B-P Coupling: Metal Stabilized Phosphinoborate Complexes.

Area of Science:

• Organometallic Chemistry
• Synthetic Chemistry
• Catalysis

Background:

• Traditional methods for boron-phosphorus (B-P) bond formation often rely on phosphine-borane dehydrocoupling agents.
• Developing alternative, efficient synthetic routes for B-P coupling is crucial for accessing novel chemical structures.
• Ruthenium complexes offer unique reactivity for bond activation and formation.

Purpose of the Study:

• To establish a new synthetic methodology for B-P coupling reactions without phosphine-borane dehydrocoupling agents.
• To synthesize and characterize novel ruthenium-containing heterocycles with B-P bonds.
• To investigate the mechanism and electronic properties of the B-P bond formation.

Main Methods:

• Synthesis of a group 8 metal σ-borate complex, specifically a ruthenium complex [{κ³ -H,S,S'-BH₂L₂}Ru{κ³ -H,H,S-BH₃L}] (L=NC₅H₄S), denoted as 1.
• Reaction of complex 1 with chlorodiphenyl phosphine (PPh₂Cl) to yield a 1,5-P,S chelated Ru-dihydridoborate species (2).
• Exploration of reactions involving complex 1 and a Ru-bis(dihydridoborate) complex (5) with secondary phosphine oxide (SPO) and phosphite ligands.

Main Results:

• A novel B-P bond formation was achieved through the insertion of a phosphine moiety via cleavage of a σ(Ru…H-B) bonding interaction, forming complex 2.
• Complex 2 features a rare, all-heteroatom six-membered ring with a boat conformation.
• Reactions with secondary phosphine oxide and phosphite ligands yielded novel phosphinous(III) acid incorporated Ru(σ-borate)(dihydridoborate) complexes (6 and 7).

Conclusions:

• A new synthetic route for B-P coupling has been successfully developed, utilizing a ruthenium σ-borate complex.
• The study demonstrates the formation of unique heteroatomic ring systems and provides electronic insights into B-P coupling via transition metal stabilization.
• Alternative pathways for B-P bond formation were explored, leading to the synthesis of novel organometallic complexes.