Zirconocene and rac-[1,2-Ethylene-1,1‘-bis(η5-tetrahydroindenyl)]zirconium Complexes of 2-Vinylpyridine: Syntheses, X-ray Crystal Structures, and Reactions with H2CCH2, H2O, HBF4, and CO2

Reactions of Cp 2 Zr(thf)(η 2 -Me 3 SiC 2 SiMe 3 ) ( 1 ) and rac -(ebthi)Zr(η 2 -Me 3 SiC 2 SiMe 3 ) ( 2; ebthi = 1,2-ethylene-1,1‘-bis(η 5 -tetrahydroindenyl)) with 2-vinylpyridine lead, under elimination of the alkyne, to the five-membered azazirconacycles, which are best described as 1-zircona-2-azacyclopent-3-enes (1-azadiene complexes). One of these complexes couples with ethylene to yield a stable α-2-pyridyl-substituted zirconacyclopentane and reacts in a 2:1 ratio with water to yield a β-2-pyridyl-substituted dimeric σ-ethylzirconoxane. In the reaction of the 2 -derived complex with HBF 4, rac -[1,2-ethylene-1,1‘-bis(η 5 -tetrahydroindenyl)]zirconium difluoride was obtained. Both 1-zircona-2-azacyclopent-3-enes insert carbon dioxide to give structurally different binuclear carbonate-bridged complexes.