Synthesis and Characterization of Lithium, Zirconium, and Hafnium Derivatives of N-Isopropyl-2-(isopropylamino)troponiminate

Abstract

The reaction of N-isopropyl-2-(isopropylamino)troponimine, [(i-Pr)2ATI]H, with n-BuLi in Et2O−THF gave [(i-Pr)2ATI]Li(THF)2 in excellent yield. The [(i-Pr)2ATI]2ZrCl2 and [(i-Pr)2ATI]2HfCl2 complexes were prepared by treating the respective metal tetrachlorides with 2 equiv of the lithium adduct. These metal complexes were characterized by NMR spectroscopy and X-ray crystallography. X-ray crystallographic data of the lithium, zirconium, and hafnium complexes show monomeric structures in the solid state. The lithium complex has a tetrahedral lithium ion and a slightly twisted C7N2Li framework. The zirconium and hafnium metal centers in [(i-Pr)2ATI]2ZrCl2 and [(i-Pr)2ATI]2HfCl2 show pseudooctahedral geometry with chlorides occupying the cis positions. The dialkyl derivative [(i-Pr)2ATI]2Zr(CH2SiMe3)2 was prepared by treating Zr(CH2SiMe3)4 with 2 equiv of the free ligand [(i-Pr)2ATI]H. Crystal data with Mo Kα (λ = 0.710 73 A) at 193 K: [(i-Pr)2ATI]Li(THF)2, C21H35LiN2O2, a = 9.2318(8) A, b = 14.624(2) A, c ...