Syntheses, Reactivity and Molecular Structures of RSRS-[Ni(tmc)SC6H5](PF6), RRSS-[Ni(tmc)SC6H5](CF3SO3) and RRSS-[Ni(tmc)](CF3SO3) (tmc = 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane)

Ram, M. S.; Riordan, Charles G.; Ostrander, Robert L.; Rheingold, Arnold L.

doi:10.1021/ic00127a029

Cited by 73 publications

(94 citation statements)

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“…The crystal structure of RRSS-[Ni I (tmc)] (CF 3 SO 3 ) · NaCF 3 SO 3 shows that the geometry around the Ni I ion is exactly planar with two sets of Ni-N bond distances (209.5 and 212.0 pm), 76 analogous to the results for [Ni + has not, to our knowledge, been previously reported. However, the spectra for other fully saturated tetraaza macrocyclic complexes of electrochemically generated Ni I have been reported, such as with Me 2 [14]aneN 4 (g || = 2.261, g^ = 2.060) and Me 6 [14]aneN 4 (g || = 2.266, g^ = 2.055 in acetonitrile solution; g || = 2.253, g^ = 2.054 in propylene carbonate solution).…”

supporting

confidence: 80%

“…The final isolable tetraaza macrocyclic complex to be described is that of the fully saturated ligand 1,4,8,1l-tetramethyl-1,4,8,1l-tetraazacyclotetradecane (tetramethylcyclam, tmc, [14]ane(NMe) 4 76 however the solutions studied here contain both isomers, albeit in unknown proportion. At equilibrium in aqueous solution, the RRSS/RSRS ratio is roughly 3:1.…”

Section: Overview Of Case Studies Of Individual Ni Complexesmentioning

confidence: 99%

“…76,78 The relative amount of the two isomers in nitrile solutions is unknown, but at equilibrium is ca. 3:1 in aqueous solution, 78 so that the deconvolution into 69% major component and 31% two minor components is not that far off from the aqueous solution result.…”

mentioning

confidence: 99%

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Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Telser

2010

J. Braz. Chem. Soc.

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Complexos de cobre(II) (3d 9 , S = 1/2) são estáveis e amplamente investigados por espectroscopia de ressonância paramagnética eletrônica (EPR). Já o isoeletrônico níquel(I) é muito menos comum e muito menos estudado. No entanto, níquel(I) tem interesse biológico, uma vez que o sítio ativo da metil coenzima M redutase (MCR) , S = 1/2) complexes are stable and widely investigated by electron paramagnetic resonance (EPR) spectroscopy. In contrast, isoelectronic nickel(I) is much less common and much less investigated. Nickel(I), however, is of biological interest as the active site of methyl coenzyme M reductase (MCR) contains a tetraaza macrocyclic ligand, F 430 , which coordinates Ni I in its active form, MCR red1 . As result, the redox behavior and spectroscopy of tetraaza macrocyclic complexes of nickel is of importance in biomimetic chemistry. Such efforts are complicated by the difficulty in generating Ni I from their stable, Ni II , precursors. Reduction of Ni II macrocyclic complexes can afford Ni I in certain cases, but in many other cases can lead instead to reduction of the macrocycle to generate an organic radical anion. Previous studies on the formation of tetraaza macrocyclic complexes of Ni I are discussed in terms of the competition between metal-centered and ligandcentered reduction. EPR results are particularly important in making the distinction between these two reduction processes, as formation of Ni I gives characteristic EPR spectra similar to those for Cu II , while ligand-centered reduction gives narrow EPR spectra at g = 2.00, typical of organic radicals. Even if metal-centered reduction occurs, the geometry of the resulting Ni I macrocyclic complex is highly variable and, as a result, the EPR spectral appearance is highly variable. In this case, the comparison is between the extremes of spectra typical for tetragonally distorted complexes (dx2-y2 1 ground state, which includes tetragonally distorted octahedral, square pyramidal and square planar geometries) and those for trigonal bipyramidal complexes (dz2 1 ground state). Previous work on Cu II was related to the situation for Ni I . The different types of EPR spectra for such systems are specifically discussed using previously unpublished examples of several tetraaza macrocyclic complexes of nickel, including F 430 and MCR itself.

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confidence: 80%

Section: Overview Of Case Studies Of Individual Ni Complexesmentioning

confidence: 99%

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Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Telser

2010

J. Braz. Chem. Soc.

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“…Consequently, we turned our attention to macrocyclic tetradentate ligands that coordinate in a planar array, reasoning that such an attribute would render access to the m-h 2 ,h 2 -peroxo coordination more difficult. Herein, we report on the successful pursuit of this strategy, which led to the discovery of a Ni 2 (m-O 2 ) complex in which the peroxo moiety spans the metals in the m-1,2 mode.Addition of dry O 2 to [Ni(tmc)]OTf [8,9] (1; tmc = 1, 4,8,4,8, OTf = [CF 3 SO 3 ] À ) in THF or acetonitrile at room temperature resulted in a color change from pale blue to clover green. The FT-IR spectrum of the paramagnetic product (m eff = 2.7(1) m B ) included a prominent new feature at 3628 cm À1 assigned to the ñ(OÀH) mode…”

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confidence: 99%

Spectroscopic Elucidation of a Peroxo Ni₂(μ‐O₂) Intermediate Derived from a Nickel(I) Complex and Dioxygen

et al. 2004

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The preparative chemistry and reactivity of NiÀO x intermediates has advanced significantly in the past few years with the identification of a number of new structure types. The most common synthetic approach, reaction of a nickel(ii) precursor with H 2 O 2 , has yielded bis-m-oxo [1][2][3][4] and bis-msuperoxo complexes.[4] An attractive alternate route utilizes the reaction of nickel(i) complexes with O 2 . This strategy relies on, and is limited by, the ability to prepare suitable nickel(i) species. We have utilized this latter approach to[5] (PhTt tBu = phenyltris((tertbutylthio)methyl)borate) and the related side-on bound superoxo complex, [{PhTt Ad }Ni(O 2 )] (PhTt Ad = phenyltris((1-adamantylthio)methyl)borate).[6] During the course of these studies, we considered whether a m-peroxo Ni 2 species was a possible intermediate along the reaction trajectory leading to the bis-m-oxo dimer. Lacking experimental evidence, a m-h 2 ,h 2 -peroxo bridged Ni 2 dimer supported by the tris(thioether) borato ligand was evaluated by density functional methods. [7] This hypothetical species was deemed to be of high energy, significantly destabilized (DH8 = 32 kcalmol À1 ) relative to the bis-m-oxo dimer and, therefore, an unlikely intermediate. Consequently, we turned our attention to macrocyclic tetradentate ligands that coordinate in a planar array, reasoning that such an attribute would render access to the m-h 2 ,h 2 -peroxo coordination more difficult. Herein, we report on the successful pursuit of this strategy, which led to the discovery of a Ni 2 (m-O 2 ) complex in which the peroxo moiety spans the metals in the m-1,2 mode.Addition of dry O 2 to [Ni(tmc)]OTf [8,9] (1; tmc = 1, 4,8,4,8, OTf = [CF 3 SO 3 ] À ) in THF or acetonitrile at room temperature resulted in a color change from pale blue to clover green. The FT-IR spectrum of the paramagnetic product (m eff = 2.7(1) m B ) included a prominent new feature at 3628 cm À1 assigned to the ñ(OÀH) mode

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“…A flexibilidade do ligante é suficiente para permitir a ligação de ligantes exógenos nos sítios de coordenação axial 35 , além de favorecer processos redutivos centrados no metal, o que os diferencia de muitas porfirinas de níquel onde predominantemente se observam processos redutivos centrados no anel porfirínico, gerando espécies π-aniônicas 26 [14]anuleno, Figura 4), ou simplesmente chamados de dibenzotetraazaanulenos, são estudados desde há muito tempo, devido à sua semelhança estrutural com metaloporfirinas. Ambos, tetraazas e porfirinas, são ligantes dianiônicos conjugados com 4 nitrogênios como pontos coordenantes ao metal 36 .…”

Section: Complexos De Níquel(ii) Dibenzotetraazaanulenos (Nitmtaa)unclassified

Metil coenzima M redutase (MCR) e o fator 430 (F430)

Nakagaki¹,

Friedermann²,

Caiut³

2006

Quím. Nova

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Syntheses, Reactivity and Molecular Structures of RSRS-[Ni(tmc)SC6H5](PF6), RRSS-[Ni(tmc)SC6H5](CF3SO3) and RRSS-[Ni(tmc)](CF3SO3) (tmc = 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane)

Cited by 73 publications

References 2 publications

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Spectroscopic Elucidation of a Peroxo Ni₂(μ‐O₂) Intermediate Derived from a Nickel(I) Complex and Dioxygen

Metil coenzima M redutase (MCR) e o fator 430 (F430)

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Syntheses, Reactivity and Molecular Structures of RSRS-[Ni(tmc)SC6H5](PF6), RRSS-[Ni(tmc)SC6H5](CF3SO3) and RRSS-[Ni(tmc)](CF3SO3) (tmc = 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane)

Cited by 73 publications

References 2 publications

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Spectroscopic Elucidation of a Peroxo Ni2(μ‐O2) Intermediate Derived from a Nickel(I) Complex and Dioxygen

Metil coenzima M redutase (MCR) e o fator 430 (F430)

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Spectroscopic Elucidation of a Peroxo Ni₂(μ‐O₂) Intermediate Derived from a Nickel(I) Complex and Dioxygen