STRUCTURES AND SPECTROSCOPIC PROPERTIES CALCULATED FOR C$_6$H$_7^+$ AND ITS COMPLEXES WITH Ne, Ar, N$_2$, OR CO$_2$

Abstract

Explicitly correlated coupled cluster theory at the CCSD(T)-F12x (x = a, b) level nderline{\textbf{127}}, 221106 (2007);\\ \hspace*{0.45cm} G.~Knizia, T.~B.~Adler, and H.-J.~Werner, \textit{J.~Chem.~Phys.} nderline{\textbf{130}}, 054104 (2009).} in conjunction with the double-hybrid density functional B2PLYP-D nderline{\textbf{9}}, 3397 (2007).} has been employed in a study of the benzenium ion (C$_6$H$_7^+$) and its complexes with simple ligands (L = Ne, Ar, N$_2$, or CO$_2$). nderline{\textbf{115}}, 13664 (2011);\\ \hspace*{0.45cm} P.~Botschwina and R.~Oswald, \textit{J.~Chem.~Phys.} submitted.} The ground-state rotational constants of C$_6$H$_7^+$ are predicted to be A$_0$ = 5445 MHz, B$_0$ = 5313 MHz, and C$_0$ = 2731 MHz. For the complexes with L = Ne, Ar or N$_2$, the energetically most favourable structure is of $\pi$-bonded type, but for the most strongly bound complex C$_6$H$_7^+$ $\cdot$ CO$_2$ a conformer with the CO$_2$ ligand lying in the ring-plane of the C$_6$H$_7^+$ moiety is slightly lower in energy.