Abstract
Both second-order vibrational perturbation theory (VPT2) and vibrational configuration interaction (VCI) theory have been employed to compute the fundamental vibrational frequencies of the isolated 2-phosphaethynolate and 2-phosphaethynthiolate anions (OCP and SCP
) near the CCSD(T) complete basis set (CBS) limit. Our best estimates of the fundamental frequency associated with the doubly degenerate bending mode of these linear triatomic ions (
) are 492 cm
for OCP
and 362 cm
for SCP
. Due to strong coupling, the stretching motions of SCP
are best described as pseudo-symmetric (
) and pseudo-antisymmetric (
) stretches that we estimate to be 588 cm
and 1367 cm
, respectively. For OCP
, our best predictions are 792 cm
for
and 1795 cm
for
, with the latter having predominantly CO stretching character. In the absence of experimental gas-phase vibrational spectra for these species, these computed anharmonic frequencies provide important reference values to help quantify spectroscopic perturbations induced by environmental effects such as those from solvents or counter ions.
GRAPHICAL ABSTRACT
![](/cms/asset/3f4013e7-dc1d-4dc2-adb2-442d392608d5/tmph_a_1967495_uf0001_oc.jpg)
Acknowledgments
This work is dedicated to Professor John F. Stanton on the occasion of his 60th birthday. The Mississippi Center for Supercomputing Research (MCSR) is acknowledged for a generous allocation of time on their computational resources. KRB would also like to thank Dr. Thomas Sexton and Dr. Shane Autry at the University of Mississippi for many helpful discussions and their technical expertise.
Disclosure statement
No potential conflict of interest was reported by the author(s).