Studies of Low-Coordinate Iron Dinitrogen Complexes

Description:

This article discusses low-coordinate iron dinitrogen complexes. Understanding the interaction of N₂ with iron is relevant to the iron catalyst used in the Haber process and to possible roles of the FeMoco active site of nitrogenase.

Creator(s):
Creation Date: December 31, 2005
Partner(s):
UNT College of Arts and Sciences
Collection(s):
UNT Scholarly Works
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Smith, Jeremy M.

University of Rochester; New Mexico State University

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Sadique, Azwana R.

University of Rochester

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Cundari, Thomas R., 1964-

University of North Texas

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Rodgers, Kenton R.

North Dakota State University

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Lukat-Rodgers, Gudrun

North Dakota State University

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Lachicotte, Rene J.

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Flaschenriem, Christine J.

University of Rochester

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Vela, Javier

University of Rochester

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Holland, Patrick L.

University of Rochester

Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, D.C.]
Date(s):
  • Creation: December 31, 2005
Description:

This article discusses low-coordinate iron dinitrogen complexes. Understanding the interaction of N₂ with iron is relevant to the iron catalyst used in the Haber process and to possible roles of the FeMoco active site of nitrogenase.

Degree:
Department: Chemistry
Note:

Reprinted with permission from the Journal of the American Chemical Society. Copyright 2005 American Chemical Society.

Note:

Abstract: The work reported here uses synthetic compounds to evaluate the extent of NN weakening in low-coordinate iron complexes with an FeNNFe core. The steric effects, oxidation level, presence of alkali metals, and coordination number of the iron atoms are varied, to gain insight into the factors that weaken the NN bond. Diiron complexes with a bridging N2 ligand, LRFeNNFeLR (LR = β-diketiminate; R = Me, tBu), result from reduction of [LRFeCl]n under a dinitrogen atmosphere, and an iron(I) precursor of an N2 complex can be observed. X-ray crystallographic and resonance Raman data for LRFeNNFeLR show a reduction in the N-N bond order, and calculations (density functional and multireference) indicate that the bond weakening arises from cooperative back-bonding into the N2 π* orbitals. Increasing the coordination number of iron from three to four through binding of pyridines gives compounds with comparable N-N weakening, and both are substantially weakened relative to five-coordinate iron-N2 complexes, even those with a lower oxidation state. Treatment of LRFeNNFeLR with KC8 gives K2LRFeNNFeLR, and calculations indicate that reduction of the iron and alkali metal coordination cooperatively weaken the N-N bond. The complexes LRFeNNFeLR react as iron(I) fragments, losing N2 to yield iron(I) phosphine, CO, and benzene complexes. They also reduce ketones and aldehydes to give the products of pinacol coupling. The K2LRFeNNFeLR compounds can be alkylated at iron, with loss of N2.

Physical Description:

14 p.

Language(s):
Subject(s):
Keyword(s): low-coordinate iron | dinitrogen complexes
Source: Journal of the American Chemical Society, 2005, Washington DC: American Chemical Society, pp. 756-769
Partner:
UNT College of Arts and Sciences
Collection:
UNT Scholarly Works
Identifier:
  • DOI: 10.1021/ja052707x |
  • ARK: ark:/67531/metadc77137
Resource Type: Article
Format: Text
Rights:
Access: Public
Citation:
Publication Title: Journal of the American Chemical Society
Volume: 128
Page Start: 756
Page End: 769
Pages: 14
Peer Reviewed: Yes