Optical and Magnetic Properties of the Complex Bis(dicyclooctatetraenyl)diuranium. A Theoretical View

Abstract

A systematic study on bis(dicyclooctatetraenyl)diuranium (U 2 COT 4 ) has been performed using relativistic density functional theory. The molecule was calculated in four different electronic configurations and the two symmetries C 2 and D 2h . First we considered the high-spin quintuplet ( 5 A) state, and from this state we built the broken-symmetry configuration following Noodleman's approach. Also, the triplet state was considered as a formal interaction of both uranocene fragments in triplet and singlet states simultaneously, and finally the low-spin singlet configuration was calculated. For both symmetries the ground state of the complex was the quintuplet, and on the basis of the broken-symmetry approach a significant ferromagnetic coupling between both metals was found. Time-dependent density functional theory (TDDFT) was used to calculate the excitation energies with the GGA SAOP functional. The obtained electronic transitions are in good correlation with reported experimental values, which are found between 600 and 720 nm: 633, 658, 664, 673, 685, and 717 nm.

DFT Investigations of the Magnetic Properties of Actinide Complexes

“…Actinide complexes exhibiting magnetic exchange properties are rarely mentioned in the literature [1,2], relatively to the rich d-transition metal magnetochemistry. Most documented cases involve diuranium(V) systems [8,[23][24][25][26][27]37,[49][50][51]106,[111][112][113][114][115][116], and only a few studies of magnetic coupling in diuranium(III) and (IV) complexes or mixed uranium(IV)-transition metal have been reported [46,52,105,107,[117][118][119][120][121][122]. Among them, remarkable examples of unusual U(V)-U(V) coupling involving a pentavalent bis(imido) uranium dimer [106] and within diuranium(V) dioxo diamond cores [46,49,[114][115][116][123][124][125][126] have been reported, which can exhibit Néel temperatures of up to 70 and even 110 K [23,24,27,114,115,127].…”

“…Indeed, DFT emerged in the early 2000s as a powerful technique, particularly when used in combination with the hybrid B3LYP functional [86,87] and the Broken-Symmetry (BS) Noodleman's approach [88,89], for satisfactory simulations of magnetic properties. This is true not only in the case of d-transition metal systems [82,83,[90][91][92][93][94][95][96][97][98][99][100][101][102][103][104], but also for actinide-containing molecules [105][106][107]. It is worth noting that actinide-based SMMs are multiconfigurational systems, and the use of the monodeterminantal approach with DFT is a subject of debate [63,[108][109][110].…”

Fluorescence probes for prokaryotic and eukaryotic cells using Re(CO)3+complexes with an electron withdrawing ancillary ligand

“…[48] The molecular structures were fully optimized by an analytical energy gradient method as implemented by Verluis and Ziegler, [49][50] using the PBE functional [51] and the standard Slater-type-orbital (STO) basis set with triple-ζ quality double plus polarization functions (TZ2P) for all the atoms. [48] The molecular structures were fully optimized by an analytical energy gradient method as implemented by Verluis and Ziegler, [49][50] using the PBE functional [51] and the standard Slater-type-orbital (STO) basis set with triple-ζ quality double plus polarization functions (TZ2P) for all the atoms.…”

“…[51][52] Epithelial cells (T84) were co-incubated 24 h with different concentrations of either C3 or C4 prior to performing the neutral red uptake assay. [51][52] Epithelial cells (T84) were co-incubated 24 h with different concentrations of either C3 or C4 prior to performing the neutral red uptake assay.…”

Advances in bonding and properties of inorganic systems from relativistic calculations in Latin America

“…[148] It [149][150][151] For the bis(dicyclooctatetraenyl)diuranium complex studied in two symmetries (D 2h and C 2 ), the optical and magnetic properties have been accounted for by Paez-Hernandez, showing that for both symmetries the preferred ground state of the complex is a quintuplet spin state denoting significant ferromagnetic coupling between the metal centers. [152] A benchmark study from ab initio calculations by Celis-Barros et al, [153] used a multi-configurational CASSCF and NEVPT2 procedures to include static and dynamical correlation effects and then spin-orbit coupling applied to berkelium (Bk), californium (Cf ), einsteinium (Es) and fermium (Fm) hexahalides. The results for these trivalent actinides indicate that the electronic structure of the low-lying states is accurately reproduced with small basis sets.…”