Crystal structures of (E)-1-naphthaldehyde oxime and (E)-phenanthrene-9-carbaldehyde oxime

The aldoximes (E)-1-naphthaldehyde oxime (I) and E-phenanthrene-9-carbaldehyde oxime (II) were synthesized and characterized using NMR and XRD. The crystal structures of both (I) and (II) are similar with a single intermolecular O—H⋯N hydrogen-bonding interaction, giving rise to the formation of one-dimensional polymeric chains extending along the 21 (b) screw axes in each.


Supramolecular features
Similar intermolecular interactions are observed in the crystal structures of both (I) and (II). In each, molecules are linked through a single intermolecular O1-HÁ Á ÁN1 i hydrogenbonding interaction [Tables 2 and 3 for (I) and (II), respectively]. These basic interactions are shown in Fig. 3, defining an oxime C(3) type II motif. It is well known that oximes are able to form different types of hydrogen-bonding motifs (Bruton et al., 2003). In the structures of both (I) and (II), the formation of a one-dimensional polymeric chain arrangement of molecules results, extending along the 2 1 (b) screw axes in each (Fig. 4) The molecular conformation and atom-numbering scheme for (II), with non-H atoms represented as 30% probability ellipsoids. Table 1 Selected torsion angles ( ) for the aldoxime groups in (I) and (II).

Figure 3
Intermolecular hydrogen-bonding associations for (I) (left) and (II) (right), shown as dashed lines. Non-associative H atoms have been omitted for clarity.

Database survey
Many naphthalene-carbaldehyde oxime derivatives are present in the Cambridge Structural Database (Version 5.38; Groom et al. 2016) but no one crystal structure containing only an aldoxime group in position 1 of the naphthalene ring system has been reported. The most similar structures that can be found are LIVROY/LIVROY01 (Guo et al., 2008;Tarai & Baruah, 2016) with an additional hydroxyl group in position 2 and TIJPOS (Asaad et al., 2005) with a dimethylamino group in position 9. The most important difference between (I) and LIVROY/LIVROY01 are the two hydrogen bonds: one intramolecular O-HÁ Á ÁN and another intermolecular O-HÁ Á ÁO. As a result of the intramolecular hydrogen-bonding interaction, the aldoxime group in the latter compound is coplanar with the central naphthalene ring with a dihedral angle of 1.21 and torsion angles C1-C11-N1-O2 = 179.27, C3-C1-C11-N1 = À179.91 and C4-C1-C11-N1 = À0.76 . However, TIJPOS (Asaad et al., 2005), with just one type of intermolecular hydrogen bond, shows a rotation in the aldoxime group that is more dramatic than in (I) and (II) (

Synthesis and crystallization
The aldoximes (E)-1-naphthaldehyde oxime (I) and (E)phenanthrene-9-carbaldehyde oxime (II) were synthesized, in ca 90% yield, by treatment of 1-naphthaldehyde or phenanthrene-9-carbaldehyde, respectively, with hydroxylamine hydrochloride and sodium carbonate in MeOH at room temperature. To a solution of hydroxylamine hydrochloride (41.6 mg, 0.60 mmol) in MeOH (10 ml) was added sodium carbonate (31.7 mg, 0.30 mmol). The reaction mixture was stirred at room temperature for 5 min. 1-Naphthaldehyde (85.0 mg, 0.54 mmol) or phenanthrene-9-carbaldehyde (112.2 mg, 0.54 mmol) was added and the reaction mixture was stirred at room temperature for 12 h. The precipitate formed was then filtered off and the filtrate was evaporated in vacuo. The crude residue was purified by column chromatography on silica (CHCl 3 as the eluent, 50 ml), followed by evaporation of the solvent in vacuo to give the pure aldoximes [(I), 84 mg, 90% yield and (II), 107 mg, 89% yield] (see reaction scheme).
Single crystals of the aldoximes (I) and (II) suitable for X-ray diffraction were obtained by slow evaporation of their 10 ml CHCl 3 solutions at room temperature. Compounds (I) and (II) were characterized by IR, 1 H, 13 C and DEPT-135 NMR spectroscopies and also by single crystal X-ray diffraction analysis.
In the IR spectra of (I) and (II), the characteristic bands at wavenumbers 3389 and 3200 cm À1 (O-H), and 1614 and 1607 cm-1 (C N), confirm the formation of the aldoximes (I) and (II), respectively. In the 1 H NMR spectra, we observed the absence of the signal of the aldehyde at ca 10 ppm and a new signal at ca 8.8 ppm due to the imine proton CH N was detected. Moreover, in the 13 C and DEPT-135 NMR spectra, the signal of the aldehyde at ca 190 ppm was not observed, and a new signal at ca 150 ppm due to the oxime carbon CH NOH was detected, confirming the formation of the aldoximes (I) and (II).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4. All C-bound H atoms were located in difference-Fourier maps but were subsequently treated as riding with C-H = 0.93 Å and with U iso (H) = 1.2U eq (C). The H atoms of the OH groups were positioned with idealized geometry and were refined freely in both structures.

Computing details
For both structures, data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: SHELXL2014 (Sheldrick, 2015b). Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.3294 (