Peculiarity in the Electronic Structure of Cu(II) Complex Ferromagnetically Coupled with Bisimino Nitroxides

摘要: By means of the electron spin resonance (ESR) technique, we have investigated electronic structures tridentate imino nitroxyl diradical complex with copper(II) (Cu−bisimpy), which has a square planar structure and ground quartet state an extremely strong ferromagnetic exchange interaction, its related compounds (bisimpy = 2,6-bis(1′-oxyl-4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1′H-imidazol-2′-yl)pyridine). It was clarified that Cu−bisimpy had unique magnetic orbitals, compared biradical ligand (bisimpy), zinc(II) (Zn−bisimpy) terpyridine (Cu−tpy) (tpy 2,2′;6′,2′′-terpyridine). Multifrequency ESR spectroscopy provided reliable set parameters Cu−bisimpy, small g anisotropy (gx 2.02, gy 2.01, gz 2.08) hyperfine coupling Cu (|Ax| 42.0 MHz, |Ay| ≤ 14 |Az| 153 MHz) but huge zero-field splitting (D +17.4 GHz, E −1.0 GHz). The maximum principal axis interaction (...