Substituent Effects on Isocyanate Insertion into a Lanthanide−Sulfur Bond. Unexpected Construction of a Coordinated Thiazolate Ring

[Cp2Yb(o-H2NC6H4S)]2·2THF (1) and Cp2Yb(p-H2NC6H4S)(THF) (2) were prepared in good
yields by the protonolysis of Cp3Yb with the corresponding amino-substituted thiophenol in
THF at room temperature, respectively. Treatment of [Cp2Yb(o-H2NC6H4S)]2·2THF (1) with
PhNCO gives the unexpected intermolecular addition/cyclization/elimination product [(C5H5)2Yb(μ-η1:η3-OSNC7H4)]2 (3), while Cp2Yb(p-H2NC6H4S)(THF) (2) reacts with PhNCO under
the same conditions to form the simple insertion product {Cp2Yb[μ-η1:η3-OC(p-H2NC6H4S)NPh]}2·2THF (4), demonstrating that the neighboring NH2 group participation could lead
to unique isocyanate insertion reactivity. The structures of all the complexes were confirmed
by X-ray single-crystal diffraction analysis, indicating that complexes 1 and 4 have an
unusual intermolecular hydrogen bond interaction involving THF, and a novel intramolecular
π−π weak interaction between aromatic rings is also observed in 4.