Strong electronic influence of equatorial ligands on frontier orbitals in paddlewheel dichromium(ii,ii) complexes?

Dalton Transactions Pub Date: 2018-12-11 DOI: 10.1039/C8DT04347G

Abstract

A series of substituted benzoate-bridged dichromium(II,II) complexes [Cr2(RCO2)4(THF)2] ([Cr2]), where RCO2? is substituted benzoate, was synthesized and its structural and magnetic properties were investigated. The orbital energies, as well as magnetic coupling energies, were also investigated using computational approaches. The HOMO/LUMO energy levels of the complexes are strongly dependent on the acidity, i.e., pKa, of the corresponding benzoic acids (RCO2H), revealing a linear trend in the respective groups of non-ortho, mono-ortho, and bi-ortho substituted groups. The Cr?Cr magnetic coupling constant (ES–T) is little affected by pKa; instead, the ES–T is associated with the HOMO/LUMO gap and strongly correlated with the Cr?Cr distance.

Graphical abstract: Strong electronic influence of equatorial ligands on frontier orbitals in paddlewheel dichromium(ii,ii) complexes
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