Examination of Structure and Bonding in 10-Coordinate Europium and Americium Terpyridyl Complexes

Abstract

M(TpyNO 2 )(NO 3 ) 3 (H 2 O)•THF (M = La, Nd, Sm, Eu, Tb, Am; TpyNO 2 = 4′-nitrophenyl terpyridyl) have been prepared from the reaction of M(NO 3 ) 3 •nH 2 O with TpyNO 2 in THF. Structural analysis shows that the metal centers are 10-coordinate, providing the first example of Am III with this coordination number. Further spectroscopic and theoretical evaluation of these complexes reveals utilization of the 5f orbitals in bonding in the Am III complex. Comparison of Nd−L, Eu−L, and Am−L bond distances demonstrates that some caution should be taken in comparing Eu III versus Am III in extraction experiments.

Advancing understanding of actinide(iii) (Ac, Am, Cm) aqueous complexation chemistry

“…1À to Th 4+ , U 4+ , Np 4+ , Pu 3+ , Am 3+ , Nd 3+ , Sm 3+ , Gd 3+ , and Eu 3+ . 20,[42][43][44][45][46][47][48] This structural data was consistent with the EXAFS model included here. It is unclear to us why metal-ligand bonds would be shorter for neutral H 2 O vs. anionic O 2 CMe 1À ligands.…”

Role of the Hydroxo Group in the Coordination of Citric Acid to Trivalent Americium

“…Even if the CN of 9 is usual for the americium, the CN of 10 cannot be ruled out. This unusual CN for americium has recently been reported for other systems for Am and trans‐americium from XRD structures. In our case, the small size and the polydenticity of the ligands may be responsible for this potential large CN.…”

Tuning the Kinetic Inertness of Bi3+ Complexes: The Impact of Donor Atoms on Diaza-18-Crown-6 Ligands as Chelators for 213Bi Targeted Alpha Therapy

“…Increased covalent character is reflected by more negative values of this parameter. 91,92,96,97 As seen in Table 5, the covalency of the Bi-O and Bi-N bonds increases with the ligand basicity and agrees well with the trend in experimental kinetic properties of the chelators. A similar trend is observed for δ, which is an integral property that can be considered as a measure of covalent bond order.…”

“…88,89 To avoid this issue, the energy density parameters V(r), G(r), and H(r), the ratio of potential and kinetic energies |V|/G, and the normalized total energy density H/ρ are commonly used to interpret the nature of bonding interactions in heavy metal complexes. [90][91][92][93][94][95] Complete QTAIM results are compiled in Tables 5 and S3-S8. In agreement with our X-ray crystallographic and NBO analysis, the interactions of the Bi 3+ center with the crown ether oxygen (O1-O4) and amine nitrogen (N1 and N3) atoms of the diaza-18-crown-6 core are almost purely ionic nature, as evidenced by the values of H(r) ≥ 0 and |V|/G < 1 (Table S3- S8).…”