A Ferroelectric Iron(II) Spin Crossover Material. Issue 45 (4th October 2017)

• Record Type: Journal Article
• Authors: Jornet‐Mollá, Verónica; Duan, Yan; Giménez‐Saiz, Carlos; Tang, Yuan‐Yuan; Li, Peng‐Fei; Romero, Francisco M.; Xiong, Ren‐Gen
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 45(2017)
• Page Start: 14052
• Page End: 14056
• Publication Date: 2017-10-04
• Subjects: ferroelectrics -- hydrogen bonds -- iron(II) complexes -- solvent exchange -- spin crossover; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201707401
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A dual‐function material in which ferroelectricity and spin crossover coexist in the same temperature range has been obtained. Our synthetic strategy allows the construction of acentric crystal structures in a predictable way and is based on the high directionality of hydrogen bonds. The well‐known iron(II) spin crossover complex [Fe(bpp)2 ] 2+ (bpp=2, 6‐bis(pyrazol‐3‐yl)pyridine), a four‐fold noncentrosymmetric H‐bond donor, was combined with a disymmetric H‐bond acceptor such as the isonicotinate (isonic) anion to afford [Fe(bpp)2 ](isonic)2 ⋅2 H2 O. This low‐spin iron(II) compound crystallizes in the acentric nonpolar I 4 ‾ space group and shows piezoelectricity and SHG properties. Upon dehydration, it undergoes a single‐crystal to single‐crystal structural rearrangement to a monoclinic polar Pc phase that is ferroelectric and exhibits spin crossover. Abstract : A two‐in‐one crystal : A designed strategy is reported for the assembly of iron(II) spin crossover complexes into noncentrosymmetric crystal structures based on hydrogen bonding. A piezoelectric low‐spin compound was obtained that undergoes a reversible single‐crystal to single‐crystal dehydration to yield a dual‐function material exhibiting ferroelectricity and spin crossover.