Cation-Cation Interaction in Np(V) Perchlorates and Their Electronic Absorption Spectra
Mikhail S Grigoriev1, Alexei A Bessonov1, Iraida A Charushnikova1
1Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Bldg 4, 31 Leninsky Prosp., Moscow 119071, Russian Federation.
Inorganic Chemistry
|December 18, 2024
Summary
This study synthesized and characterized four new neptunium(V) perchlorate complexes, revealing cation-cation interactions crucial for crystal structure formation. These findings advance understanding of neptunium coordination chemistry and solid-state structures.
Area of Science:
- Inorganic Chemistry
- Radiochemistry
- Crystallography
Background:
- Neptunium (Np) and Uranium (U) complexes are critical in nuclear fuel cycles and waste management.
- Understanding the coordination chemistry and crystal structures of Np(V) compounds is essential for predicting their behavior in various environments.
- Previous studies have identified various Np(V) structures, but detailed characterization of perchlorate complexes is ongoing.
Purpose of the Study:
- To synthesize and structurally characterize new neptunium(V) perchlorate complexes.
- To investigate the role of cation-cation (CC) interactions in the crystal structures of these complexes.
- To analyze the coordination environment of Np and U atoms and their bonding characteristics.
Main Methods:
- Synthesis of four new Np(V) perchlorate complexes.
- Single-crystal X-ray diffraction for structural characterization.
- Spectroscopic analysis in the visible-near-IR range.
Main Results:
- Four new Np(V) perchlorate complexes, including a mixed Np/U compound, were synthesized and characterized: [NpO2(H2O)4]ClO4 (1), [(NpO2)2(ClO4)(H2O)4]ClO4·H2O (3), [(NpO2)(UO2)(H2O)8](ClO4)3 (4), and [(NpO2)2Cl(H2O)4]ClO4·2H2O (5).
- The structure of the known monoclinic NpO2ClO4·4H2O (2) was determined at 100 K.
- Pentagonal bipyramidal coordination environments were observed for Np and U atoms.
- Cation-cation (CC) interactions were identified, with NpO2+ acting as a monodentate or bidentate ligand, playing a fundamental role in the crystal structures of compounds 1, 2, and 4.
Conclusions:
- The synthesis and characterization of these Np(V) perchlorate complexes provide new insights into neptunium coordination chemistry.
- Cation-cation interactions are confirmed as significant structure-directing forces in these Np(V) systems.
- The study contributes to a better understanding of the solid-state chemistry of actinides, relevant for nuclear materials science and environmental remediation.
More Related Videos
Related Concept Videos
03:07Electron Affinity
35.2K
The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).
35.2K
02:42Valence Bond Theory
8.5K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
8.5K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
1.4K
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this...
1.4K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
41.4K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
41.4K
01:32UV–Vis Spectroscopy of Conjugated Systems
6.9K
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent...
One of the factors influencing λmax is the extent...
6.9K
02:48Ionic Bonding and Electron Transfer
41.2K
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
41.2K