Redox transformations of bis(2,2′-bipyridine)(1-methyl-1-pyridin-2- yl-ethylamine)ruthenium(II)

Justin Neill; Anna S. Nam; Kevin M. Barley; Benjamin Meza; David N. Blauch

doi:10.1021/ic800483g

Redox transformations of bis(2,2′-bipyridine)(1-methyl-1-pyridin-2- yl-ethylamine)ruthenium(II)

Justin Neill, Anna S. Nam, Kevin M. Barley, Benjamin Meza, David N. Blauch

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

The amineruthenium(II) complex Ru(bpy)₂(mpea)²⁺ has been prepared by the direct reaction of 1-methyl-1-pyridin-2-yl-ethylamine (mpea) with Ru(bpy)₂Cl₂ in ethanol/water and isolated as the hexafluorophosphate salt. Electrochemical analysis of this complex shows that it undergoes sequential one-electron oxidations to an amidoruthenium(III) intermediate (E°′ = 1.086 V vs NHE) and then to an amidoruthenium(IV) (E°′ = 0.928 V) or imidoruthenium(IV) (E°′ = 1.083 V) complex, depending upon the solution pH (pK_a = 2.62 for the amidoruthenium(IV) species). At higher potentials (E_pa = 1.5 V in 1.0 M H₂SO₄), the amido- or imidoruthenium(IV) species is irreversibly oxidized to the corresponding nitrosoruthenium(II) complex. The mechanism for this transformation appears, on the basis of b3lyp/cpcm/cep-31g(d) computations, to proceed through an imidoruthenium(V) intermediate, which is rapidly attacked by water to yield a Ru(II)-bound hydroxylamine radical, which is readily oxidized and deprotonated to produce the nitrosoruthenium(II) complex. The nitrosoruthenium(II) complex is quantitatively reduced to the original [Ru(bpy)₂(mpea)]²⁺ complex at relatively negative potentials (E_pc = -0.2 V in 1.0 M H₂SO₄).

Original language	English (US)
Pages (from-to)	5314-5323
Number of pages	10
Journal	Inorganic Chemistry
Volume	47
Issue number	12
DOIs	https://doi.org/10.1021/ic800483g
State	Published - Jun 16 2008
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

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@article{834aee564456458b85f208654f0d300b,

title = "Redox transformations of bis(2,2′-bipyridine)(1-methyl-1-pyridin-2- yl-ethylamine)ruthenium(II)",

abstract = "The amineruthenium(II) complex Ru(bpy)2(mpea)2+ has been prepared by the direct reaction of 1-methyl-1-pyridin-2-yl-ethylamine (mpea) with Ru(bpy)2Cl2 in ethanol/water and isolated as the hexafluorophosphate salt. Electrochemical analysis of this complex shows that it undergoes sequential one-electron oxidations to an amidoruthenium(III) intermediate (E°′ = 1.086 V vs NHE) and then to an amidoruthenium(IV) (E°′ = 0.928 V) or imidoruthenium(IV) (E°′ = 1.083 V) complex, depending upon the solution pH (pKa = 2.62 for the amidoruthenium(IV) species). At higher potentials (Epa = 1.5 V in 1.0 M H2SO4), the amido- or imidoruthenium(IV) species is irreversibly oxidized to the corresponding nitrosoruthenium(II) complex. The mechanism for this transformation appears, on the basis of b3lyp/cpcm/cep-31g(d) computations, to proceed through an imidoruthenium(V) intermediate, which is rapidly attacked by water to yield a Ru(II)-bound hydroxylamine radical, which is readily oxidized and deprotonated to produce the nitrosoruthenium(II) complex. The nitrosoruthenium(II) complex is quantitatively reduced to the original [Ru(bpy)2(mpea)]2+ complex at relatively negative potentials (Epc = -0.2 V in 1.0 M H2SO4).",

author = "Justin Neill and Nam, {Anna S.} and Barley, {Kevin M.} and Benjamin Meza and Blauch, {David N.}",

year = "2008",

month = jun,

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doi = "10.1021/ic800483g",

language = "English (US)",

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pages = "5314--5323",

journal = "Inorganic Chemistry",

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T1 - Redox transformations of bis(2,2′-bipyridine)(1-methyl-1-pyridin-2- yl-ethylamine)ruthenium(II)

AU - Neill, Justin

AU - Nam, Anna S.

AU - Barley, Kevin M.

AU - Meza, Benjamin

AU - Blauch, David N.

PY - 2008/6/16

Y1 - 2008/6/16

N2 - The amineruthenium(II) complex Ru(bpy)2(mpea)2+ has been prepared by the direct reaction of 1-methyl-1-pyridin-2-yl-ethylamine (mpea) with Ru(bpy)2Cl2 in ethanol/water and isolated as the hexafluorophosphate salt. Electrochemical analysis of this complex shows that it undergoes sequential one-electron oxidations to an amidoruthenium(III) intermediate (E°′ = 1.086 V vs NHE) and then to an amidoruthenium(IV) (E°′ = 0.928 V) or imidoruthenium(IV) (E°′ = 1.083 V) complex, depending upon the solution pH (pKa = 2.62 for the amidoruthenium(IV) species). At higher potentials (Epa = 1.5 V in 1.0 M H2SO4), the amido- or imidoruthenium(IV) species is irreversibly oxidized to the corresponding nitrosoruthenium(II) complex. The mechanism for this transformation appears, on the basis of b3lyp/cpcm/cep-31g(d) computations, to proceed through an imidoruthenium(V) intermediate, which is rapidly attacked by water to yield a Ru(II)-bound hydroxylamine radical, which is readily oxidized and deprotonated to produce the nitrosoruthenium(II) complex. The nitrosoruthenium(II) complex is quantitatively reduced to the original [Ru(bpy)2(mpea)]2+ complex at relatively negative potentials (Epc = -0.2 V in 1.0 M H2SO4).

AB - The amineruthenium(II) complex Ru(bpy)2(mpea)2+ has been prepared by the direct reaction of 1-methyl-1-pyridin-2-yl-ethylamine (mpea) with Ru(bpy)2Cl2 in ethanol/water and isolated as the hexafluorophosphate salt. Electrochemical analysis of this complex shows that it undergoes sequential one-electron oxidations to an amidoruthenium(III) intermediate (E°′ = 1.086 V vs NHE) and then to an amidoruthenium(IV) (E°′ = 0.928 V) or imidoruthenium(IV) (E°′ = 1.083 V) complex, depending upon the solution pH (pKa = 2.62 for the amidoruthenium(IV) species). At higher potentials (Epa = 1.5 V in 1.0 M H2SO4), the amido- or imidoruthenium(IV) species is irreversibly oxidized to the corresponding nitrosoruthenium(II) complex. The mechanism for this transformation appears, on the basis of b3lyp/cpcm/cep-31g(d) computations, to proceed through an imidoruthenium(V) intermediate, which is rapidly attacked by water to yield a Ru(II)-bound hydroxylamine radical, which is readily oxidized and deprotonated to produce the nitrosoruthenium(II) complex. The nitrosoruthenium(II) complex is quantitatively reduced to the original [Ru(bpy)2(mpea)]2+ complex at relatively negative potentials (Epc = -0.2 V in 1.0 M H2SO4).

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EP - 5323

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 12

ER -

Redox transformations of bis(2,2′-bipyridine)(1-methyl-1-pyridin-2- yl-ethylamine)ruthenium(II)

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