Comparison of the crystal structures of methyl 4-bromo-2-(methoxymethoxy)benzoate and 4-bromo-3-(methoxymethoxy)benzoic acid

摘要

The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo-hydroxy-benzoic acids. Compound (II) crystallizes with two independent molecules (A and B) in the asymmetric unit. In both (I) and (II), the O-CH2-O-CH3 side chain is not in its fully extended conformation; the O-C-O-C torsion angle is 67.3 (3) degrees in (I), and -65.8 (3) and -74.1 (3)degrees in molecules A and B, respectively, in compound (II). In the crystal of (I), molecules are linked by C-H...O hydrogen bonds, forming C(5) chains along [010]. The chains are linked by short Br...O contacts [3.047 (2) A], forming sheets parallel to the bc plane. The sheets are linked via C-H...[pi] interactions, forming a three-dimensional architecture. In the crystal of (II), molecules A and B are linked to form R22(8) dimers via two strong O-H...O hydrogen bonds. These dimers are linked into ...A-B...A-B...A-B... [C22(15)] chains along [011] by C-H...O hydrogen bonds. The chains are linked by slipped parallel [pi]-[pi] interactions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) A], leading to the formation of slabs parallel to the bc plane.