When Martin's Spirosilane Meets a N-Heterocyclic Carbene (NHC)

Martin’s spirosilane first synthetized in 1979, has attracted some interest due to its high Lewis acidity, steric hindrance and the intrinsic ability of the silicon atom to become hypervalent. In our study we were particularly interested in the interactions between this spirosilane and different NHCs, known as stable species, with a tunable Lewis basicity and steric hindrance. We started studying the interactions between the two partners that allowed us to obtain different adducts: the normal one with small carbenes (IMe, IMes), and the abnormal one in presence of hindered carbenes (ItBu, IPr). This last result can be a hint of a Frustrated Lewis Pair behaviour for the activation of small molecules like H2, CO2 and formaldehyde. We also investigated their potential use as ligands for metal catalysis.