Synthesis and structure of a new lithium amide ligand precursor: A tridentate nitrogen-based donor set of the formula N(SiMe2CH2NMe2)(2). Synthesis and structure of the group 4 amides MCl3[N(SiMe2CH2NMe2)2] (M=Ti, Zr, Hf)

The new lithium amide LiN(SiMe2CH2NMe2)(2) was prepared by reaction of NH3 with the corresponding silylamine Me2NSiMe2CH2NMe2 followed by addition of butyllithium. This lithium derivative exists as a dimer in the solid state wherein the two lithium ions are bridged by the two amido units with the amine arms of each unit bonded to opposite Lithium centers in an overall pseudo 9 structure; however, in solution, a fluxional process serves to interconvert the enantiomeric forms of the dimer unit The coordination chemistry of the lithium amide dimer has been investigated; reaction with a series of group 4 starting halides, MCl4, leads to the corresponding complexes MCl3[N(SiMe2CH2NMe2)(2)], where M = Ti, Zr, and Hf. The structures of these starting trihalides in solution and in the solid state are presented.