Tris‐{hydridotris(1‐pyrazolyl)borato}actinide Complexes: Synthesis, Spectroscopy, Crystal Structure, Bonding Properties and Magnetic Behaviour

Abstract

The isostructural compounds of the trivalent actinides uranium, neptunium, plutonium, americium, and curium with the hydridotris(1‐pyrazolyl)borato (Tp) ligand An[η3‐HB(N2C3H3)3]3 (AnTp3) have been obtained through several synthetic routes. Structural, spectroscopic (absorption, infrared, laser fluorescence) and magnetic characterisation of the compounds were performed in combination with crystal field, density functional theory (DFT) and relativistic multiconfigurational calculations. The covalent bonding interactions were analysed in terms of the natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) models.

Tris-{Hydridotris(1-pyrazolyl)borato}lanthanide Complexes: Synthesis, Spectroscopy, Crystal Structure and Bonding Properties

“…The covalent part of bonding corresponds to the Tp → Ln charge transfer, in which the N lone pairs donate electrons to the empty valence orbitals of the Ln 3+ ions. The charge transfer interactions in the CN9 structures of LaTp 3 and LuTp 3 complexes have recently been studied [14] by means of the natural bond orbital (NBO) model [39]. This analysis predicted an energetically somewhat stronger Tp → Ln charge transfer in the LuTp 3 complex, in agreement with the present ETS results.…”

“…In the LnTp 3 complexes, the above conditions for CT in terms of transferred electrons appear to be most favorable in the Ce 3+ -Sm 3+ region. Less favorable is the CT to Ln 3+ ions with 4f 0 , 4f 7 , 4f 14 configurations as well as in the second half of the Ln row.…”

“…The bonding properties of the complexes were analyzed using the extended transition state (ETS) energy decomposition [15,18] and the quantum theory of atoms in molecules (QTAIM) models [16]. These theoretical models have been successfully applied in numerous studies of bonding trends in organometallic complexes [14,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34].…”

“…Our previous DFT calculations on AnTp 3 , LaTp 3 , and LuTp 3 were performed with the Gaussian09 code utilizing small-core relativistic pseudopotentials [14]. Unfortunately, this 4f-in-valence approach failed for most LnTp 3 complexes because of severe self-consistent field (SCF) convergence problems.…”

“…The thermal behavior of some LnTp 3 compounds was also analyzed using TG/DTG and DSC methods [13]. Recently, we reported a joint experimental and theoretical study on the structural, bonding, and magnetic properties of AnTp 3 complexes, in which LaTp 3 and LuTp 3 were also included for comparison [14].…”