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Panda S, Dhara S, Singh A, Dey S, Kumar Lahiri G. Metal-coordinated azoaromatics: Strategies for sequential azo-reduction, isomerization and application potential. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Rhenium Tricarbonyl Complexes of Azodicarboxylate Ligands. Molecules 2022; 27:molecules27238159. [PMID: 36500250 PMCID: PMC9740152 DOI: 10.3390/molecules27238159] [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: 10/24/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
The excellent π-accepting azodicarboxylic esters adcOR (R = Et, iPr, tBu, Bn (CH2-C6H5) and Ph) and the piperidinyl amide derivative adcpip were used as bridging chelate ligands in dinuclear Re(CO)3 complexes [{Re(CO)3Cl}2(µ-adcOR)] and [{Re(CO)3Cl}2(µ-adcpip)]. From the adcpip ligand the mononuclear derivatives [Re(CO)3Cl(adcpip)] and [Re(CO)3(PPh3)(µ-adcpip)]Cl were also obtained. Optimised geometries from density functional theory (DFT) calculations show syn and anti isomers for the dinuclear fac-Re(CO)3 complexes at slightly different energies but they were not distinguishable from experimental IR or UV-Vis absorption spectroscopy. The electrochemistry of the adc complexes showed reduction potentials slightly below 0.0 V vs. the ferrocene/ferrocenium couple. Attempts to generate the radicals [{Re(CO)3Cl}2(µ-adcOR)]•- failed as they are inherently unstable, losing very probably first the Cl- coligand and then rapidly cleaving one [Re(CO)3] fragment. Consequently, we found signals in EPR very probably due to mononuclear radical complexes [Re(CO)3(solv)(adc)]•. The underlying Cl-→solvent exchange was modelled for the mononuclear [Re(CO)3Cl(adcpip)] using DFT calculations and showed a markedly enhanced Re-Cl labilisation for the reduced compared with the neutral complex. Both the easy reduction with potentials ranging roughly from -0.2 to -0.1 V for the adc ligands and the low-energy NIR absorptions in the 700 to 850 nm range place the adc ligands with their lowest-lying π* orbital being localised on the azo function, amongst comparable bridging chelate N^N coordinating ligands with low-lying π* orbitals of central azo, tetrazine or pyrazine functions. Comparative (TD)DFT-calculations on the Re(CO)3Cl complexes of the adcpip ligand using the quite established basis set and functionals M06-2X/def2TZVP/LANL2DZ/CPCM(THF) and the more advanced TPSSh/def2-TZVP(+def2-ECP for Re)/CPCMC(THF) for single-point calculations with BP86/def2-TZVP(+def2-ECP for Re)/CPCMC(THF) optimised geometries showed a markedly better agreement of the latter with the experimental XRD, IR and UV-Vis absorption data.
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Olmo F, Rodriguez A, Colina A, Heras A. UV/Vis absorption spectroelectrochemistry of folic acid. J Solid State Electrochem 2022. [DOI: 10.1007/s10008-021-05026-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractUV/Vis absorption spectroelectrochemistry is a very promising analytical technique due to the complementary information that is simultaneously obtained from electrochemistry and spectroscopy. In this work, this technique is used in a parallel configuration to study the oxidation of folic acid in alkaline medium. Herein, UV/Vis absorption spectroelectrochemistry has been used to detect both the oxidation products and the folic acid consumed at the electrode/solution interface, allowing us to develop an analytical protocol to quantify vitamin B9 in pharmaceutical tablets. Linear ranges of three orders of magnitude have been achieved in basic medium (pH = 12.9), obtaining high repeatability and low detection limits. The spectroelectrochemical determination of folic acid in pharmaceutical tablets at alkaline pH values is particularly interesting because of the changes that occur in the optical signal during the electrochemical oxidation of FA, providing results with very good figures of merit and demonstrating the utility and versatility of this hyphenated technique, UV/Vis absorption spectroelectrochemistry.
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Delano Iv F, Castellanos E, McCracken J, Demir S. A rare earth metallocene containing a 2,2'-azopyridyl radical anion. Chem Sci 2021; 12:15219-15228. [PMID: 34976342 PMCID: PMC8634996 DOI: 10.1039/d1sc04285h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/12/2021] [Indexed: 11/21/2022] Open
Abstract
Introducing spin onto organic ligands that are coordinated to rare earth metal ions allows direct exchange with metal spin centres. This is particularly relevant for the deeply buried 4f-orbitals of the lanthanide ions that can give rise to unparalleled magnetic properties. For efficacy of exchange coupling, the donor atoms of the radical ligand require high-spin density. Such molecules are extremely rare owing to their reactive nature that renders isolation and purification difficult. Here, we demonstrate that a 2,2′-azopyridyl (abpy) radical (S = 1/2) bound to the rare earth metal yttrium can be realized. This molecule represents the first rare earth metal complex containing an abpy radical and is unambigously characterized by X-ray crystallography, NMR, UV-Vis-NIR, and IR spectroscopy. In addition, the most stable isotope 89Y with a natural abundance of 100% and a nuclear spin of ½ allows an in-depth analysis of the yttrium–radical complex via EPR and HYSCORE spectroscopy. Further insight into the electronic ground state of the radical azobispyridine-coordinated metal complex was realized through unrestricted DFT calculations, which suggests that the unpaired spin density of the SOMO is heavily localized on the azo and pyridyl nitrogen atoms. The experimental results are supported by NBO calculations and give a comprehensive picture of the spin density of the azopyridyl ancillary ligand. This unexplored azopyridyl radical anion in heavy element chemistry bears crucial implications for the design of molecule-based magnets particularly comprising anisotropic lanthanide ions. Unambiguous characterization of the first 2,2′-azobispyridine radical-containing rare earth metal complex through X-ray crystallography, DFT computations, EPR and HYSCORE spectroscopy.![]()
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Affiliation(s)
- Francis Delano Iv
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
| | - Ernesto Castellanos
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
| | - John McCracken
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
| | - Selvan Demir
- Department of Chemistry, Michigan State University 578 South Shaw Lane East Lansing Michigan 48824 USA
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Kawakita K, Kakiuchi Y, Beaumier EP, Tonks IA, Tsurugi H, Mashima K. Synthesis of Pyridylimido Complexes of Tantalum and Niobium by Reductive Cleavage of the N═N Bond of 2,2'-Azopyridine: Precursors for Early-Late Heterobimetallic Complexes. Inorg Chem 2019; 58:15155-15165. [PMID: 31553585 PMCID: PMC7017918 DOI: 10.1021/acs.inorgchem.9b02043] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the syntheses of 2-pyridylimido complexes of tantalum and niobium by N═N bond cleavage of 2,2'-azopyridine. Reaction of MCl5 (M = Ta and Nb) with 2,2'-azopyridine in the presence of 0.5 equiv of 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (abbreviated Si-Me-CHD) afforded a dark red solution (for Ta) and a dark blue solution (for Nb) with some insoluble precipitates. After removing the solids, another 0.5 equiv of Si-Me-CHD was added to each solution, giving [M(═Npy)Cl3]n (1a: M = Ta; 1b: M = Nb) through reductive cleavage of the N═N bond of 2,2'-azopyridine. The initial products of the above reactions were determined to be 2,2'-azopyridine-bridged dinuclear complexes, [(MCl4)2(μ-pyNNpy)] (2a: M = Ta; 2b: M = Nb), which were isolated by treating MCl5 with 2,2'-azopyridine and Si-Me-CHD in a 2:1:1 molar ratio. In 2a and 2b, the N═N bond was reduced to a single bond via two-electron reduction. Further reduction of complexes 2a and 2b with 1 equiv of Si-Me-CHD afforded complexes 1a and 1b. An anionic doubly μ-imido-bridged ditantalum complex, [nBu4N][Ta2(μ-Npy)2Cl7] (3a), was generated upon addition of nBu4NCl to complex 1a, while addition of nBu4NCl to niobium complex 1b gave a polymeric terminal imido complex, [nBu4N]n/2[{Nb(═Npy)Cl3}2(μ-Cl)]n/2 (3b). Complexations of 1a and 1b with 1 equiv of 2,2'-bipyridine resulted in the formation of mononuclear 2-pyridylimido complexes, M(═Npy)Cl3(bipy) (4a: M = Ta; 4b: M = Nb), whose main structural feature is intramolecular hydrogen bonding between the ortho hydrogen atom of 2,2'-bipyridine and the nitrogen atom of the pyridyl group on the imido ligand. Isolated 2-pyridylimido complexes 4a and 4b reacted with [RhCl(cod)]2 to produce the corresponding early-late heterobimetallic complexes, (bipy)MCl3(μ-Npy)RhCl(cod) (5a: M = Ta; 5b: M = Nb).
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Affiliation(s)
- Kento Kawakita
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yuya Kakiuchi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Evan P. Beaumier
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota–Twin Cities, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Hayato Tsurugi
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kazushi Mashima
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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Haiduc I. Review. Inverse coordination. Organic nitrogen heterocycles as coordination centers. A survey of molecular topologies and systematization. Part 2. Six-membered rings. J COORD CHEM 2019. [DOI: 10.1080/00958972.2019.1670349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Ionel Haiduc
- Facultatea de Chimie, Universitatea Babeş-Bolyai, Cluj-Napoca, Romania
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Grupp A, Bubrin M, Ehret F, Kvapilová H, Záliš S, Kaim W. Oxidation and reduction response of α-diimine complexes with tricarbonylrhenium halides and pseudohalides. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2013.08.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Tsurugi H, Tanahashi H, Nishiyama H, Fegler W, Saito T, Sauer A, Okuda J, Mashima K. Salt-Free Reducing Reagent of Bis(trimethylsilyl)cyclohexadiene Mediates Multielectron Reduction of Chloride Complexes of W(VI) and W(IV). J Am Chem Soc 2013; 135:5986-9. [DOI: 10.1021/ja401589a] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hayato Tsurugi
- Department of Chemistry, Graduate
School of Engineering Science, Osaka University, and CREST, JST, Toyonaka, Osaka 560-8531, Japan
| | - Hiromasa Tanahashi
- Department of Chemistry, Graduate
School of Engineering Science, Osaka University, and CREST, JST, Toyonaka, Osaka 560-8531, Japan
| | - Haruka Nishiyama
- Department of Chemistry, Graduate
School of Engineering Science, Osaka University, and CREST, JST, Toyonaka, Osaka 560-8531, Japan
| | - Waldemar Fegler
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen,
Germany
| | - Teruhiko Saito
- Department of Chemistry, Graduate
School of Engineering Science, Osaka University, and CREST, JST, Toyonaka, Osaka 560-8531, Japan
| | - Andreas Sauer
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen,
Germany
| | - Jun Okuda
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen,
Germany
| | - Kazushi Mashima
- Department of Chemistry, Graduate
School of Engineering Science, Osaka University, and CREST, JST, Toyonaka, Osaka 560-8531, Japan
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Das A, Scherer TM, Mobin SM, Kaim W, Lahiri GK. Application of a Structure/Oxidation-State Correlation to Complexes of Bridging Azo Ligands. Chemistry 2012; 18:11007-18. [DOI: 10.1002/chem.201201049] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Indexed: 11/06/2022]
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Yin Z, Yan Y, Sun S, Wang W. Syntheses, structures, and properties of Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane. J COORD CHEM 2012. [DOI: 10.1080/00958972.2012.663493] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Zhenming Yin
- a College of Chemistry , Tianjin Key Laboratory of Structure and Performance for Functional Molecule, Tianjin Normal University , Tianjin 300387 , China
| | - Ying Yan
- a College of Chemistry , Tianjin Key Laboratory of Structure and Performance for Functional Molecule, Tianjin Normal University , Tianjin 300387 , China
| | - Shipeng Sun
- a College of Chemistry , Tianjin Key Laboratory of Structure and Performance for Functional Molecule, Tianjin Normal University , Tianjin 300387 , China
| | - Wuyan Wang
- a College of Chemistry , Tianjin Key Laboratory of Structure and Performance for Functional Molecule, Tianjin Normal University , Tianjin 300387 , China
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Drozdz A, Bubrin M, Fiedler J, Záliš S, Kaim W. (α-Diimine)tricarbonylhalorhenium complexes: the oxidation side. Dalton Trans 2012; 41:1013-9. [DOI: 10.1039/c1dt11449b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Roy S, Kubiak CP. Tricarbonylrhenium(i) complexes of highly symmetric hexaazatrinaphthylene ligands (HATN): structural, electrochemical and spectroscopic properties. Dalton Trans 2010; 39:10937-43. [DOI: 10.1039/c0dt00780c] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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