Spin-Singlet Transition in the Magnetic Hybrid Compound from a Spin-Crossover Fe(III) Cation and π-Radical Anion

• Published in: Inorganics 2017-09, Vol.5 (3), p.54
• Main Authors: Takahashi, Kazuyuki, Sakurai, Takahiro, Zhang, Wei-Min, Okubo, Susumu, Ohta, Hitoshi, Yamamoto, Takashi, Einaga, Yasuaki, Mori, Hatsumi
• Format: Article
• Language: English
• Subjects: Anions; Cations; Coexistence; Crystal structure; Dimerization; Electron paramagnetic resonance; Fe(III) complex; Genetic transformation; magnetic correlation; Magnetic induction; Magnetic permeability; Magnetic relaxation; Magnetic resonance; Magnetic susceptibility; Ni dithiolene complex; Nickel compounds; spin transition; spin-crossover; spin-singlet formation; Temperature dependence; Temperature effects; Transition temperature; π-radical; π-stacking interaction
• ISSN: 2304-6740; 2304-6740
• DOI: 10.3390/inorganics5030054

To develop a new spin-crossover functional material, a magnetic hybrid compound [Fe(qsal)2][Ni(mnt)2] was designed and synthesized (Hqsal = N-(8-quinolyl)salicylaldimine, mnt = maleonitriledithiolate). The temperature dependence of magnetic susceptibility suggested the coexistence of the high-spin (HS) Fe(III) cation and π-radical anion at room temperature and a magnetic transition below 100 K. The thermal variation of crystal structures revealed that strong π-stacking interaction between the π-ligand in the [Fe(qsal)2] cation and [Ni(mnt)2] anion induced the distortion of an Fe(III) coordination structure and the suppression of a dimerization of the [Ni(mnt)2] anion. Transfer integral calculations indicated that the magnetic transition below 100 K originated from a spin-singlet formation transformation in the [Ni(mnt)2] dimer. The magnetic relaxation of Mössbauer spectra and large thermal variation of a g-value in electron paramagnetic resonance spectra below the magnetic transition temperature implied the existence of a magnetic correlation between d-spin and π-spin.