Crystallographic Evidence for Reversible Symmetry Breaking in a Spin‐Crossover d⁷ Cobalt(II) Coordination Polymer

Abstract

All in a spin: A cobalt(II) coordination polymer has a highly cooperative spin‐crossover (SCO) behavior with a small hysteresis loop (see picture; HS=high spin, LS=low spin). The correlation of the magnetic properties with the crystal structures was determined at different temperatures. This study reveals an unprecedented reversible symmetry breaking in a d7 SCO coordination polymer.

Microscopic Origin for Multistability in a Photomagnetic CoFe Prussian Blue Analogue

“…[2][3][4] Most studies describe their switching properties in terms of a two-state model involving a ground (low-temperature) state and an excited metastable state, which can be either thermally populated or light-induced. While some studies point out symmetry breaking in spin transition sys- [ tems, [9][10][11][12] some other structural distortions remain unexplained in switchable coordination networks. [1,7,8] However, the existence of multistability in closed switchable systems made of crystallographically equivalent switching sites remains a controversial topic.…”

Synthesis and physico-chemical studies of a novel organo-metallic compound CdCl2(C6H4FNH2)2

“…Among ligands commonly used in coordination chemistry, Schiff bases are an extremely important class, thanks to their facile synthesis, and their easily tunable steric and electronic properties [14,15]. They are known to be a class of versatile ligands, capable of generating a variety of molecular architectures and coordination polyhedral [16][17][18].…”

Co–NC–W and Fe–NC–W Electron‐Transfer Channels for Thermal Bistability in Trimetallic {Fe6Co3[W(CN)8]6} Cyanido‐Bridged Cluster

“…The {M II 9 M' V 6 (CN) 48 (L) 24 }·n solv compound family (M = Mn, Co, Ni; M' = Mo, W; L = blocking ligands; Figure 1) reveal highspin ground states [22][23][24][25][26] and SMM (M' = Ni; L = tmphen, 3,4,7,8-tetramethyl-1,10-phenanthroline) [24] or SMM-like (M = Co, L = MeOH, 2) [25,26] behavior. Herein, we present for the first time a coexistence and cooperativity between two different active electron-transfer channels in one coordination skeleton, owing to the specific distribution of Co II and Fe II centers at M sites of {Co II 3 Fe II 6 [W V (CN) 8 ] 6 (MeOH) 24 cluster.…”

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The design and construction of switchable materials attracts tremendous interest owing to the potential in information storing and processing or molecular sensing. [1][2][3][4] The archetypal examples involve a diversity of Fe II -, [5,6] Fe III - [7] or Co IIbased [8][9][10] spin-crossover (SCO) compounds, Co III/II -catecholate/semiquinone systems, [1,11] as well as d-d bimetallic and sd-d trimetallic cyanide-bridged systems revealing chargetransfer-induced spin transitions (CTIST). [12][13][14][15][16][17][18] Some of these compounds, for example Prussian blue analogues, are particularly promising from the point of view of photoswitching between nonmagnetic and magnetized (that is, T B , T C ) states, owing to magnetic coupling through molecular bridges in discrete species [14,15] and extended networks.

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“…As a continuing effort to obtain innovative bistable systems, we explored the simultaneous embedding of Co II and Fe II cations into one octacyanido-bridged coordination skeleton. We have engineered and isolated the novel trimetallic {Co II 3 Fe II 6 [W V (CN) 8 ] 6 (MeOH) 24 }·x MeOH (1) material built of nanosized (ca. 20 ) pentadecanuclear six-capped body-centered cubic Co 3 Fe 6 W 6 clusters with MeOH molecules of crystallization (see the Supporting Information).…”