Elementary molecular orbital calculation on U(C8H8)2 and its application to the electronic structures of U(C8H8)2, NP(C8H8)2, and Pu(C8H8)2

Hayes, Robert G.; Edelstein, Norman M.

doi:10.1021/ja00780a008

Cited by 68 publications

(36 citation statements)

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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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“…This was confirmed by Hayes and Edelstein (14) in their analysis of the magnetic susceptibility of powders of uranocene, neptunocene, and plutonocene. Amberger et al (15) fitted their susceptibility data to a model in which the ground state was 14,O) with the 14,?…”

supporting

confidence: 53%

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

McGarvey¹

1984

Can. J. Chem.

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The paramagnetic shift resulting from f orbital covalency for lanthanide fluorides has been successfully treated theoretically in earlier studies. This theoretical method has been modified to calculate the paramagnetic shift for 13C and 1H in uranocenes. It is shown that the very large anisotropy in the magnetic moment makes the treatments in the literature incorrect. The so-called "contact shift" in 13C is in reality three terms: (1) a dipolar contribution from spin in the carbon pz orbital, (2) a dipolar contribution from spin in the nearest neighbor carbon pz orbitals, and (3) an induced Fermi contact term. Contribution (1) is the largest. For 1H there are contributions from the direct dipolar interaction of spin in the nearest carbon pz orbital and the induced Fermi contact term. Both terms are nearly equal in magnitude. The theory, however, predicts a much smaller magnitude and the incorrect sign for the shift as measured experimentally. The measured shift must, therefore, result from a polarization mechanism in which exchange interactions between the f electrons and electrons in filled orbitals cause spin delocalization into the ligand σ orbitals. It is argued that this polarization mechanism operates primarily through the overlap of the outer 6s and 6p orbitals of the uranium atom with the σ orbitals of the ligand making the observed nmr shifts insensitive to the nature of the bonding between the ligand and the uranium atom. We conclude, therefore, that the question of how much f orbitals are involved in covalent bonds between uranium and the ligands in uranocene cannot be answered by measuring the paramagnetic shift in 13C or 1H.

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“…[8] The molecule has a single Np IV ion between two planar COT rings in a sandwich structure ( Figure 1) with D 8h symmetry. [10] The presence of slow relaxation of the magnetization was suggested by the splitting of zero-field 237 Np Mössbauer spectra between 4.2 and 40 K, but never confirmed experimentally. [10] The presence of slow relaxation of the magnetization was suggested by the splitting of zero-field 237 Np Mössbauer spectra between 4.2 and 40 K, but never confirmed experimentally.…”

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Magnetic Memory Effect in a Transuranic Mononuclear Complex

et al. 2011

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Selective memory: Using actinides in designing molecular nanomagnets could provide better performance and higher anisotropy barriers, owing to the peculiar properties of the 5f electron shell. Neptunocene is found to display an open magnetic hysteresis cycle at low temperatures (see picture), and interaction with the hyperfine degrees of freedom determines whether the magnetic relaxation is fast or slow at a given field value.

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Elementary molecular orbital calculation on U(C8H8)2 and its application to the electronic structures of U(C8H8)2, NP(C8H8)2, and Pu(C8H8)2

Cited by 68 publications

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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)

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

Magnetic Memory Effect in a Transuranic Mononuclear Complex

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Elementary molecular orbital calculation on U(C8H8)2 and its application to the electronic structures of U(C8H8)2, NP(C8H8)2, and Pu(C8H8)2

Cited by 68 publications

References 0 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)

Theory of 13C and 1H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

Magnetic Memory Effect in a Transuranic Mononuclear Complex

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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)

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?