Tellurium-Centered Bent Allenes: Synthesis, Characterization, and Reactivity

Compounds with multiple bonds between elements of the second and fifth periods are extremely unstable, and systematic investigations into their properties remain elusive. Herein, we report a tellurium-centered heteroallene that contains multiple bonds between carbon and tellurium. This compound is the first example of bis(methylene)-λ4-tellane, which was synthesized and fully characterized using multinuclear NMR spectroscopy and X-ray crystallography. In the solid state, this λ4-tellane exhibits a bent allene structure for the CTeC moiety and unsaturated Te–C bonds. Interestingly, the allene-type structure is retained in the solution, which is reflected in an absorption band due to the π–π* transition at 610 nm. This λ4-tellane also exhibits unique reactivity toward dihalogermylenes, which yielded rare cyclic telluragermetanes.