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

[Cp 2 Yb( o -H 2 NC 6 H 4 S)] 2 ·2THF ( 1 ) and Cp 2 Yb( p -H 2 NC 6 H 4 S)(THF) ( 2 ) were prepared in good yields by the protonolysis of Cp 3 Yb with the corresponding amino-substituted thiophenol in THF at room temperature, respectively. Treatment of [Cp 2 Yb( o -H 2 NC 6 H 4 S)] 2 ·2THF ( 1 ) with PhNCO gives the unexpected intermolecular addition/cyclization/elimination product [(C 5 H 5 ) 2 Yb(μ-η 1:η 3 -OSNC 7 H 4 )] 2 ( 3 ), while Cp 2 Yb( p -H 2 NC 6 H 4 S)(THF) ( 2 ) reacts with PhNCO under the same conditions to form the simple insertion product {Cp 2 Yb[μ-η 1:η 3 -OC( p -H 2 NC 6 H 4 S)NPh]} 2 ·2THF ( 4 ), demonstrating that the neighboring NH 2 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 .