[:pb]Crystal structures and Hirshfeld surfaces of four methoxybenzaldehyde oxime derivatives, 2-MeO- C H C=NOH ( = H and 2-, 3- and 4-MeO): different conformations and hydrogen-bonding patterns[:]

[:pb]Authors: Gomes, L. R.; De Souza, M. V. N.; Da Costa, C. F.; Wardell, J. L.; Low, J. N.
Source: Acta Crystallographica Section e, Crystallographic Communications, v. 74, p. 1553-1560, 2018
Publisher: Crystallographic Communications

Abstract

The crystal structures of four (E)-meth­oxy­benzaldehyde oxime derivatives, namely (2-meth­oxy­benzaldehyde oxime, 1, 2,3-di­meth­oxy­benzaldehyde oxime, 2, 4-di­meth­oxy­benzaldehyde oxime, 3, and 2,5-di­meth­oxy­benzaldehyde oxime, 4, are discussed. The arrangements of the 2-meth­oxy group and the H atom of the oxime unit are s-cis in compounds 1–3, but in both independent mol­ecules of compound 4, the arrangements are s-trans. There is also a difference in the conformation of the two mol­ecules in 4, involving the orientations of the 2- and 5-meth­oxy groups. The primary inter­molecular O—H(oxime)O(hy­droxy) hydrogen bonds generate C(3) chains in 1 and 2. In contrast, in compound 3, the O—H(oxime)O(hy­droxy) hydrogen bonds generate symmetric R₂²(6) dimers. A more complex dimer is generated in 4 from the O—H(oxime)O(hy­droxy) and C—H(2-meth­oxy)O(hy­droxy) hydrogen bonds. In all cases, further inter­actions, C—HO and C—Hπ or π–π, generate three-dimensional arrays. Hirshfeld surface and fingerprint analyses are discussed.

Keywords: crystal structure; oxime derivative; hydrogen bonding

Document Type: Research Article

DOI: 10.1107/S2056989018014020

Publication date: 2018

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