Trisyl-based multidentate ligands: synthesis and their transition-metal complexes

Herein we report the synthesis and applications of unusual trisyl-based multidentate ligands [trisyl = tris(trimethylsilyl)methyl, -C(SiMe3)(3)]. First, by applying a new trisyl synthon (Me3Si)(2)CH(SiMe2CH2Cl) 1, trisyl-based S- or N-containing compounds 2 were efficiently obtained. On treatment of these compounds 2 with MeLi, their corresponding S- or N-coordinated pincer-like trisyl-based lithium salts 3, including the S-bridged ditrisyl compound 3a [Li{C(SiMe3)(2)SiMe2CH2SCH2SiMe2C(SiMe3)(2)}Li(DME)(3)] and the N-coordinated monotrisyl compounds 3b [(NacNac(Dipp)LiCH(2)SiMe(2)C(SiMe3)(2)Li(THF)], 3c [Li(THF){C(SiMe3)(2)SiMe2CH2N(Me)CH2C5H4N-2}], and 3d [Li{C(SiMe3)(2)SiMe2CH2N(Me)CH2CH2N(Pr-i)(2)}] were synthesized and structurally characterized by single-crystal X-ray structural analysis. Second, to test these novel lithium salts as straightforward precursors for the synthesis of transition-metal complexes with unique structures, these lithium salts were applied to react with MCl2 (M = Cr, Mn, Fe, Co). Their corresponding transition-metal complexes 4-8 were obtained in high yields and structurally characterized by single-crystal X-ray structural analysis. Third, the preliminary reactivities of compound 4 were explored.