Halogen-Exchange Reactions of Iminophosphonamido-Chlorosilylenes with Alkali Halides: Convenient Synthesis of Heavier Halosilylenes.

Halogen-substituted silylenes are an important building block for synthesizing silicon-based low-valent and multiple-bond species. However, the number of reports on heavier halosilylenes that contain bromine and iodine is still limited. Here, we present a convenient synthesis for bromo- and iodosilylenes supported by an iminophosphonamide ligand. The heavier halosilylenes [PhP(BuN)]SiX (: X = Br, : X = I) were successfully synthesized via the halogen-exchange reaction of chlorosilylene with alkali halides in THF. As a demonstration of the reactivity of and , oxidative addition reactions of and with elemental selenium in CD afforded the corresponding bromo- () or iodosilylene-selone () as colorless crystals. The molecular structures of , , , and were fully characterized by spectroscopic means and single-crystal X-ray diffraction analysis. Furthermore, the effects of the halogen atom on the electronic state of halosilylenes - and halosilylene-selones - were investigated using density functional theory (DFT) calculations.