Activation of Bis(guanidinate)lanthanide Alkyl and Aryl Complexes on Elemental Sulfur: Synthesis and Characterization of Bis(guanidinate)lanthanide Thiolates and Disulfides

The treatment of [(Me3Si)(2)NC(NCy)(2)](2)Ln(mu-Cl)(2)Li(THF)(2) with 1 equiv of BnK (Bn = benzyl) in toluene affords [(Me3Si)(2)NC(NCy)(2)](2)LnBn [Ln = Er (1-Er), Y (1-Y)] in good yields. Similarly, [(Me3Si)(2)NC(NCy)(2)](2)LnSu [Ln = Er (2-Er), Yb (2-Yb)] are obtained in satisfactory yields by the reaction of [(Me3Si)(2)NC(NCy)(2)](2)Ln(mu-Cl)(2)Li(THF)(2) with (BuLi)-Bu-t in hexane. 1 reacts with (1)/(8) equiv of S-8 in toluene to form the sulfur insertion products {[(Me3Si)(2)NC(NCy)(2)](2)Ln(mu-SBn)}(2) [Ln = Er (3-Er), Y (3-Y)], while the reaction of 2 with elemental sulfur under the same conditions affords the oxidation products {[(Me3Si)(2)NC(NCy)(2)](2)Ln}(2)(mu-eta(2)center dot eta(2)-S-2) [Ln = Er (4-Er), Yb (4-Yb)] regardless of the equivalency of S-8 employed. Disulfide complexes 4 can also be obtained by the reaction of 3 with (1)/(4) equiv of S-8. Furthermore, the treatment of [(Me3Si)(2)NC(NCy)(2)](2)Ln(mu-Cl)2Li(THF)(2) with 1 equiv of (BuLi)-Bu-n in hexane, followed by reaction with (1)/(8) equiv of S-8, affords the dinuclear thiolate complexes {[(Me3Si)(2)NC(NCy)(2)](2)Ln(mu-(SBu)-Bu-n)}(2) [Ln = Y (5-Y), Er (5-Er)] in good yields. However, under the same conditions, [(Me3Si)(2)NC(NCY)(2)](2)Yb(mu-Cl)(2)Li(THF)(2) reacts with (BuLi)-Bu-n and S-8 to give {[(Me3Si)(2)NC(NCY)(2)](2)Yb}(2)(mu-eta(2):eta(2)-S-2) (4-Yb) as the main metal-containing product. [(Me3Si)(2)NC(NCy)(2)](2)LnPh (generated in situ from [(Me3Si)(2)NC(NCy)(2)](2)Ln(mu-Cl)(2)Ln(THF)(2) and PhLi) also undergoes sulfur insertion, affording {[(Me3Si)(2)NC(NCY)(2)](2)Ln(mu-SPh)}(2) [Ln = Er (6-Er), Yb (6-Yb)] in good yields. All of the complexes were characterized by spectroscopic and elemental analyses. The structures of all of these compounds, except 3-Y, are also determined by single-crystal X-ray diffraction analysis. Surprisingly, 3, 5, and 6 bear the same space group and very similar cell parameters, despite the different thiolate ligands.