Amido/amine triazacyclononane-based zirconium complexes: Syntheses, reactivity, and structures

The reactions of [Zr(NMe2)(4)](2) with triamido-triazacyclonane ligand precursors, {NH(Ph)SiMe2}(3)tacn (H3N3[9]N-3) and {NH(C6H4F)SiMe2}(3)tacn (H3N3-F[9]N-3), led to the formation of complexes [Zr(NMe2)(2){N(Ph)SiMe2}(2){NH(Ph) SiMe2}tacn], 1, and [Zr(NMe2)(2){N(o-C6H4F)SiMe2}(2){NH(o-C6H4F)SiMe2} tacn], 2, where the zirconium is coordinated to two remaining dimethylamido ligands and to a dianionic tacn-based ligand, [{N(Ph')SiMe2}(2){NH(Ph')SiMe2}tacn](2-), that formed from deprotonation of two amine pendent arms of the ligands' precursors. The third pendent arm of H3N3[9]N-3 and H3N3-F[9]N-3 remains neutral and not bonded to the zirconium. Treatment of 1 with NaH led to the synthesis of [Zr(NMe2){N(Ph)SiMe2}(2)tacn], 3, that results from the cleavage of the N-Si bond of the original neutral pendent arm. Complexes [ZrCl{N(Ph')SiMe2}(2)tacn] (Ph' = C6H5, 4, and C6H4F, 5) have been obtained by reactions of ZrCl4 with {MN(Ph')SiMe2}(3)tacn center dot 2THF (M = Li, Na). Reactions of 4 and 5 with LiCCPh led to the syntheses of [Zr(CCPh){N(Ph')SiMe2}(2)tacn] (Ph' = C6H5, 6, and C6H4F, 7). The solid-state structure of 3 shows a chiral metal center.