Synthesis and structures of monomeric magnesium, calcium, strontium, and barium amides involving the N,N-(2,4,6-trimethylphenyl)(trimethylsilyl)amido ligand

An extended family of aryl-substituted alkaline earth metal silylamides M{N(2,4,6-Me₃C₆H₂)(SiMe₃)}donor _n was prepared using alkane elimination (Mg), salt elimination (Ca, Sr, Ba), and direct metalation (Sr, Ba). Three different donors, THF, TMEDA (TMEDA = N,N,N′,N′-tetramethylethylenediamine), and PMDTA (PMDTA = N,N,N′,N″,N″-pentamethyldiethylenetriamine) were employed to study their influence on the coordination chemistry of the target compounds, producing monomeric species with the composition M{N(2,4,6-Me₃C ₆H₂)(SiMe₃)}₂(THF)₂ (M = Mg, Ca, Sr, Ba), M{N(2,4,6-Me₃C₆H₂)(SiMe ₃)}₂TMEDA (M = Ca, Ba), and M{N(2,4,6-Me₃C ₆H₂)(SiMe₃)}₂PMDTA (M = Sr, Ba). For the heavier metal analogues, varying degrees of agostic interactions are completing the coordination sphere of the metals. Compounds were characterized using IR and NMR spectroscopy in addition to X-ray crystallography.