Light-Enhanced Synthesis of TiSb₂ and TiBi₂ Metallacycles

The synthesis of small metallacycles of early transition metals and heavy pnictogens has been primarily achieved by reductive coupling of the pnictane moiety with a transition metal fragment. Herein, we report a light-enhanced synthesis of titanocene Sb₂ and Bi₂ metallacycles starting from the dipnictene (RSb=SbR, RBi=BiR) and a suitable titanocene synthon Cp₂Ti-(btmsa) (Cp = C₅H₅, btmsa = bistrimethylsilylacetylene). We further explored the reactivity of the TiSb₂ complex by employing a diazoolefin, leading to the formation of an unusual six membered heterocycle. These findings were supported by thorough theoretical analysis of the electronic features of these complexes and expand upon previous studies of 3d transition metal dipnictene complexes.