3-(4-Methoxybenzoyl)-6-nitrocoumarin

In the title coumarin derivative (also known as 2H-chromen-2-one or 2H-1-benzopyran-2-one), C17H11NO6, the coumarin ring system is nearly planar, with a dihedral angle of 3.35 (9)° between the pyrone and the benzene rings. The dihedral angle between the planes formed by the coumarin ring system and the benzene substituent is 54.60 (7)°, clearly showing the non-coplanarity of the whole aromatic system. The crystal studied was a non-merohedral twin; the minor component refined to approximately 0.44.

In the title coumarin derivative (also known as 2H-chromen-2one or 2H-1-benzopyran-2-one), C 17 H 11 NO 6 , the coumarin ring system is nearly planar, with a dihedral angle of 3.35 (9) between the pyrone and the benzene rings. The dihedral angle between the planes formed by the coumarin ring system and the benzene substituent is 54.60 (7) , clearly showing the noncoplanarity of the whole aromatic system. The crystal studied was a non-merohedral twin; the minor component refined to approximately 0.44.

3-(4-Methoxybenzoyl)-6-nitrocoumarin Saleta Vazquez-Rodriguez, Eugenio Uriarte and Lourdes Santana Comment
Coumarin derivative compounds present a great interest in the medicinal chemistry field due to the displayed biological properties that they present (Borges et al. 2009, Matos et al. 2011a, Matos et al. 2011b, Matos et al. 2011c, Vazquez-Rodriguez et al. 2013, Viña et al. 2012aand Viña et al. 2012b. The title structure is a 3-substituted coumarin derivative containing a 4-methoxybenzoyl ring at the mentioned position and a nitro group at position 6 of the coumarin scaffold. Therefore, the X-ray analysis of this compound (figure 1) aims to contribute to the elucidation of structural requirements needed to understand the partial planarity of the compound (coumarin nucleus) and the torsion of the 3-benzoyl moiety regarding to this nucleus. From the single-crystal diffraction measurements one can conclude that both the pyrone and benzene rings in the coumarin motif are essentially planar, presenting dihedral angle of 3.35 (9)°. The planarity of the coumarin moiety is also evident by the torsion angle value between their carbons C3-C2-C7-C8 (-175.89 (18)°).
In addition, the torsion angles of the carbonyl group versus the coumarin moiety and the phenyl ring are C10-C9-C15-O16 (43.2 (2)°) and O16-C15-C17-C18 (-152.9 (2)°) respectively. These values are typical of the torsion permitted by the rotation present at position 3. Presence of the carbonyl group at position 3 provokes a non coplanarity of the benzoyl moiety regarding to the coumarin scaffold. This fact is evident taking into account the dihedral angles formed by the planes of the coumarin, the carbonyl and the phenyl groups. Dihedral angle between the coumarin moiety and the carbonyl group is 38.66 (9)°; between the carbonyl and the phenyl group is 25.76 (10)° and between the coumarin scaffold and the phenyl group is 54.60 (7)°.

Refinement
H atoms were treated as riding atoms with C-H(aromatic), 0.95Å with U iso = 1.2U eq (C), C-H(methyl) = 0.98Å, with U iso = 1.5U eq (C). The positions of methyl hydrogens were checked on a final difference map. The structure was refined as a two-component non-merohedral twin with a BASF parameter of 0.4374.

Figure 2
Packing diagram of the title structure viewed along the b axis.  m. 192.91, 177.98, 166.65, 162.34, 138.75, 131.40, 130.83, 130.47, 129.32, 128.05, 127.28, 121.24, 120.67, 113.84, 55 Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. 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 > 2σ(F 2 ) is used only for calculating R-factors(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.