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

Research paper by Po-Jung PJ Huang, Yoshiki Y Natori, Yasutaka Y Kitagawa, Yoshihiro Y Sekine, Wataru W Kosaka, Hitoshi H Miyasaka

Indexed on: 20 Dec '18Published on: 20 Dec '18Published in: Dalton Transactions



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 CrCr 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 CrCr distance.