Metal ion complexes of 2-pyridylcarbinol N-oxide

Boyd, Stephen A.; Kohrman, Robert E.; West, Douglas X.

doi:10.1016/0022-1902(76)80644-6

Cited by 28 publications

(2 citation statements)

References 16 publications

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“…24,25 IR spectra showed that the N−O stretching frequencies for the N-oxides have shifted to lower values after complexation, indicating their bonding through the N-oxide O atom. 20,23,25 quinoxalinecarboxylic acid with Cu II , 21 2-picolinate N-oxide with Fe III , Cu II and Zn II , 26 2-pyridylcarbinol N-oxide with a number of metal ions, 27 and 2-picolinic acid N-oxide with lanthanides. 28 In addition, 5-or 7-membered rings are able to form with metals through the N or O atoms on the non-Noxide side chains, such as complexes between Cu II and N-(3hydroxypropyl)glycinamide, and between Cu II and N-(3hydroxypropyl)-DL-alaninamide.…”

Section: ■ Introductionmentioning

confidence: 99%

“…First, the N -oxide O atom can directly complex with the transition metal. − For example, simple aromatic N -oxides such as pyridine N -oxide has been reported to form complex with Fe II . Co II and Ni II complexes with a series of substituted quinoline N -oxides have been investigated. , IR spectra showed that the N–O stretching frequencies for the N -oxides have shifted to lower values after complexation, indicating their bonding through the N -oxide O atom. ,, Second, 6-membered chelate rings form between metals and N -oxides via the N -oxide O atom and a neighboring O or N atom, such as the bidentate chelates of 2-quinoxalinecarboxylic acid with Cu II , 2-picolinate N -oxide with Fe III , Cu II and Zn II , 2-pyridylcarbinol N -oxide with a number of metal ions, and 2-picolinic acid N -oxide with lanthanides . In addition, 5- or 7-membered rings are able to form with metals through the N or O atoms on the non- N -oxide side chains, such as complexes between Cu II and N-(3-hydroxypropyl)glycinamide, and between Cu II and N-(3-hydroxypropyl)- dl -alaninamide .…”

Section: Introductionmentioning

confidence: 99%

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Complexation Facilitated Reduction of AromaticN-Oxides by Aqueous Fe^II–Tiron Complex: Reaction Kinetics and Mechanisms

Zhang

2013

Environ. Sci. Technol.

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Rapid reduction of carbadox (CDX), olaquindox and several other aromatic N-oxides were investigated in aqueous solution containing Fe(II) and tiron. Consistent with previous work, the 1:2 Fe(II)-tiron complex, FeL2(6-), is the dominant reactive species as its concentration linearly correlates with the observed rate constant kobs under various conditions. The N-oxides without any side chains were much less reactive, suggesting direct reduction of the N-oxides is slow. UV-vis spectra suggest FeL2(6-) likely forms 5- or 7-membered rings with CDX and olaquindox through the N and O atoms on the side chain. The formed inner-sphere complexes significantly facilitated electron transfer from FeL2(6-) to the N-oxides. Reduction products of the N-oxides were identified by HPLC/QToF-MS to be the deoxygenated analogs. QSAR analysis indicated neither the first electron transfer nor N-O bond cleavage is the rate-limiting step. Calculations of the atomic spin densities of the anionic N-oxides confirmed the extensive delocalization between the aromatic ring and the side chain, suggesting complex formation can significantly affect the reduction kinetics. Our results suggest the complexation facilitated N-oxide reduction by Fe(II)-tiron involves a free radical mechanism, and the subsequent deoxygenation might also benefit from the weak complexation of Fe(II) with the N-oxide O atom.

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