Zirconium Complexes of Symmetric and of Chiral Diketiminate Ligands: Synthesis, Crystal Structures, and Reactivities

Reaction of N,N-dialkyl-2-amino-4-iminopent-2-enes (nacnacRH; R = Bn (1a), Cy (1b), R-CH(Me)Ph (1c)) with nBuLi afforded the lithium salts nacnacRLi(THF), 2a−c. Further reaction with ZrCl4 or ZrCl4(THF)2 yielded the cis-dichloride complexes nacnacR2ZrCl2, 3a−c. As a side reaction in the synthesis of 3c, CH activation of CH(Me)Ph under formal HCl elimination was observed. Complex 3a could also be obtained by reaction of nacnacBnH with nBu2ZrCl2. nacnacBn2ZrMe2, 5, was formed in reactions of 3a with MeLi in the presence of excess AlMe3 and was isolated from the reaction of Me2ZrCl2 with 2a. Complex 5 reacts with aluminum chloride compounds, but not with lithium chloride, to form the dichloride complex 3a and with ethanol to form nacnacBn2Zr(OEt)2, 6. X-ray diffraction studies have been performed for 3a−c, 5, and 6.