2-silylpyrrolidines <i>N</i>-Heterocyclic tetrylene <i>N</i>-heterocyclic carbene <i>N</i>-heterocyclic carbenes <i>N</i>-heterocyclic carbines ²⁹Si NMR spectroscopy ?-chloro-?-hydrooligosilane ?-electron systems AIM Baird’s rule DFT Photostability Q1-390 QD1-999 QD146-197 Si–Cl activation TiO₂ X-ray crystallography X-ray diffraction adsorption bond activation bonding analysis bridging silylene ligand bromosilylenes cluster computation computational chemistry condensation cyclic organopolysilane dehydrobromination