BULKY CHELATING DIAMIDE COMPLEXES OF ZIRCONIUM - SYNTHESIS, STRUCTURE, AND REACTIVITY OF D(0) ALKYL DERIVATIVES

The reaction of 2 equiv of LiNHAr (Ar = 2,6-(Pr2C6H3)-Pr-i) with 1,3-d ibromopropane yields the diamine ArHN(CH2)(3)NHAr ((BAIP)H-2, 1). The reaction of (BAIP)H-2 with Zr(NMe2)(4) yields the complex (BAIP)Zr(NMe 2)(2) (2) and 2 equiv of NHMe2. Compound 2 reacts with 2 equiv of [Me2 NH2]Cl to yield (BAIP)ZrCl2(NHMe2)(2) (3) and in the presence of exces s pyridine affords the complex (BAIP)ZrCl(2)py(2) (4). The base-free d ichloride complex (BAIP)ZrCl2 (5) can be prepared from 2 and excess Cl SiMe3. The alkylation of 4 or 5 with 2 equiv of MeMgBr, 2 equiv of PhC H2MgCl, and 1 equiv of NaCp(DME) yields the alkyl derivatives (BAIP)Zr R2 (6a, R = Me; 6b, R = CH2Ph) and (BAIP)Zr(eta(5)-C5H5)Cl (8), respec tively. The reaction of 2 equiv of PhMe2CCH2MgCl with complex 4 yields the eta(2)-pyridyl complex (BAIP)Zr(eta(2)-N,C-NC5H4)(CH2CMe2Ph) (7). An X-ray study of 7 revealed a capped tetrahedron geometry with the p yridyl nitrogen occupying the capping position. Complex 7 is likely fo rmed via proton abstraction from coordinated pyridine. The catalyst sy stem 6a/MAO polymerizes 1-hexene to a mixture of high polymer and olig omers. Activation with {Ph3C}[B(C6F5)(4)] yields only oligomers (n = 2 -7). Rapid beta-hydride elimination precludes polymer formation in the se systems.