Interaction of η²-C₂B₁₀H₁₀ and Its Derivatives with Group-X Transition Metals: A Theoretical Study Using DFT

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Computational Chemistry

Background:

• Carboranes are stable boron-carbon clusters with applications in drug delivery and organometallic chemistry.
• Dehydrogenated o-carborenes act as versatile ligands for transition metals.
• Classical Dewar-Chatt-Duncanson (DCD) model describes transition-metal-ligand bonding, but deviations exist for some ligands.

Purpose of the Study:

• To investigate the bonding interactions in Group X transition metal complexes with o-carborene ligands.
• To determine if o-carborenes follow the DCD model or an alternative bonding paradigm.
• To explore the electronic flexibility of o-carborenes as ligands.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Natural Bond Orbital (NBO) analysis.
• Quantum Theory of Atoms in Molecules (QTAIM).
• Electron Localizer Function (ELF) analysis.
• Energy Decomposition Analysis with Natural Orbitals for Chemical Valence (EDA-NOCV).

Main Results:

• o-Carborene complexes of Ni, Pd, and Pt adopt a D + E bonding paradigm.
• This involves interactions between a cationic transition metal fragment and an anionic o-carborene fragment.
• Dominant electrostatic contributions complemented by pi-sharing stabilize the complexes.
• This contrasts with alkyne/aryne analogues that adhere to the DCD model.

Conclusions:

• o-Carborenes exhibit unique bonding adaptability, deviating from classical models.
• They function as electronically flexible ligands, expanding beyond traditional bonding descriptions.
• This finding opens new avenues for designing transition metal complexes with tailored electronic properties.