Search results for "crossover"

High-temperature spin crossover in a mononuclear six-coordinate cobalt(II) complex.

2014

The six-coordinate cobalt(II) complex of formula [Co(tppz)2](tcm)2 exhibits a thermally induced spin-crossover behavior from a high spin (S = 3/2) at higher temperatures to a low spin (S = 1/2) at lower temperatures, with the low-spin phase being achieved at T ≤ 200 K.

Synthesis, crystal structure, EXAFS, and magnetic properties of catena [mu-tris(1,2-bis(tetrazol-1-yl)propane-N1,N1')iron(II)] bis(perchlorate). Firs…

2000

[Fe(btzp)3](ClO4)2 (btzp = 1,2-bis(tetrazol-1-yl)propane) represents the first structurally characterized Fe(II) linear chain compound exhibiting thermal spin crossover. It shows a very gradual spin transition (T1/2 = 130 K) which has been followed by magnetic susceptibility measurements and 57Fe Mössbauer spectroscopy. The structure has been solved at 200 and 100 K by single-crystal X-ray analysis. It crystallizes in the trigonal space group P3c1 with Z = 2 Fe(II) units at both temperatures. The molecular structure consists of chains running along the c axis in which the Fe(II) ions are linked by three N4,N4' coordinating bis(tetrazole) ligands. The main difference between the two forms ap…

One-dimensional and two-dimensional anilate-based magnets with inserted spin-crossover complexes.

2014

The syntheses, structures, and magnetic properties of a family of bimetallic anilate-based compounds with inserted spin-crossover cationic complexes are reported. The structures of 1-4 present a two-dimensional anionic network formed by Mn(II) and Cr(III) ions linked through anilate ligands with inserted [Fe(III)(sal2-trien)](+) (1), [Fe(III)(4-OH-sal2-trien)](+) (2), [Fe(III)(sal2-epe)](+) (3), or [Fe(III)(5-Cl-sal2-trien)](+) (4) complexes. The structure of 5 is formed by anionic [Mn(II)Cl2Cr(III)(Cl2An)3](3-) chains surrounded by [Fe(II)(tren(imid)3)](2+), Cl(-), and solvent molecules. The magnetic properties indicate that 1-4 undergo a long-range ferrimagnetic ordering at ca. 10 K. On t…

Structural Transformations and Magnetic Effects Induced by Solvent Exchange in the Spin Crossover Complex [Fe(bpp) 2 ][Cr(bpy)(ox) 2 ] 2

2005

Structural, thermal, magnetic and solvent-exchange properties of the spin crossover compound [Fe(bpp)2][Cr(bpy)(ox)2]2 containing paramagnetic anions are given. This complex salt 1 crystallises as a dihydrate with two inequivalent (high-spin and low-spin) FeII sites. The dehydrated compound is a spin-crossover material with T1/2 ↑ = 369 K and T1/2 ↓ = 353 K. Rehydration takes place without loss of crystallinity, yielding a polymorph (2) with 100 % high-spin Fe II sites. The different high-spin fractions in 1 and 2 have been correlated to structural changes in the FeII second coordination sphere. The magnetic response to the presence of different sorbed molecules has also been explored. © Wi…

Structural, Thermal, and Magnetic Study of Solvation Processes in Spin-Crossover [Fe(bpp)2][Cr(L)(ox)2]2·nH2O Complexes

2007

The influence of lattice water in the magnetic properties of spin-crossover [Fe(bpp)2]X2.nH2O salts [bpp = 2,6-bis(pyrazol-3-yl)pyridine] is well-documented. In most cases, it stabilizes the low-spin state compared to the anhydrous compound. In other cases, it is rather the contrary. Unraveling this mystery implies the study of the microscopic changes that accompany the loss of water. This might be difficult from an experimental point of view. Our strategy is to focus on some salts that undergo a nonreversible dehydration-hydration process without loss of crystallinity. By comparison of the structural and magnetic properties of original and rehydrated samples, several rules concerning the r…

Thermal, pressure and light switchable spin-crossover materials

2005

This article reviews the most relevant chemical and structural aspects that influence the spin-crossover phenomenon (SCO). Special attention is focussed on the recent development of SCO coordination polymers. The different approaches currently being explored in order to achieve multifunctionality in SCO materials are discussed.

Spin Crossover – Quo Vadis?

2013

This retrospective essay is an attempt to span the bridge over eight decades of research on spin crossover (SCO), one of the most fascinating dynamic electron structure phenomena of inorganic coordination chemistry. The occurrence of SCO compounds of 3d transition metal ions and their characterization regarding magnetic, optical, vibrational, structural, and thermodynamic properties are briefly addressed. Selected case studies of chemical influences and physical effects (pressure, magnetic field, light) on SCO behavior are discussed. Particular attention is paid to the importance of Mossbauer spectroscopy in SCO studies. Light-induced excited spin state trapping (LIESST) and related photoph…

A Family of Dinuclear Iron(II) SCO Compounds Based on a 1,3,4‐Thiadiazole Bridging Ligand (Eur. J. Inorg. Chem. 22/2015)

2015

Hybrid magnetic superconductors formed by TaS2 layers and spin crossover complexes.

2013

The restacking of charged TaS2 nanosheets with molecular counterparts has so far allowed for the combination of superconductivity with a manifold of other molecule-intrinsic properties. Yet, a hybrid compound that blends superconductivity with spin crossover switching has still not been reported. Here we continue to exploit the solid-state/molecule-based hybrid approach for the synthesis of a layered TaS2-based material that hosts Fe(2+) complexes with a spin switching behavior. The chemical design and synthetic aspects of the exfoliation/restacking approach are discussed, highlighting how the material can be conveniently obtained in the form of highly oriented easy-to-handle flakes. Finall…

Spin‐Crossover Complexes

2013

EurJIC is proud to present a bumper issue on Spin-Crossover Complexes. Our Guest Editors, Keith Murray, Hiroki Oshio and Jose Antonio Real, have worked hard to put together a fantastic issue. With a valuable personal account of the field by Philipp Gutlich and inspiring papers by leading experts, you will not be disappointed.