benzenediyl

Benzenediyl is a divalent aryl group derived from benzene by removal of two hydrogens, creating two points of attachment for bonding to other groups. The core is the benzene ring C6H4, and the two attachment points are specified by the positions on the ring, leading to benzene-1,2-diyl (ortho), benzene-1,3-diyl (meta), or benzene-1,4-diyl (para). In systematic nomenclature, benzene-<n>,<m>-diyl denotes a diyl bridge between two substituents.

The benzenediyl unit is commonly used in chemistry to name arylene bridges in polymers and in coordination chemistry as a bridging ligand between two metal centers. For example, p-phenylene linkers in poly(phenylene) materials are built from para-benzenediyl fragments.

As a fragment, benzenediyl is not typically isolated as a stable discrete molecule; it is a reactive intermediate or a structural motif. In radical or diradical contexts, benzenediyl can refer to a benzene ring with two unpaired electrons at the attachment sites, but in conventional substituent naming it is treated as a divalent aryl group with two bonds to other parts of a molecule. Its properties depend on the substituents and the connectivity pattern on the ring, as well as on whether the two attachments are at adjacent or opposite positions, which affects sterics and electronics in the resulting compound.

In literature, the term is mostly encountered in systematic naming and discussions of arylene linkers, rather than as a discrete, isolable compound.