3-(4-Fluorobenzyl)-1H-isochromene-1-thione

In the molecule of the title compound, C16H11FOS, the benzene ring is oriented at a dihedral angle of 89.68 (3)° with respect to the planar [maximum deviation 0.009 (2) Å] isocoumarin ring system. An intramolecular C—H⋯S interaction results in the formation of a planar five-membered ring. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules into chains parallel to the c axis. A π–π contact between the isocoumarin rings [centroid–centroid distance = 3.818 (3) Å] may further stabilize the structure.

In the molecule of the title compound, C 16 H 11 FOS, the benzene ring is oriented at a dihedral angle of 89.68 (3) with respect to the planar [maximum deviation 0.009 (2) Å ] isocoumarin ring system. An intramolecular C-HÁ Á ÁS interaction results in the formation of a planar five-membered ring. In the crystal structure, intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into chains parallel to the c axis. Acontact between the isocoumarin rings [centroid-centroid distance = 3.818 (3) Å ] may further stabilize the structure.

Comment
The isocoumarin nucleus is an abundant structural motif in natural products (Barry, 1964). Many constituents of the steadily growing class of known isocoumarins exhibit valuable biological properties such as antifungal (Sturtz et al., 2002), antitumor or cytotoxic, anti-inflammatory, anti-allergic (Rossi et al., 2003) and enzyme inhibitory (Powers et al., 2002) activities.
Naturally occurring halo-isocoumarins and their halogeno-3,4-dihydroiscoumarin derivatives are very rare. However, a few examples of naturally occurring chlorine containing isocoumarins are known (Thomas & Jens, 1999). In view of the importance of this class of compounds, the title compound, an isocoumarine derivative containing 4-fluorobenzyl substituent has been synthesized, and we report herein its crystal structure.
In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 1) link the molecules into chains parallel to the c-axis (Fig. 2), in which they may be effective in the stabilization of the structure. The π-π contact between the isocoumarine rings, Cg1-Cg2 i [symmetry code: (i) -x, -y, 1 -z, where Cg1 and Cg2 are centroids of the rings A (C1-C6) and B (O1/C5-C9), respectively] may further stabilize the structure, with centroid-centroid distance of 3.818 (3) Å.

Refinement
H atoms were positioned geometrically, with C-H = 0.93 and 0.97 Å for aromatic and methylene H, respectively, and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme.  3-(4-Fluorobenzyl)-1H-isochromene-1-thione Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.