Titanium Ester Homoenolates: A Structural and Synthetic Study

The synthesis and structural characterization of the novel monomeric titanium homoenolates [(Cl)2-(cp)Ti-CH2CH2COOEt] (2), and [(cp)2Ti-CH2CH2COOEt]+ZnI3-(3; cp = eta5-C5H5) are reported, along with a structural study on the well-known homoenolate [{(Cl)2-Ti-CH2CH2COOEt)2(mu-Cl)2] (1), which is dimeric both in solution and in the solid state. In both classes of titanium homoenolates we observed the presence of a five-membered metallacycle containing a titanium-carbon bond which is significantly longer in 3 than in 1. Crystallographic details: 1 is monoclinic, space group P2(1)/c, with a = 8.889(2) angstrom, b = 11.266(2) angstrom, c = 11.040(2) angstrom, alpha = gamma = 90-degrees, beta = 107.12(2)degrees, Z = 2, and R = 0.077; 3 is monoclinic, space group P2(1)/n, with a = 11.814(2) angstrom, b = 12.084(3) angstrom, c = 15.182(2) angstrom, alpha = gamma = 90-degrees, beta = 97.95(1)degrees, Z = 4, and R = 0.052.