title: Heterometallic Fe(III) /K Coordination Polymer with a Wide Thermal Hysteretic Spin Transition at Room Temperature.
abstract: The anionic Fe(III) complex exhibiting cooperative spin transition with a wide thermal hysteresis near room temperature, K[Fe(5-Brthsa)2 ] (5-Brthsa-H2 =5-bromosalicylaldehyde thiosemicarbazone), is reported. The hysteresis (Δ=69 K in the first cycle) shows a one-step transition in heating mode and a two-step transition in cooling mode. X-ray structure analysis showed that the coexistence of hydrogen bond and cation-π interactions, as well as alkali metal coordination bonds, to give 2D coordination polymer structure. This result is contrary to previous reports of broad thermal hysteresis induced by coordination bonds of Fe(II) spin crossover coordination polymers (with 1D/3D structures), and by strong intermolecular interactions in the molecular packing through π-π stacking or hydrogen-bond networks. As a consequence, the importance, or the very good suitability of alkali metal-based coordination bonds and cation-π interactions for communicating cooperative interactions in spin-crossover (SCO) compounds must be reconsidered.
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku Fukuoka, 819-0395 (Japan), Fax: (+81) 92-802-6205.
authors.forename: Soonchul
authors.initials: S
authors.lastname: Kang
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku Fukuoka, 819-0395 (Japan), Fax: (+81) 92-802-6205.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shiota
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku Fukuoka, 819-0395 (Japan), Fax: (+81) 92-802-6205.
authors.forename: Akira
authors.initials: A
authors.lastname: Kariyazaki
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku Fukuoka, 819-0395 (Japan), Fax: (+81) 92-802-6205.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kanegawa
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku Fukuoka, 819-0395 (Japan), Fax: (+81) 92-802-6205.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yoshizawa
authors.affiliation: Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka Nishi-ku Fukuoka, 819-0395 (Japan), Fax: (+81) 92-802-6205. sato@cm.kyushu-u.ac.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Sato
keywords: cations; hydrogen bonds; hysteresis; potassium; spin crossover