Spontaneous Si-C bond cleavage in (Triphos^Si)-nickel complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Nickel complexes with polydentate phosphine ligands are crucial in catalysis.
• Understanding ligand effects on complex stability and reactivity is essential for designing new catalysts.
• The synthesis and characterization of novel nickel complexes with unique electronic structures remain an active research area.

Purpose of the Study:

• To investigate the reactivity and stability of nickel complexes derived from CH3C(CH2PPh2)3 and CH3Si(CH2PPh2)3 ligands.
• To characterize the unprecedented pseudo-tetrahedral phosphino methanide complex (5) formed from the CH3Si(CH2PPh2)3 system.
• To elucidate the mechanism of formation of complex 5 and explore scalable routes to isolable nickel(I) complexes.

Main Methods:

• Synthesis and characterization of novel nickel complexes.
• X-ray absorption and emission spectroscopy for electronic structure determination.
• Density Functional Theory (DFT) calculations for electronic structure and mechanistic studies.
• Comparative analysis with structurally related complexes.
• Mechanistic investigation using experimental data and quantum chemical calculations.

Main Results:

• Ni[CH3C(CH2PPh2)3] complexes exhibit high stability.
• Ni[CH3Si(CH2PPh2)3] analogs decompose rapidly, yielding the pseudo-tetrahedral phosphino methanide complex 5.
• Detailed electronic structure of complex 5 was determined using spectroscopy and DFT.
• A mechanistic pathway for the formation of complex 5 was proposed.
• A straightforward method for gram-scale isolation of nickel(I) complexes was developed.

Conclusions:

• The choice of ligand significantly impacts the stability and reactivity of nickel complexes.
• The study successfully characterized a novel phosphino methanide nickel complex.
• The mechanistic insights provide a foundation for controlling nickel complex formation.
• A practical route to valuable nickel(I) complexes has been established, facilitating further research and applications.