Synthesis, structure and reactivity of scandium bis(trimethylsilyl)amido derivatives

The synthesis of scandium complexes supported by two bis(trimethylsilyl)amido ligands and their reactivity to generate a variety of organometallic derivatives is reported. The monomeric scandium complex Sc{N(SiMe3)2}2(THF)Cl, 1, and the “ate” complex Sc{N(SiMe3)2}2Cl2Li(THF)3, 2, were generated by salt metathesis routes from ScCl3(THF)3 and LiN(SiMe3)2. Complex 1 reacts cleanly with MeLi or KCH2Ph to form the compounds Sc{N(SiMe3)2}2(THF)R, (R = Me, 3; CH2Ph, 4), respectively. Upon reaction of 1 with bulky lithium reagents such as LiCH2SiMe3 or TripLi, cyclometalation at scandium occurs to generate the bimetallic species Sc{N(SiMe3)2}2(μ-CH2)2Sc{N(SiMe3)SiMe2}2(THF), 5. Finally, the scandium iodide congener Sc{N(SiMe3)2}2(THF)I, 6, was produced by reaction of 3 with the iodide transfer reagent [Et3NH]I. Attempts to access a low valent scandium complex, by reduction of 6 with either KC8 or [(nacnac)Mg]2, where nacnac = (2,6-iPr2-C6H3)NC(Me)CHC(Me)N(2,6-iPr2-C6H3) failed to afford well-defined low valent organometallic scandium species. All compounds were characterized by single crystal X-ray diffraction studies.