Metallionene

Metallionene is a term used in contemporary chemistry to denote a class of compounds in which metal centers are embedded in conjugated hydrocarbon frameworks, yielding metal-containing polyenes or metallaaromatic systems. The concept sits at the interface of organometallic chemistry and π-conjugated carbon chemistry. In proposed motifs, metals (commonly transition metals such as Ni, Pd, Pt, or copper) are bonded to carbon frameworks in a manner that preserves or extends π-conjugation, producing linear, cyclic, or fused architectures.

Common descriptors include metallionenes or metallopolyenes, depending on structure. Synthesis is exploratory; routes include assembly from metal-alkynyl or alkenyl precursors, oxidative coupling, cyclization of precursors, or dehydrogenative coupling to extend conjugation; characterization methods include NMR, UV-Vis-NIR spectroscopy, cyclic voltammetry, and X-ray crystallography.

Properties and research status: predicted to exhibit tunable HOMO-LUMO gaps, redox activity, and potential for spin coupling; early demonstrations exist in limited systems; stability remains a challenge due to metal-carbon bond lability and oxidative sensitivity.

Potential applications include molecular electronics, nonlinear optics, photocatalysis, and energy storage, though none are established. Related topics include organometallic chemistry, metallacycles, conjugated polymers, and metallaaromatic compounds.