Proton Transfer versus Hydrogen Bonding in a Reduced Iron Porphyrin Nitrosyl Complex

Md Hafizur Rahman; Yilin Liu; Michael D Ryan

doi:10.1021/acs.inorgchem.9b01447

Proton Transfer versus Hydrogen Bonding in a Reduced Iron Porphyrin Nitrosyl Complex

Inorg Chem. 2019 Oct 21;58(20):13788-13795. doi: 10.1021/acs.inorgchem.9b01447. Epub 2019 Sep 30.

Authors

Md Hafizur Rahman¹, Yilin Liu¹, Michael D Ryan¹

Affiliation

¹ Chemistry Department , Marquette University , PO Box 1881, Milwaukee , Wisconsin 53201 , United States.

PMID: 31565930
DOI: 10.1021/acs.inorgchem.9b01447

Abstract

The ¹H NMR spectra of Fe(OEP)(HNO), which was formed from Fe(OEP)(NO)^- in the presence of 3,5-dichlorophenol, were studied as a function of temperature. The chemical shift of the HNO proton showed a unique behavior which could be explained based on the equilibrium between the protonated complex, Fe(OEP)(HNO), and the hydrogen-bonded complex, Fe(OEP)(NO)^-···HOPh. This equilibrium was consistent with UV/visible spectroscopy and the voltammetric data. UV/visible stopped-flow experiments showed that the hydrogen-bonded complex, which was formed when weak acids such as phenol were added, and the Fe(OEP)(HNO) complex were quite similar. In addition to the HNO proton resonance, the meso-resonances were consistent with the proposed equilibrium. Density functional theory calculations of various Fe(OEP)(NO)^-/Fe(OEP)(HNO) species were calculated, and the results were consistent with experimental data.