An investigation of the electron density of a Jahn–Teller-distorted CrII cation: the crystal structure and charge density of hexakis(acetonitrile-κN)chromium(II) bis(tetraphenylborate) acetonitrile disolvate

摘要

In the crystal structure of the title homoleptic CrII complex, [Cr(CH3CN)6](C24H20B)2·CH3CN, the [Cr(CH3CN)6]2+ cation is a high-spin d4 complex with strong static, rather than dynamic, Jahn–Teller distortion. The electron density of the cation was determined by single-crystal X-ray refinements using aspherical structure factors from wavefunction calculations. The detailed picture of the electronic density allowed us to assess the extent and directionality of the Jahn–Teller distortion of the CrII cation away from idealized octahedral symmetry. The topological analysis of the aspherical d-electron density about the CrII cation showed that there are significant valence charge concentrations along the axial Cr—N axes. Likewise, there were significant valence charge depletions about the CrII cation along the equatorial Cr—N bonds. These charge concentrations are in accordance with a Jahn–Teller-distorted six-coordinate complex.