Iron(II) and ruthenium(II) complexes containing P, N, and H ligands

Structure, spectroscopy, electrochemistry, and reactivity

Jinzhu Chen, David J. Szalda, Etsuko Fujita, Carol Creutz

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The purpose of this work was to explore the possibility of using iron(II) hydrides in CO2 reduction and to compare their reactivity to that of their ruthenium analogues. Fe(bpy)(P(OEt)3)3H+ and Ru(bpy)(P(OEt)3)3H+ do not react with CO2 in acetonitrile, but the one-electron-reduction products of Ru(bpy)(P(OEt)3)3H+ and Ru(bpy) 2(P(OEt)3)H+ and the two-electron-reduction product of Fe(bpy)(P(OEt)3)3H+ do. Ru(bpy) 2(P(OEt)3)H+ also reacts slowly with CO 2 to give a formate complex [as reported previously by Albertin et al. (Inorg. Chem. 2004, 43, 1336)] with a second-order rate constant of ∼4 × 10-3 M-1 s-1 in methanol. The structures for the hydride complexes [Fe(bpy)(P(OEt)3) 3H]+ and [Ru(bpy)2(P(OEt)3)H] + and for the (η5-Cp)bis-and-tris-PTA complexes (PTA = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.13.7]decane) of iron(II) are reported. These and the CpFe(CO)(bpy)+ and FeIIPNNP compounds have been subjected to electrochemical and UV-vis spectroscopic characterization. Fe(bpy)(P(OEt)3)3H+ exhibits a quasireversible oxidation at +0.42 V vs AgCl/Ag in acetonitrile; Ru(bpy)(P(OEt) 3)3H+ and Ru(bpy)2(P(OEt) 3)H+ are oxidized irreversibly at +0.90 and +0.55 V, respectively, vs AgCl/Ag. The reduction site for Fe(bpy)(P(OEt) 3)3H+ and Fe(bpy)(P(OEt)3) 3(CH3CN)2+ appears to be the metal and gives rise to a two-electron process. The bpy-centered reductions are negatively shifted in the ruthenium(II) hydride complexes, compared to the acetonitrile complexes. The results of attempts to prepare other iron(II) hydrides are summarized.

Original languageEnglish
Pages (from-to)9380-9391
Number of pages12
JournalInorganic Chemistry
Volume49
Issue number20
DOIs
Publication statusPublished - Oct 18 2010

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Ruthenium
Electrochemistry
electrochemistry
ruthenium
Iron
reactivity
Hydrides
hydrides
Spectroscopy
Ligands
iron
ligands
acetonitrile
formic acid
spectroscopy
Carbon Monoxide
Electrons
electrons
formates
products

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Iron(II) and ruthenium(II) complexes containing P, N, and H ligands : Structure, spectroscopy, electrochemistry, and reactivity. / Chen, Jinzhu; Szalda, David J.; Fujita, Etsuko; Creutz, Carol.

In: Inorganic Chemistry, Vol. 49, No. 20, 18.10.2010, p. 9380-9391.

Research output: Contribution to journalArticle

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abstract = "The purpose of this work was to explore the possibility of using iron(II) hydrides in CO2 reduction and to compare their reactivity to that of their ruthenium analogues. Fe(bpy)(P(OEt)3)3H+ and Ru(bpy)(P(OEt)3)3H+ do not react with CO2 in acetonitrile, but the one-electron-reduction products of Ru(bpy)(P(OEt)3)3H+ and Ru(bpy) 2(P(OEt)3)H+ and the two-electron-reduction product of Fe(bpy)(P(OEt)3)3H+ do. Ru(bpy) 2(P(OEt)3)H+ also reacts slowly with CO 2 to give a formate complex [as reported previously by Albertin et al. (Inorg. Chem. 2004, 43, 1336)] with a second-order rate constant of ∼4 × 10-3 M-1 s-1 in methanol. The structures for the hydride complexes [Fe(bpy)(P(OEt)3) 3H]+ and [Ru(bpy)2(P(OEt)3)H] + and for the (η5-Cp)bis-and-tris-PTA complexes (PTA = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.13.7]decane) of iron(II) are reported. These and the CpFe(CO)(bpy)+ and FeIIPNNP compounds have been subjected to electrochemical and UV-vis spectroscopic characterization. Fe(bpy)(P(OEt)3)3H+ exhibits a quasireversible oxidation at +0.42 V vs AgCl/Ag in acetonitrile; Ru(bpy)(P(OEt) 3)3H+ and Ru(bpy)2(P(OEt) 3)H+ are oxidized irreversibly at +0.90 and +0.55 V, respectively, vs AgCl/Ag. The reduction site for Fe(bpy)(P(OEt) 3)3H+ and Fe(bpy)(P(OEt)3) 3(CH3CN)2+ appears to be the metal and gives rise to a two-electron process. The bpy-centered reductions are negatively shifted in the ruthenium(II) hydride complexes, compared to the acetonitrile complexes. The results of attempts to prepare other iron(II) hydrides are summarized.",
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