Investigations on Organolanthanide Derivatives with the Hydrazonido (⁻NHN═CPh₂) Ligand: Synthesis, Crystal Structure, and Reactivity

Two organolanthanide complexes with the benzophenone hydrazonido(1−) ligand, [Cp 2 Yb(μ-NHN═CPh 2 )] 2 ( 1 ) and Cp 2 Er[η 2 -NHN═CPh 2 ](THF) ( 2 ), were synthesized by abstraction of cyclopentadienyl from Cp 3 Ln with 1 equiv of benzophenone hydrazone in THF. Reaction of 1 and 2 with phenyl isocyanate gives Ln−N bond insertion with the 1,3-H migration products Cp 2 Ln(η 2 -OC(NHPh)NN═CPh 2 )(HMPA) (Ln = Yb ( 3 ), Er ( 4 )). However, 1 and 2 react with PhNCS to give Ln−N bond insertion without the 1,3-H migration products Cp 2 Ln(η 2 -SC(NHN═CPh 2 )NPh)(HMPA) (Ln = Yb ( 5 ), Er ( 6 )) under the same conditions. PhCN inserts into the Er−N bond of 2 with 1,3-hydrogen migration to form the organolanthanide heterometallacycles Cp 2 Er[η 2 -NHC(Ph)NN═CPh 2 ] ( 7 ). However, t BuNC does not insert into the Er−N bond of 2 under the same conditions, and treatment of 2 with t BuNC leads to the isolation of the solvent-free dimer [Cp 2 Er(μ-η 1:η 2 -NHN═CPh 2 )] 2 ( 2′ ). All new compounds have been characterized through X-ray single-crystal diffraction analysis.