Derivatization of niobium complexes bearing imido and acetophenone imine ligands

摘要

The successful isolation and characterization of derivatization reaction products of the niobium imido complex L_2NbCl(NAr) (L = ortho-metalated acetophenone imine, Ar = 2,6-~iPr_2C _6H_3) with carbon and oxygen donor ligands such as Me, Me_3SiCH_2, PhCC, Me_3SiCC, CF_3SO _3, and MeO are described. These more reactive σ-donor ligands were readily installed in place of the chloride ligand through salt metathesis reactions. The (trimethylsilyl)methyl complex showed significant α-agostic interactions between the methylene group and the niobium center. Similar strategies to derivatize the chloride complex utilizing lithiated amides (LiNMe_2, LiNEt_2, LiN~iPr_2, and LiNC_5H_(10)) resulted in the production of a niobium hydride species due to β-hydrogen elimination processes. All of the resulting C_1-symmetric complexes were formed as predominantly a single isomer and were fully characterized using a combination of ~1H and ~(13)C NMR spectroscopy, elemental analyses, and X-ray crystallography, when possible.