Silicon-carbonyl complex is stable at room temperature

Transition metals are attractively reactive but can be expensive and toxic. For years, chemists have been probing the reactivity of main-group elements to provide suitable alternatives, but they have not had much luck making carbonyl complexes from non-d-block elements, presumably because of these elements’ lack of π back-bonding orbitals. Now, Stephan Schulz and coworkers at the University of Duisburg-Essen and Justus Liebig University Giessen have synthesized the first known silicon-carbonyl complex that’s stable at room temperature (Nat. Chem. 2020, DOI: 10.1038/s41557-020-0456-x). They were able to accomplish this by beefing up the silicon with two gallium β-diketiminate ligands, which are known to stabilize low-valent main-group complexes. The group then directly reacted CO with the electron-rich silylene in benzene at 60 °C to make the carbonyl complex in 30% yield. In the past, scientists have been able to isolate these compounds only under cryogenic conditions in solid argon. The new compound is stable in solution and can be used in C–C and H–H bond activation reactions in mild conditions. It also undergoes CO substitution, which shows that it can do similar chemistry to its transition-metal counterparts.