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 C 26 H 42 N 2 O 2 Zn 2 are monoclinic, space group P 2 1 /c, with unit cell parameters a = 7.972(1) Å, b = 15.741(2) Å, c = 11.062(2) Å, 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.