An Unprecedented Homochiral Mixed‐Valence Spin‐Crossover Compound

Abstract

The phenomenon of spin-crossover between the low-spin (LS) and high-spin (HS) states, [1] which is observed in some octahedral 3d n (4 n 7) metal complexes and is induced by an external perturbation, such as temperature, pressure, or light irradiation, is one of the most spectacular examples of molecular bistability. [2, 3] Such phenomena can be utilized in new electronic devices, such as molecular memories and switches that are controlled by many different physical channels. [4,5] It is now established that cooperative spincrossover, the interaction between spin-crossover sites, is the predominant factor governing bistability. [6,7] We now report the first homochiral mixed-valence spin-crossover compound, in which three independent properties are united, namely, mixed valence states of iron metal centers, spin-crossover of the Fe II

A Variety of Spin‐Crossover Behaviors Depending on the Counter Anion: Two‐Dimensional Complexes Constructed by NH⋅⋅⋅Cl− Hydrogen Bonds, [FeIIH3LMe]Cl⋅X (X = PF6−, AsF6−, SbF6−, CF3SO3−; H3LMe = Tris[2‐{[(2‐methylimidazol‐4‐yl)methylidene]amino}ethyl]amine)

“…It is also known that the presence of solvent molecules in the crystal lattice and the nature of the counter anion significantly affect the SC behavior, although such species do not directly interact with the SC site. [6] This highlights the need for a more systematic investigation of such subfactors, as well as for a rational explanation of the complicated results.…”

“…[7] Of these, iron complexes with tripod ligands containing three imidazole groups, H 3 L R (R = H, Me, Ph), H 3 L R = tris[2-{[(2-R-imidazoyl-4-yl)methylidene]amino}-ethyl]amine, have been found to constitute a new family of SC complexes. [6] , are connected through an imidazole-imidazolate hydrogen bond to produce a two-dimensional (2D) extended network structure, have been found to exhibit steep and multistep SC behavior. [6] We have also identified another new type of 2D SC complex with the chemical formula [ …”

“…[6] , are connected through an imidazole-imidazolate hydrogen bond to produce a two-dimensional (2D) extended network structure, have been found to exhibit steep and multistep SC behavior. [6] We have also identified another new type of 2D SC complex with the chemical formula [ …”

Concerted Spin Crossover and Symmetry Breaking Yield Three Thermally and One Light‐Induced Crystallographic Phases of a Molecular Material

“…[6] Over the last ten years, we have investigated supramolecular Fe II SC materials including imidazolyl groups. [5,8,9,11] 2 , 1 has been synthesized. Here we report on its two rare types of behavior: long-range LS-HS-HS-LS ordering in the INT phase, and structural symmetry breaking in the LS phase.…”

Structure and Heme-Independent Peroxidase Activity of a Fully-Coordinated Mononuclear Mn(II) Complex with a Schiff-Base Tripodal Ligand Containing Three Imidazole Groups

“…Structures and characteristics of several M(imtren) complexes, where M = Co(III), Fe(II), Fe(III), Mg(II), and Ru(II), have been reported. [13][14][15][16][17][18][19][20] In those, the imtren ligand hexadentately coordinates to the metal ions, forming highly symmetric octahedral geometries. For Mn(II) ion, using the methylated imtren ligand at the 4-position of the imidazole ring, Mn(II) complexes have been synthesized and structurally characterized but Mn(II)(imtren) has not been structurally characterized and its reactivity has not reported.…”