X-ray crystal structure of the ethylzinc enolate of 1-(2,4-cyclopentadienyl)-2-(diethylamino)-1-ethanone, the unexpected reaction product from cyclopentadienyl(ethyl)zinc and ethyl N, N-diethylglycinate

Reaction of cyclopentadienyl(ethyl)zinc with ethyl N, N-diethylglycinate affords the dimeric ethylzinc enolate (2) of 1-(2,4-cyclopentadienyl)-2-(diethylamino)-1-ethanone in quantitative yield. Its molecular structure was determined by X-ray crystallography. Crystals of 2 C₂₆H₄₂N₂O₂Zn₂ are monoclinic, space group P2₁/c, with unit cell parameters a = 7.972(1) A ̊, b = 15.741(2) A ̊, c = 11.062(2) A ̊, β = 91.85(2)°. The crystal structure was solved using standard Patterson methods (Zn) and subsequent difference Fourier techniques. Anisotropic full-matrix least-squares refinement with 1989 observed reflections and 160 parameters converged at R = 0.0335.