Bonding analysis of the C₂precursor Me₃E-C₂-I(Ph)FBF₃(E = C, Si, Ge)

A series of possible precursors for generating C2 with the general formula Me3E-C2-I(Ph)FBF3 [E = C (1), Si (2), and Ge (3)] has been theoretically investigated using quantum chemical calculations. The equilibrium geometries of all species show a linear E-C2-I+ backbone. The inspection of the electronic structure of the Me3E-C2 bond by energy decomposition analysis coupled with the natural orbital for chemical valence (EDA-NOCV) method suggests a combination of electron sharing C-C σ-bond and v weak π-dative bond between Me3C and C2 fragments in the doublet state for species 1 (E = C). For species 2 (Si) and 3 (Ge), the analysis reveals σ-dative Me3E-C2 bonds (E = Si, Ge; Me3EC2) resulting from the interaction of singly charged (Me3E)+ and (C2-IPh(BF4))- fragments in their singlet states. The C2-I bond is diagnosed as an electron sharing σ-bond in all three species, 1, 2 and 3.