An unusual but informative synthesis and the crystal structure of [Co(tpaCO2)Cl](ClO4) (tpaCO2−=6-carboxylato-2- (pyridylmethyl)-bis(2-pyridylmethyl)amine)

Lonnon, David G.; Craig, Donald C.; Colbran, Stephen B.

doi:10.1016/j.inoche.2003.08.001

Cited by 12 publications

(4 citation statements)

References 16 publications

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“…Hence, although acid was added to the crystallization medium, there is no evidence that the complex is protonated under these conditions. We note that Kojima and co-workers have previously noted the tendency for this carboxylate group to coordinate to the metal center in their allied Ru and Cr complexes, , and Lonnon et al have similarly reported a Co(III) complex of ligand 2 in which the carboxylate group also coordinates to the metal center, giving a distorted-octahedral geometry at the metal …”

Section: Resultsmentioning

confidence: 58%

“…We note that Kojima and co-workers have previously noted the tendency for this carboxylate group to coordinate to the metal center in their allied Ru and Cr complexes, 76,77 and Lonnon et al have similarly reported a Co(III) complex of ligand 2 in which the carboxylate group also coordinates to the metal center, giving a distorted-octahedral geometry at the metal. 85 The geometry around the copper center in [4-NO 2 ] is probably best described as distorted octahedral, with a Jahn− Teller elongation along the N1−Cu−O1 axis. This leads to a rather long Cu−N1 distance (2.384(2) Å), while the Cu− N pyridyl lengths are all significantly shorter (2.047(2)−2.031(2) Å) and more similar to the Cu−N1N distance between the copper center and the bound nitrite (1.983(3) Å).…”

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confidence: 99%

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Proton-Coupled Electron Transfer Enhances the Electrocatalytic Reduction of Nitrite to NO in a Bioinspired Copper Complex

et al. 2018

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The selective and efficient electrocatalytic reduction of nitrite to nitric oxide (NO) is of tremendous importance, both for the development of NO-release systems for biomedical applications and for the removal of nitrogen oxide pollutants from the environment. In nature, this transformation is mediated by (among others) enzymes known as the copper-containing nitrite reductases. The development of synthetic copper complexes that can reduce nitrite to NO has therefore attracted considerable interest. However, there are no studies describing the crucial role of proton-coupled electron transfer during nitrite reduction when such synthetic complexes are used. Herein, we describe the synthesis and characterization of two previously unreported Cu complexes (3 and 4) for the electrocatalytic reduction of nitrite to NO, in which the role of proton-relaying units in the secondary coordination sphere of the metal can be probed. Complex 4 bears a pendant carboxylate group in close proximity to the copper center, while complex 3 lacks such functionality. Our results suggest that complex 4 is twice as effective an electrocatalyst for nitrite reduction than is complex 3 and that complex 4 is the best copper-based molecular electrocatalyst for this reaction yet discovered. The differences in reactivity between 3 and 4 are probed using a range of electrochemical, spectroscopic, and computational methods, which shed light on the possible catalytic mechanism of 4 and implicate the proton-relaying ability of its pendant carboxylate group in the enhanced reactivity that this complex displays. These results highlight the critical role of proton-coupled electron transfer in the reduction of nitrite to NO and have important implications for the design of biomimetic catalysts for the selective interconversions of the nitrogen oxides.

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Section: Resultsmentioning

confidence: 58%

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confidence: 99%

Proton-Coupled Electron Transfer Enhances the Electrocatalytic Reduction of Nitrite to NO in a Bioinspired Copper Complex

et al. 2018

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“…The Co-N (tertiary amine nitrogen) bond distances are unusually long (2.200 Å and 2.199 Å) compared to those in other compounds with similar coordination spheres (octahedral Co(II) with four nitrogen donor atoms, one oxygen donor atom and one chloride ion), which are on average 1.952 Å. 19,20 The distances between the cobalt centres and the nearest disulfide sulfur atom are around 5.8 Å, which is slightly shorter than in [1 SS ] (5.961 and 5.937 Å). The structure does not contain hydrogen bonds, but a short intermolecular contact of 3.340 Å between the methylated pyridine ring and the neighbouring non-methylated pyridine ring indicates the presence of π-π stacking interactions.…”

Section: Dalton Transactions Papermentioning

confidence: 86%

Cleaner and stronger: how 8-quinolinolate facilitates formation of Co(iii)–thiolate from Co(ii)–disulfide complexes

et al. 2022

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“…Alternatively, the hemiaminal can be overoxidized into an amide intermediate (path B), 34 which can potentially be hydrolyzed into a picolinic acid (path C), as reported by Browne 40 and others. 28,41,42 Efforts have been taken in order to prevent deleterious oxidations on the 2-pyridinylmethylene sites in N2Py2 ligands. For example, Britovsek et al proposed to introduce a methyl group or a carbonyl linkage at the 2pyridinylmethylene positions in the BPMEN ligand.…”

Section: ■ Introductionmentioning

confidence: 99%

Deuterated N2Py2 Ligands: Building More Robust Non-Heme Iron Oxidation Catalysts

Chen

Gebbink

2019

ACS Catal.

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Fe(N2Py2)/H 2 O 2 /AcOH catalytic systems provide powerful tools for efficient C−H and CC bond oxidations (N2Py2 = bis-alkylamine-bis-pyridine ligand). Yet, the stability of these catalysts under the oxidizing conditions still remains a problem. The generally accepted catalyst decomposition pathway of Fe(N2Py2) complexes is through oxidative dimerization to form inactive oxo-bridged Fe 2 (μ-O)(N2Py2) 2 dimers. Detailed ESI-MS analysis has now shown a catalyst decomposition pathway of ligand oxidation via C−H oxidation on the 2-pyridinylmethylene sites, followed by dissociation of the oxidized ligand from the iron center. By deuterating the 2-pyridinylmethylene sites of a series of N2Py2 ligands with variations on both alkylamine and pyridine fragments, providing access to the corresponding Fe(N2Py2-D 4 ) complexes, longer catalysts lifetimes are achieved in catalytic oxidation reactions with all complexes. As a consequence, improved substrate conversions and product yields were consistently observed in both aliphatic C−H oxidations and alkene epoxidations. Kinetic and catalytic studies revealed that deuteration does not change the intrinsic reactivity and product selectivity of Fe(N2Py2) complexes. In addition, different Fe(N2Py2-D 4 ) complexes provide different improvements in catalytic performances and lifetimes, responding to the differences in ligand rigidity and robustness of the corresponding nondeuterated N2Py2 ligands. Accordingly, these improvements are more pronounced for ligands with a more flexible bisalkylamine backbone. These observations provide insights into the development of more robust ligands for homogeneous oxidation catalysis.

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An unusual but informative synthesis and the crystal structure of [Co(tpaCO2)Cl](ClO4) (tpaCO2−=6-carboxylato-2- (pyridylmethyl)-bis(2-pyridylmethyl)amine)

Cited by 12 publications

References 16 publications

Proton-Coupled Electron Transfer Enhances the Electrocatalytic Reduction of Nitrite to NO in a Bioinspired Copper Complex

Proton-Coupled Electron Transfer Enhances the Electrocatalytic Reduction of Nitrite to NO in a Bioinspired Copper Complex

Cleaner and stronger: how 8-quinolinolate facilitates formation of Co(iii)–thiolate from Co(ii)–disulfide complexes

Deuterated N2Py2 Ligands: Building More Robust Non-Heme Iron Oxidation Catalysts

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