Facile Transformations of Lanthanocene Alkyls to Lanthanocene Thiolate, Sulfide, and Disulfide Derivatives by Reaction with Elemental Sulfur

Treatment of [Cp2Ln(μ-Me)]2 with 2 equiv of elemental sulfur in toluene at room
temperature leads to the formation of the methylthiolate complexes [Cp2Ln(μ-SMe)]2 [ Ln =
Yb (1a), Y (1b), Er (1c), Dy (1d)] in good yields. While reaction of Cp2Y(nBu) with elemental
sulfur in 1:1 stoichiometric ratio under the same conditions yields [(Cp2Y)2(μ3-S)(THF)]2 (2a)
as the metal-containing product with the extrusion of nBuSnBu and nBuSSnBu, the
corresponding insertion intermediate [Cp2Y(μ-SnBu)]2 (1e) could be isolated only by decreasing
the relative amount of S8 under more mild reaction conditions. Furthermore, [Cp2Yb(μ-SEt)]2
reacts with 2 equiv of sulfur to give a mixture of [(Cp2Yb)2(μ3-S)(THF)]2 (2b) and [Cp2Yb(THF)]2(μ-η2:η2-S2) (3). 2b and 3 can also be prepared from the reaction of [Cp2Yb(μ-Me)]2
with excess elemental sulfur in THF. All these results demonstrate that lanthanocene thiolate
complexes are unstable in solution with S8, and the nature of the alkyl ligands and reaction
conditions has a great influence on the final product structures from the reaction of
lanthanocene alkyls with elemental sulfur and provides an easy access to trivalent
lanthanocene thiolate, sulfide, and disulfide complexes as well as thioethers and organic
disulfides. Complexes 1−3 were characterized by elemental analysis and IR and mass
spectroscopies. The structures of complexes 1a, 1e, 2a, 2b, and 3 are also determined through
X-ray single-crystal diffraction analysis.