New chelating ligands based on S-organosulfurdiimides: synthesis and single crystal X-ray structures of their lithium complexes.

Three new diimidosulfinates, [TMSCH(2)S(N(t)Bu)(2)Li](2) (1), [2-PyCH(2)S(N(t)Bu)(2)Li](2) (2), and [{PhCH(2)S(N(t)Bu)(2)Li}(2) x THF] (3) (TMS = trimethylsilyl; Py = 2-pyridyl), have been synthesized by the reaction of functionalized alpha-CH(2)-organolithium compounds with bis-tert-butylsulfurdiimide. These new organolithium chelates are characterized by NMR ((1)H, (13)C, (7)Li, and (29)Si) spectroscopy and single-crystal X-ray diffraction analyses. Compounds 1 and 2 crystallize as dimers without donor molecules, whereas one of the lithium atoms in 3 is coordinated by a single THF molecule. The crystal structure of 1 shows significant intramolecular proximity between one methyl group of the trimethylsilyl (TMS) and one lithium atom, which could be described as an electrostatic Li...C interaction. The coordination sphere of each lithium atom in 2 is completed by donation from the nitrogen atom of the pyridyl ring; however, one of the lithium atoms in 3 is coordinated by a THF molecule. In addition, the first mixed sulfurdiimide species containing a diimidosulfinate and a diimidosulfite fragment, [{PhCHS(N(t)Bu)(2)Li(2)(THF)(2)}{MeS(N(t)Bu)(2)Li(THF)}] (4), was isolated by deprotonation of the alpha-CH(2) group in 3. The single-crystal X-ray structure of 4 revealed two different S-bound substituents coexisting in one dimer and two asymmetrically coordinated lithium atoms.