Density functional theory study on the geometric, electronic and vibrational structures of alkali metal porphyrin complexes

Abstract

The ground-state geometry, electronic structures and vibrational frequencies of alkali metal porphyrin complexes, M 2P (M=Li, Na, K), have been studied using B3LYP/6-31G(d) method. The computed structures were compared with the crystallographic data of related compounds. The Na 2P and K 2P molecules have D 4h symmetry with the two alkali metal atoms locating on the different sides of the porphyrin plane. For Li 2P, the energy of D 4h structure is higher than the symmetry broken C 2h structure, but the energy difference is very small. Natural population analysis suggests a significant charge transfer from the alkali metals to the porphyrin ring.The vibrational frequencies of M 2P (M=Li, Na, K) were calculated and the results were compared with zinc porphyrin (ZnP).