Tuning a phosphine-substituted diimine ligand to afford an iron monocarbonyl complex

Chandrani Ghosh; Gavin C. Slater; Thomas L. Groy; Ryan J. Trovitch

doi:10.1016/j.poly.2024.116910

Tuning a phosphine-substituted diimine ligand to afford an iron monocarbonyl complex

Chandrani Ghosh, Gavin C. Slater, Thomas L. Groy, Ryan J. Trovitch

Molecular Sciences, School of (SMS)

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

Abstract

A series of low-valent iron complexes that feature a phosphine-substituted α-diimine (DI) ligand have been synthesized. Reduction of (^Ph2PPrDI)FeBr₂ with an excess of Na/Hg in the presence of carbon monoxide afforded the corresponding dicarbonyl complex, (^Ph2PPrDI)Fe(CO)₂. Through multinuclear NMR and single crystal X-ray diffraction analysis, this complex was found to possess a 3-coordinate DI ligand. Upon heating for 10 days at 110 °C while applying intermittent vacuum, (^Ph2PPrDI)Fe(CO)₂ was successfully converted to the corresponding monocarbonyl complex, (^Ph2PPrDI)Fe(CO), which was found to feature a tetradentate chelate. Similar reactivity was explored using the analogous bis(tert-butyl)phosphine-substituted ligand, ^tBu2PPrDI. Addition of this chelate to FeBr₂ afforded (^tBu2PPrDI)FeBr₂, and subsequent reduction yielded (^tBu2PPrDI)FeBr, which was found to possess a tridentate DI ligand by single crystal X-ray diffraction. Performing the reduction of (^tBu2PPrDI)FeBr₂ in the presence of CO afforded the corresponding dicarbonyl complex, (^tBu2PPrDI)Fe(CO)₂. Like aryl-substituted (^Ph2PPrDI)Fe(CO)₂, alkyl-substituted (^tBu2PPrDI)Fe(CO)₂ was found to feature a pendant phosphine arm. However, heating (^tBu2PPrDI)Fe(CO)₂ under vacuum did not allow for phosphine substitution and conversion to the corresponding monocarbonyl complex, highlighting the importance of phosphine π-acidity for substitution and the stabilization of low-valent iron.

Original language	English (US)
Article number	116910
Journal	Polyhedron
Volume	253
DOIs	https://doi.org/10.1016/j.poly.2024.116910
State	Published - May 1 2024

Keywords

Bromide compounds
Carbonyl compounds
Earth-abundant metal
Ligand design
Substitution

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

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10.1016/j.poly.2024.116910

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title = "Tuning a phosphine-substituted diimine ligand to afford an iron monocarbonyl complex",

abstract = "A series of low-valent iron complexes that feature a phosphine-substituted α-diimine (DI) ligand have been synthesized. Reduction of (Ph2PPrDI)FeBr2 with an excess of Na/Hg in the presence of carbon monoxide afforded the corresponding dicarbonyl complex, (Ph2PPrDI)Fe(CO)2. Through multinuclear NMR and single crystal X-ray diffraction analysis, this complex was found to possess a 3-coordinate DI ligand. Upon heating for 10 days at 110 °C while applying intermittent vacuum, (Ph2PPrDI)Fe(CO)2 was successfully converted to the corresponding monocarbonyl complex, (Ph2PPrDI)Fe(CO), which was found to feature a tetradentate chelate. Similar reactivity was explored using the analogous bis(tert-butyl)phosphine-substituted ligand, tBu2PPrDI. Addition of this chelate to FeBr2 afforded (tBu2PPrDI)FeBr2, and subsequent reduction yielded (tBu2PPrDI)FeBr, which was found to possess a tridentate DI ligand by single crystal X-ray diffraction. Performing the reduction of (tBu2PPrDI)FeBr2 in the presence of CO afforded the corresponding dicarbonyl complex, (tBu2PPrDI)Fe(CO)2. Like aryl-substituted (Ph2PPrDI)Fe(CO)2, alkyl-substituted (tBu2PPrDI)Fe(CO)2 was found to feature a pendant phosphine arm. However, heating (tBu2PPrDI)Fe(CO)2 under vacuum did not allow for phosphine substitution and conversion to the corresponding monocarbonyl complex, highlighting the importance of phosphine π-acidity for substitution and the stabilization of low-valent iron.",

keywords = "Bromide compounds, Carbonyl compounds, Earth-abundant metal, Ligand design, Substitution",

author = "Chandrani Ghosh and Slater, {Gavin C.} and Groy, {Thomas L.} and Trovitch, {Ryan J.}",

note = "Publisher Copyright: {\textcopyright} 2024 Elsevier Ltd",

year = "2024",

month = may,

day = "1",

doi = "10.1016/j.poly.2024.116910",

language = "English (US)",

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journal = "Polyhedron",

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T1 - Tuning a phosphine-substituted diimine ligand to afford an iron monocarbonyl complex

AU - Ghosh, Chandrani

AU - Slater, Gavin C.

AU - Groy, Thomas L.

AU - Trovitch, Ryan J.

PY - 2024/5/1

Y1 - 2024/5/1

N2 - A series of low-valent iron complexes that feature a phosphine-substituted α-diimine (DI) ligand have been synthesized. Reduction of (Ph2PPrDI)FeBr2 with an excess of Na/Hg in the presence of carbon monoxide afforded the corresponding dicarbonyl complex, (Ph2PPrDI)Fe(CO)2. Through multinuclear NMR and single crystal X-ray diffraction analysis, this complex was found to possess a 3-coordinate DI ligand. Upon heating for 10 days at 110 °C while applying intermittent vacuum, (Ph2PPrDI)Fe(CO)2 was successfully converted to the corresponding monocarbonyl complex, (Ph2PPrDI)Fe(CO), which was found to feature a tetradentate chelate. Similar reactivity was explored using the analogous bis(tert-butyl)phosphine-substituted ligand, tBu2PPrDI. Addition of this chelate to FeBr2 afforded (tBu2PPrDI)FeBr2, and subsequent reduction yielded (tBu2PPrDI)FeBr, which was found to possess a tridentate DI ligand by single crystal X-ray diffraction. Performing the reduction of (tBu2PPrDI)FeBr2 in the presence of CO afforded the corresponding dicarbonyl complex, (tBu2PPrDI)Fe(CO)2. Like aryl-substituted (Ph2PPrDI)Fe(CO)2, alkyl-substituted (tBu2PPrDI)Fe(CO)2 was found to feature a pendant phosphine arm. However, heating (tBu2PPrDI)Fe(CO)2 under vacuum did not allow for phosphine substitution and conversion to the corresponding monocarbonyl complex, highlighting the importance of phosphine π-acidity for substitution and the stabilization of low-valent iron.

AB - A series of low-valent iron complexes that feature a phosphine-substituted α-diimine (DI) ligand have been synthesized. Reduction of (Ph2PPrDI)FeBr2 with an excess of Na/Hg in the presence of carbon monoxide afforded the corresponding dicarbonyl complex, (Ph2PPrDI)Fe(CO)2. Through multinuclear NMR and single crystal X-ray diffraction analysis, this complex was found to possess a 3-coordinate DI ligand. Upon heating for 10 days at 110 °C while applying intermittent vacuum, (Ph2PPrDI)Fe(CO)2 was successfully converted to the corresponding monocarbonyl complex, (Ph2PPrDI)Fe(CO), which was found to feature a tetradentate chelate. Similar reactivity was explored using the analogous bis(tert-butyl)phosphine-substituted ligand, tBu2PPrDI. Addition of this chelate to FeBr2 afforded (tBu2PPrDI)FeBr2, and subsequent reduction yielded (tBu2PPrDI)FeBr, which was found to possess a tridentate DI ligand by single crystal X-ray diffraction. Performing the reduction of (tBu2PPrDI)FeBr2 in the presence of CO afforded the corresponding dicarbonyl complex, (tBu2PPrDI)Fe(CO)2. Like aryl-substituted (Ph2PPrDI)Fe(CO)2, alkyl-substituted (tBu2PPrDI)Fe(CO)2 was found to feature a pendant phosphine arm. However, heating (tBu2PPrDI)Fe(CO)2 under vacuum did not allow for phosphine substitution and conversion to the corresponding monocarbonyl complex, highlighting the importance of phosphine π-acidity for substitution and the stabilization of low-valent iron.

KW - Bromide compounds

KW - Carbonyl compounds

KW - Earth-abundant metal

KW - Ligand design

KW - Substitution

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U2 - 10.1016/j.poly.2024.116910

DO - 10.1016/j.poly.2024.116910

M3 - Article

SN - 0277-5387

VL - 253

JO - Polyhedron

JF - Polyhedron

M1 - 116910

ER -

Tuning a phosphine-substituted diimine ligand to afford an iron monocarbonyl complex

Abstract

Keywords

ASJC Scopus subject areas

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