An Organometallic Analogue of the “Criss‐Cross” Cycloaddition Reaction

High reactivity characterizes the rhenium vinylidene complex 1, which can function, for example, as a potent 1,3-dienophile in the [3 + 2] cycloaddition with azines: its reaction with PhHCNNCHPh yields the complex 2 (M = Re), which has an almost planar bridging ligand composed of two condensed five-membered rings. [2 + 2] Cycloadditions are also possible as demonstrated by the reaction of 1 with tBuNCNtBu, which provides isocyanide complexes.