Transition-Metal-Stabilized Heavy Tetraphospholide Anions

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Ligand Design

Background:

• Cyclopentadienyl (Cp) ligands are fundamental in organometallic chemistry.
• Phosphorus analogues of Cp, such as phospholes, are known but less explored.
• Compounds incorporating heavier group 14 elements (Si, Ge, Sn, Pb) with Cp-like structures are rare.

Purpose of the Study:

• To synthesize and characterize the first metal complexes with heavy SnP4^2- and PbP4^2- anions.
• To investigate the structural and electronic properties of these novel compounds.
• To explore the reactivity and stability of these unique phosphorus-based ligands.

Main Methods:

• Reaction of white phosphorus (P4) with specific cyclooctadiene cobalt complexes containing tin or lead.
• Isolation and characterization of the resulting metal complexes.
• Theoretical analysis including intrinsic bond orbitals and magnetic response theory.

Main Results:

• Successful isolation of stable tin-SnP4^2- (6) and less stable lead-PbP4^2- (7) containing cobalt complexes.
• Compound 7 decomposed to form a rare tripledecker complex with a P4^2- middle deck (8).
• Theoretical studies confirmed the aromaticity of P5^- and SnP4^2-, and revealed unique weak paramagnetism in P4^2-.

Conclusions:

• Demonstrated the feasibility of incorporating heavy group 14 elements into Cp-like phosphorus anions.
• Highlighted the distinct stability and electronic properties of SnP4^2- and PbP4^2- ligands.
• Provided insights into the electronic structure and magnetic behavior of novel phosphorus clusters in metal complexes.