Bis-Dichlorosilyl Functionalized C₄-Cumulene With Unique Bonding Scenario

This work reports the preparation and computational investigation of a bis-dichlorosilyl functionalized C₄-cumulene (2), which was synthesized by employing Amidinato-chlorosilylene, L(Cl)Si: (L = PhC(N^tBu)₂). Compound 2 was characterized by single-crystal X-ray diffraction, mass spectrometry, and NMR spectroscopy. The stability, distribution of spin densities, and the nature of Si-C bonds of 2 were studied by employing natural bond orbital (NBO) analysis, atoms in molecules (AIM), and energy decomposition analysis-natural orbital for chemical valence (EDA-NOCV). The EDA-NOCV analysis showed that compound 2 possesses electron-sharing covalent sigma and dative covalent sigma bonds (Si↔C and C→Si) between the Ph₂C₄ fragment in the anionic doublet state and silyl-amidine groups in the cationic doublet state. This may be due to the electron-deficient nature of olefin and electron-rich N-donating functional groups on silicon atoms. Compound 2 displays unprecedented chemical bonding in this class of compounds as predicted by EDA-NOCV calculations. We have also compared the bonding situation of compound 2 with a previously reported compound 3.