organic compounds
Selected geometric parameters for the two molecules are
given in Tables 1 and 3. The N1ÐC1 and N2ÐC8 distances in
(I) and the corresponding N1ÐC1 and N2ÐC10 bond lengths
in (II) are shorter than the standard NÐC bond length
the CÐHÁ Á ÁCl hydrogen bond. For the sake of simplicity, we
shall omit any further consideration of the CÐHÁ Á ÁC
hydrogen bonds, which are too weak to in¯uence the overall
dimensionality of the supramolecular structure. In the ®rst
substructure, atom C9 in the molecule at (x, y, z) acts as a
hydrogen-bond donor to the C1±C6 ring in the molecule at
Ê
(1.47 A; Mak et al., 2002). This is similar to what has been
found in diphenylamine (Wang et al., 2005). This difference is
considered to be the result of ꢀ conjugation between the N
atom and the aromatic ring. In (I), the C2ÐC1ÐN1ÐC7 and
(x, y + 12, z 1 ), thus forming a C22(8) chain running along the
2
1
(34, , z) direction and generated by a 21 screw axis along
4
1
4
C9ÐC8ÐN2ÐC7 torsion angles ( 177.2 and
176.6ꢀ,
(34, , z) (Fig. 3). In the second substructure, atom C4 in the
respectively) are consistent with the equivalent angles in (II)
( 175.3 and 6.2ꢀ), showing that the N atoms lie approxi-
mately in the same plane as the aromatic rings to which they
are bonded. However, compared with the ideal value of 120ꢀ,
the C7ÐN2ÐC8 bond angle in (I) and the C1ÐN1ÐC8 angle
in (II) are strikingly large. The deviation is due to a van der
Waals repulsion between atoms H7 and H13 in (I), and
between H6 and H8 in (II).
molecule at (x, y, z) acts as a hydrogen-bond donor to
1
trichloromethyl atom Cl3 in the molecule at (x 1, y + ,
2
z + 12 ), so forming a C22(9) chain running parallel to the (21, 0, 34 )
1
4
1
direction and generated by a 21 screw axis along (x, ,
)
2
(Fig. 4). The combination of the two chain motifs is suf®cient
to link all the molecules into a two-dimensional sheet parallel
to (040) (Fig. 4). Two such sheets pass through each unit cell,
1
1
in the domains 0 < y < and < y < 1.
2
2
The two NH hydrogens in each molecule gave identical
chemical shifts and coupling constants with the adjacent CH H
atom [J = 7.2 Hz in (I) and 8.4 Hz in (II)], suggesting that in
solution on the NMR timescale the molecules relax to a
conformation where the two HÐNÐCÐH torsion angles
have similar average magnitudes, though the two HÐNÐCÐ
H torsion angles in each molecule in the solid state are
different [131.5 and 161.7ꢀ for H1DÐN1ÐC7ÐH7 and
H2DÐN2ÐC7ÐH7, respectively, in (I), and 149.9 and 155.5ꢀ
for H1DÐN1ÐC8ÐH8 and H2DÐN2ÐC8ÐH8, respec-
tively, in (II)].
The molecules of (I) (Fig. 1) are linked into sheets by two
hydrogen bonds, one of CÐHÁ Á ÁCl and one of CÐ
HÁ Á Áꢀ(arene) type (Table 2), the formation of which is readily
analyzed in terms of two one-dimensional substructures, one
formed by the CÐHÁ Á Áꢀ hydrogen bond and one formed by
Figure 4
Part of the crystal structure of (I), viewed along the (010) direction,
showing the formation of a (040) sheet. For the sake of clarity, H atoms
not involved in the motif shown have been omitted. Intermolecular
interactions are represented by dashed lines. Selected atoms are labelled.
[Symmetry codes: (i) x 1, y + , z + ; (ii) x, y + , z 12; Cg is the
1
2
1
2
1
2
centroid of the C1±C6 ring.]
Figure 3
Figure 5
Part of the crystal structure of (I), showing the formation of a C22(8) chain
along the (34, 14, y) direction. For the sake of clarity, H atoms not involved
in the motif shown have been omitted. Atoms marked with an asterisk (*)
or a hash (#) are at the symmetry positions (x, y + 12, z 21 ) and (x, y + 21,
z + 12 ), respectively. (Cg is the centroid of the C1±C6 ring.)
Part of the crystal structure of (II), showing the formation of an R22(16)
dimer centred at (12, 0, 0) and a C(7) chain along the (100) direction.
Atoms marked with an asterisk (*), a hash (#) or an `at' symbol (@) are at
the symmetry positions (x + 1, y, z), ( x + 2, y, z) and ( x + 1, y,
z), respectively.
ꢁ
Acta Cryst. (2007). C63, o524±o527
Zhang et al. C14H13Cl3N2 and C16H17Cl3N2 o525