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 3 ) 3 ]. First, by applying a new trisyl synthon (Me 3 Si) 2 CH(SiMe 2 CH 2 Cl) 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 3 ) 2 SiMe 2 CH 2 SCH 2 SiMe 2 C(SiMe 3 ) 2 }Li(DME) 3 ] and the N-coordinated monotrisyl compounds 3b [(NacNac Dipp LiCH 2 SiMe 2 C(SiMe 3 ) 2 Li(THF)], 3c [Li(THF){C(SiMe 3 ) 2 SiMe 2 CH 2 N(Me)CH 2 C 5 H 4 N-2}], and 3d [Li{C(SiMe 3 ) 2 SiMe 2 CH 2 N(Me)CH 2 CH 2 N( i Pr) 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 MCl 2 (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.