Exploration of the synthesis and chemistry of a new class of hydrocarbons is described, the "phenylenes", composed of alternating fused benzene and cyclobutadiene rings. Related structures include extended sp-carbon nets and heterocyclic analogs. These molecules are of great theoretical and potentially practical interest in the search for novel molecules that may exhibit (super)conductive behavior. Their unique topology makes them also excellent candidates as precursors to novel (hydro)carbon cages and related assemblies. Facile access to these compounds is made possible by the application of transition metal catalysis.