What is "borabenzene"

A borabenzene is a heteroaromatic compound that has a boron atom instead of the carbon atom of a benzene molecule. A free borabenzene, which has no donor ligand on the boron atom, has not yet been isolated despite its simple structure and the chemical robustness of boron- carbon bonds. The instability of this molecule results from the high Lewis acidity of the boron atom due to its electron deficiency. All attempts to create a free borabenzene have resulted in formations of complexes with anionic or neutral ligands (even a nitrogen molecule can coordinate to a borabenzene). However, the complexes with anionic ligands, called boratabenzenes, show rich chemistry including the coordination chemistry as anionic π-type ligands. Borabenzene also forms stable adducts with electron donor molecules such as pyridine (the adduct with which is isoelectronic with biphenyl) or triphenylphosphine (the adduct with which is isoelectronic with tetraphenylsilane).