Unusual coordination mode for 1,3-diphosphete ligands towards a Cr-Cr quintuple bond complex

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Phosphorus Chemistry

Background:

• Chromium-chromium multiple bonds are known but their reactivity with unsaturated phosphorus compounds is less explored.
• Phosphaalkynes are versatile building blocks in inorganic and organometallic synthesis.

Purpose of the Study:

• To investigate the reactivity of a dinuclear chromium complex with various phosphaalkynes.
• To synthesize and characterize novel organometallic compounds featuring unusual phosphorus ligands.

Main Methods:

• Reaction of a dinuclear chromium precursor (1) with different phosphaalkynes (R-C≡P).
• Isolation and structural characterization of the resulting complexes using X-ray crystallography and spectroscopy.

Main Results:

• Formation of neutral dimerisation compounds [L2Cr2(μ,η1:η1:η2:η2-P2C2R2)] (2, 3) with R = tBu, Me.
• Synthesis of a tetrahedrane complex [L2Cr2(μ,η2:η2-PCAd)] (4) with R = Ad.
• Complexes 2 and 3 feature the first 1,3-diphosphete ligands spanning a chromium-chromium multiple bond.
• The adamantyl phosphaalkyne forms a monomeric complex 4 with side-on coordination.

Conclusions:

• The dinuclear chromium complex undergoes diverse reactions with phosphaalkynes, leading to novel ligand formations.
• The study demonstrates the utility of phosphaalkynes in constructing unique organometallic structures with metal-metal bonds.