Metal-Metal Bonding in Uranium-Group 10 Complexes

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Computational Chemistry

Background:

• Heterobimetallic complexes featuring uranium and group 10 metals are of interest for understanding d-f block bonding.
• Previous studies have explored uranium-metal interactions, but short uranium-group 10 metal bonds require further investigation.

Purpose of the Study:

• To synthesize and characterize novel heterobimetallic uranium-group 10 metal complexes.
• To investigate the nature and strength of the uranium-metal (U-M) bond using experimental and computational methods.
• To compare the bonding characteristics across different group 10 metals (Ni, Pd, Pt) and explore the effect of ligand substitution.

Main Methods:

• Synthesis of IU(IV)(OAr(P)-κ(2)O,P)3 and subsequent reaction with Ni(0), Pd(0), and Pt(0).
• Characterization using variable-temperature NMR spectroscopy, electrochemistry, and single crystal X-ray diffraction.
• Density Functional Theory (DFT) calculations, including Natural Population Analysis (NPA), Natural Localized Molecular Orbital (NLMO) composition, and Quantum Theory of Atoms-in-Molecules (QTAIM) analysis.

Main Results:

• Successfully prepared heterobimetallic complexes with short U-M bonds, shorter than previously reported d-f-block bimetallics.
• Experimental and DFT data show excellent agreement for U-Ni and U-Pd complexes.
• Analysis indicates significant U 5f and 6d orbital involvement in covalent bonding, with U-Ni bonds having a larger delocalization index (bond order) than U-Pd.
• Uranium-metal bond strength decreases from Ni to Pt, and fluoride substitution strengthens the bond compared to iodide.
• Despite short distances, computational methods suggest low U-TM bond orders, with more localized valence orbitals for Pd than Ni.

Conclusions:

• The study demonstrates the formation of exceptionally short U-M bonds in heterobimetallic complexes.
• DFT and experimental results provide insights into the covalent nature and electronic structure of these U-M bonds.
• The findings contribute to understanding bonding principles in d-f block elements and offer a basis for designing new uranium-based materials.