From an Isolable Acyclic Phosphinosilylene Adduct to Donor-Stabilized Si = E Compounds (E = O, S, Se)

Reaction of the arylchlorosilylene-NHC adduct ArSi(NHC) Cl [Ar= 2,6-Trip(2)C(6)H(3); NHC=(MeC)(2)(NMe)(2)C:] 1 with one molar equiv of lithium diphenylphosphanide affords the first stable NHC-stabilized acyclic phosphinosilylene adduct 2 (ArSi(NHC)PPh2), which could be structurally characterized. Compound 2, when reacted with one molar equiv selenium and sulfur, affords the silanechalcogenones 4a and 4b (ArSi(NHC)(= E)PPh2, 4a: E= Se, 4b: E= S), respectively. Conversion of 2 with an excess of Se and S, through additional insertion of one chalcogen atom into the Si - P bond, leads to 3a and 3b (ArSi(NHC)(= E)-E-P(= E)Ph-2, 3a: E= Se, 3b: E= S), respectively. Additionally, the exposure of 2 to N2O or CO2 yielded the isolable NHC-stabilized silanone 4c, Ar(NHC)(Ph2P) Si=O.