Isolation of Base-Coordinated 1,4-Disilaquinones

Despite the importance of quinones in organic synthesis and materials chemistry, their silicon analogues remain largely unexplored to date. Herein, we report the synthesis of two base-coordinated 1,4-disilaquinones through dimerization of ketenyl-substituted silylenes, which were in situ generated by reaction of two differently substituted metalated ketenes with the amidinato-stabilized chlorosilylene (PhC(NtBu)2SiCl). X-ray crystallography combined with density functional theory (DFT) calculations revealed a planar but unsymmetrical structure of the disilaquinone core, arising from its unusual bonding situation. The central heterocyclic motif is best described as a resonance hybrid of three principal forms: a silaquinone-type structure or as a dimer of two enolates and carbanionic ketones, respectively. Despite its nonaromatic character, the disilaquinone core exhibits remarkable thermal and chemical stability, showing no tendency toward ring-opening. Although unreactive toward nucleophiles, treatment with Lewis or Brønsted acids perturbs the π-electron density but preserves the integrity of the six-membered ring scaffold.