Evaluation of attractive interactions in the second coordination sphere of iron complexes containing pendant amines

Qian Liao, Tianbiao Liu, Samantha I. Johnson, Christina M. Klug, Eric Wiedner, R Morris Bullock, Daniel L DuBois

Research output: Contribution to journalArticle

Abstract

The interactions between pendant amines in the second coordination sphere and ligands in the first coordination sphere are important for understanding the structures and reactivity of complexes containing P R 2 N R′ 2 ligands, which have been shown to be highly active H 2 oxidation/production catalysts. A series of [Fe(P Ph 2 N Bn 2 ) 2 (X)(Y)] n+ complexes have been prepared and structurally characterized. These complexes have two different ligands with which the pendant amines of the diphosphine ligand can interact. The solid state structure of cis-Fe(P Ph 2 N Bn 2 ) 2 Cl 2 reveals that the six-membered rings adjacent to the P atoms are in a boat confirmation, resulting in close N⋯P distances that suggests the P atoms have a greater affinity for the lone pair of electrons on the N atom than chloride ligands. Similarly, boat conformations are observed for both rings adjacent to the hydride ligands of trans-[HFe(P Ph 2 N Bn 2 ) 2 (CH 3 CN)] + and trans-HFe(P Ph 2 N Bn 2 ) 2 Cl, resulting in short N⋯H distances. Spectroscopic and computational studies of trans-[HFe(P Ph 2 N Bn 2 ) 2 (CO)] + , trans-[HFe(P Ph 2 N Bn 2 )(P Ph 2 N Bn 2 H)(CO)] 2+ , and trans-[HFe(P Ph 2 N Bn 2 ) 2 (H 2 )] + indicate the complexes are more stable when the pendant amines in boat conformations are adjacent to the hydride ligand. These data suggest an attractor ordering of H - > CO > H 2 > PR 3 > Cl - ∼ CH 3 CN.

Original languageEnglish
Pages (from-to)4867-4878
Number of pages12
JournalDalton Transactions
Volume48
Issue number15
DOIs
Publication statusPublished - Jan 1 2019

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Amines
Iron
Ligands
Boats
Carbon Monoxide
Hydrides
Atoms
Conformations
Chlorides
Oxidation
Catalysts
Electrons

ASJC Scopus subject areas

  • Inorganic Chemistry

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Evaluation of attractive interactions in the second coordination sphere of iron complexes containing pendant amines. / Liao, Qian; Liu, Tianbiao; Johnson, Samantha I.; Klug, Christina M.; Wiedner, Eric; Bullock, R Morris; DuBois, Daniel L.

In: Dalton Transactions, Vol. 48, No. 15, 01.01.2019, p. 4867-4878.

Research output: Contribution to journalArticle

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abstract = "The interactions between pendant amines in the second coordination sphere and ligands in the first coordination sphere are important for understanding the structures and reactivity of complexes containing P R 2 N R′ 2 ligands, which have been shown to be highly active H 2 oxidation/production catalysts. A series of [Fe(P Ph 2 N Bn 2 ) 2 (X)(Y)] n+ complexes have been prepared and structurally characterized. These complexes have two different ligands with which the pendant amines of the diphosphine ligand can interact. The solid state structure of cis-Fe(P Ph 2 N Bn 2 ) 2 Cl 2 reveals that the six-membered rings adjacent to the P atoms are in a boat confirmation, resulting in close N⋯P distances that suggests the P atoms have a greater affinity for the lone pair of electrons on the N atom than chloride ligands. Similarly, boat conformations are observed for both rings adjacent to the hydride ligands of trans-[HFe(P Ph 2 N Bn 2 ) 2 (CH 3 CN)] + and trans-HFe(P Ph 2 N Bn 2 ) 2 Cl, resulting in short N⋯H distances. Spectroscopic and computational studies of trans-[HFe(P Ph 2 N Bn 2 ) 2 (CO)] + , trans-[HFe(P Ph 2 N Bn 2 )(P Ph 2 N Bn 2 H)(CO)] 2+ , and trans-[HFe(P Ph 2 N Bn 2 ) 2 (H 2 )] + indicate the complexes are more stable when the pendant amines in boat conformations are adjacent to the hydride ligand. These data suggest an attractor ordering of H - > CO > H 2 > PR 3 > Cl - ∼ CH 3 CN.",
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AU - Bullock, R Morris

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AB - The interactions between pendant amines in the second coordination sphere and ligands in the first coordination sphere are important for understanding the structures and reactivity of complexes containing P R 2 N R′ 2 ligands, which have been shown to be highly active H 2 oxidation/production catalysts. A series of [Fe(P Ph 2 N Bn 2 ) 2 (X)(Y)] n+ complexes have been prepared and structurally characterized. These complexes have two different ligands with which the pendant amines of the diphosphine ligand can interact. The solid state structure of cis-Fe(P Ph 2 N Bn 2 ) 2 Cl 2 reveals that the six-membered rings adjacent to the P atoms are in a boat confirmation, resulting in close N⋯P distances that suggests the P atoms have a greater affinity for the lone pair of electrons on the N atom than chloride ligands. Similarly, boat conformations are observed for both rings adjacent to the hydride ligands of trans-[HFe(P Ph 2 N Bn 2 ) 2 (CH 3 CN)] + and trans-HFe(P Ph 2 N Bn 2 ) 2 Cl, resulting in short N⋯H distances. Spectroscopic and computational studies of trans-[HFe(P Ph 2 N Bn 2 ) 2 (CO)] + , trans-[HFe(P Ph 2 N Bn 2 )(P Ph 2 N Bn 2 H)(CO)] 2+ , and trans-[HFe(P Ph 2 N Bn 2 ) 2 (H 2 )] + indicate the complexes are more stable when the pendant amines in boat conformations are adjacent to the hydride ligand. These data suggest an attractor ordering of H - > CO > H 2 > PR 3 > Cl - ∼ CH 3 CN.

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