SUPERALKALI MOLECULES CONTAINING HALOGENOIDS

Abstract

The structure and properties of hypermetalated Li 2X and Na 2X and their corresponding Li 2X+ and Na 2X+ cations utilizing halogenoids X (SCN, OCN, and CN) were investigated using ab initio methods at the CCSD(T)/6-311+G(3df)//MP2/6-311+G(d) level of theory. The vertical ionization potentials of Li 2X and Na 2X radicals were calculated at the outer valence Green function level (OVGF) with the 6-311+G(3df) basis sets. It was found that all Na 2X molecules studied possess the vertical ionization potentials (VIP) that are smaller than the IP of the Na atom (5.14 eV) and thus may be termed superalkali molecules, whereas the Li 2X radicals exhibit slightly larger IPs. The smallest VIP of 4.728 eV was calculated for the Na 2 CN system. The IP dependence on the structure and the singly occupied molecular orbital (SOMO) character is also discussed.