title: Bistability of magnetization without spin-transition in a high-spin cobalt(II) complex due to angular momentum quenching.
abstract: [Co(NO(3))(2)L] (L: 2,6-di(pyrazol-1-yl)pyrazine) (1) exhibits an abrupt transition with hysteresis in magnetic susceptibility between 228 and 240 K. The results of spectroscopic and XRD measurements showed that 1 is in the high spin state in the whole temperature range. Therefore the observed hysteresis is not due to a spin transition but corresponds to a partial quenching of the angular momentum contribution to the magnetic susceptibility. Crystallographic measurements on the low- and high-temperature form of 1, combined with DFT calculations, showed that a symmetric twisting of the coordinating nitrate ions upon the transition is the most important factor in the orbital quenching mechanism. Utilizing such quenching to control magnetic properties can be a new approach to engineer transition metal complexes with magnetic functionalities without changing their spin or oxidation state.
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Gergely
authors.initials: G
authors.lastname: Juhász
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Matsuda
authors.forename: Shinji
authors.initials: S
authors.lastname: Kanegawa
authors.forename: Kaori
authors.initials: K
authors.lastname: Inoue
authors.forename: Osamu
authors.initials: O
authors.lastname: Sato
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yoshizawa