Controlled oligomerization of [1.1.1]propellane through radical polarity matching: selective synthesis of SF₅- and CF₃SF₄-containing [2]staffanes

Selectivity in radical chain oligomerizations involving [1.1.1]propellane – i.e., to make [n]staffanes – has been notoriously challenging to control when n > 1 is desired. Herein, we report selective syntheses of SF₅- and CF₃SF₄-containing [2]staffanes from SF₅Cl and CF₃SF₄Cl, demonstrating cases whereby oligomerization is preferentially truncated after incorporation of two bicyclopentane (BCP) units. Synthetic and computational studies suggest this phenomenon can be attributed to alternating radical polarity matching. In addition, single-crystal X-ray diffraction (SC-XRD) data reveal structurally interesting features of the CF₃SF₄-containing [2]staffane in the solid state.