Unprecedented Inequivalent Metal Coordination Environments in a Mixed‐Ligand Dicobalt Complex

Cioncoloni, Giacomo; Sproules, Stephen; Wilson, Claire; Symes, Mark D.

doi:10.1002/ejic.201700803

Cited by 5 publications

(3 citation statements)

References 134 publications

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“…Inspired by the successful use of a particular benzimidazole-based dinucleating ligand, H N -Et-HPTB (where N -Et-HPTB is the anion of N , N , N ′, N ′-tetrakis[2-(1-ethylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane; Scheme ), in different aspects of various model diiron(II) complexes, ,,− we started using the ligand for the synthesis and reactivity study of Fe(II) and Co(II) complexes. While in general, a large number of Fe(II)/Co(II)–thiolate complexes are available in the literature, nonheme diiron(II)/dicobalt(II) complexes with bridging or free thiolates/thiocarboxylates are relatively less explored , and thus offer an opportunity to explore the synthetic aspects and reactivity of the later complexes in detail. In this line, we recently reported the reactivity study of carboxylate bridged diiron(II) complexes (using H N -Et-HPTB) in comparison with their thiolate bridged analogues .…”

Section: Introductionmentioning

confidence: 99%

C–S Bond Cleavage, Redox Reactions, and Dioxygen Activation by Nonheme Dicobalt(II) Complexes

Jana

Majumdar

2017

Inorg. Chem.

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Synthesis and reactivity of a series of thiolate/thiocarboxylate bridged dicobalt(II) complexes were investigated in comparison with their carboxylate bridged analogues bearing free thiol/hydroxyl groups. Upon one-electron oxidation, complexes [Co(N-Et-HPTB)(μ-SR)](BF) (R = Ph, 1a; Et, 1b; Py, 1c) and [Co(N-Et-HPTB)(μ-SCOR)](BF) (R = Ph, 2a; Me, 2b) yielded [Co(N-Et-HPTB)(DMF)](BF) (6) (DMF = dimethylformamide) along with the corresponding disulfides (where N-Et-HPTB is the anion of N,N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane). Unlike the inertness of carboxylate bridged complexes [Co(N-Et-HPTB)(μ-OC-R-SH)](BF) (R = Ph, 3a; CHCH, 3b) and [Co(N-Et-HPTB)(μ-OCR)](BF) (R = Ph, 4a; Me, 4b; CHCHCHOH, 5) toward O, the bridging ethanethiolate in 1b was oxidized to yield a sulfinate bridged complex, [Co(N-Et-HPTB)(μ-OSEt)](BF) (10). Detailed investigation of the synthetic aspects of 1a-1c led to the discovery of a C-S bond cleavage reaction and yielded the dicobalt(II) complexes [Co(N-Et-HPTB)(SH)(HO)](BF) (8a), [Co(N-CHPy-HPTB)(SH)(HO)](BF) (8b) (where N-CHPy-HPTB is the anion of N,N,N',N'-tetrakis[2-(1-picolylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane)), and [Co(N-Et-HPTB)(μ-S)](BF) (9). Both 8a and 8b feature nonheme dinuclear Co(II) units containing a terminal hydrosulfide. The present study thus reports comparative redox reactions for a rare class of 16 dicobalt(II) complexes and introduces a selective synthetic strategy for the synthesis of unprecedented dicobalt(II) complexes featuring only one terminal hydrosulfide.

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Section: Introductionmentioning

confidence: 99%

C–S Bond Cleavage, Redox Reactions, and Dioxygen Activation by Nonheme Dicobalt(II) Complexes

Jana

Majumdar

2017

Inorg. Chem.

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“…In the course of our own studies into the various electronic and spectroscopic properties of cobalt coordination complexes containing diimine ligands (31,32), we became intrigued by the effect of bulky substituents close to the diimine N-donor atoms and how this might affect the assembly of the resulting structures and their redox properties. In particular, we were interested to know whether having methyl substituents adjacent to the N-donor would prevent the formation of tris-and/or bis-diimine complexes of Co(II) for steric reasons, and in probing whether the cobalt centres in any of these complexes (if they could form at all) would be amenable to oxidation to Co(III).…”

Section: Introductionmentioning

confidence: 99%

Probing the effects of steric bulk on the solution-phase behaviour and redox chemistry of cobalt-diimine complexes

Symes

Wilson

2017

Supramolecular Chemistry

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Cobalt-diimine complexes have been used as structural and redox-active elements in a number of supramolecular assemblies. Frequently, it is necessary to functionalise the diimine ligand in order to incorporate it into a larger ensemble, and this can have a dramatic effect on the types of Co-diimine complexes that can form and their redox activity. Herein, we compare the solution-phase and redox chemistry of Co(II) complexes with 1,10-phenanthroline, 5,5′-dimethyl-2,2′-bipyridine and 2,9-dimethyl-1,10-phenanthroline (neocuproine), and show that in solutions containing Co(II) nitrate and neocuproine, the dominant species that forms is the mono-diimine complex [Co(neocuproine)(NO3)(CH3CN)2] +. The mono-neocuproine Co(II) complex is resistant to oxidation, either electrochemically or with iodine. We rationalise this behaviour by considering the steric constraints placed upon the metal centre by the bulky methyl substituents on the neocuproine ligand. Furthermore, from solutions of [Co(neocuproine)(NO3)(CH3CN)2] + , we isolate (and determine the structure of) crystals 2 of formula [Co(neocuproine)2(NO3)] + •[Co(neocuproine)(NO3)3] − for the first time. We believe that this work will help to guide the development of Co-diimine supramolecular assemblies by highlighting the extent to which substituents close to the N-donor atoms can affect which species form in solution, and their likely redox activity.

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“…The lively topic of coordination chemistry of synthetic macrocycles originated during the 1960s, in which the Co(II) ion was employed as a templating agent 8 . Condensation between carbonyl group with primary amine has played an important role in the development of synthetic macrocyclic ligands [9][10][11][12][13][14][15] . Due to the growing interest in macrocyclic ligands and their transition metal complexes we report here the synthesis, spectral characterization and antifungal studies of Co(II)complexes with macrocyclic ligands 2,7,9,14-tetrahydroxy phenyl-1, 3, 6, 8, 10, 13-hexaazacyclooctadecane (L 1 ) and 2, 7, 9, 14-tetracyclohexane-1,3,6,8, 10, 13-hexaazacyclo-octadecane (L 2 ).…”

Section: Introductionmentioning

confidence: 99%

Biological Studies, Synthesis and Spectral Characterization of Nitrogen Donor Macrocyclic Co(II) Complexes

Kataria¹,

BHAYANA²

2017

juc

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New Co(II) complexes with macrocyclic ligands 2, 7, 9, 14-tetrahydroxy phenyl-1, 3, 6, 8, 10, 13-hexaazacyclooctadecane (L 1 ), 2, 7, 9, 14-tetracyclohexane-1, 3, 6, 8, 10, 13-hexaazacyclo octadecane(L 2 ) have been synthesized by template method. The structure of complexes was determined by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, IR and electronic spectral studies. Based on the analytical analysis i.e. molar conductance the complexes were found to be non-electrolytic in nature except the complexes [Co(L . Magnetic moment and the electronic spectra of the complexes suggest that the ligands coordinate to metal ion via four donor sites to give six coordinate complexes having octahedral geometry except [Co(L 1,2 )] (NO 3 ) 2 ] which is four coordinated tetrahedral geometry. Food Poison Technique was employed for screening the in vitro antifungal studies of the complexes. The complexes were also examined for antifungal studies against pathogenic strains like Alternaria brassicae, Fusarium moniliformae, Rhizoctonia solani.

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Unprecedented Inequivalent Metal Coordination Environments in a Mixed‐Ligand Dicobalt Complex

Cited by 5 publications

References 134 publications

C–S Bond Cleavage, Redox Reactions, and Dioxygen Activation by Nonheme Dicobalt(II) Complexes

C–S Bond Cleavage, Redox Reactions, and Dioxygen Activation by Nonheme Dicobalt(II) Complexes

Probing the effects of steric bulk on the solution-phase behaviour and redox chemistry of cobalt-diimine complexes

Biological Studies, Synthesis and Spectral Characterization of Nitrogen Donor Macrocyclic Co(II) Complexes

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