An Alkali-Metal Halide-Bridged Actinide Phosphinidiide Complex

Area of Science:

• Organometallic Chemistry
• Actinide Chemistry
• Computational Chemistry

Background:

• Thorium complexes are crucial in organometallic chemistry and catalysis.
• Understanding bonding in actinide metallocenes informs reactivity and stability.
• Phosphinidiide ligands offer unique electronic and steric properties.

Purpose of the Study:

• To synthesize and characterize a novel alkali-metal halide-bridged phosphinidiide actinide metallocene.
• To investigate the electronic structure and bonding characteristics of the thorium-phosphorus bond using DFT.
• To comprehensively study the reactivity of the synthesized complex with diverse unsaturated substrates.

Main Methods:

• Salt metathesis reaction to synthesize the target actinide metallocene.
• Single-crystal X-ray diffraction for structural determination.
• Density Functional Theory (DFT) calculations to analyze electronic structure and bonding.
• Reactivity studies with alkynes, heterounsaturated molecules, and elemental selenium/sulfur compounds.

Main Results:

• Successful synthesis of the alkali-metal halide-bridged phosphinidiide actinide metallocene {[η⁵-1,3-(Me₃C)₂C₅H₃]₂Th(═P-2,4,6-tBu₃C₆H₂)(ClK)}₂.
• DFT studies indicate significant 5f orbital contribution to the Th═P bond, with more covalent bonding compared to thorium imido complexes.
• Extensive reactivity observed with various unsaturated molecules, yielding diverse metallacycles and heterocycles, including phospholes and imidos.
• Reaction with elemental selenium and PhSSPh produced selenido and sulfido compounds.

Conclusions:

• The synthesized phosphinidiide actinide metallocene exhibits unique structural and electronic properties.
• The 5f orbitals play a critical role in the covalent bonding of the phosphinidene moiety in thorium complexes.
• The complex demonstrates broad synthetic utility, reacting with a wide range of unsaturated substrates to form novel organometallic compounds.