Theoretical investigations on the d-p hybridized aromaticity, photoelectron spectroscopy and neutral salts of the LaX2− (X=Al, Ga, In) clusters

Abstract

We present an extensive density functional theory (DFT) calculations on the geometrical and electronic structures of the triatomic LaX2− (X=Al, Ga, In) clusters. Various trail structures and spin states have been attempted to determine the lowest-energy geometries of these La-doped metal clusters. The ground states of all three clusters are calculated to possess the trigonal structures with the singlet multiplicities. The calculations on molecular orbitals (MOs) and nucleus-independent chemical shift (NICS) values have been performed to examine the aromatic characteristics of the LaX2− (X=Al, Ga, In) clusters. The present calculations disclose that all these metal clusters are doubly aromatic, namely d-p hybridized σ and π aromaticity resulting from the effective overlap between the 5d atomic orbital of the La atom and the p orbitals of the IIIA group elements. Theoretical vertical detachment energies (VDEs) were also calculated to simulate the photoelectron spectra (PES) of the clusters. In addition, by adding the alkali cations (Li+ and Na+) into the LaX2− (X=Al, Ga, In) clusters, the geometries and electronic structures of the corresponding neutral salts have also been investigated to gain more insights in the potential of using these aromatic anions as building blocks.