed by Ethylene Dehydrogenation.
abstract: A Ce atom reaction with ethylene was carried out in a laser-vaporization metal cluster beam source. Ce(C2H2) formed by hydrogen elimination from ethylene was investigated by mass-analyzed threshold ionization (MATI) spectroscopy, isotopic substitutions, and relativistic quantum chemical computations. The theoretical calculations include a scalar relativistic correction, dynamic electron correlation, and spin-orbit coupling. The MATI spectrum exhibits two nearly identical band systems separated by 128 cm(-1). The separation is not affected by deuteration. The two-band systems are attributed to spin-orbit splitting and the vibrational bands to the symmetric metal-ligand stretching and in-plane carbon-hydrogen bending excitations. The spin-orbit splitting arises from interactions of a pair of nearly degenerate triplets and a pair of nearly degenerate singlets. The organolanthanide complex is a metallacyclopropene in C2v symmetry. The low-energy valence electron configurations of the neutral and ion species are Ce 4f(1)6s(1) and Ce 4f(1), respectively. The remaining two electrons that are associated with the isolated Ce atom or ion are spin paired in a molecular orbital that is a bonding combination between a 5d Ce orbital and a π* antibonding orbital of acetylene.
authors.affiliation: Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506-0055, United States.
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011-3111, United States.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Schmidt
authors.affiliation: Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506-0055, United States.
authors.forename: Sudesh
authors.initials: S
authors.lastname: Kumari
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011-3111, United States.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Gordon
authors.affiliation: Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506-0055, United States.
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Yang