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Observation of proton-transfer-coupled spin transition by single-crystal neutron-diffraction measurement.

Takumi NakanishiYuta HoriYasuteru ShigetaHiroyasu SatoShu-Qi WuRyoji KiyanagiKoji MunakataTakashi OhharaOsamu Sato
Published in: Physical chemistry chemical physics : PCCP (2023)
The application of single-crystal neutron diffraction (SCND) to observe proton-transfer phenomena in crystalline compounds exhibiting unusual protonation states or proton dynamics has garnered significant research interest in recent years. However, proton tautomerism, which results in different protonation states before and after proton transfer, has never been observed using the SCND technique. Thus, to observe the proton tautomerism phenomenon by SCND measurements, we developed an iron(II) complex that forms a large crystal and exhibits a proton-transfer-coupled spin transition (PCST). The presence of the two types of proton tautomers was determined by conventional analysis of the proton position by X-ray crystallography, infrared spectroscopy, and density functional theory calculations. Finally, our results confirmed that proton tautomerism was successfully observed for the first time using variable-temperature SCND measurements.
Keyphrases
  • density functional theory
  • electron transfer
  • molecular dynamics
  • room temperature
  • high resolution
  • computed tomography
  • mass spectrometry
  • ionic liquid
  • transition metal