Mössbauer Spectroscopic Study on Hofmann-like Coordination Polymer Fe(4-Clpy)2[Ni(CN)4]

Abstract

57 Fe Mössbauer spectroscopic results on the 2D Hofmann-like coordination polymer Fe(4-Clpy)2Ni(CN)4 (sample 1) indicate that iron(II) ions are in a high spin state both at R.T. and T = 80 K, showing that the compound exhibits no spin crossover (SCO) behavior. Mössbauer spectra at R.T. and T = 80 K show one major doublet which corresponds to the HS1 is due to high spin iron(II) sites coordinated by four N atoms of cyano groups and two N atoms of 4-Clpy ligand in the sample 1. Two minor doublets coexisted in sample 1. One minor doublet with a large quadrupole splitting can be explained by the presence of defects in the coordination polymer frameworks. Another minor doublet is with a small quadrupole splitting, indicating the presence of iron(III) high spin species or iron(II) low spin species.

Effects of Both Methyl and Pyrimidine Groups in Fe–Ag Spin-Crossover Hofmann-Type Complex {Fe(4-Methylpyrimidine)2[Ag(CN)2]2}

“…To investigate the SCO phenomenon, 57 Fe Mössbauer spectroscopy can be successfully used owing to its sensitivity to the valence, spin state, and coordination environment. Thus, numerous Fe-type, Hofmann-type complexes have been investigated using this spectroscopic technique. − Following the first report on the Mössbauer effect of 191 Ir in 1958 by Mössbauer, Pound described in 1959 that effect in 57 Fe for the first time . Recently, we have investigated a Hofmann-type complex bearing a pyrimidine-type ligand, i.e., {Fe­(4-methylpyrimidine) 2 [Au­(CN) 2 ] 2 } ( 1Au ) .…”

Soft X-ray Absorption Spectroscopy Study of Spin Crossover Fe-Compounds: Persistent High Spin Configurations under Soft X-ray Irradiation

“…The SCO phenomena can be explored by various magnetic and spectroscopic techniques including magnetic susceptibility measurement, Mössbauer spectroscopy [28,29], optical absorption and X-ray absorption spectroscopy (XAS) [4,30,31]. In those experimental techniques, external stimuli are applied to the specimen in order to observe the responses related to the spin states.…”

Local Coordination and Electronic Structure Ramifications of Guest-Dependent Spin Crossover in a Metal–Organic Framework: A Combined X-ray Absorption and Emission Spectroscopy Study

“…Variable temperature magnetic susceptibility measurements clearly established the overall SCO behavior and in situ diffraction studies tracked the corresponding long-range structure changes in these SCOFs, yet these measurements do not fully capture local electronic and structural changes associated with spin transition at the Fe sites. Mossbauer spectroscopy is a valuable tool for studying Fe-based SCO systems, ,− but isotopic labeling, cryogenic temperatures, and/or very long data acquisition times are often required to produce the data quality needed for deeper electronic structure insight beyond spin state assignment, particularly for lower-concentration Fe samples.…”