Spin-orbit effects on electronic delocalization. Aromaticity in a discrete square tetrapalladium sandwich complex

• Published in: The Journal of chemical physics 2010-04, Vol.132 (16), p.164308-164308-6
• Main Authors: Muñoz-Castro, A., Mac-Leod Carey, D., Arratia-Pérez, R.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.3382340

In this article, we report the relativistic electronic structure, including spin-orbit interaction, employing all-electron density functional theory calculations on the multimetallic sandwich compound [ ( CNT ) Pd 4 ( COT ) ] 1 + ( 1 ), which can be considered as a [ Pd 4 ] 2 + fragment flanked by two ring-ligands, namely, cyclononatetraenyl ( CNT 1 − ) and cyclooctatetraene (COT), as well as the dimer of 1 , hereafter 2 . The calculations suggest that the Pd 4 -ligand interaction is mainly electrostatic, being the main responsible term for the stabilization of the almost fully occupied 4 d shell [ Pd 4 ] 2 + fragment. The ring currents and electronic delocalization estimated via the nuclear independent chemical shifts indices and electron localization function, allow us to describe a significant σ - aromaticity at the center of the Pd 4 square in 1 , which in conjunction with the aromaticity arising from the ligands induce considerable aromatic character inside of the multimetallic metallocene.