Acta Crystallographica Section C

Crystal Structure Communications

Volume 69, Part 4 (April 2013)

organic compounds

Acta Cryst. (2013). C69, 407-411    [ ]

Similarities and differences in the structures of 5-bromo-6-hy­droxy-7,8-dimethyl­chroman-2-one and 6-hy­droxy-7,8-dimethyl-5-nitro­chroman-2-one

S. K. Goswami, L. R. Hanton, C. J. McAdam, S. C. Moratti and J. Simpson

Abstract: The title compounds, C11H11BrO3, (I), and C11H11NO5, (II), respectively, are derivatives of 6-hy­droxy-5,7,8-trimethyl­chroman-2-one substituted at the 5-position by a Br atom in (I) and by a nitro group in (II). The pyran­one rings in both mol­ecules adopt half-chair conformations, and intra­molecular O-H...Br [in (I)] and O-H...Onitro [in (II)] hydrogen bonds affect the dispositions of the hy­droxy groups. Classical inter­molecular O-H...O hydrogen bonds are found in both mol­ecules but play quite dissimilar roles in the crystal structures. In (I), O-H...O hydrogen bonds form zigzag C(9) chains of molecules along the a axis. Because of the tetragonal symmetry, similar chains also form along b. In (II), however, similar contacts involving an O atom of the nitro group form inversion dimers and generate R22(12) rings. These also result in a close inter­molecular O...O contact of 2.686 (4) Å. For (I), four additional C-H...O hydrogen bonds combine with [pi]-[pi] stacking inter­actions between the benzene rings to build an extensive three-dimensional network with mol­ecules stacked along the c axis. The packing in (II) is much simpler and centres on the inversion dimers formed through O-H...O contacts. These dimers are stacked through additional C-H...O hydrogen bonds, and further weak C-H...O inter­actions generate a three-dimensional network of dimer stacks.

Formula: C11H11BrO3 and C11H11NO5

hkldisplay filedownload file

Structure factor file (CIF format) (84.6 kbytes)
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Contains datablock I

hkldisplay filedownload file

Structure factor file (CIF format) (113.9 kbytes)
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Contains datablock II


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