Supramolecular networks in (9-fluoro-4H-chromeno[4,3-c]isoxazol-3-yl)methanol and its 9-chloro analogue at 100 K.

The title compounds, (9-fluoro-4H-chromeno[4,3-c]isoxazol-3-yl)methanol, C(11)H(8)FNO(3), (I), and (9-chloro-4H-chromeno[4,3-c]isoxazol-3-yl)methanol, C(11)H(8)ClNO(3), (II), crystallize in the orthorhombic space group Pbca with Z' = 1 and the triclinic space group P-1 with Z' = 6, respectively. The simple replacement of F by Cl in the main molecular scaffold of (I) and (II) results in significant differences in the intermolecular interaction patterns and a corresponding change in the point-group symmetry from D(2h) to C(i) = S(2). These striking differences are manifested through the presence of C-H···F and the absence of O-H···O and C-H···O interactions in (I), and the absence of C-H···Cl and the presence of O-H···O and C-H···O interactions in (II). However, the geometry of the synthons formed by the O-H···N and O-H···X (X = F or Cl) interactions observed in the constitution of the supramolecular networks of both (I) and (II) remains similar. Also, C-H···O interactions are not preferred in the presence of F in (I), while they are much preferred in the presence of Cl in (II).