Syntheses and reactivities of strained fused-ring metallaaromatics containing planar eleven-carbon chains

Carbolong complexes are one of the primary types of metallaaromatics, and they include metallapentalynes and metallapentalenes. A series of 7C-10C and 12C-carbolong complexes with planar ligand skeletons respectively containing 7-10 and 12 carbon atoms in their backbones, have been previously reported. Herein, two classes of strained substances, metallabenzyne-fused metallapentalenes and metallabenzene-fused metallapentalynes, were prepared, both representing 11C-carbolong complexes with a planar carbon-chain ligand. Furthermore, the former type is also the carbolong derivatives containing a metallabenzyne skeleton, another primary metallaaromatic framework. Metallabenzyne-fused metallapentalenes show versatile reactivities, and the most interesting one is the metal carbyne bond shift from a 6-membered to a more strained 5-membered ring, affording the above-mentioned metallabenzene-fused metallapentalyne. This work makes carbolong chemistry more complete, and provides a method to achieve metallabenzynes, which is anticipated to concurrently advance the development of these two types of metallaaromatics.