Synthesis, Reactivity, and Theoretical Insights of Co-Sb2 and Co-Bi2 Rings

The experimental realization of a variety of multimetallic systems composed by transition metals (TM) and heavier pnictogens has been widely explored via σ-bond activation of dipnictanes (Pn2R4), or even poly pnictanes (cyclo-(RnPn)n, Pn = Sb and Bi and R = any substituent). In contrast, isolation of stable metallacyclic rings via TM-mediated activation of Sb and Bi multiple bonds are underexplored. Here, we reported the reactivity of "Sb = Sb" and "Bi = Bi" compounds with Jonas' complex (CpCo(C2H4)2, Cp = C5H5) as the key electrophile to generate the "Co-Pn2" unit. Further exploiting of the synthetic potential of complex 2 using various reagents led to a series of stable multimetallic compounds (5, 6, and 7) containing low-valent heavy pnictogens. These findings have been supported by a thorough investigation of the electronic features of these multimetallic complexes.