Lewis Acid Stabilized Diatomic Molecules of Group 14: A Computational Study on [(CO)Fe]E (E = C, Si, Ge, Sn, Pb).

A Lewis base and acid combination has been effectively employed to stabilize and isolate the low-valent group 14 compounds. We report DFT studies on stabilizing low-valent group 14 diatomics as adducts of Lewis acids employing transition metal carbonyl fragment iron tetracarbonyl [Fe(CO)] as Lewis acid. Computational studies on [(CO)Fe]E, E = C, Si, Ge, Sn, and Pb, predict five plausible isomers on its potential energy surface: linear (), bent (), three-membered (), dibridged (), and four-membered (). For the carbon analogue, the lowest energy configuration is linear and has a typical cumulenic structure, while silicon and germanium analogues favor three-membered cyclic isomers. Four-membered cyclic isomers are the most stable for tin and lead analogues.