title: On the equilibrium structures of the complexes H2C3H+ · Ar and c-C3H3(+) · Ar: results of explicitly correlated coupled cluster calculations.
abstract: Explicitly correlated coupled cluster theory at the CCSD(T)-F12x (x = a, b) level [T. B. Adler et al., J. Chem. Phys. 127, 221106 (2007)] has been employed in a study of the potential energy surfaces for the complexes H(2)C(3)H(+) · Ar and c-C(3)H(3)(+) · Ar. For the former complex, a pronounced minimum with C(s) symmetry was found (D(e) ≈ 780 cm(-1)), well below the local "H-bound" minimum with C(2v) symmetry (D(e) ≈ 585 cm(-1)). The absorption at 3238 cm(-1) found in the recent infrared photodissociation spectra [A. M. Ricks et al., J. Chem. Phys. 132, 051101 (2010)] is, thus, interpreted as an essentially free acetylenic CH stretching vibration of the propargyl cation. A global minimum of C(s) symmetry was also obtained for c-C(3)H(3)(+) (D(e) ≈ 580 cm(-1)), but the energy difference with respect to the local C(2v) minimum is only 54 cm(-1).
authors.affiliation: Institute of Physical Chemistry, University of Göttingen, Tammannstr. 6, 37077 Göttingen, Germany. pbotsch@gwdg.de
authors.forename: Peter
authors.initials: P
authors.lastname: Botschwina
authors.forename: Rainer
authors.initials: R
authors.lastname: Oswald