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Title: Tuning a phosphine-substituted diimine ligand to afford an iron monocarbonyl complex
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.  more » « less
Award ID(s):
2154359
PAR ID:
10508498
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Polyhedron
Volume:
253
Issue:
C
ISSN:
0277-5387
Page Range / eLocation ID:
116910
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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