N-Phosphinoamidinato Silylene- and Phosphine-Borylborylene Complexes

Area of Science:

• Organometallic Chemistry
• Main Group Chemistry
• Boron Chemistry

Background:

• Borylborylenes are reactive intermediates crucial for understanding boron chemistry.
• Previous synthesis methods often involve diborene rearrangements, limiting accessibility.
• Stabilization of low-coordinate boron species remains a significant challenge.

Purpose of the Study:

• To establish a direct and straightforward synthetic route to borylborylenes.
• To synthesize and characterize novel silylene-borylborylene and phosphine-borylborylene complexes.
• To investigate the stability and reactivity of these newly formed boron compounds.

Main Methods:

• Reaction of an amidinato amidosilylene with an N-phosphinoamidinato diborane and KC8.
• Isolation and characterization of the resulting silylene-borylborylene and phosphine-borylborylene products.
• Study of the reactivity of the phosphine-borylborylene with an isocyanide ligand.

Main Results:

• A stable silylene-borylborylene (compound 2) was successfully synthesized and characterized.
• A persistent phosphine-borylborylene (compound 3) was formed but found to be unstable in solution.
• Compound 3 reacted with an isocyanide (Ar'NC), displacing PMe3 and forming a new adduct (compound 4).

Conclusions:

• A facile method for synthesizing borylborylenes, bypassing diborene rearrangement, has been developed.
• The electronic stabilization provided by the silylene donor significantly enhances borylborylene stability.
• The lability of the phosphine ligand in phosphine-borylborylenes influences their reactivity and stability.