journal menu
organic compounds
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—HOnitro [in (II)] hydrogen bonds affect the dispositions of the hydroxy groups. Classical intermolecular O—HO hydrogen bonds are found in both molecules but play quite dissimilar roles in the crystal structures. In (I), O—HO 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 OO contact of 2.686 (4) Å. For (I), four additional C—HO hydrogen bonds combine with π–π 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—HO contacts. These dimers are stacked through additional C—HO hydrogen bonds, and further weak C—HO interactions generate a three-dimensional network of dimer stacks.
Br [in (I)] and O—HOnitro [in (II)] hydrogen bonds affect the dispositions of the hydroxy groups. Classical intermolecular O—HO hydrogen bonds are found in both molecules but play quite dissimilar roles in the crystal structures. In (I), O—HO 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 OO contact of 2.686 (4) Å. For (I), four additional C—HO hydrogen bonds combine with π–π 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—HO contacts. These dimers are stacked through additional C—HO hydrogen bonds, and further weak C—HO interactions generate a three-dimensional network of dimer stacks.organic compounds
The title compound, C10H11BrO4, a useful precursor to pharmaceutically active isocoumarin and isochroman derivatives, crystallizes with two unique molecules in the asymmetric unit. A ![[pi]](/logos/entities/pi_rmgif.gif)
- stacking interaction links the planar molecules in the asymmetric unit. Additional - contacts stack pairs of molecules along the c axis. A feature of the crystal packing is the presence of a number of short BrO contacts. A particularly unusual arrangement involves the formation of dimers, with pairs of BrO contacts imposing a close BrBr interaction and generating five-membered rings within an eight-membered ring formed by two BrO contacts. Only two comparable arrangements have been reported previously. The BrO contacts combine with weak C-HO hydrogen bonds to form corrugated sheets of molecules approximately parallel to (001). These sheets are stacked along the c axis by - interactions to generate a three-dimensional network.
- stacking interaction links the planar molecules in the asymmetric unit. Additional - contacts stack pairs of molecules along the c axis. A feature of the crystal packing is the presence of a number of short BrO contacts. A particularly unusual arrangement involves the formation of dimers, with pairs of BrO contacts imposing a close BrBr interaction and generating five-membered rings within an eight-membered ring formed by two BrO contacts. Only two comparable arrangements have been reported previously. The BrO contacts combine with weak C-HO hydrogen bonds to form corrugated sheets of molecules approximately parallel to (001). These sheets are stacked along the c axis by - interactions to generate a three-dimensional network.
