Dialkylboron guanidinates: syntheses, structures and carbodiimide de-insertion reactions

Area of Science:

• Organometallic Chemistry
• Boron Chemistry
• Coordination Chemistry

Background:

• Guanidinate ligands are versatile in coordinating with metal and main group elements.
• Dialkylboron compounds are important in synthesis and catalysis.
• Understanding the reactivity and stability of boron-guanidinate complexes is crucial.

Purpose of the Study:

• To synthesize and characterize novel symmetrical and asymmetrical dialkylboron guanidinate compounds.
• To investigate the structural features and coordination modes of these new compounds.
• To study the equilibrium and kinetic behavior of these compounds with aminoboranes and carbodiimides.

Main Methods:

• Synthesis via salt metathesis reaction between lithium guanidinates and chloroboranes.
• Structural characterization using X-ray diffraction.
• Equilibrium and kinetic studies to determine thermodynamic and activation parameters.

Main Results:

• Successful synthesis of various symmetrical and asymmetrical dialkylboron guanidinates.
• X-ray diffraction confirmed chelate coordination of guanidinate ligands and additional boron attachments.
• Compounds 1-4 showed slow equilibrium with aminoboranes and carbodiimides at 25 °C, while compounds 5-8 required higher temperatures for similar reactions.

Conclusions:

• The study reports a new class of dialkylboron guanidinate compounds with diverse structures.
• The coordination chemistry and reactivity, including reversible carbodiimide de-insertion, have been elucidated.
• The findings contribute to the understanding of boron-nitrogen bonding and reactivity.