Synthesis, DFT Studies, and Reactions of Scandium and Yttrium Dialkyl Cations Containing Neutral fac-N3 and fac-S3 Donor Ligands

Abstract

Reaction of Sc(CH2SiMe3)3(THF)2 with 1,4,7-trithiacyclononane gave Sc([9]aneS3)(CH2SiMe3)3, the first organometallic group 3 complex of [9]aneS3 ([9]aneS3 = 1,4,7-trithiacyclononane). The corresponding reaction for yttrium gave equilibrium mixtures of Y([9]aneS3)(CH2SiMe3)3 and starting materials. Density functional theory (DFT) was used to compare the energies of formation and metal−ligand interaction energies for M([9]aneS3)R3 with those for the previously reported fac-N3 donor complexes M(fac-N3)R3 (R = Me or CH2SiMe3; fac-N3 = 1,4,7-trimethyltriazacyclononane (Me3[9]aneN3) or HC(Me2pz)3). Reaction of M(CH2SiMe3)3(THF)2 with [NHMe2Ph][BArF4] (ArF = C6F5) in the presence of a face-capping ligand L (L = HC(Me2pz)3, Me3[9]aneN3, or [9]aneS3) gave the cationic complexes [M(L)(CH2SiMe3)2(THF)]+, which has been structurally characterized for M = Sc and L = [9]aneS3. The corresponding base-free cations [M(L)(CH2SiMe3)2]+ were studied by 29Si NMR spectroscopy and/or DFT and found to possess β-Si−C agostic alky...