Ligand field theory of metal sandwich complexes.  Magnetic properties of fx configurations

Warren, Keith D.

doi:10.1021/ic50154a047

Cited by 42 publications

(37 citation statements)

References 6 publications

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“…Figure 7 shows that the SOC-CASPT2 ground state is nondegenerate, defining it as an A 1g state with |M J | ) 0 in D 8h * symmetry, in agreement both with previous SOCI calculations 36 and analysis based on crystal field theory. 4,42,43 The identification of this |M J | ) 0 ground state is consistent with the TIP reported in ref 12. Experimentally observed UV/vis absorption peaks occur for plutonocene at 2.768, 2.995, and 3.069 eV. 9 Our SOC-CASPT2 calculations give a large number of excited states with nonnegligible oscillator strengths; the most strongly allowed of the low-lying states are found at 3.328 (f ) 0.034), 3.556 (f ) 0.0017), and 3.705 eV (f ) 0.0017).…”

Section: 2b Soc Calculationssupporting

confidence: 91%

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η⁸-C₈H₈)₂(An = Th, U, Pu, Cm)

Kerridge

Kaltsoyannis

2009

J. Phys. Chem. A

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Spin-orbit free and spin-orbit coupled CASPT2 wave functions and energies are presented for the ground and low-lying excited states of four actinide element sandwich molecules; thorocene (ThCOT(2)), uranocene (UCOT(2)), plutonocene (PuCOT(2)), and curocene (CmCOT(2)). Spin-orbit coupling is found to make little difference to the equilibrium geometry of uranocene and plutonocene but has a significant effect on the energy spectrum of all the systems considered here other than thorocene. In all cases, however, the spin-orbit free ground states make the dominant contribution to their spin-orbit coupled counterparts. Following work presented in J. Phys. Chem. A 2009, 113, 2896, the variation in the multiconfigurational character of the ground-state wave functions as the 5f series is crossed is quantified via the occupation of the a(u)/b(1u) (e(2u)) metal-ring bonding and antibonding natural orbitals. The ground state of plutonocene is found to be nondegenerate with |M(J)| = 0, in agreement with its temperature-independent paramagnetism.

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Section: 2b Soc Calculationssupporting

confidence: 91%

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η⁸-C₈H₈)₂(An = Th, U, Pu, Cm)

Kerridge

Kaltsoyannis

2009

J. Phys. Chem. A

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“…According to this first model, Cp − and COT 2− generate a

B_{2}^{0}

of the same sign, whereas no field would be generated for Bz. Warren showed that this simple ionic model led to a positive

B_{2}^{0}

…”

Section: Resultsmentioning

confidence: 99%

“…[68] Due to the symmetry of the complexes, the first terms of the multipole expansion of the electrostatic fieldg enerated by the ligandsr educe to the charge, quadrupole, and hexadecapole moments. The ratio d/r equals 1.97, 1.76, and 0.90 in DyCp, DyBz,a nd DyCOT,r espectively;a ll values are larger than 1= ffiffi ffi 2 p ,b ut the last one is much closer.A lthough q equals À1a nd À2f or Cp À and COT 2À ,r espectively,i ts hould be 0f or Bz.…”

Section: Cfps In [Lnmentioning

confidence: 99%

Crystal Field in Rare‐Earth Complexes: From Electrostatics to Bonding

Alessandri

Zulfikri

Autschbach

et al. 2018

Chemistry A European J

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The flexibility of first-principles (ab initio) calculations with the SO-CASSCF (complete active space self-consistent field theory with a treatment of the spin-orbit (SO) coupling by state interaction) method is used to quantify the electrostatic and covalent contributions to crystal field parameters. Two types of systems are chosen for illustration: 1) The ionic and experimentally well-characterized PrCl crystal; this study permits a revisitation of the partition of contributions proposed in the early days of crystal field theory; and 2) a series of sandwich molecules [Ln(η -C H ) ] , with Ln=Dy, Ho, Er, and Tm and n=5, 6, and 8, in which the interaction between Ln and the aromatic ligands is more difficult to describe within an electrostatic approach. It is shown that a model with three layers of charges reproduces the electrostatic field generated by the ligands and that the covalency plays a qualitative role. The one-electron character of crystal field theory is discussed and shown to be valuable, although it is not completely quantitative. This permits a reduction of the many-electron problem to a discussion of the energy of the seven 4f orbitals.

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“…This value is in good agreement with the limiting value of 2.14 μ B predicted by Warren. 16,17 At T< 200 K, the plot of χT vs. T is linear with a sharp deviation at T< 10 K. The reason for the nonlinear behavior at low T is unknown but is assumed to be due to intermolecular antiferromagnetic interactions. The linear behavior of the χT vs. T is caused by mixing of a thermally isolated ground (M J ) state with a low-lying but thermally unpopulated excited state with ΔM J = ±1 resulting in strong second-order Zeeman effects.…”

Section: Synthesis and Physical Properties Of [Li(thf)mentioning

confidence: 99%

Cerocene Revisited: The Electronic Structure of and Interconversion Between Ce₂(C₈H₈)₃and Ce(C₈H₈)₂

et al. 2009

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New synthetic procedures for the preparation of Ce(cot) 2 , cerocene, from [Li(thf) 4 ][Ce(cot) 2 ], and Ce 2 (cot) 3 in high yield and purity are reported. Heating solid Ce(cot) 2 yields Ce 2 (cot) 3 and COT while heating Ce 2 (cot) 3 with an excess of COT in C 6 D 6 to 65 °C over four months yields Ce(cot) 2 . The solid state magnetic susceptibility of these three organocerium compounds shows that Ce(cot) 2 behaves as a TIP (temperature independent paramagnet) over the temperature range of 5-300 K, while that of Ce 2 (cot) 3 shows that the spin carriers are antiferromagnetically coupled below 10 K; above 10 K, the individual spins are uncorrelated, and [Ce (cot) Ce 2 (cot) 3 over 30-500 K are reported; the Ce(cot) 2 XANES spectra show Ce(III) and Ce(IV) signatures up to a temperature of approximately 500 K, whereupon the Ce(IV) signature disappears, consistent with the thermal behavior observed in the melting experiment. The EXAFS of Ce(cot) 2 and Ce 2 (cot) 3 are reported at 30 K; the agreement between the molecular parameters for Ce(cot) 2 derived from EXAFS and single crystal X-ray diffraction data are excellent. In the case of Ce 2 (cot) 3 no X-ray diffraction data are known to exist, but the EXAFS are consistent with a "triple-decker" sandwich structure. A molecular rationalization is presented for the electronic structure of cerocene having a multiconfiguration ground state that is an admixture of the two configurations Ce(III, 4f 1 )(cot

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Ligand field theory of metal sandwich complexes. Magnetic properties of fx configurations

Cited by 42 publications

References 6 publications

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η⁸-C₈H₈)₂(An = Th, U, Pu, Cm)

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η⁸-C₈H₈)₂(An = Th, U, Pu, Cm)

Crystal Field in Rare‐Earth Complexes: From Electrostatics to Bonding

Cerocene Revisited: The Electronic Structure of and Interconversion Between Ce₂(C₈H₈)₃and Ce(C₈H₈)₂

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Ligand field theory of metal sandwich complexes. Magnetic properties of fx configurations

Cited by 42 publications

References 6 publications

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η8-C8H8)2(An = Th, U, Pu, Cm)

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η8-C8H8)2(An = Th, U, Pu, Cm)

Crystal Field in Rare‐Earth Complexes: From Electrostatics to Bonding

Cerocene Revisited: The Electronic Structure of and Interconversion Between Ce2(C8H8)3and Ce(C8H8)2

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Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η⁸-C₈H₈)₂(An = Th, U, Pu, Cm)

Are the Ground States of the Later Actinocenes Multiconfigurational? All-Electron Spin−Orbit Coupled CASPT2 Calculations on An(η⁸-C₈H₈)₂(An = Th, U, Pu, Cm)

Cerocene Revisited: The Electronic Structure of and Interconversion Between Ce₂(C₈H₈)₃and Ce(C₈H₈)₂