Experimental and Computational Studies on a Base-Free Terminal Uranium Phosphinidene Metallocene

Area of Science:

• Organometallic Chemistry
• Uranium Chemistry
• Main Group Chemistry

Background:

• Metallocene complexes are crucial in organometallic chemistry.
• Terminal phosphinidene complexes are reactive intermediates.
• Uranium's unique electronic structure offers novel reactivity.

Purpose of the Study:

• To synthesize and characterize the first stable base-free terminal uranium phosphinidene metallocene.
• To compare its structure and reactivity with the analogous thorium derivative.
• To investigate the electronic structure and bonding in the uranium phosphinidene moiety.

Main Methods:

• Salt metathesis reaction using Cp'''2U(I)Me and Mes*PHK.
• Characterization of the resulting uranium phosphinidene complex Cp'''2U=PMes*.
• Density Functional Theory (DFT) calculations to probe electronic structure and bonding.

Main Results:

• Successful synthesis of the first stable base-free terminal uranium phosphinidene metallocene.
• DFT studies reveal significant 5f orbital contributions to the U-P bond, indicating covalent character.
• The uranium derivative shows distinct reactivity patterns compared to the thorium analog.

Conclusions:

• The uranium phosphinidene complex is a stable compound with unique electronic properties.
• The observed reactivity differences are attributed to electronic and steric factors.
• The uranium phosphinidene complex can serve as a Cp'''2U(II) synthon, releasing the phosphinidene moiety in reactions with unsaturated molecules.