Tuning the reactivity of an yttrium complex bearing a functionalized silylamido ligand using solvated KCl†‡
Abstract
Distinguished functionalization of the silyl-bridged amido PhSiH2-substituted alkyl ligand in an yttrium complex under solvated KCl additive conditions is described. Treatment of the TpMe2-supported yttrium silyl-bridged amido PhSiH2-substituted alkyl complex 1 (TpMe2Y[η2-(C,N)-CH(SiH2Ph)Si(Me2)NSiMe3]) with elemental sulfur S8 under KCl additive conditions afforded three structurally characterized yttrium complexes (TpMe2)3Y4[μ3–η1:η2:η2-(S3)SiPh]2(μ–η2:η2-S2)(μ-Cl)(THF) (2), [(TpMe2)2Y]22+{(TpMe2Y)3[μ3–η1:η2:η3-(S3)SiPh]3K(THF)}2− (3), and [(TpMe2)2Y]+{[TpMe2Y(ClN(SiMe3)2)2]μ-(Cl)2K}− (4), providing a straightforward method for construction of phenylsilyl trisulfide PhSiS33− under mild conditions. Without KCl, 1 reacted with S8 to give a routine Y–C insertion product 5 (TpMe2Y[η2-(S,N)-SCH(SiH2Ph)Si(Me2)NSiMe3]). Similarly, the reaction of 1 with isothiocyanate under KCl additive conditions formed a double insertion product (TpMe2)2Y2{μ–η3:η2-(S,S,N,N,N)-N(SiMe3)Si(Me2)CH[C(S) = NC6H4CH3-p]2}Cl (7), accompanied by the elimination of an intermolecular silyl-migration product KNSiMe3Si(Me2)CH(SiH2Ph)2 (I). The intermolecular silyl migration was also observed in the three-component reaction of 1 with tBuNC, and CO2. The reaction of 1 and PhNCS without KCl additive only produced 8 (TpMe2Y[η2-(S,N)-SC(N(SiH2Ph)Ph) = CHSi(Me2)NSiMe3]). These results indicate that the possible weak interaction between a rare-earth ion and KCl might play a crucial role in the conversion of this modified silylamino ligand.