DFT study of H--H activation by Cp(2) LnH d(0) complexes

Area of Science:

• Organometallic Chemistry
• Computational Chemistry
• Inorganic Chemistry

Background:

• The H-H bond activation is a key step in many catalytic processes.
• Lanthanide complexes are increasingly studied for their unique electronic properties and potential catalytic applications.

Purpose of the Study:

• To calculate the energy required for H-H bond activation in Cp(2)LnH complexes.
• To investigate the factors influencing the activation energy and elucidate the reaction mechanism.

Main Methods:

• Density Functional Theory (DFT) calculations using the B3PW91 functional were employed.
• Activation energies for the H-H bond cleavage were computed for a series of lanthanide complexes.

Main Results:

• Calculated activation energies ranged from 0.5 to 8.0 kcal/mol, indicating facile H-H bond activation.
• Lanthanide electronegativity in its stable oxidation state was identified as a primary factor correlating with activation energy trends.
• The transition state geometry features an almost linear H(3)(-) ligand with short H-H distances and strong metal-hydrogen interactions.

Conclusions:

• The H-H bond activation in Cp(2)LnH complexes is an energetically accessible process.
• The reaction proceeds via a sigma bond metathesis mechanism.
• Electronegativity of the lanthanide metal plays a crucial role in modulating the H-H bond activation energy.