Valence tautomerism: More actors than just electroactive ligands and metal ions

Evangelio, Emi; Ruiz‐Molina, Daniel

doi:10.1016/j.crci.2008.09.007

Cited by 138 publications

(68 citation statements)

References 130 publications

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“…The increase of the N=C bond lengths (N4ÀC9/N1ÀC4) to 1.346(4) /1.342(4) in [5(CuCl 2 ) 2 ] can be rationalized by the p-contribution of the ligand-tometal bonding interaction [25] and is also in line with other transition-metal complexes with neutral, bridging GFA ligands. [18] Based on these N=C bond distances, twofold oxidation of the ligand unit in [5 Table 1). The measured dihedral angle a(CuCl 2 ,CuN 2 ) involving the copper atoms directly bound to 5 is 518.…”

Section: Resultsmentioning

confidence: 99%

“…The bright-green precipitate was separated by filtration, washed with Et 2 O, and dried in vacuo to give 56. 5 Let's switch! By varying the temperature, it is possible to switch between a red diamagnetic copper(I) complex and a green paramagnetic copper(II) complex based on the phenomenon of valence tautomerism.…”

Section: Synthesis Of [5(cucl 2 ) 2 ]mentioning

confidence: 98%

“…In case of GFA ligand 4, the complex [4(Cu II (OAc) 2 ) 2 ] was shown to be paramagnetic (a dinuclear Cu II complex with neutral 4), whereas [4(Cu I Br 2 ) 2 ] is diamagnetic and may be best described as a dinuclear Cu I complex with dicationic 4 2 + (see Figure 1). [22] Similarly, the reaction between GFA 5 and two equivalents of CuBr 2 yielded the diamagnetic dinuclear complex [5 . [23] From previous studies on copper-o-dioxolene complexes, it is known that small modifications can have a large impact on both the electronic structure and activation energy for the interconversion between both valence tautomers.…”

Section: Introductionmentioning

confidence: 99%

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A Valence Tautomeric Dinuclear Copper Tetrakisguanidine Complex

Wiesner

Wagner

Kaifer

et al. 2016

Chemistry A European J

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We report on the first valence tautomeric dinuclear copper complex, featuring 2,3,5,6-tetrakis(tetramethylguanidino)pyridine as a bridging redox-active GFA (guanidino-functionalized aromatic) ligand. The preferred electronic structure of the complex is massively influenced by the environment. In the solid state and in nonpolar solvents a paramagnetic, dinuclear Cu(II) complex with a neutral GFA ligand is present. In polar solvents, the electronic structure changes to a diamagnetic, dinuclear Cu(I) complex with a twofold-oxidized GFA ligand. Using acetone as a solvent, both electronic structures are accessible due to a temperature-dependent equilibrium between the two valence tautomeric complexes. Our results pave the way for a broader use of valence tautomeric transition-metal complexes in catalytic reactions since anionic coligands can now be tolerated owing to the neutral/positively charged GFA ligand.

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Section: Resultsmentioning

confidence: 99%

Section: Synthesis Of [5(cucl 2 ) 2 ]mentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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A Valence Tautomeric Dinuclear Copper Tetrakisguanidine Complex

Wiesner

Wagner

Kaifer

et al. 2016

Chemistry A European J

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“…[16] Even more interesting was the fact that this complex also exhibits a reversible thermally induced IET between the metal ion and the ligand, a process named with the generic term of valence tautomerism (VT). [17] Therefore, this family of complexes contains unique systems that exhibit more than one type of thermally induced, intramolecular, electron-transfer process-ligand-to-metal (IET LM ) [18] and ligand-to-ligand (IET LL ). [19] A schematic representation of the different thermally induced IET processes that take place in a metal-based complex bearing catechol-based noninnocent ligands is shown in Figure 1.…”

Section: Ma C H T U N G T R E N N U N G (Cat-n-bq)a C H T U N G T R Ementioning

confidence: 99%

Coexistence of Two Thermally Induced Intramolecular Electron Transfer Processes in a Series of Metal Complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)₂] (M=Co, Fe, and Ni) bearing Non‐Innocent Catechol‐Based Ligands: A Combined Experimental and Theoretical Study

Evangelio

Bonnet

Cabañas³

et al. 2010

Chemistry A European J

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The different thermally induced intermolecular electron transfer (IET) processes that can take place in the series of complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)2], for which M=Co (2), Fe (3) and Ni(4), and Cat‐N‐BQ and Cat‐N‐SQ denote the mononegative (Cat‐N‐BQ−) or dinegative (Cat‐N‐SQ2−) radical forms of the tridentate Schiff‐base ligand 3,5‐di‐tert‐butyl‐1,2‐quinone‐1‐(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)imine, have been studied by variable‐temperature UV/Vis and NMR spectroscopies. Depending on the metal ion, rather different behaviors are observed. Complex 2 has been found to be one of the few examples so far reported to exhibit the coexistence of two thermally induced electron transfer processes, ligand‐to‐metal (IETLM) and ligand‐to‐ligand (IETLL). IETLL was only found to take place in complex 3, and no IET was observed for complex 4. Such experimental studies have been combined with ab initio wavefunction‐based CASSCF/CASPT2 calculations. Such a strategy allows one to solicit selectively the speculated orbitals and to access the ground states and excited‐spin states, as well as charge‐transfer states giving additional information on the different IET processes.

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“…59 Este processo pode ser observado em complexos de metais de transição contendo radicais do tipo fenoxil ou semiquinona. 60 A transição pode ocorrer com a variação da temperatura 61 e diversos fatores podem influenciar a faixa de temperatura na qual ocorre a transferência de elétrons. De fato, como o fenômeno é acompanhado por mudanças estruturais nas vizinhanças do íon metálico um aumento da pressão, 62 por exemplo, aumenta a rigidez do sistema e como consequência a energia necessária para que a transição ocorra se torna maior.…”

Section: Compostos Com Multiestabilidade Magnéticaunclassified

Compostos magnéticos moleculares: o desenvolvimento de novos materiais magnéticos nanoestruturados

Guedes¹,

Allão²,

Mercante³

et al. 2010

Quím. Nova

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Recebido em 7/11/09; aceito em 21/4/10; publicado na web em 9/8/10 MOLECULAR MAGNETIC COMPOUNDS -THE DEVELOPMENT OF NEW NANOSTRUTURED MAGNETIC MATERIALS. The development of new magnetic materials has attracted attention of researchers of different areas. In the last decades, a distinguished class of materials emerged in magnetism, in which the magnetic moment is delocalized over molecules. By varying the synthetic conditions it is possible to obtain a large variety of structures and properties using the same starting molecules. These materials have a great scientific appeal due to the possibility of presenting not only magnetic, but also optical or electrical transport properties. In this review we will present an overview of some molecular magnetic compounds, in particular molecular nanomagnets.Keywords: molecular magnetic compounds; deposition on surfaces; magnetic materials. INTRODUÇÃOO magnetismo molecular é uma área de pesquisa interdisciplinar relativamente nova que pode ser considerada uma evolução da magnetoquímica.1 As possibilidades de atuação neste tema são amplas e pesquisadores de diversas especialidades estão trabalhando cada vez mais em conjunto. Esta interação envolve sínteses orgânica e inorgânica e o uso de técnicas de caracaterização magnética, difração de raios-x, eletroquímica e espectroscopias diversas, entre outras técnicas. Um dos objetivos é compreender a origem das propriedades magnéticas, sendo uma área que apresenta grandes desafios também para pesquisadores que fazem cálculos, envolvendo desde a simulação de dados experimentais até cálculos mais elaborados de modelagem molecular e energia dos sistemas possibilitando fazer correlações magneto-estruturais. 2Esta interdisciplinaridade tem possibilitado a descoberta e o entendimento de novos fenômenos como o tunelamento quântico da magnetização, coerência e emaranhamento quântico, que são fundamentais para aplicações na área de computação quântica. Além disso, outro grande atrativo é que estes materiais moleculares podem apresentar sinergia entre propriedades magnéticas, condutoras e ópticas, o que é interessante para aplicações tecnológicas. 4 Neste artigo de revisão são apresentadas algumas das diversas estratégias utilizadas na síntese de compostos magnéticos moleculares. Também será abordado o progresso na obtenção e deposição em superfícies de um dos sistemas mais interessantes da área, os chamados magnetos de uma molécula ou nanomagnetos moleculares. Esta é uma etapa de extrema importância que visa a formação de sistemas magnéticos nanoestruturados para aplicação em dispositivos. COMPOSTOS MAGNÉTICOS MOLECULARES PURAMENTE ORGÂNICOSMoléculas orgânicas paramagnéticas são conhecidas por apresentarem alta reatividade, além de não serem estáveis termicamente. No entanto, certas classes de radicais orgânicos apresentam estabilidade à temperatura ambiente e relativa facilidade sintética, o que vêm fascinando químicos e físicos pela variedade de propriedades magnéticas, ópticas e condutoras que podem exibir. 5O estudo das propriedades magn...

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Valence tautomerism: More actors than just electroactive ligands and metal ions

Cited by 138 publications

References 130 publications

A Valence Tautomeric Dinuclear Copper Tetrakisguanidine Complex

A Valence Tautomeric Dinuclear Copper Tetrakisguanidine Complex

Coexistence of Two Thermally Induced Intramolecular Electron Transfer Processes in a Series of Metal Complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)₂] (M=Co, Fe, and Ni) bearing Non‐Innocent Catechol‐Based Ligands: A Combined Experimental and Theoretical Study

Compostos magnéticos moleculares: o desenvolvimento de novos materiais magnéticos nanoestruturados

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Valence tautomerism: More actors than just electroactive ligands and metal ions

Cited by 138 publications

References 130 publications

A Valence Tautomeric Dinuclear Copper Tetrakisguanidine Complex

A Valence Tautomeric Dinuclear Copper Tetrakisguanidine Complex

Coexistence of Two Thermally Induced Intramolecular Electron Transfer Processes in a Series of Metal Complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)2] (M=Co, Fe, and Ni) bearing Non‐Innocent Catechol‐Based Ligands: A Combined Experimental and Theoretical Study

Compostos magnéticos moleculares: o desenvolvimento de novos materiais magnéticos nanoestruturados

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Coexistence of Two Thermally Induced Intramolecular Electron Transfer Processes in a Series of Metal Complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)₂] (M=Co, Fe, and Ni) bearing Non‐Innocent Catechol‐Based Ligands: A Combined Experimental and Theoretical Study