Journal of Physical Chemistry A, Vol.115, No.46, 13664-13672, 2011
Explicitly Correlated Coupled Cluster Calculations for the Benzenium Ion (C6H7+) and Its Complexes with Ne and Ar
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 pi-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.