ESR analyses of picket fence MnII and 6th ligand coordinated FeIII porphyrins (S = 5/2) and a CoII(hfac) complex (S = 3/2) with sizable ZFS parameters revisited: a full spin Hamiltonian approach and quantum chemical calculations

Yamane, Takeshi; Sugisaki, Kenji; Matsuoka, Hideto; Sato, Kazunobu; Toyota, Kazuo; Shiomi, Daisuke; Takui, Takeji

doi:10.1039/c8dt02988a

Cited by 8 publications

(4 citation statements)

References 62 publications

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“…However, direct experimental determination of these parameters for transition-metal complexes with large ZFS is far from trivial. Earlier , and more recent. ,, reviews discuss this issue.…”

Section: Introductionmentioning

confidence: 99%

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

et al. 2019

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Accurate determination of the spin Hamiltonian parameters in transition-metal complexes with large zero-field splitting (ZFS) is an actual challenge in studying magnetic and spectroscopic properties of high-spin transition metal complexes. Recent critical papers have convincingly shown that previous determinations of these parameters, based only on the magnetic data, have low accuracy and reliability. A combination of X-band electron paramagnetic resonance (EPR) spectroscopy and SQUID magnetometry seems to be a more convincing and accurate approach. However, even in this case, the accuracy of the determination of the spin Hamiltonian parameters is strongly limited. In this work, we propose a purely spectroscopic approach, in which three complementary EPR spectroscopic techniques are used to unambiguously with high accuracy determine the spin Hamiltonian parameters for transition-metal complexes with S = 3/2. The applicability of this approach is demonstrated by analyzing the new quasi-octahedral high-spin Co(II) complex [Co(hfac) 2 (bpy)] (I). Along with the conventional X-band EPR spectroscopy, we also use such advanced techniques as multi-high-frequency EPR spectroscopy (MHF-EPR) and frequency-domain Fouriertransform THz-EPR (FD-FT THz-EPR). We demonstrate that the experimental data derived from the X-band and MHF-EPR EPR spectra allow determination of the g tensor (g x = 2.388, g y = 2.417, g z = 2.221) and the ZFS rhombicity parameter E/D = 0.158. The axial ZFS parameter D = 37.1 cm −1 is measured for I with the aid of FD-FT THZ-EPR spectroscopy, which is able to detect the high-energy EPR transition between the two Kramers doublets. CASSCF/NEVPT2 quantum-chemical calculations of magnetic parameters and magnetic direct current (dc) measurements are performed as well as testing options, and the results obtained in these ways are in good agreement with those derived using the proposed spectroscopic approach.

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“…However, direct experimental determination of these parameters for transition-metal complexes with large ZFS is far from trivial. Earlier , and more recent. ,, reviews discuss this issue.…”

Section: Introductionmentioning

confidence: 99%

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

et al. 2019

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“…This D value is relatively large, but possible in comparison with the literature values. 62–65 The large D value seems to be related to the five-coordinate cobalt( ii ) ion (Co4, Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

Lanthanide induced variability in localised Co^II geometries of four triangular L₃Co₃^IILn^III complexes

et al. 2022

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“…The 1 H-HYSCORE signals spreading over a frequency range of 3–4 MHz in the angular selective spectra were assigned to the protons belonging to the Cp groups. Based on the cw-EPR spectrum and the modulation effects, we determined spin-Hamiltonian parameters of 1 with S = 3/2 47 (Supplementary Fig. 33 , Supplementary Table 1 ) as well as fictitious S = 1/2 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of a formal 21-electron cobaltocene derivative

Takebayashi,

Ariai,

Gellrich

et al. 2023

Nat Commun

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Metallocenes are highly versatile organometallic compounds. The versatility of the metallocenes stems from their ability to stabilize a wide range of formal electron counts. To date, d-block metallocenes with an electron count of up to 20 have been synthesized and utilized in catalysis, sensing, and other fields. However, d-block metallocenes with more than formal 20-electron counts have remained elusive. The synthesis and isolation of such complexes are challenging because the metal–carbon bonds in d-block metallocenes become weaker with increasing deviation from the stable 18-electron configuration. Here, we report the synthesis, isolation, and characterization of a 21-electron cobaltocene derivative. This discovery is based on the ligand design that allows the coordination of an electron pair donor to a 19-electron cobaltocene derivative while maintaining the cobalt–carbon bonds, a previously unexplored synthetic approach. Furthermore, we elucidate the origin of the stability, redox chemistry, and spin state of the 21-electron complex. This study reveals a synthetic method, structure, chemical bonding, and properties of the 21-electron metallocene derivative that expands our conceptual understanding of d-block metallocene chemistry. We expect that this report will open up previously unexplored synthetic possibilities in d-block transition metal chemistry, including the fields of catalysis and materials chemistry.

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ESR analyses of picket fence Mn^II and 6th ligand coordinated Fe^III porphyrins (S = 5/2) and a Co^II(hfac) complex (S = 3/2) with sizable ZFS parameters revisited: a full spin Hamiltonian approach and quantum chemical calculations

Abstract: The conventional X-band ESR spectra are fully reanalyzed by a full spin Hamiltonian approach.

Cited by 8 publications

References 62 publications

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

Lanthanide induced variability in localised Co^II geometries of four triangular L₃Co₃^IILn^III complexes

Synthesis and characterization of a formal 21-electron cobaltocene derivative

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ESR analyses of picket fence MnII and 6th ligand coordinated FeIII porphyrins (S = 5/2) and a CoII(hfac) complex (S = 3/2) with sizable ZFS parameters revisited: a full spin Hamiltonian approach and quantum chemical calculations

Abstract: The conventional X-band ESR spectra are fully reanalyzed by a full spin Hamiltonian approach.

Cited by 8 publications

References 62 publications

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

Lanthanide induced variability in localised CoII geometries of four triangular L3Co3IILnIII complexes

Synthesis and characterization of a formal 21-electron cobaltocene derivative

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ESR analyses of picket fence Mn^II and 6th ligand coordinated Fe^III porphyrins (S = 5/2) and a Co^II(hfac) complex (S = 3/2) with sizable ZFS parameters revisited: a full spin Hamiltonian approach and quantum chemical calculations

Lanthanide induced variability in localised Co^II geometries of four triangular L₃Co₃^IILn^III complexes