Probing Hydrogen Bonding Interactions to Iron‐Oxido/Hydroxido Units by 57Fe Nuclear Resonance Vibrational Spectroscopy

• Published in: Angewandte Chemie Vol. 130; no. 49; pp. 16242 - 16246
• Main Authors: Weitz, Andrew C., Hill, Ethan A., Oswald, Victoria F., Bominaar, Emile L., Borovik, Andrew S., Hendrich, Michael P., Guo, Yisong
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 03-12-2018
• Subjects: 57Fe-Kernresonanz-Schwingungsspektroskopie; C-H-Aktivierung; Chemistry; Coordination compounds; Hydrogen bonding; Hydrogen bonds; Intermediates; Iron; Iron 57; Nichthäm-Eisen-Oxo/Hydroxo-Komplexe; Organic chemistry; Resonance; Sekundäre Koordinationssphäre; Spectroscopy; Spectrum analysis; Vibrations; Wasserstoffbrücken
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201810227

Hydrogen bonds (H‐bonds) have been shown to modulate the chemical reactivities of iron centers in iron‐containing dioxygen‐activating enzymes and model complexes. However, few examples are available that investigate how systematic changes in intramolecular H‐bonds within the secondary coordination sphere influence specific properties of iron intermediates, such as iron‐oxido/hydroxido species. Here, we used 57Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the Fe‐O/OH vibrations in a series of FeIII‐hydroxido and FeIV/III‐oxido complexes with varying H‐bonding networks but having similar trigonal bipyramidal primary coordination spheres. The data show that even subtle changes in the H‐bonds to the Fe‐O/OH units result in significant changes in their vibrational frequencies, thus demonstrating the utility of NRVS in studying the effect of the secondary coordination sphere to the reactivities of iron complexes.
Die Stärke von H‐Brücken zu Eisen(III)‐Oxido/Hydroxido‐Einheiten (FeIII‐O/OH) in Nichthäm‐Eisenkomplexen wurde durch 57Fe‐Kernresonanz‐Schwingungsspektroskopie ermittelt. Die Messungen geben Einblick in den Einfluss von Wasserstoffbrücken in der sekundären Koordinationssphäre auf die Stabilität von FeIII‐O/OH‐Einheiten sowie in die Reaktivität von FeIV‐O‐Einheiten.