Structure and potential energy surface of K+·CX2

The potential energy surface of K+·CO2 and K+·CS2 complexes are determined at high levels of ab initio theory (CCSD), B3LYP, and MP2 using different basis sets. These calculations predict the existence of three minima for K+·CO2 complex; linear, quadrilateral and Y-shape, and two minima for K+·CS2 complex; bent and Y-shape. In addition, the binding energies, and other thermodynamic quantities are calculated at different levels of theories. Our calculations show that the difference in the global minima geometries of both complexes is mainly due to the sign of the quadrupole moment of CO2 and CS2 molecules.