Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

Layered Salts with Iron Hexadecachlorophthalocyanine Anions – The Formation of [{FeCl16Pc}2]3– Dimers Containing [FeICl16Pc(2–)]– and Diamagnetic [Fe0Cl16Pc(2–)]2–

“…A similar spectrum of [Fe I Pc] – was observed in the case of the electrochemical reduction of Fe II Pc in pyridine (with hyperfine splitting from pyridine) and chemical reduction of Fe II Pc in THF 22,23. The EPR spectrum of 2 (Figure 7) is similar in shape and parameters to those of Fe I porphyrins and corresponds to the electron configuration of Fe I : (d xy ) 2 (d xz ,d yz ) 4 (d) 1 24–26. In addition to the major components with g ⟂ = 2.249 and g ∥ = 1.989, split and weak signals are also observed in the magnetic field from 292 up to 322 mT (the signal separation varies in the range 2.1–3.4 mT at 300 K, Figure 7).…”

“…On the whole, 2 has a layered structure, in which hexagonal phthalocyanine layers consisting of [(FeCl 16 Pc) 2 ] 3– dimers (Figure 4, b) are separated by TBA + layers. The intermolecular overlap integrals for 2 were calculated by using the extended Hückel method22,23 on the basis of single‐crystal X‐ray diffraction data. The interactions between the FeCl 16 Pc skeletons were evaluated by overlap integrals among the frontier HOMO, frontier LUMO, and NLUMO orbitals (Table 1).…”

Unveiling the In Situ Generation of a Monovalent Fe(I) Site in the Single-Fe-Atom Catalyst for Electrochemical CO2 Reduction

“…As shown in Figures a and S11a, three doublets assigned to LS Fe 2+ in Fe II N 4 C 12 , MS Fe 2+ in Fe II N 4 C 10 , and HS Fe 2+ in N–Fe II N 4 C 10 with the similar content compared to the fresh sample could be detected in CO 2 -saturated 0.5 M KHCO 3 solution. However, when polarized at −0.3 V ( vs RHE), a new doublet with the fitted IS of 0.41 mm s –1 and a double pole splitting (QS) of 1.40 mm s –1 were observed, which could be assigned to the four pyrrolic nitrogen atom-coordinated LS Fe­(I) species (LS Fe I N 4 , S = 1/2) . Correspondingly, the relative content of the D1 moiety (LS Fe II N 4 ) was decreased from 63.9 to 49.2% (Figure S11c).…”

“…However, when polarized at −0.3 V (vs RHE), a new doublet with the fitted IS of 0.41 mm s −1 and a double pole splitting (QS) of 1.40 mm s −1 were observed, which could be assigned to the four pyrrolic nitrogen atom-coordinated LS Fe(I) species (LS Fe I N 4 , S = 1/2). 56 Correspondingly, the relative content of the D1 moiety (LS Fe II N 4 ) was decreased from 63.9 to 49.2% (Figure S11c). Furthermore, the relative content of LS Fe I N 4 was observed to be gradually increased upon decreasing the applied potential.…”

Zwitterionic {Fe(i)Pc(−2)−}·(TMP+) assemblies comprising anionic iron(i) phthalocyanines and coordinating N,N,N′-trimethylpiperazinium cations

“…This signal can be attributed to the iron(I) centers with the low-spin d 7 electron configuration. 25,26 It is interesting to note that EPR spectra of isolated Fe(I)Pc(−2) − anions with four-coordinated iron(I) atoms were fitted well by two lines down to 4 K, 13 whereas compounds containing weakly bonded coordination {Fe(I)Pc(−2) − } 2 dimers manifested two-component EPR signals at high temperature which become three-component below 100 K when the coordination N-Fe bond in the dimers becomes shorter. 15 Thus, stronger asymmetry of the EPR signal is observed for the Fe(I)Pc(−2) − anions with five-coordinate iron(I) atoms.…”