Synthesis and Structure of the First Terminal Borylene Complexes

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Boron Chemistry

Background:

• Terminal borylene complexes are rare, with limited examples of two-coordinate metal-bound boron.
• Understanding the electronic and steric properties of borylene ligands is crucial for their synthetic applications.

Purpose of the Study:

• To synthesize and characterize a novel tungsten borylene complex, [(CO)5WBN(SiMe3)2].
• To investigate the structural and electronic properties of the borylene ligand in this complex.
• To determine if the borylene ligand exhibits a trans effect in the tungsten complex.

Main Methods:

• Synthesis of the tungsten complex [(CO)5WBN(SiMe3)2] via established organometallic routes.
• Single-crystal X-ray diffraction analysis to determine the molecular structure and bonding.
• Infrared spectroscopy to analyze the carbonyl ligand environment and probe the trans effect.

Main Results:

• A nearly linear W-B-N arrangement (177.9°) was observed in the crystal structure of [(CO)5WBN(SiMe3)2].
• This complex represents one of the first terminal borylene complexes featuring a two-coordinate metal-bound boron atom.
• Similar geometries of axial and equatorial carbonyl groups suggest the absence of a significant trans effect from the borylene ligand.

Conclusions:

• The successful synthesis and characterization of [(CO)5WBN(SiMe3)2] expand the scope of terminal borylene chemistry.
• The structural data indicate unique bonding interactions involving the two-coordinate boron atom.
• The lack of a trans effect implies that borylene ligands may behave differently from other unsaturated ligands in organometallic complexes.