Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese-Radical Coordination Framework

Anthony Lannes (1) , Yan Suffren (2) , Jean Bernard Tommasino (1) , Rodica Chiriac (1) , François Toche (1) , Lhoussain Khrouz (3) , Florian Molton (4) , Carole Duboc (4) , Isabelle Kieffer (5, 6) , Jean-Louis Hazemann (7) , Christian Reber (8) , Andreas Hauser (9) , Dominique Luneau (1)

1 LMI - Laboratoire des Multimatériaux et Interfaces
2 ISCR - Institut des Sciences Chimiques de Rennes
3 LC - Laboratoire de Chimie - UMR5182
4 DCM - Département de Chimie Moléculaire
5 OSUG - Observatoire des Sciences de l'Univers de Grenoble
6 ESRF - European Synchrotron Radiation Facility
7 NEEL - MRS - Matériaux, Rayonnements, Structure
8 Département de chimie [UdeM-Montréal]
9 Department of Physical Chemistry, University of Geneva

The manganese-nitronyl-nitroxide two-dimensional coordination polymer {[Mn2(NITIm)3]ClO4}n (1) (NITImH = 2-(2-imidazolyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-3-oxide-1-oxyl) undergoes an unusual hysteretic thermo-induced valence tautomeric transition near room temperature, during which the manganese(II) ions are oxidized to manganese(III) and two of the three deprotonated radicals (NITIm-) are reduced to their diamagnetic aminoxyl form (denoted NITRed2-). Upon cooling, the high-temperature species {[MnII2(NITIm)3]ClO4}n (1HT) turns into the low-temperature species {[MnIII2(NITRed)2(NITIm)]ClO4}n (1LT) around 274 K, while on heating the process is reversed at about 287 K. This valence tautomeric phenomenon is supported by temperature-dependent magnetic susceptibility measurements, differential scanning calorimetry (DSC), crystal structure determination, UV-vis absorption, X-ray absorption (XAS), and emission (XES) and electron paramagnetic resonance (EPR) spectroscopies in the solid state.

Domaines: Chimie inorganique

Anthony Lannes, Yan Suffren, Jean Bernard Tommasino, Rodica Chiriac, François Toche, et al.. Room Temperature Magnetic Switchability Assisted by Hysteretic Valence Tautomerism in a Layered Two-Dimensional Manganese-Radical Coordination Framework. Journal of the American Chemical Society, 2016, 138 (50), pp.16493-16501. ⟨10.1021/jacs.6b10544⟩. ⟨hal-01419234⟩