organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
terminal benzene rings, A and B, are nearly coplanar, whereas
the central ring, C, is nearly normal to them [interplanar
angles: 6.1 (1)ꢀ for A/B, 81.7 (1)ꢀ for A/C and 86.1 (1)ꢀ for
B/C]. Very similar conformations have been observed
previously in (III), (IV) and (V), as well as in analogues
without substituents in the 2-position, such as (VI) (Saraogi et
al., 2003) or (VII) (Abdulla et al., 1985). Such a conformation
brings the C1 O1 and NÐH1 bonds into a syn orientation,
and apparently favours the formation of a centrosymmetric
dimer of molecules, linked via a pair of strong NÐHÁ Á ÁO
hydrogen bonds. A dimer of topology R22(10) according to the
graph-set nomenclature (Etter, 1990) is present in the struc-
ture (Fig. 2), but the molecules are so widely separated that
only weak NÐHÁ Á ÁO interactions can exist. The NÁ Á ÁO10
ISSN 0108-2701
2-(4-Chloroanilino)- and
2-(4-methoxyanilino)-1,2-diphenyl-
ethanone
a
a
Â
Andrei S. Batsanov, Andres E. Goeta, Judith A. K.
Howard,a Bernardino Sotob and Oscar Au-Alvarezb*
aDepartment of Chemistry, University of Durham, South Road, Durham DH1 3LE,
England, and bDepartment of Chemistry, University of Oriente, P. Lumumba s/n,
Santiago de Cuba 90500, Cuba
Ê
distance 0 [3.479 (2) A] is much longer and the corrected
Ê
H1Á Á ÁO1 distance [2.59 (2) A] is only marginally shorter than
Ê
the corresponding sums of van der Waals radii, 3.22 and 2.68 A
Correspondence e-mail: o.au-alvarez@cnt.uo.edu.cu
(Rowland & Taylor, 1996).
Two molecules of (I), related via the inversion (2 x, y,
1 z), have their PhCOCNHC6H4Cl systems stacked face-to-
face, the C O bond of each molecule overlapping with the B
Received 27 March 2006
Accepted 9 April 2006
Online 29 April 2006
ring of another. Notwithstanding the tight interplanar
Ê
separation of 3.33 A, there is no evidence of intermolecular
charge transfer, such as occurs in the intensely coloured crystal
of (VII). The formation of continuous stacks is rendered
impossible by the perpendicular phenyl ring C.
The title compounds, C20H16ClNO and C21H19NO2, adopt syn
orientations of the C O and NÐH bonds but, like their
analogues, form no strong intermolecular hydrogen bonds.
Comment
Compound (II) (Fig. 1) has a more twisted conformation of
the backbone (see Fig. 3, and the torsion angles in Tables 1 and
Few 1-arylanilinoethanone derivatives have been structurally
studied so far, although some of them are important in
synthesis (Saraogi et al., 2003), while others possess interesting
charge-transfer properties (Abdulla et al., 1985). These
compounds also display rather unusual supramolecular
arrangements (see below). The present low-temperature study
of compounds (I) and (II) follows on from our structural
determinations of the parent compound 2-anilino-1,2-
diphenylethanone, (III) (Au & Tafeenko, 1987), its methyl
derivative 1,2-diphenyl-2-(p-toluidino)ethanone, (IV) (Au &
Tafeenko, 1986), and 1,2-bis(2-furyl)-2-(p-toluidino)ethanone,
(V) (Au & Tafeenko, 1988).
The structures of (I) and (II) both contain one molecule per
asymmetric unit. Crystals of (I) and (IV) are isostructural, the
Ê
Cl atom of van der Waals radius 1.76 A (Rowland & Taylor,
Ê
1996) replacing the methyl group of effective radius 2.0 A. In
Figure 1
The molecular structures of (I) (top) and (II) (bottom). Displacement
ellipsoids are drawn at the 50% probability level.
(I), the C3ÐC1ÐC2ÐNÐC15 backbone adopts an all-trans
Ê
conformation and is planar within Æ0.1 A (Fig. 1). The
o304 # 2006 International Union of Crystallography
DOI: 10.1107/S0108270106012881
Acta Cryst. (2006). C62, o304±o306
Batsanov, Andrei S.
