Hydrogen bonds. Part III. Crystal structures of p-bromophenacyl dichloroacetate and difluoroacetate

Abstract

Though previous i.r. measurements have shown that the dichloroacetyl group can participate in C–H ⋯ O hydrogen bonding in solution, the crystal structures of p-bromophenacyl dichloroacetate and difluoroacetate do not contain RCl₂CH ⋯ O or RF₂CH ⋯ O hydrogen bonds. The difluoroacetate crystallizes in the orthorhombic space group P2₁2₁2₁ with Z= 4 in a unit cell of dimensions a= 6·32, b= 35·12, c= 4·84 Å. The dichloroacetate is monoclinic, space group Pc, with Z= 2 in a unit cell of dimensions a= 13·11, b= 7·63, c= 6·08 Å, β= 94° 50′. The atomic parameters were adjusted by Fourier and least-squares methods, and the final values of R are 0·080 over 732 independent reflections for the difluoroacetate and 0·131 over 726 independent reflections for the dichloroacetate.