Spin equilibria in octahedral iron(II) poly((1-pyrazolyl)-borates

Jesson, J. P.; Trofimenko, Swiatoslaw; Eaton, D. R.

doi:10.1021/ja00989a015

Cited by 183 publications

(138 citation statements)

References 1 publication

Supporting

Mentioning

128

Contrasting

Order By: Relevance

“…In agreement with experimental results put forward by Jesson et al, [29] we obtained a diamagnetic low-spin ground state for the [N 6 ] complex; the corresponding high-spin paramagnetic state lies 4.3 kcal mol -1 higher in energy. As already discussed above, almost degenerate spin states resulted for the cis and the trans isomers of [N 4 S 2 ], with slightly more stable high-spin states {by 0.6 kcal mol [5] brought to light a disorder of all six sulfur atoms over two positions with equal occupancy factors.…”

Section: Magnetic Properties Of [{Phb(pz)supporting

confidence: 92%

“…[26] The magnetic moment of 2 is higher than that of the tris(pyrazol-1-yl)borate complex [{PhB(pz) 3 } 2 Fe], which has been reported to be fully diamagnetic in CDCl 3 at room temp. [29] On the other hand, the population of the high-spin state in the [N,N,S] species 2 is lower than in the case of the [N,S,S] complex [{PhB(pz)(CH 2 SMe) 2 } 2 Fe] (μ eff = 4.1 μ B ; CDCl 3 ). [28] In view of the trend in the ligand-field strengths along the series of [N x S 3-x ] scorpionates, one should expect a further increase in μ eff in the [S,S,S] complex [{PhB(CH 2 SMe) 3 } 2 -Fe].…”

Section: Characterization Of Magnetic Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)₂(CH₂SMe)}₂M] (M = Mn^II, Fe^II; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

et al. 2011

View full text Add to dashboard Cite

-have been synthesized and characterized by Xray crystallography, magnetic measurements, cyclic voltammetry, and various spectroscopic techniques. In the solid state, both complexes 2 and 3 possess a distorted octahedral ligand sphere, but adopt different configurations (2: cis; 3: trans). According to X-ray diffraction data, Mössbauer spectroscopy, and SQUID measurements, compound 2 exists as low-spin complex in the solid state at temperatures T Յ 20°C (μ eff ≈ 0.5 μ B ). Upon heating, the magnetic moment μ eff increases continuously to a value of 1.8 μ B at 90°C, which indicates a temperature dependent high-spin ↔ low-spin transition above room temp. Solutions of 2 in CDCl 3 showed paramagnetic behavior at 25°C (μ eff = 3.1 μ B ; Evans NMR method

show abstract

Section: Magnetic Properties Of [{Phb(pz)supporting

confidence: 92%

Section: Characterization Of Magnetic Propertiesmentioning

confidence: 99%

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)₂(CH₂SMe)}₂M] (M = Mn^II, Fe^II; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

et al. 2011

View full text Add to dashboard Cite

show abstract

“…We did not detect individual sets of resonances for either the diamagnetic low-spin complex (LS-3; (27a 1g ) 2 , (27e g ) 4 ) or the paramagnetic high-spin complex HS-3. A similar rapid exchange has been observed previously by Trofimenko et al for the complex [Fe{HB(pz) 3 } 2 ], [26] whereas two distinct sets of resonances were observed by Reger and Long for [Fe{HC(pz) 3 …”

Section: ½Liðsupporting

confidence: 87%

Syntheses, Structures and Electronic Properties of Zwitterionic Iron(II) and Cobalt(II) Complexes Featuring Ambidentate Tris(pyrazolyl)methanide Ligands

Kuzu

Krummenacher

Hewitt

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

By deprotonation of the corresponding tris(pyrazolyl)methane ((Me)Tpm) precursor complexes [M((Me)Tpm)(2)][(OTf)(2)] (1 and 2), the zwitterionic tris(pyrazolyl)methanide iron(II) (3) and cobalt(II) (4) "sandwich" complexes of the general formula [M((Me)Tpmd)(2)] are easily accessible. The structurally characterised complexes 3 and 4 are the first such homoleptic 3d transition metal species to feature two "naked", outward pointing pyramidal carbanions. Density functional theory calculations show metal-centred HOMOs and LUMOs with the destabilised carbanion orbitals in the energy region of the filled transition-metal-centred frontier orbitals. The electronic structures of these complexes have been investigated in detail by various spectroscopic techniques such as NMR, EPR, SQUID, Mössbauer, etc. Both complexes adopt a high-spin (HS) configuration at room temperature in solution and in the solid state. A thermally induced high-spin to low-spin (HS-LS) transition is observed for the iron(II) complex 3. The HS-LS transition temperature of 3 in solution differs from that in the solid state, which in turn strongly depends on the amount of solvent molecules in the crystal lattice. Electrochemical studies on the corresponding cobalt(II) complex 4 provide evidence for a HS-Co(II) <==> LS-Co(III) transition upon oxidation, which was confirmed by preliminary synthetic oxidation reactions. Overall, it can be concluded that the related kappa(3)N-donor ligands tris(pyrazolyl)hydroborates (Tp(R)) and (R)Tpmd ligands have similar bonding properties and that the metal cations experience more or less the same ligand environment.

show abstract

“…Among the field of SCO complexes, the influence of different types of N-or O-donor on metal ions spin states is more subtle, and harder to quantify from available solution-phase data. On one hand, SCO equilibria in [Fe(HBpz 3 ) 2 ] (in thf or a chlorinated solvent [33,34] [86] (Scheme 6). Thus, replacement of pyridyl by pyrazinyl donors stabilizes the low-spin state of these complexes to a small extent.…”

Section: Influence Of Ligand Donor Types On Metal Ion Spin Statementioning

confidence: 99%

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

2016

View full text Add to dashboard Cite

Abstract:The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small changes in spin state energetics can be easily detected from shifts in the spin crossover equilibrium temperature. Published structure-function relationships relating ligand design and spin state from the spin crossover literature give varied results. A sterically crowded ligand sphere favors the expanded metal-ligand bonds associated with the high-spin state. However, steric clashes at the molecular periphery can stabilize either the high-spin or the low-spin state in a predictable way, depending on their effect on ligand conformation. In the absence of steric influences, the picture is less clear since electron-withdrawing ligand substituents are reported to favor the low-spin or the high-spin state in different series of compounds. A recent study has shed light on this conundrum, showing that the electronic influence of a substituent on a coordinated metal ion depends on its position on the ligand framework. Finally, hydrogen bonding to complexes containing peripheral N-H groups consistently stabilizes the low-spin state, where this has been quantified.

show abstract

Spin equilibria in octahedral iron(II) poly((1-pyrazolyl)-borates

Cited by 183 publications

References 1 publication

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)₂(CH₂SMe)}₂M] (M = Mn^II, Fe^II; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)₂(CH₂SMe)}₂M] (M = Mn^II, Fe^II; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

Syntheses, Structures and Electronic Properties of Zwitterionic Iron(II) and Cobalt(II) Complexes Featuring Ambidentate Tris(pyrazolyl)methanide Ligands

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

Contact Info

Product

Resources

About

Spin equilibria in octahedral iron(II) poly((1-pyrazolyl)-borates

Cited by 183 publications

References 1 publication

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)2(CH2SMe)}2M] (M = MnII, FeII; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)2(CH2SMe)}2M] (M = MnII, FeII; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

Syntheses, Structures and Electronic Properties of Zwitterionic Iron(II) and Cobalt(II) Complexes Featuring Ambidentate Tris(pyrazolyl)methanide Ligands

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

Contact Info

Product

Resources

About

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)₂(CH₂SMe)}₂M] (M = Mn^II, Fe^II; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)₂(CH₂SMe)}₂M] (M = Mn^II, Fe^II; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand