title: Threshold photoelectron spectroscopy of cyclopropenylidene, chlorocyclopropenylidene, and their deuterated isotopomeres.
abstract: Cyclopropenylidene (c-C(3)H(2)), chlorocyclopropenylidene (c-C(3)HCl), and their deuterated isotopomers were studied by the threshold photoelectron-photoion coincidence (TPEPICO) technique using VUV synchrotron radiation. The carbenes were generated via flash pyrolysis. In all species a change in geometry is visible upon ionization, with significant activity in the C═C, C-C-stretching mode and, in the case of c-C(3)H(2)/D(2), the C-H-bending mode. The electron is removed from an sp(2) like hybrid orbital centered on the carbene C atom. The mass selected threshold photoelectron (TPE) spectra were fitted by a Franck-Condon simulation, yielding the equilibrium geometry of the cation ground state ((1)A(1)). The adiabatic ionization energy IE(ad) of c-C(3)H(2) was determined to be 9.17 eV, in good agreement with calculations and literature values. Two vibrational wavenumbers of the cation were determined experimentally (ν(3)(+) = 1150 cm(-1) and ν(2)(+) = 1530 cm(-1)). Chlorocyclopropenylidene was also studied by TPE spectroscopy and has a similar IE(ad) of 9.17 eV. The spectrum also shows a vibrational progression that corresponds to the C═C- and C-C-stretching modes of the cation. The equilibrium geometry was also determined by a Franck-Condon fit. The IE(ad) of the deuterated isotopomers, c-C(3)D(2) and c-C(3)DCl, were also determined to be 9.17 eV. The spectra confirm the assignments for the nondeuterated species.
authors.affiliation: Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hemberger
authors.forename: Bastian
authors.initials: B
authors.lastname: Noller
authors.forename: Michael
authors.initials: M
authors.lastname: Steinbauer
authors.forename: Ingo
authors.initials: I
authors.lastname: Fischer
authors.forename: Christian
authors.initials: C
authors.lastname: Alcaraz
authors.forename: Bárbara K
authors.initials: BK
authors.lastname: Cunha de Miranda
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Garcia
authors.forename: Héloïse
authors.initials: H
authors.lastname: Soldi-Lose
mesh_terms: D003521:Cyclopropanes / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D006844:Hydrocarbons, Cyclic / Q000737:chemistry*; D013058:Mass Spectrometry; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D056951:Photoelectron Spectroscopy; D011789:Quantum Theory
chemical_list: D003521:Cyclopropanes; D006844:Hydrocarbons, Cyclic; C555685:chlorocyclopropenylidene; C555684:cyclopropenylidene; D003903:Deuterium