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(SiMe)]. First, by applying a new trisyl synthon (MeSi)CH(SiMeCHCl) 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(SiMe)SiMeCHSCHSiMeC(SiMe)}Li(DME)] and the N-coordinated monotrisyl compounds 3b [(NacNacLiCHSiMeC(SiMe)Li(THF)], 3c [Li(THF){C(SiMe)SiMeCHN(Me)CHCHN-2}], and 3d [Li{C(SiMe)SiMeCHN(Me)CHCHN(Pr)}] 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 MCl (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.