Ab initio and hybrid DFT study on the electronic states of fluorenone–Na complexes

Abstract

Structures and electronic states of a molecular complex formed between fluorenone and sodium atom (denoted by FL–Na) have been investigated by means of ab initio density functional theory (DFT). The most stable structure of FL–Na has a C_s symmetry where the sodium atom is located on the C_s plane perpendicular to the molecular plane of FL where all atoms are located. The sodium atom binds to the carbonyl oxygen of FL and the angle of Na–O–C is calculated to be 157° at the B3LYP/6-311+G(d) level. The charge on the Na atom shows a positive value (∼+0.80), and unpaired electron is delocalized over the FL molecule, indicating that the FL–Na complex exists as an ion-pair state expressed by (CO)^δ−(Na)^δ+ at the ground state (δ ∼ +0.80). The proton hyperfine coupling constants and excitation energies calculated at the B3LYP/6-311+G(d) and B3LYP/6-31++G(d,p) levels are in good agreement with previous experiments. The electronic states at the ground and first excited states were discussed.