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M Zahir FZ, Hay MA, Janetzki JT, Gable RW, Goerigk L, Boskovic C. Predicting valence tautomerism in diverse cobalt-dioxolene complexes: elucidation of the role of ligands and solvent. Chem Sci 2024; 15:5694-5710. [PMID: 38638213 PMCID: PMC11023039 DOI: 10.1039/d3sc04493a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 03/08/2024] [Indexed: 04/20/2024] Open
Abstract
The ability of molecular switches to reversibly interconvert between different forms promises potential applications at the scale of single molecules up to bulk materials. One type of molecular switch comprises cobalt-dioxolene compounds that exhibit thermally-induced valence tautomerism (VT) interconversions between low spin Co(iii)-catecholate (LS-CoIII-cat) and high spin Co(ii)-semiquinonate (HS-CoII-sq) forms. Two families of these compounds have been investigated for decades but have generally been considered separately: neutral [Co(diox)(sq)(N2L)] and cationic [Co(diox)(N4L)]+ complexes (diox = generic dioxolene, N2L/N4L = bidentate/tetradentate N-donor ancillary ligand). Computational identification of promising new candidate compounds prior to experimental exploration is beneficial for environmental and cost considerations but requires a thorough understanding of the underlying thermochemical parameters that influence the switching. Herein, we report a robust approach for the analysis of both cobalt-dioxolene families, which involved a quantitative density functional theory-based study benchmarked with reliable quasi-experimental references. The best-performing M06L-D4/def2-TZVPP level of theory has subsequently been verified by the synthesis and experimental investigation of three new complexes, two of which exhibit thermally-induced VT, while the third remains in the LS-CoIII-cat form across all temperatures, in agreement with prediction. Valence tautomerism in solution is markedly solvent-dependent, but the origin of this has not been definitively established. We have extended our computational approach to elucidate the correlation of VT transition temperature with solvent stabilisation energy and change in dipole moment. This new understanding may inform the development of VT compounds for applications in soft materials including films, gels, and polymers.
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Affiliation(s)
- F Zahra M Zahir
- School of Chemistry, University of Melbourne Victoria 3010 Australia
| | - Moya A Hay
- School of Chemistry, University of Melbourne Victoria 3010 Australia
| | - Jett T Janetzki
- School of Chemistry, University of Melbourne Victoria 3010 Australia
| | - Robert W Gable
- School of Chemistry, University of Melbourne Victoria 3010 Australia
| | - Lars Goerigk
- School of Chemistry, University of Melbourne Victoria 3010 Australia
| | - Colette Boskovic
- School of Chemistry, University of Melbourne Victoria 3010 Australia
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2
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Mörtel M, Goodner SJ, Oschwald J, Scheurer A, Drewello T, Khusniyarov MM. Low-spin to low-spin valence tautomeric transition in cobalt bis-dioxolenes. Dalton Trans 2024; 53:4098-4107. [PMID: 38314834 DOI: 10.1039/d3dt03935h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Cobalt dioxolenes are a well-known class of switchable coordination compounds showing intramolecular electron transfer, which is always accompanied by a spin state change at the cobalt center. Here, we present the first example of thermally switchable cobalt bis-dioxolenes where intramolecular electron transfer seems to take place, but the spin state change is suppressed. This leads to the detection of thermal transition between a common ls-CoIII(SQ˙-)(Cat2-) and an extremely rare ls-CoII(SQ˙-)2 electronic state (hs - high-spin, ls - low-spin, SQ˙- - benzosemiquinonate(1-) radical and Cat2- - catecholate(2-)). Parallel to the present work, a similar work but on cobalt mono-dioxolenes has just appeared (Chem. Eur. J., 2023, 29, e202300091), suggesting thermal transition between ls-CoIII(Cat2-) and ls-CoII(SQ˙-) electronic states.
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Affiliation(s)
- Max Mörtel
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Germany.
| | - Stephen J Goodner
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Germany.
| | - Johannes Oschwald
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstraße 3, 91058, Germany
| | - Andreas Scheurer
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Germany.
| | - Thomas Drewello
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstraße 3, 91058, Germany
| | - Marat M Khusniyarov
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Germany.
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Fleming C, Vu S, Brook DJR, Agrestini S, Pellegrin E, DaRos J. Metal-ligand interactions in a redox active ligand system. Electrochemistry and spectroscopy of [M(dipyvd) 2] n+ (M=Zn, Ni, n=0, 1, 2). Front Chem 2023; 11:1295289. [PMID: 38033468 PMCID: PMC10684738 DOI: 10.3389/fchem.2023.1295289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/27/2023] [Indexed: 12/02/2023] Open
Abstract
Reaction of nickel and zinc triflates with the tridentate leucoverdazyl 1-isopropyl-3,5-di (2'-pyridyl)-6-oxo-2H-tetrazine (dipyvdH) and triethylamine resulted in the neutral coordination compounds M(dipyvd)2 (M = Ni,Zn). In acetonitrile, both compounds undergo two one electron oxidation processes, Zn (dipyvd)2 at -0.28 V and -0.12 V and Ni(dipyvd)2 at -0.32 V and -0.15 V vs ferrocene/ferricenium. Oxidations are ligand based resulting in an intermediate mixed valence species and a cationic bis(verdazyl) compound respectively. Oxidation of the ligand changes a localized, antiaromatic, non-planar 8π electron anion to a planar, delocalized 7π electron radical. The change in ligand structure results in an increase in the octahedral ligand field splitting from 10,500 cm-1 to ∼13,000 cm-1, suggesting an increase in the pi acceptor character of the ligand. In the mixed valence species, spectroscopic data suggests minimal interaction between ligands mediated by the metal center; i.e., these are class I-II systems in the Robin-Day classification.
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Affiliation(s)
- Connor Fleming
- Department of Chemistry, San Jose State University, San Jose, CA, United States
| | - Son Vu
- Department of Chemistry, San Jose State University, San Jose, CA, United States
| | - David J. R. Brook
- Department of Chemistry, San Jose State University, San Jose, CA, United States
| | - Stefano Agrestini
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Eric Pellegrin
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Jeffrey DaRos
- Department of Chemistry, San Jose State University, San Jose, CA, United States
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4
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Janetzki JT, Chegerev MG, Gransbury GK, Gable RW, Clegg JK, Mulder RJ, Jameson GNL, Starikova AA, Boskovic C. Controlling Spin Crossover in a Family of Dinuclear Fe(III) Complexes via the Bis(catecholate) Bridging Ligand. Inorg Chem 2023; 62:15719-15735. [PMID: 37691232 DOI: 10.1021/acs.inorgchem.3c02598] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Spin crossover (SCO) complexes can reversibly switch between low spin (LS) and high spin (HS) states, affording possible applications in sensing, displays, and molecular electronics. Dinuclear SCO complexes with access to [LS-LS], [LS-HS], and [HS-HS] states may offer increased levels of functionality. The nature of the SCO interconversion in dinuclear complexes is influenced by the local electronic environment. We report the synthesis and characterization of [{FeIII(tpa)}2spiro](PF6)2 (1), [{FeIII(tpa)}2Br4spiro](PF6)2 (2), and [{FeIII(tpa)}2thea](PF6)2 (3) (tpa = tris(2-pyridylmethyl)amine, spiroH4 = 3,3,3',3'-tetramethyl-1,1'-spirobi(indan)-5,5',6,6'-tetraol, Br4spiroH4 = 3,3,3',3'-tetramethyl-1,1'-spirobi(indan)-4,4',7,7'-tetrabromo-5,5',6,6'-tetraol, theaH4 = 2,3,6,7-tetrahydroxy-9,10-dimethyl-9,10-dihydro-9,10-ethanoanthracene), utilizing non-conjugated bis(catecholate) bridging ligands. In the solid state, magnetic and structural analysis shows that 1 remains in the [HS-HS] state, while 2 and 3 undergo a partial SCO interconversion upon cooling from room temperature involving the mixed [LS-HS] state. In solution, all complexes undergo SCO from [HS-HS] at room temperature, via [LS-HS] to mixtures including [LS-LS] at 77 K, with the extent of SCO increasing in the order 1 < 2 < 3. Gas phase density functional theory calculations suggest a [LS-LS] ground state for all complexes, with the [LS-HS] and [HS-HS] states successively destabilized. The relative energy separations indicate that ligand field strength increases following spiro4- < Br4spiro4- < thea4-, consistent with solid-state magnetic and EPR behavior. All three complexes show stabilization of the [LS-HS] state in relation to the midpoint energy between [LS-LS] and [HS-HS]. The relative stability of the [LS-HS] state increases with increasing ligand field strength of the bis(catecholate) bridging ligand in the order 1 < 2 < 3. The bromo substituents of Br4spiro4- increase the ligand field strength relative to spiro4-, while the stronger ligand field provided by thea4- arises from extension of the overlapping π-orbital system across the two catecholate units. This study highlights how SCO behavior in dinuclear complexes can be modulated by the bridging ligand, providing useful insights for the design of molecules that can be interconverted between more than two states.
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Affiliation(s)
- Jett T Janetzki
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
| | - Maxim G Chegerev
- Institute of Physical and Organic Chemistry, Southern Federal University, Rostov-on-Don 344090, Russian Federation
| | - Gemma K Gransbury
- Department of Chemistry, The University of Manchester, Manchester M13 9PL, U.K
| | - Robert W Gable
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
| | - Jack K Clegg
- University of Queensland, St Lucia, Queensland 4072, Australia
| | | | - Guy N L Jameson
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
| | - Alyona A Starikova
- Institute of Physical and Organic Chemistry, Southern Federal University, Rostov-on-Don 344090, Russian Federation
| | - Colette Boskovic
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
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Albavera-Mata A, Hennig RG, Trickey SB. Transition Temperature for Spin-Crossover Materials with the Mean Value Ensemble Hubbard- U Correction. J Phys Chem A 2023; 127:7646-7654. [PMID: 37669434 DOI: 10.1021/acs.jpca.3c03520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Calculation of transition temperatures T1/2 for thermally driven spin-crossover in condensed phases is challenging, even with sophisticated state-of-the-art density functional approximations. The first issue is the accuracy of the adiabatic crossover energy difference ΔEHL between the low- and high-spin states of the bistable metal-organic complexes. The other is the proper inclusion of entropic contributions to the Gibbs free energy from the electronic and vibrational degrees of freedom. We discuss the effects of treatments of both contributions upon the calculation of thermochemical properties for a set of 20 spin-crossover materials using a Hubbard-U correction obtained from a reference ensemble spin-state. The U values obtained from a simplest bimolecular representation may overcorrect, somewhat, the ΔEHL values, hence giving somewhat excessive reduction of the T1/2 results with respect to their U = 0 values in the crystalline phase. We discuss the origins of the discrepancies by analyzing different sources of uncertainties. By use of a first-coordination-sphere approximation and the assumption that vibrational contributions from the outermost atoms in a metal-organic complex are similar in both low- and high-spin states, we achieve T1/2 results with the low-cost, widely used PBE generalized gradient density functional approximation comparable to those from the more costly, more sophisticated r2SCAN meta-generalized gradient approximation. The procedure is promising for use in high-throughput materials screening, because it combines rather low computational effort requirements with freedom from user manipulation of parameters.
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Affiliation(s)
- Angel Albavera-Mata
- Center for Molecular Magnetic Quantum Materials, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Department of Materials Science and Engineering, University of Florida, 1885 Stadium Road, Gainesville, Florida 32611, United States
| | - Richard G Hennig
- Center for Molecular Magnetic Quantum Materials, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Department of Materials Science and Engineering, University of Florida, 1885 Stadium Road, Gainesville, Florida 32611, United States
| | - S B Trickey
- Center for Molecular Magnetic Quantum Materials, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Department of Physics and Department of Chemistry, University of Florida, P.O. Box 118435, Gainesville, Florida 32611, United States
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Moledo Vicente Guedes A, Sodré de Abreu L, Maldonado IAV, Fernandes WS, Cardozo TM, A Allão Cassaro R, Scarpellini M, Poneti G. Valence tautomerism in a cobalt-dioxolene complex containing an imidazolic ancillary ligand. RSC Adv 2023; 13:20050-20057. [PMID: 37409047 PMCID: PMC10318486 DOI: 10.1039/d3ra03235c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/22/2023] [Indexed: 07/07/2023] Open
Abstract
This work reports the synthesis, structural, spectroscopic and magnetic investigation of two complexes, [Co(bmimapy)(3,5-DTBCat)]PF6·H2O (1) and [Co(bmimapy)(TCCat)]PF6·H2O (2), where bmimapy is an imidazolic tetradentate ancillary ligand and 3,5-DTBCat and TCCat are the 3,5-di-tert-butyl-catecholate and tetrachlorocatecholate anions, respectively. Their structures have been elucidated using single crystal X-ray diffraction, showing a pseudo-octahedral cobalt ion bound to a chelating dioxolene ligand and the ancillary bmimapy ligand in a folded conformation. Magnetometry displayed an entropy-driven, incomplete, Valence Tautomeric (VT) process for 1 in the 300-380 K temperature range, while 2 displayed a temperature independent, diamagnetic low-spin cobalt(iii)-catecholate charge distribution. This behaviour was interpreted on the basis of the cyclic voltammetric analysis, allowing the estimation of the free energy difference associated with the VT interconversion of +8 and +96 kJ mol-1 for 1 and 2, respectively. A DFT analysis of this free energy difference highlighted the ability of the methyl-imidazole pendant arm of bmimapy favouring the onset of the VT phenomenon. This work introduces the imidazolic bmimapy ligand to the scientific community working in the field of valence tautomerism, increasing the library of ancillary ligands to prepare temperature switchable molecular magnetic materials.
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Affiliation(s)
| | - Leandro Sodré de Abreu
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | | | - William Silva Fernandes
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Thiago Messias Cardozo
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Rafael A Allão Cassaro
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Marciela Scarpellini
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
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Hay MA, Janetzki JT, Kumar VJ, Gable RW, Clérac R, Starikova AA, Low PJ, Boskovic C. Modulation of Charge Distribution in Cobalt-α-Diimine Complexes toward Valence Tautomerism. Inorg Chem 2022; 61:17609-17622. [DOI: 10.1021/acs.inorgchem.2c02659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Moya A. Hay
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jett T. Janetzki
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Varshini J. Kumar
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Robert W. Gable
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Rodolphe Clérac
- University of Bordeaux, CNRS, CRPP, UMR 5031, F-33600 Pessac, France
| | - Alyona A. Starikova
- Institute of Physical and Organic Chemistry, Southern Federal University, 344090 Rostov-on-Don, Russian Federation
| | - Paul J. Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Colette Boskovic
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
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Cheng F, Wu S, Zheng W, Su S, Nakanishi T, Xu W, Sadhukhan P, Sejima H, Ikenaga S, Yamamoto K, Gao K, Kanegawa S, Sato O. Macroscopic Polarization Change of Mononuclear Valence Tautomeric Cobalt Complexes Through the Use of Enantiopure Ligand. Chemistry 2022; 28:e202202161. [DOI: 10.1002/chem.202202161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Feng Cheng
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Shuqi Wu
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Wenwei Zheng
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Shengqun Su
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Takumi Nakanishi
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Wenhuang Xu
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Pritam Sadhukhan
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Hibiki Sejima
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Shimon Ikenaga
- Department of Physics Okayama University of Science Okayama Japan
| | - Kaoru Yamamoto
- Department of Physics Okayama University of Science Okayama Japan
| | - Kaige Gao
- College of Physical Science and Technology Yangzhou University Yangzhou Jiangsu P. R. China
| | - Shinji Kanegawa
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Osamu Sato
- Institute for Materials Chemistry and Engineering & IRCCS Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
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Wang JP, Liu WT, Yu M, Ji XY, Liu JL, Chi MZ, Starikova AA, Tao J. One-Step versus Two-Step Valence Tautomeric Transitions in Tetraoxolene-Bridged Dinuclear Cobalt Compounds. Inorg Chem 2022; 61:4428-4441. [PMID: 35234043 DOI: 10.1021/acs.inorgchem.1c03944] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The syntheses of valence tautomeric compounds with multistep transitions using new redox-active ligands are the long-term goal of the field of bistable materials. The redox-active tetraoxolene ligand, 2,7-di-tert-butylpyrene-4,5,9,10-tetraone (pyreneQ-Q), is now developed to synthesize a pair of dinuclear compounds {[CoL2]2(pyreneSq-Sq)}[Co(CO)4]2·xCH2Cl2·2C6H5CH3 (1, x = 2, L = 1,10-phenanthroline, phen; 2, x = 1.5, L = 2,2'-bipyridine, bpy). Variable-temperature magnetic susceptibilities and single-crystal X-ray diffraction measurements indicate a partial one-step valence tautomeric transition for 1 and a rare two-step valence tautomeric transition for 2, respectively. DFT calculation results are consistent with the experimental data, revealing the correlation between thermodynamic parameters and the one-step/two-step valence tautomeric behaviors.
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Affiliation(s)
- Jia-Ping Wang
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
| | - Wen-Ting Liu
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
| | - Meng Yu
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
| | - Xue-Yang Ji
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
| | - Jing-Lin Liu
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
| | - Man-Zhou Chi
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
| | - Alyona A Starikova
- Institute of Physical and Organic Chemistry, Southern Federal University, Stachka Avenue 194/2, Rostov-on-Don 344090, Russian Federation
| | - Jun Tao
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Liangxiang Campus, Beijing Institute of Technology, Beijing 102488, PR China
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10
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Nadurata VL, Hay MA, Janetzki JT, Gransbury GK, Boskovic C. Rich redox-activity and solvatochromism in a family of heteroleptic cobalt complexes. Dalton Trans 2021; 50:16631-16646. [PMID: 34752591 DOI: 10.1039/d1dt03327a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The combination of redox-active metals with redox-active ligands can lead to interesting charge transfer behaviours, including valence tautomerism and solvatochromism. With the aim of investigating a relatively underexplored redox-active metal/redox-active ligand combination, complexes [CoII(acac)2(X-BIAN)] (acac- = acetylacetonate; X-BIAN = bis(4-X-phenyl)iminoacenaphthene; 1: X = -CF3, 2: X = -Cl, 3: X = -H, 4: X = -Me) and [CoIII(acac)2(Me-BIAN)]+ (5+) have been synthesised and characterised. At all temperatures investigated, and in both the solid and solution state, complexes 1-4 exist in a CoII-BIAN0 charge distribution, while 5+ adopts a CoIII-BIAN0 charge distribution. In the case of 1-4, the potential CoIII-BIAN˙- valence tautomer is inaccesible; the energy ordering between the ground CoII-BIAN0 state and the excited CoIII-BIAN˙- state must be reversed in order for an entropically driven interconversion to be possible. The energy gap between the states can be monitored via metal-to-ligand charge transfer bands in the visible region. We demonstrate tuning of this energy gap by varying the electronic properties of the BIAN ligand, as well as by controlling the molecular environment through solvent choice. Solvatochromic analysis, in combination with crystallographic evidence, allows elucidation of the specific solvent-solute interactions that govern the molecular behaviour of 1-4, affording insights that can inform potential future applications in sensing and switching.
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Affiliation(s)
- Vincent L Nadurata
- School of Chemistry, University of Melbourne, Melbourne, 3010 Victoria, Australia.
| | - Moya A Hay
- School of Chemistry, University of Melbourne, Melbourne, 3010 Victoria, Australia.
| | - Jett T Janetzki
- School of Chemistry, University of Melbourne, Melbourne, 3010 Victoria, Australia.
| | - Gemma K Gransbury
- School of Chemistry, University of Melbourne, Melbourne, 3010 Victoria, Australia.
| | - Colette Boskovic
- School of Chemistry, University of Melbourne, Melbourne, 3010 Victoria, Australia.
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