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Complexes of “late” transition metals of the 3d row based on functionalized o-iminobenzoquinone type ligands: Interrelation of molecular and electronic structure, magnetic behaviour. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214399] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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2
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A diamagnetic iron complex and its twisted sister - structural evidence on partial spin state change in a crystalline iron complex. Dalton Trans 2021; 50:15831-15840. [PMID: 34708847 DOI: 10.1039/d1dt01607e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report here the syntheses of a diamagnetic Fe complex [Fe(HL)2] (1), prepared by reacting a redox non-innocent ligand precursor N,N'-bis(3,5-di-tert-butyl-2-hydroxy-phenyl)-1,2-phenylenediamine (H4L) with FeCl3, and its phenoxazine derivative [Fe(L')2] (2), which was obtained via intra-ligand cyclisation of the parent complex. Magnetic measurements, accompanied by spectroscopic, structural and computational analyses show that 1 can be viewed as a rather unusual Fe(III) complex with a diamagnetic ground state in the studied temperature range due to a strong antiferromagnetic coupling between the low-spin Fe(III) ion and a radical ligand. For a paramagnetic high-spin Fe(II) complex 2 it was found that, when crystalline, it undergoes a thermally induced process where 25% of the molecules in the material change to a diamagnetic low-spin ground state below 100 K. Single crystal X-ray studies conducted at 95 K afforded detailed structural evidence for this partial change of spin state of 2 showing the existence of crystallographically distinct molecules in a 3 : 1 ratio which exist in high- and low-spin states, respectively. Also, the magnetic behaviour of 2 was found to be related with the crystallinity of the material as demonstrated by near-IR radiation to unpaired electrons conversion ability of amorphous sample of 2.
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Temperature and Time-resolved XANES Studies of Novel Valence Tautomeric Cobalt Complex. CHEM LETT 2021. [DOI: 10.1246/cl.210426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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4
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Solid State Characterization of One‐ and Two‐Electron Oxidized Cu
II
‐salen Complexes with
para
‐Substituents: Geometric Structure‐Magnetic Property Relationship. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Electrochemical and Spectroscopic Studies on Triarylamine‐Polychlorotriphenylmethyl Dyads with Particularly Strong Triarylamine Donors. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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6
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Complexes of the Bis(di‐
tert
‐butyl‐aniline)amine Pincer Ligand: The Case of Copper. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000379] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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7
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Valence tautomerism and delocalization in transition metal complexes of o-amidophenolates and other redox-active ligands. Some recent results. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213240] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Structural and spectroscopic investigations of nine-coordinate redox active lanthanide complexes with a pincer O,N,O ligand. Dalton Trans 2020; 49:8238-8246. [PMID: 32510087 DOI: 10.1039/d0dt01388a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The lanthanide complexes EuL3, GdL3, YbL3 and LuL3 of the N,N'-bis(2-hydroxy-di-3,5-tert-butylphenyl)amine were prepared. The X-Ray crystal structures of GdL3 and LuL3 demonstrated a nine-coordinate sphere with three ligand molecules under their anionic diamagnetic form (Cat-N-BQ)-. The complexes showed three oxidation events (Eox11/2 = 0.15-0.16 V, E1/22 = 0.51-55 V, and E1/23 = 0.75-0.78 V vs. Fc+/Fc) via cyclic voltammetry, corresponding to the successive oxidation of the aminophenolate moeities to iminosemiquinone species. The complexes GdL3 and YbL3 were characterized by EPR spectroscopy, allowing for the determination of the zero field splitting (ZFS) parameters in the first case. The monocations (LnL3)+ and monoanions (LnL3)- were electrochemically generated (Ln = Eu, Gd, Yb, Lu), as well as the dications YbL32+ and LuL32+. The spins are antiferromagnetically exchange coupled in the diradical species LuL32+ (|D| = 260 MHz, E = 0). All the complexes (incl. neutral) possess a strong absorption band in the NIR region (730-840 nm, ε > 19 mM-1 cm-1) corresponding to ligand-based transitions.
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Mononuclear Cu(II) and Ni(II) complexes of bis(naphthalen-2-ol) Schiff base ligands. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2018.09.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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10
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Hydrazone-based cobalt complexes toward multielectron redox and spin crossover. RSC Adv 2018; 8:17159-17167. [PMID: 35539225 PMCID: PMC9081832 DOI: 10.1039/c8ra02963f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 04/19/2018] [Indexed: 01/14/2023] Open
Abstract
Hydrazone-based derivatives modified by substitution at different positions were utilized to prepare a series of bis-homoleptic cobalt complexes. One species, [CoIII(L1)2]+ (1), which incorporated deprotonated ligands, adopted a Co(iii) diamagnetic ground state. However, the substituent of a hydrogen atom with a methyl group precluded the possibility of deprotonation upon metal coordination, which led to two species, [CoII(L2Me)2]2+ (2) and [CoII(L3NO2)2]2+, (3) which underwent a gradual spin crossover with an adjustable substituent effect and a mixed character of low-spin (doublet) and high-spin (quartet) populations in wide temperature ranges. Depending on the electronic effects of the substituents on the ligand, the multielectron redox behavior of the cobalt center was systematically modulated as well. This result demonstrates redox-switchable spin crossover in a new hydrazone-based Co(ii) system, in which the deprotonation of the coordination pocket and substituent groups in aromatic ligands can have a profound effect on the redox potential and spin state of the metal center. Hydrazone-based derivatives modified by substitution at different positions were utilized to prepare a series of bis-homoleptic cobalt complexes toward multielectron redox and spin crossover.![]()
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Bifunctional iminopyridino-catechol and its o-quinone: Synthesis and investigation of coordination abilities. Polyhedron 2017. [DOI: 10.1016/j.poly.2016.12.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Switching and redox isomerism in first-row transition metal complexes containing redox active Schiff base ligands. Dalton Trans 2015; 43:15958-67. [PMID: 25233051 DOI: 10.1039/c4dt01699h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reversible redox isomerisms in first row transition metal complexes of the type ML2 were studied. The six ML2 complexes (M = Mn(III) (), Fe(II) (), Co(III) (), Ni(II) (), Cu(II) () and Zn(II) ()) were synthesized with a redox active Schiff base ligand [2-(3,5-di-tert-butyl-2-hydroxyphenylamino)-4-chlorophenol] (H3L) presenting different oxidation states from -2 to 0 (L(2-), L(-) and L(0)). EPR spectra and magnetic susceptibility measurements indicate the presence of complexes of the type [Mn(III)(L(2-))(L(-))] () with S = 1/2, [Fe(II)(L(-))2] () with S = 2, [Co(III)(L(2-))(L(-))] () with S = 1/2, [Ni(II)(L(-))2] () with S = 1, [Cu(II)(L(-))2] () with S = 1/2 and [Zn(II)(L(-))2] () with S = 0 at high temperatures. Temperature and solvents influence the electronic structures of the species and give several valence tautomers. At low temperatures these complexes present thermally induced metal-to-ligand (, , ) or ligand-to-ligand (in , ) electron transfer (partial or total), resulting in compounds of the type [Mn(IV)(L(2-))2] () with S = 1/2, [Fe(III)(L(-))(L(2-))] () with S = 1, [Ni(III)(L(2-))(L(-))] () with S = 0, [Cu(II)(L(2-))(L(0))] () with S = 1/2 and [Zn(II)(L(2-))(L(0))] () with S = 1. This electron transfer is in agreement with the general trend in the redox potentials of the first row transition metal ions from Mn(ii) to Zn(ii), and it allows us to prepare and stabilize reversibly switchable tautomeric forms in transition metal complexes with redox-active ligands.
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Metal and Ligand Effects on Bonding in Group 6 Complexes of Redox-Active Amidodiphenoxides. Inorg Chem 2014; 53:10203-16. [DOI: 10.1021/ic501222n] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Octahedral to trigonal prismatic distortion driven by subjacent orbital π antibonding interactions and modulated by ligand redox noninnocence. Chem Commun (Camb) 2014; 50:7956-9. [DOI: 10.1039/c4cc03404j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ruthenium and osmium bis(amidodiphenoxides) distort towards trigonal prismatic geometries to minimize aryloxide-to-metal π* interactions, limited by increasing degree of oxidation of the redox-active ligand.
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Vanadium(IV/V)-p-dioxolene temperature induced electron transfer associated with ligation/deligation of solvent molecules. Dalton Trans 2013; 42:11831-40. [PMID: 23812561 DOI: 10.1039/c3dt50619c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reaction of an aqueous solution of NaVO3 or a methanol solution of [VO(acac)2] with 2,5-bis((bis(2-hydroxyethyl)amino)methyl)hydroquinone, H6bdeah, results in the formation of two major vanadium species characterized by X-ray crystallography: the [(V(5+)O)2(bdeah)] and the [(V(4.5+)O)2(bdeas)S2] (S = DMSO or MeOH). The vanadium ions in the two species have a trigonal pyramidal and an octahedral coordination sphere respectively. Variable temperature UV-Vis and (51)V NMR spectroscopy as well as EPR and electrochemistry showed a temperature induced electron transfer. The diamagnetic [(V(5+)O)2(bdeah)] is the main species at high temperature. At low temperature one electron is transferred from the bdeah(6-) to the two vanadium centers resulting in the [(V(4.5+)O)2(bdeas)S2] species [H5bdeas = 2,5-bis((bis(2-hydroxyethyl)amino)methyl)-1,4-semiquinone]. The thermodynamic parameters of this intramolecular electron transfer were calculated by UV-Vis (ΔH = -36 ± 2 kJ mol(-1) and ΔS = -129 ± 5 J mol(-1) K(-1)) and (51)V NMR spectroscopy (ΔH = -37 ± 2 kJ mol(-1) and ΔS = -109 ± 5 J mol(-1) K(-1)). The electron transfer is a result of the large change of entropy which is associated with the ligation of the solvent molecules and the geometry change. EPR spectroscopy shows that most of the electron density in [(V(4.5+)O)2(bdeas)S2] is mainly located on the two vanadium ions.
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The structures of two aldazines: [1,1'-(1E,1'E)-hydrazine-1,2-diylidenebis(methan-1-yl-1-ylidene)dinaphthalen-2-ol] (Lumogen) and 2,2'-(1E,1'E)-hydrazine-1,2-diylidenebis(methan-1-yl-1-ylidene)diphenol (salicylaldazine) in the solid state and in solution. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:530-540. [PMID: 23836625 DOI: 10.1002/mrc.3983] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 05/20/2013] [Accepted: 06/03/2013] [Indexed: 06/02/2023]
Abstract
A combination of NMR spectroscopy and theoretical methods Density functional theory including dispersion corrections (DFT-D) was used to study the structures of Lumogen and salicylaldazine. In the solid state, Lumogen exists as the dihydroxy tautomer 1a (an azine, C=N-N=C) as was already known from an X-ray determination. In a deuterated dimethyl sulfoxide solution, another tautomer is observed besides 1a; its structure corresponds to the hydroxy-oxo tautomer 1b (a hydrazone, C=N-NH-Csp(2)). In what concerns salicylaldazine, we have observed only the dihydroxy tautomer 2a.
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Synthesis and Characterization of a Redox-Active Bis(thiophenolato)amide Ligand, [SNS]3–, and the Homoleptic Tungsten Complexes, W[SNS]2 and W[ONO]2. Inorg Chem 2013; 52:2110-8. [DOI: 10.1021/ic302506e] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Abstract
Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o-dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex oxidation mechanisms; its excellent chelating properties, greatly exemplified by, but by no means exclusive, to the binding of Fe(3+); and the diverse modes of interaction of the vicinal hydroxyl groups with all kinds of surfaces of remarkably different chemical and physical nature. Thanks to this diversity, catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds. Such versatility has allowed catechols to participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of some transition metal ions. As a result of such an astonishing range of functionalities, catechol-based systems have in recent years been subject to intense research, aimed at mimicking these natural systems in order to develop new functional materials and coatings. A comprehensive review of these studies is discussed in this paper.
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Effects of solvation on charge distribution of 1,2-semiquinonato/catecholatocobalt complexes containing bis(3-pyridyl) phenylvinylsilane. TRANSIT METAL CHEM 2012. [DOI: 10.1007/s11243-012-9622-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Bis(acetonitrile)bis(acetylacetonato)ruthenium(III) mediated chemical transformations of coordinated 2-methylthioanilide. Dalton Trans 2012; 41:7057-66. [PMID: 22555595 DOI: 10.1039/c2dt30344b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemical reaction of [Ru(III)(acac)(2)(CH(3)CN)(2)]ClO(4) (1) with 2-methylthioaniline, HL(1) in ethanol under basic conditions yielded three new complexes Ru(II)(acac)(2)(L(1b)) (1b), (L(1b) = 4-imino-3-(methylsulfanyl)cyclohexa-2,5-dien-1-one), Ru(III)(acac)(2)(L(1c)) (1c), (HL(1c) = N-(2-methylthiophenyl)formamide) and (acac)(2)Ru(II)(μ-L(1d))Ru(II)(acac)(2) (1d), (L(1d) = 1,4-bis(2-methylthioaniline)-1,4-diazabutadiene) via the intermediate Ru(III)(acac)(2)(L(1a)) (1a, L(1a) = (L(1))(-) = 2-methylthioanilide). The reaction proceeded through temperature induced valence tautomerisation between the Ru(III) center and its 2-methylthioanilide counterpart in 1a with concomitant reduction of ruthenium from +III to +II oxidation state and oxidation of ligand L(1a), resulting in aromatic ring hydroxylation, N-formylation and C-C bond formation reactions. All the complexes have been characterised by their single-crystal X-ray structure determination and various spectroscopic and electrochemical techniques. The identity of complex 1a has been confirmed by X-ray crystal structure determination of complex 2, a phenyl analogue of complex 1a. The complexes (1a-d) showed intense charge transfer (MLCT/LMCT) transition in the long wavelength region. The paramagnetic compounds, 1a and 1c, along with the diamagnetic compound 1b showed two one-electron responses in the ranges, -0.4 to -1.0 V and 0.3 to 1.1 V. The diamagnetic complex 1d displayed two successive one-electron reversible reductions (-1.31 and -1.55 V) and two one-electron reversible oxidation processes (-0.036 and 0.51 V). The redox processes are characterized by EPR spectroscopy and spectroelectrochemistry. The compound 1c has been found to exhibit solvatochromism and concentration dependent aggregation in solution.
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Mono-o-semiquinonato mixed-halogenato tin(IV) complexes: EPR spectroscopic and X-ray investigations. Inorganica Chim Acta 2012. [DOI: 10.1016/j.ica.2011.08.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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23
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Magnetic and luminescent properties of Cd(ii)- and Fe(ii)-anion radical frameworks: various networks or structures influenced by metal ion sizes or in situ forming mechanisms of anion radical ligand. CrystEngComm 2012. [DOI: 10.1039/c1ce05641g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Playing with organic radicals as building blocks for functional molecular materials. Chem Soc Rev 2012; 41:303-49. [DOI: 10.1039/c1cs15165g] [Citation(s) in RCA: 600] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Inducing Effect of Additive Agents on Coordination Assembly of Silver(I) Nitrate with 3,5-Bis(2-pyridyl)-4-amino-1,2,4-triazole: Supramolecular Isomerism and Interconversion. Inorg Chem 2011; 50:9284-9. [PMID: 21902177 DOI: 10.1021/ic200540c] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Synthesis, Molecular and Electronic Structures of Six-Coordinate Transition Metal (Mn, Fe, Co, Ni, Cu, and Zn) Complexes with Redox-Active 9-Hydroxyphenoxazin-1-one Ligands. Inorg Chem 2011; 50:7022-32. [DOI: 10.1021/ic2004062] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Quantum-chemical study of valence tautomerism of a cobalt complex with phenoxybenzoquinone imine. DOKLADY CHEMISTRY 2011. [DOI: 10.1134/s0012500810120037] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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New metal-anion radical framework materials: CoII compounds showing ferromagnetic to antiferromagnetic phase transition at about 344 K, and ZnII compounds exhibiting terminal anion ligand induced direct white-light-emission. Dalton Trans 2011; 40:4131-9. [DOI: 10.1039/c0dt01667e] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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New morpholine- and piperazine-functionalized triphenylantimony(V) catecholates: The spectroscopic and electrochemical studies. J Organomet Chem 2010. [DOI: 10.1016/j.jorganchem.2010.01.029] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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X-ray Absorption Spectroscopy as a Probe of Photo- and Thermally Induced Valence Tautomeric Transition in a 1:1 Cobalt-Dioxolene Complex. Chemphyschem 2009; 10:2090-5. [DOI: 10.1002/cphc.200900098] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Transition metal complexes with bulky 4,6-di-tert-butyl-N-aryl(alkyl)-o-iminobenzoquinonato ligands: Structure, EPR and magnetism. Coord Chem Rev 2009. [DOI: 10.1016/j.ccr.2008.02.004] [Citation(s) in RCA: 297] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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32
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Cooperativity from electrostatic interactions: understanding bistability in molecular crystals. CrystEngComm 2009. [DOI: 10.1039/b907184a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Synthesis of nitrogen- and oxygen-containing macrocycles with several polyamine and anthracene or anthraquinone fragments in reactions of palladium-catalyzed amination. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2008. [DOI: 10.1134/s1070428008110195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Thermodynamics of valence tautomeric interconversion in a tetrachlorodioxolene:cobalt 1:1 adduct. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.02.044] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Bistability in Fc-PTM crystals: the role of intermolecular electrostatic interactions. J Am Chem Soc 2008; 130:12064-72. [PMID: 18698776 DOI: 10.1021/ja803049g] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fc-PTM is a valence tautomeric radical, where the ferrocene (Fc) group, a good electron donor, is linked by an ethylenic spacer to a perchlorotriphenylmethyl radical (PTM(*)), a good electron acceptor. In solution this compound exists mainly in the neutral Fc-PTM(*) form which can be photoexcited through an intramolecular electron transfer to the zwitterionic Fc(+*)-PTM(-) form. By contrast, in crystals of Fc-PTM at room temperature both the neutral and the zwitterionic forms coexist, pointing to a true bistability phenomenon. We rationalize these findings accounting for the role of intermolecular electrostatic interactions in Fc-PTM crystals. In fact the energy of the zwitterionic Fc(+*)-PTM(-) form is lowered in the crystal by attractive electrostatic intermolecular interactions and the cooperative nature of these interactions explains the observed coexistence of neutral Fc-PTM(*) and zwitterionic Fc(+*)-PTM(-) species. The temperature evolution of Mossbauer spectra of Fc-PTM is quantitatively reproduced adopting a bottom-up modeling strategy that combines a molecular model, derived from optical spectra of Fc-PTM in solution, with a model for intermolecular electrostatic interactions, supported by quantum-chemical calculations. Fc-PTM then offers the first experimental demonstration of bistability induced by electrostatic interactions in crystals of valence tautomeric donor-acceptor molecules.
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Diradical Bis-o-iminosemiquinonato Zinc Complex: Spectroscopy, Magneto- and Electrochemistry. Z Anorg Allg Chem 2008. [DOI: 10.1002/zaac.200700596] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Synthesis, X-ray Structure and Reactivity of a Sterically Protected Azobisphenol Ligand: On the Quest for New Multifunctional Active Ligands. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200701339] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Tuning the Charge Distribution and Photoswitchable Properties of Cobalt–Dioxolene Complexes by Using Molecular Techniques. Chemistry 2008; 14:1804-13. [DOI: 10.1002/chem.200701163] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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A hexacarboxylic open-shell building block: synthesis, structure and magnetism of a three-dimensional metal–radical framework. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b713705b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Europium (III) complexes derived from carboxylic-substituted polychlorotriphenylmethyl radicals. Inorganica Chim Acta 2007. [DOI: 10.1016/j.ica.2007.03.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
A number of photofunctional molecular compounds have been developed recently. Typical examples of these are phototunable valence tautomeric compounds, which are now attracting great attention. When the charge-transfer bands of some Co valence tautomeric compounds are excited at low temperature, metastable redox isomers can be created after irradiation. The lifetimes of the metastable states can be more than several hours. These transformations can involve changes in the magnetic properties of the compounds, as well as their color. Hence, these compounds can be regarded as novel photomagnetic materials. The photoresponsive behaviors of these valence tautomeric compounds are similar to those of spin-crossover complexes (light-induced excited spin-state trapping effects).
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Abstract
The magnetic properties of many magnetic materials can be controlled by external stimuli. The principal focus here is on the thermal, photochemical, electrochemical, and chemical control of phase transitions that involve changes in magnetization. The molecular compounds described herein range from metal complexes, through pure organic compounds to composite materials. Most of the Review is devoted to the properties of valence-tautomeric compounds, molecular magnets, and spin-crossover complexes, which could find future application in memory devices or optical switches.
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Magnetische Molekülverbindungen: Schaltung magnetischer Eigenschaften durch externe Stimuli. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200602205] [Citation(s) in RCA: 227] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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First-Row Transition-Metal Complexes Based on a Carboxylate Polychlorotriphenylmethyl Radical: Trends in Metal−Radical Exchange Interactions. Inorg Chem 2007; 46:1627-33. [PMID: 17286396 DOI: 10.1021/ic061815x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the synthesis, crystal structures, and magnetic properties of a series of mononuclear, metal-radical complexes with first-row transition-metal ions using a new class of radical-based ligands, the polychlorinated triphenylmethyl (PTM) radicals. Crystal structures of three new PTM-based complexes of general formula M(PTMMC)2(py)4-x(H2O)x [PTMMC = PTM radical functionalized at the para position with one carboxylic group; M = Zn(II), x = 2 (1); M = Ni(II), x = 1 (2); M = Co(II), x = 1 (3)] show similar molecular structures in which mononuclear complexes are formed by an octahedral metal ion coordinated by two monodentated PTMMC units. From a magnetic point of view, these similar configurations describe a quasilinear, trimeric magnetic model (PTMMC-M(II)-PTMMC), in which the metal [Ni(II) or Co(II)]-radical magnetic-exchange coupling constants have been determined for the first time. In all of these complexes, the temperature dependence of the magnetic susceptibility reveals moderate antiferromagnetic-exchange coupling constants between the PTMMC radicals and Ni(II) (2J/kB = -47.1 K) and Co(II) ions (2J/kB = -15.2 K) based on the exchange Hamiltonian H = -2JSM(Srad1 + Srad2).
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Valence tautomerism interconversion triggers transition to stable charge distribution in solid polymeric cobalt–polyoxolene complexes. Dalton Trans 2007:5253-9. [DOI: 10.1039/b710493f] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mixed-Ligand Copper Complexes with 8-Methylthioquinoline and Triphenylphosphane or theo-Semiquinone/Catecholate Redox System. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200500567] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Valence tautomerization and exchange coupling in a cobalt–nitronylnitroxide–semiquinone complex. Polyhedron 2005. [DOI: 10.1016/j.poly.2005.03.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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