Preparation of a Compound with a Si^II -Si^IV -Si^II Bonding Arrangement

Herein, we report the synthesis of a rare bis-silylene, 1, in which two Si^II atoms are bridged by a Si^IV atom. Compound 1 contains an unusual Si^II -Si^IV -Si^II bonding arrangement with Si^II -Si^IV bond distances of 2.4212(8) and 2.4157(7) Å. Treatment of 1 with Fe(CO)₅ afforded a dinuclear Fe⁰ complex 2 with two unusually long Si-Si bonds (2.4515(8) and 2.4488(10) Å). We have also carried out a detailed computational study to understand the nature of the Si-Si bonds in these compounds. Natural bond orbital (NBO) and energy decomposition analysis-natural orbital for chemical valence (EDA-NOCV) analyses reveal that the Si-Si bonds in 1 and 2 are of an electron-sharing nature.