Structural Characterization of Am(III)- and Pu(III)-DOTA Complexes
Matthieu Audras1, Laurence Berthon1, Claude Berthon1
1Nuclear Energy Division, Research Department on Mining and Fuel Recycling Processes, CEA , BP17171 F-30207 Bagnols-sur-Cèze, France.
Inorganic Chemistry
|October 3, 2017
Summary
The study investigated the complexation of 1,4,7,10-tetrazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) with trivalent actinides Am3+ and Pu3+. Actinide-DOTA complexes form faster and exhibit shorter bond distances than lanthanide analogs, indicating enhanced ligand affinity.
Area of Science:
- Radiochemistry
- Coordination Chemistry
- Computational Chemistry
Background:
- 1,4,7,10-tetrazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) is a versatile chelating agent.
- Trivalent actinides (Am3+, Pu3+) share ionic radii with trivalent lanthanides (Ln3+).
- Understanding actinide complexation is crucial for nuclear waste management and medical applications.
Purpose of the Study:
- To investigate the complexation behavior of DOTA with Am3+ and Pu3+.
- To compare the complexation dynamics and structural properties of An(III)-DOTA with Ln(III)-DOTA systems.
- To elucidate the electronic factors governing the preferential binding of DOTA to Am3+ over Nd3+.
Main Methods:
- UV-visible spectrophotometry
- NMR spectroscopy
- Extended X-ray absorption fine structure (EXAFS)
- Computational chemistry methods
Main Results:
- Complexation occurs in steps, forming a stable 1:1 [(An(III)DOTA)(H2O)]- complex.
- Actinide-DOTA complex formation is faster than lanthanide-DOTA systems.
- Shorter An-N bond distances compared to Ln-N distances were observed.
- Theoretical calculations revealed enhanced ligand-to-metal charge donation in Am-DOTA complexes.
Conclusions:
- DOTA effectively chelates trivalent actinides Am3+ and Pu3+ with a similar coordination environment as lanthanides.
- The faster complexation and shorter bond lengths suggest stronger interactions between DOTA and actinides.
- Enhanced ligand-to-metal charge donation contributes to the higher affinity of DOTA for Am3+ compared to Nd3+.
More Related Videos
10:31Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores
Published on: December 6, 2015
28.7K
10:51The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
12.8K
Related Concept Videos
02:42Valence Bond Theory
11.4K
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...
11.4K
02:34Structural Isomerism
21.8K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
21.8K
02:58Crystal Field Theory - Octahedral Complexes
31.1K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
31.1K
03:02Colors and Magnetism
14.2K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
14.2K
00:43Complexometric Titration: Ligands
2.4K
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...
2.4K
01:07Ladder Diagrams: Complexation Equilibria
654
Ladder diagrams are useful for evaluating equilibria involving metal-ligand complexes. The vertical scale of the ladder diagram represents the concentration of unreacted or free ligand, pL. The horizontal lines on the scale depict the log of stepwise formation constants for metal-ligand complexes and indicate the dominant species in all the regions.
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
654