New Route to the Mixed Valence Semiquinone-Catecholate Based Mononuclear FeIIIand Catecholate Based Dinuclear MnIIIComplexes:  First Experimental Evidence of Valence Tautomerism in an Iron Complex

2004 ◽  
Vol 43 (19) ◽  
pp. 5908-5918 ◽  
Author(s):  
Nizamuddin Shaikh ◽  
Sanchita Goswami ◽  
Anangamohan Panja ◽  
Xin-Yi Wang ◽  
Song Gao ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Mixed Valence ◽  
Iron Complex ◽  
Valence Tautomerism

Intervalence transfer in a new benzotriazolate bridged ruthenium-iron complex

2001 ◽  
Vol 79 (2) ◽  
pp. 145-156
Author(s):  
Reginaldo C Rocha ◽  
Henrique E Toma
Keyword(s):  
Near Infrared ◽  
Mixed Valence ◽  
Differential Pulse ◽  
Iron Complex ◽  
Electronic Coupling ◽  
Near Ir ◽  
Metal Metal ◽  
Dinuclear Ruthenium ◽  
Pulse Voltammetry ◽  
Transfer Properties

The unsymmetrical dinuclear ruthenium–iron complexes [(NH3)5Ru–bta–Fe(CN)5]n (where bta = benzotriazolate; n = –2, –1, 0) were prepared as solid sodium salts from [RuII(NH3)5(bta)]+ or [RuIII(NH3)5(bta)]2+ and [FeII(CN)5(H2O)]3– and characterized in aqueous solution by means of electrochemical and spectroelectrochemical methods. UV-vis, near-infrared, IR, and cyclic and differential pulse voltammetry data suggest that the related mixed valent species belong to a valence trapped formulation, featuring localized Ru(III) and Fe(II) oxidation states. In spite of the class II categorization in the Robin and Day scheme, this system shows a remarkable metal–metal electronic coupling, as deduced from an intense, low-energy, and very broad intervalence band in the near-IR region. In addition, the mixed valence state displays enhanced stabilization in relation to the isovalent state. The intervalence transfer properties are discussed on the basis of Hush's theory.Key words: ammineruthenium complexes, cyanoiron complexes, mixed valence, intervalence, benzotriazole, benzotriazolate.

Charge transfer phase transition and ferromagnetism in a mixed-valence iron complex, (n-C3H7)4N[FeIIFeIII(dto)3] (dto=C2O2S2)

2001 ◽  
Vol 120 (4) ◽  
pp. 165-170 ◽  
Author(s):  
N. Kojima ◽  
W. Aoki ◽  
M. Itoi ◽  
Y. Ono ◽  
M. Seto ◽  
...  
Keyword(s):  
Phase Transition ◽  
Charge Transfer ◽  
Mixed Valence ◽  
Iron Complex ◽  
Transfer Phase

Divalent metal ions modulated strong frustrated M(ii)–Fe(iii)3O (M = Fe, Mn, Mg) chains with metamagnetism only in a mixed valence iron complex

2015 ◽  
Vol 51 (83) ◽  
pp. 15336-15339 ◽  
Author(s):  
Qi-Long Wu ◽  
Song-De Han ◽  
Qing-Lun Wang ◽  
Jiong-Peng Zhao ◽  
Feng Ma ◽  
...  
Keyword(s):  
Metal Ions ◽  
Mixed Valence ◽  
Magnetic Behaviour ◽  
Iron Complex ◽  
Divalent Metal ◽  
Heterometallic Complexes ◽  
Divalent Metal Ions ◽  
Divalent Ions ◽  
Mixed Valence Complex

Using divalent ions to link the frustrated Fe(iii)3O units two isostructural chains were generated with distinct magnetic behaviour: frustrations and metamagnetism in mixed valence complex, but magnetic frustrations in heterometallic complexes.

scholarly journals Photoswitchable stable charge-distributed states in a new cobalt complex exhibiting photo-induced valence tautomerism

2015 ◽  
Vol 185 ◽  
pp. 347-359 ◽  
Author(s):  
Michael Slota ◽  
Marian Blankenhorn ◽  
Eric Heintze ◽  
Minh Vu ◽  
Ralph Hübner ◽  
...  
Keyword(s):  
Charge Distribution ◽  
Cobalt Complex ◽  
Mixed Valence ◽  
Magnetic Behavior ◽  
Inert Atmosphere ◽  
Molecular Structures ◽  
Paramagnetic Resonance ◽  
Valence Tautomerism ◽  
X Band ◽  
Huge Impact

We report the synthesis and magnetic and photomagnetic behaviour of a novel valence tautomeric cobalt complex, [Co(3,5-dbbq)2(μ-bpym)] (1) (3,5-dbbq = 3,5-di-tert-butyl-1,2-benzoquinone and μ-bpym = 2,2′-bipyrimidine). The synthesis is performed by reacting Co2(CO)8 and μ-bpym in the presence of the ligand 3,5-dbbq in a mixed solvent under inert atmosphere. The magnetic behavior clearly shows the presence of electron transfer from the catecholate ligand to the cobalt center, producing valence tautomers of [CoII(SQ)2] with a transition temperature (T1/2) of 215 K. Photomagnetic studies, performed via both SQUID magnetometry and X-band electron paramagnetic resonance, show the clear presence of photoinduced valence tautomerism, at temperatures considerably higher than previous systems. A metastable charge distribution is observed, strengthening previous investigations on the character of mixed valence ligands. Entropy-driven valence tautomeric interconversion is observed, and drives the transition to the most stable charge distribution. The complex has the ability to coordinate and can be used as a photoswitchable building block, with the photomagnetic characterisation evidencing a metastable state lifetime of the photo-induced valence tautomeric process of ca. 2.9 × 104 s below 20 K. The observed yields are higher than ones in similar systems, showing that tiny changes in the molecular structures may have a huge impact.

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