Explicitly Correlated Coupled Cluster Calculations for the Benzenium Ion (C6H7 +) and Its Complexes with Ne and Ar

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2011-11, Vol.115 (46), p.13664-13672
• Main Authors: Botschwina, Peter, Oswald, Rainer
• Format: Article
• Language: English
• Subjects: A: Molecular Structure, Quantum Chemistry, General Theory
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp207905t

Explicitly correlated coupled cluster theory at the CCSD(T)-F12x (x = a, b) level (Adler, T. B.; Knizia, G.; Werner, H.-J. J. Chem. Phys. 2007, 127, 221106) has been employed in a study of the benzenium ion (C6H7 +) and its complexes with a neon or an argon atom. The ground-state rotational constants of C6H7 + are predicted to be A 0 = 5445 MHz, B 0 = 5313 MHz, and C 0 = 2731 MHz. Anharmonic vibrational wavenumbers of this cation were obtained by combination of harmonic CCSD(T*)-F12a values with anharmonic contributions calculated by double-hybrid density functional theory at the B2PLYP-D level. For the complexes of C6H7 + with Ne or Ar, the lowest energy minimum is of π-bonded structure. The corresponding dissociation energies D 0 are estimated to be 160 and 550 cm–1, respectively. There is no indication of H-bonds to the aromatic or aliphatic hydrogen atoms. Instead, three nonequivalent local energy minima were found for nuclear configurations where the rare-gas atom lies in the ring-plane and approximatly points to the center of one of the six CC bonds.