Bulky Chelating Diamide Complexes of Zirconium: Synthesis, Structure, and Reactivity of d0 Alkyl Derivatives

The reaction of 2 equiv of LiNHAr (Ar = 2,6-iPr2C6H3) with 1,3-dibromopropane yields the diamine ArHN(CH2)3NHAr ((BAIP)H2, 1). The reaction of (BAIP)H2 with Zr(NMe2)4 yields the complex (BAIP)Zr(NMe2)2 (2) and 2 equiv of NHMe2. Compound 2 reacts with 2 equiv of [Me2NH2]Cl to yield (BAIP)ZrCl2(NHMe2)2 (3) and in the presence of excess pyridine affords the complex (BAIP)ZrCl2py2 (4). The base-free dichloride complex (BAIP)ZrCl2 (5) can be prepared from 2 and excess ClSiMe3. The alkylation of 4 or 5 with 2 equiv of MeMgBr, 2 equiv of PhCH2MgCl, and 1 equiv of NaCp(DME) yields the alkyl derivatives (BAIP)ZrR2 (6a, R = Me; 6b, R = CH2Ph) and (BAIP)Zr(η5-C5H5)Cl (8), respectively. The reaction of 2 equiv of PhMe2CCH2MgCl with complex 4 yields the η2-pyridyl complex (BAIP)Zr(η2-N,C−NC5H4)(CH2CMe2Ph) (7). An X-ray study of 7 revealed a capped tetrahedron geometry with the pyridyl nitrogen occupying the capping position. Complex 7 is likely formed via proton abstraction from coordinated pyridine. The catalyst syst...