Borabenzene

Borabenzene is a hypothetical organoboron compound with the formula C₅H₅B. Unlike the related but highly stable benzene molecule, borabenzene would be electron-deficient. Related derivatives are the boratabenzene anions, including the parent [C₅H₅BH]⁻.

Borabenzene

Names
Preferred IUPAC name Borinine
Identifiers
CAS Number	31029-61-5
3D model (JSmol)	Interactive image
ChemSpider	9074474
PubChem CID	10899214
CompTox Dashboard (EPA)	DTXSID50447608
InChI InChI=1S/C5H5B/c1-2-4-6-5-3-1/h1-5H Key: HXNZTJULPKRNPR-UHFFFAOYSA-N
SMILES B1=CC=CC=C1
Properties
Chemical formula	C5H5B
Molar mass	75.91 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Adducts

Adducts of borabenzene with Lewis bases are isolatable. Since borabenzene is unavailable, these adducts require indirect methods. 4-Silyl-1-methoxyboracyclohexadiene is used as a precursor to the borabenzene:

C
₅H
₅N + MeOBC
₅H
₅SiMe
₃ → C
₅H
₅N-BC
₅H
₅ + MeOSiMe₃

The pyridine adduct C
₅H
₅N-BC
₅H
₅ is structurally related to biphenyl.^[1] It is a yellow whereas biphenyl is colorless, indicating distinct electronic structures. The pyridine ligand is tightly bound: no exchange is observed with free pyridine, even at elevated temperatures.

Adducts of borabenzene with pyridine and triphenylphosphine.

The borabenzene-pyridine adduct behaves like a diene, not an analog of biphenyl, and will undergo Diels-Alder reactions.^[2]

See also

• 6-membered aromatic rings with one carbon replaced by another group: silabenzene, germabenzene, stannabenzene, pyridine, phosphorine, arsabenzene, stibabenzene, bismabenzene, pyrylium, thiopyrylium, selenopyrylium, telluropyrylium
• Borazine