Magnetic Properties and Electronic Structures of Ar3UIV–L Complexes with Ar = C5(CH3)4H– or C5H5 – and L = CH3, NO, and Cl

Gendron, Frédéric; Guennic, Boris Le; Autschbach, Jochen

doi:10.1021/ic502365h

Cited by 30 publications

(41 citation statements)

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“…In a scalar relativistic (SR) calculation, i.e. Spinorbit coupling greatly diminishes the f-electron contribution to back bonding in agreement with the earlier studies by Maron et al and Gendron et al 31,32 For both 2' and 5', there is reasonably good agreement between the experimental and crystal-field derived EPR gfactors (Table 3) and those from the ab-initio calculations ( Table 5). These mix with of other J = 9/2 levels due to SO coupling, and with levels having different values of J due to the low symmetry of the ligand field --as already mentioned.…”

Section: Multi-reference Wavefunction Calculationssupporting

confidence: 86%

“…24 The 5f-6d transitions are in the visible and tail into the near IR, which makes observing and assigning the weak f-f transitions difficult. 32,33 In this manuscript, we report the syntheses of complexes Cp" 3 M and Cp" 3 M•L, where Cp" is 1,3-bis-(trimethylsilyl)cyclopentadienyl, M = La, Nd, U, and L is tertbutylisocyanide (tBuNC) or cyclohexylisocyanide (CyNC). For instance, this approach has been effectively used to determine the oxidation states of uranium in K 6 Cu 12 U 2 S 15 from its magnetic susceptibility.…”

Section: Introductionmentioning

confidence: 99%

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The roles of 4f- and 5f-orbitals in bonding: a magnetochemical, crystal field, density functional theory, and multi-reference wavefunction study

et al. 2016

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The electronic structures of 4f(3)/5f(3) Cp''3M and Cp''3M·alkylisocyanide complexes, where Cp'' is 1,3-bis-(trimethylsilyl)cyclopentadienyl, are explored with a focus on the splitting of the f-orbitals, which provides information about the strengths of the metal-ligand interactions. While the f-orbital splitting in many lanthanide complexes has been reported in detail, experimental determination of the f-orbital splitting in actinide complexes remains rare in systems other than halide and oxide compounds, since the experimental approach, crystal field analysis, is generally significantly more difficult for actinide complexes than for lanthanide complexes. In this study, a set of analogous neodymium(iii) and uranium(iii) tris-cyclopentadienyl complexes and their isocyanide adducts was characterized by electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility. The crystal field model was parameterized by combined fitting of EPR and susceptibility data, yielding an accurate description of f-orbital splitting. The isocyanide derivatives were also studied using density functional theory, resulting in f-orbital splitting that is consistent with crystal field fitting, and by multi-reference wavefunction calculations that support the electronic structure analysis derived from the crystal-field calculations. The results highlight that the 5f-orbitals, but not the 4f-orbitals, are significantly involved in bonding to the isocyanide ligands. The main interaction between isocyanide ligand and the metal center is a σ-bond, with additional 5f to π* donation for the uranium complexes. While interaction with the isocyanide π*-orbitals lowers the energies of the 5fxz(2) and 5fyz(2)-orbitals, spin-orbit coupling greatly reduces the population of 5fxz(2) and 5fyz(2) in the ground state.

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Section: Multi-reference Wavefunction Calculationssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

The roles of 4f- and 5f-orbitals in bonding: a magnetochemical, crystal field, density functional theory, and multi-reference wavefunction study

et al. 2016

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“…Moreover, the discovery in 2009 of the slow magnetic relaxation for the mononuclear complex U(Ph 2 BPz 2 ) 3 [53], which is a signature of a single-molecule magnet (SMM) behavior, has motivated more research, even though lanthanide SMMs have been described in the literature for a longer time [54,55]. A growing number of uranium-containing systems [56][57][58][59][60][61][62][63][64][65][66][67][68][69]-mononuclear as well as binuclear species-have been synthesized to develop SMMs; the results have been the subject of recent reviews [70][71][72][73][74][75]. Such systems are of great interest, owing to the well-known larger spin-orbit coupling for actinide than for lanthanide ions [72], and the more diffuse 5f orbitals (5f covalency) [63,[76][77][78] than the lanthanide 4f ones, which could lead to strong magnetic super-exchange [53].…”

Section: Introductionmentioning

confidence: 99%

DFT Investigations of the Magnetic Properties of Actinide Complexes

2019

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Over the past 25 years, magnetic actinide complexes have been the object of considerable attention, not only at the experimental level, but also at the theoretical one. Such systems are of great interest, owing to the well-known larger spin–orbit coupling for actinide ions, and could exhibit slow relaxation of the magnetization, arising from a large anisotropy barrier, and magnetic hysteresis of purely molecular origin below a given blocking temperature. Furthermore, more diffuse 5f orbitals than lanthanide 4f ones (more covalency) could lead to stronger magnetic super-exchange. On the other hand, the extraordinary experimental challenges of actinide complexes chemistry, because of their rarity and toxicity, afford computational chemistry a particularly valuable role. However, for such a purpose, the use of a multiconfigurational post-Hartree-Fock approach is required, but such an approach is computationally demanding for polymetallic systems—notably for actinide ones—and usually simplified models are considered instead of the actual systems. Thus, Density Functional Theory (DFT) appears as an alternative tool to compute magnetic exchange coupling and to explore the electronic structure and magnetic properties of actinide-containing molecules, especially when the considered systems are very large. In this paper, relevant achievements regarding DFT investigations of the magnetic properties of actinide complexes are surveyed, with particular emphasis on some representative examples that illustrate the subject, including actinides in Single Molecular Magnets (SMMs) and systems featuring metal-metal super-exchange coupling interactions. Examples are drawn from studies that are either entirely computational or are combined experimental/computational investigations in which the latter play a significant role.

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“…Vittadini et al [10] reported the electronic structures of Cp 3 UX (X = F, Cl, Br) by nonrelativistic DV-Xα molecular orbital (MO) calculations. Very recently, the electronic structures and magnetic properties of (C 5 Me 4 H) 3 UCl and Cp 3 UCl have been theoretically investigated [11].…”

Section: Introductionmentioning

confidence: 99%

Binuclear trivalent and tetravalent uranium halides and cyanides supported by cyclooctatetraene ligands

Wang

Lan

et al. 2016

Radiochimica Acta

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Although the first organoactinide chloride Cp 3 UCl (Cp = η 5 -C 5 H 5 ) was synthesized more than 50 years ago, binuclear uranium halides remain very rare in organoactinide chemistry. Herein, a series of binuclear trivalent and tetravalent uranium halides and cyanides with cyclooctatetraene ligands, (COT) 2 U 2 X n (COT = η 8 -C 8 H 8 ; X = F, Cl, CN; n = 2, 4), have been systematically studied using scalarrelativistic density functional theory (DFT). The structures with bridging halide or cyanide ligands were predicted to be the most stable complexes of (COT) 2 U 2 X n , and all the complexes show weak antiferromagnetic interactions between the uranium centers. However, for each species, there is no significant uranium-uranium bonding interaction. The bonding between the metal and the ligands shows some degree of covalent character, especially between the metal and terminal halide or cyanide ligands. The U-5f and 6d orbitals are predominantly involved in the metal-ligand bonding. All the (COT) 2 U 2 X n species were predicted to be more stable compared to the mononuclear half-sandwich complexes at room temperature in the gas phase such that (COT) 2 U 2 X 4 might be accessible through the known (COT) 2 U complex. The tetravalent derivatives (COT) 2 U 2 X 4 are more energetically favorable than the trivalent (COT) 2 U 2 X 2 analogs, which may be attributed to the greater number of strong metal-ligand bonds in the former complexes.

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Magnetic Properties and Electronic Structures of Ar₃U^IV–L Complexes with Ar = C₅(CH₃)₄H^– or C₅H₅ ^– and L = CH₃, NO, and Cl

Cited by 30 publications

References 72 publications

The roles of 4f- and 5f-orbitals in bonding: a magnetochemical, crystal field, density functional theory, and multi-reference wavefunction study

The roles of 4f- and 5f-orbitals in bonding: a magnetochemical, crystal field, density functional theory, and multi-reference wavefunction study

DFT Investigations of the Magnetic Properties of Actinide Complexes

Binuclear trivalent and tetravalent uranium halides and cyanides supported by cyclooctatetraene ligands

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