Light-Enhanced Synthesis of TiSb2 and TiBi2 Metallacycles

Abstract 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.