Structural and Electronic Properties of LaSin-/0 (n = 2-6) Clusters: Anion Photoelectron Spectroscopy and Density Functional Calculations.

The structures and electronic properties of LaSin- (n = 2-6) anions and their neutral counterparts were investigated by anion photoelectron spectroscopy and theoretical calculations. The vertical detachment energies of the most stable structures of LaSin- (n = 2-6) were measured to be 1.28, 1.58, 2.30, 2.05, and 2.91 eV, respectively. The lowest-energy isomer of LaSi2- is an isosceles triangle with a C2v symmetry. For LaSi3-6- clusters, the most stable isomers are polyhedrons with La atom face-capping the Sin frameworks. The lowest-energy structures of neutral LaSi2,4,5 clusters are similar to their anionic counterparts. The most stable isomer of neutral LaSi3 is a planar structure with C2v symmetry, which is different from the triangular pyramid structure of LaSi3- anion. The lowest-energy isomer of LaSi6- is a C5v symmetric pentagonal bipyramid structure, while for neutral LaSi6 cluster, the C5v structure is not the most stable one. The natural population analysis showed that there is electron transfer from La atoms to Si atoms in LaSin-/0 (n = 2-6). The ZZ tensor component in isochemical shielding surfaces and the anisotropy of the induced current density analyses indicate that the most stable isomer of LaSi6- has aromaticity.