Tuning the reactivity of an yttrium complex bearing a functionalized silylamido ligand using solvated KCl†‡

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 Tp^Me₂-supported yttrium silyl-bridged amido PhSiH₂-substituted alkyl complex 1 (Tp^Me₂Y[η²-(C,N)-CH(SiH₂Ph)Si(Me₂)NSiMe₃]) with elemental sulfur S₈ under KCl additive conditions afforded three structurally characterized yttrium complexes (Tp^Me₂)₃Y₄[μ₃–η¹:η²:η²-(S₃)SiPh]₂(μ–η²:η²-S₂)(μ-Cl)(THF) (2), [(Tp^Me₂)₂Y]₂²⁺{(Tp^Me₂Y)₃[μ₃–η¹:η²:η³-(S₃)SiPh]₃K(THF)}²⁻ (3), and [(Tp^Me₂)₂Y]⁺{[Tp^Me₂Y(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 (Tp^Me₂Y[η²-(S,N)-SCH(SiH₂Ph)Si(Me₂)NSiMe₃]). Similarly, the reaction of 1 with isothiocyanate under KCl additive conditions formed a double insertion product (Tp^Me₂)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 (Tp^Me₂Y[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.