Three N2-benzoyloxybenzamidines: Sheet structures built from hard and soft hydrogen bonds and aromatic π-π stacking interactions

Article abstract of DOI:10.1107/S0108270103025435

The molecular structures of N²-(benzoyloxy)benzamidine, (I), N²-(2-hydroxybenzoloxy)benzamidine, (II), and N ²-benzoyloxy-2-hydroxy-benzamidine, (III), were analyzed. The molecules of (I) were linked into chains by a single N-H···N hydrogen bond and these chains were linked into sheets by aromatic π-π stacking interactions. The molecules of (I) and (III) had chain extended conformations, with the aryl groups remote from one another. It was observed that in these three compounds conformations were influenced by intermolecular hydrogen bonding involving the substituted aryl rings.

Full text of DOI:10.1107/S0108270103025435

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
most stable conformers, at least in the vapour phase, are those
with chain-extended C(Ar)ÐCÐOÐN CÐC(Ar) spacer
units. Consistent with this prediction, the structures of three
derivatives [Ar1 is 1-naphthyl and Ar2 is 2-methylphenyl,
Cambridge Structural Database (CSD; Allen, 2002) refcode
QUNMER; Ar1 is 1-naphthyl and Ar2 is 2,6-dichlorophenyl,
CSD refcode QUNMOB; Ar1 is 2-methylphenyl and Ar2 is
2,4-dichlorophenyl, CSD refcode QUNMIV] were all found to
ISSN 0108-2701
Three N2-benzoyloxybenzamidines:
sheet structures built from hard and
soft hydrogen bonds and aromatic
p±p stacking interactions
Carlos E. M. Carvalho,a Solange M. S. V. Wardell,a
James L. Wardell,b Janet M. S. Skakle,c John N.
Lowc and Christopher Glidewelld*
a
Â
Â
Instituto de Quõmica, Universidade Federal Fluminense, 24020-150 Niteroi,
b
Â
Â
Rio de Janeiro, RJ, Brazil, Instituto de Quõmica, Departamento de Quõmica
Ã
Inorganica, Universidade Federal do Rio de Janeiro, 21945-970 Rio de Janeiro,
RJ, Brazil, cDepartment of Chemistry, University of Aberdeen, Meston Walk,
Old Aberdeen AB24 3UE, Scotland, and dSchool of Chemistry, University of
St Andrews, Fife KY16 9ST, Scotland
Correspondence e-mail: cg@st-andrews.ac.uk
Received 29 October 2003
Accepted 4 November 2003
Online 6 December 2003
adopt nearly planar chain-extended conformations, with the
aryl groups remote from one another. In this paper, we report
the structure of three more compounds of this type, including
the unsubstituted parent compound, namely N2-(benzoyl-
oxy)benzamidine, (I), and two isomeric hydroxy compounds,
N2-(2-hydroxybenzoyloxy)benzamidine, (II), and N2-benz-
oyloxy-2-hydroxybenzamidine, (III). In these three com-
pounds, there exists the possibility that the overall confor-
mation may be in¯uenced by intermolecular hydrogen
bonding involving the substituted aryl rings.
The molecules of (I)±(III) (Figs. 1±3) all have chain-
extended conformations, with the aryl groups remote from
one another. In (III), the non-H atoms in the central spacer
unit between atoms C11 and C21 are almost coplanar, as
shown by the key torsion angles (Table 4), whereas in both (I)
Molecules of the title compounds N2-(benzoyloxy)benzami-
dine, C14H12N2O2, (I), N2-(2-hydroxybenzoyloxy)benzami-
dine, C14H12N2O3, (II), and N2-benzoyloxy-2-hydroxy-
benzamidine, C14H12N2O3, (III), all have extended chain
conformations, with the aryl groups remote from one another.
In (I), the molecules are linked into chains by a single NÐ
Ê
Ê
HÁ Á ÁN hydrogen bond [HÁ Á ÁN = 2.15 A, NÁ Á ÁN = 3.029 (2) A
and NÐHÁ Á ÁN = 153ꢀ] and these chains are linked into sheets
by means of aromatic ꢀ±ꢀ stacking interactions. There is one
intramolecular OÐHÁ Á ÁO hydrogen bond in (II), and a
combination of one three-centre NÐHÁ Á Á(N,O) hydrogen
Ê
Ê
Ê
bond [HÁ Á ÁN = 2.46 A, HÁ Á ÁO = 2.31 A, NÁ Á ÁN = 3.190 (2) A,
NÁ Á ÁO = 3.146 (2) A, NÐHÁ Á ÁN = 138ꢀ
and NÐHÁ Á Á
Ê
O = 154ꢀ] and one two-centre CÐHÁ Á ÁO hydrogen bond
ꢀ
Ê
Ê
[HÁ Á ÁO = 2.46 A, CÁ Á ÁO = 3.405 (2) A and CÐHÁ Á ÁO = 173 ]
links the molecules into sheets. In (III), an intramolecular OÐ
HÁ Á ÁN hydrogen bond and two NÐHÁ Á ÁO hydrogen bonds
Ê
Ê
[HÁ Á ÁO = 2.26 and 2.10 A, NÁ Á ÁO = 2.975 (2) and 2.954 (2) A,
and NÐHÁ Á ÁO = 138 and 163ꢀ] link the molecules into sheets.
Comment
Acyloxyarylamidines, Ar1C(O)ON C(NH2)Ar2, can in prin-
ciple adopt a wide range of conformations, depending on both
the con®guration at the C N double bond, and the rotational
freedom about the CÐO and NÐO single bonds. On the basis
of ab initio calculations on the simple model compound
HC(O)ON CHNH2 and qualitative estimates of 1,4-inter-
actions in the aryl analogues Ar1C(O)ON C(NH2)-
Ar2, it has been suggested (Tucker et al., 2000) that the two
Figure 1
The molecule of (I), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level.
o28 # 2004 International Union of Crystallography
DOI: 10.1107/S0108270103025435
Acta Cryst. (2004). C60, o28±o32

organic compounds
and (III), there is a modest twist about the central N2ÐO1
bond. The CÐN and CÐO distances in the spacer unit
distinguish clearly between the formal single and double
bonds; the CÐN distances are, in addition, fully consistent
with the location of the H atoms bonded to atom N4, as
deduced from a difference map. The remaining bond distances
and interbond angles show no unusual features.
Despite their very similar constitutions and their similar
molecular geometries, the supramolecular structures of (I)±
(III) are all different, with signi®cant differences even
between the isomeric compounds (II) and (III). No two
structures employ the same combination of hard and soft
(Desiraju & Steiner, 1999) interactions between the molecules.
In (I) (Fig. 1), where both aryl rings are unsubstituted, there
are no intramolecular hydrogen bonds and only a single
intermolecular hydrogen bond (NÐHÁ Á ÁO; Table 1). Amino
atom N4 in the molecule at (x, y, z) acts as a hydrogen-bond
However, the chains in (I) are weakly linked into sheets by
a single aromatic ꢀ±ꢀ stacking interaction. Phenyl rings C11±
C16 and C21±C26 in the molecules at (x, y, z) and (12 + x, 21 y,
12 + z), respectively, are nearly parallel, with an interplanar
angle of only 5.1 (2)ꢀ; the ring-centroid separation is
Ê
Ê
3.852 (2) A and the interplanar spacing is ꢁ3.50 A, giving a
Ê
centroid offset of ꢁ1.61 A. Propagation of this interaction
thus generates a chain running parallel to the [101] direction
(Fig. 5), and the combination of [101] and [101] chains
generates a (010) sheet. Two sheets pass through each unit
cell, in the domains 0.02 < y < 0.52 and 0.48 < y < 1.02, but
there are no direction-speci®c interactions between adjacent
sheets.
There is one intramolecular hydrogen bond in (II) (Fig. 2)
and there are two intermolecular hydrogen bonds, viz. one
donor, via atom H41, to imino atom N2 in the molecule at
(12 + x,
1
2
y, 12 + z), so producing a zigzag C(4) chain (Bern-
stein et al., 1995) running parallel to the [101] direction and
generated by the n-glide plane at y = 14 (Fig. 4). The second
NÐH bond plays no role in the supramolecular aggregation,
forming neither a hard NÐHÁ Á ÁO hydrogen bond nor a soft
NÐHÁ Á Áꢀ(arene) hydrogen bond. Neither of the two O atoms
plays any role in the supramolecular structure.
Figure 4
Figure 2
The molecule of (II), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level.
Part of the crystal structure of (I), showing the formation of a C(4)
hydrogen-bonded chain along [101]. For the sake of clarity, H atoms
bonded to C atoms have been omitted. Atoms marked with an asterisk
(*), a hash (#) or an ampersand (&) are at the symmetry positions (12 + x,
1
2
y, 12 + z), ( 21 + x, 12 y, 21 + z) and ( 1 + x, y, 1 + z), respectively.
Figure 5
Figure 3
The molecule of (III), showing the atom-labelling scheme. Displacement
ellipsoids are drawn at the 30% probability level.
A stereoview of part of the crystal structure of (I), showing the formation
of a ꢀ-stacked chain along [101]. For the sake of clarity, H atoms bonded
to C atoms have been omitted.
ꢂ
Acta Cryst. (2004). C60, o28±o32
Carlos E. M. Carvalho et al.
C14H12N2O2, C14H12N2O3 and C14H12N2O3 o29

organic compounds
screw axis along (14, 21, z) (Fig. 6). At the same time, atom C12 at
(x, y, z) acts as a hydrogen-bond donor to atom O5 in the
molecule at (12 + x, y, 21 z), so producing a zigzag C(8) chain
parallel to [100] and generated by the a-glide plane at z = 41
(Fig. 7). The combination of the [100] and [001] chains
generates (010) sheets, two of which pass through each unit
cell in the domains 0.26 < y < 0.74 and 0.76 < y < 1.24. There
are no direction-speci®c interactions between adjacent sheets,
although there is a single CÐHÁ Á Áꢀ(arene) hydrogen bond
within the sheet (Table 2).
In (III), an intramolecular OÐHÁ Á ÁN hydrogen bond
(Fig. 3) forms an S(6) motif and the supramolecular aggre-
gation is dominated by two intermolecular NÐHÁ Á ÁO
hydrogen bonds (Table 3). Amino atom N4 in the molecule at
(x, y, z) acts as a hydrogen-bond donor, via atoms H41 and
H42, respectively, to phenol atom O121 in the molecule at
(
12 + x, 12 y, 12 + z) and to carbonyl atom O5 in the molecule
at (12 + x, 12 y, 12 + z), thereby producing C(6) and C(7) chains
running parallel to the [101] and [101] directions, respectively.
The combination of these two chains produces a (010) sheet in
the form of a (4,4)-net (Batten & Robson, 1998) containing
equal numbers of S(6) and R45(22) rings (Fig. 8). This sheet,
which is generated by the n-glide plane at y = 14, lies in the
domain 0.02 < y < 0.52. A second such sheet, related to the
®rst by inversion, lies in the domain 0.48 < y < 1.02, this sheet
being generated by the n-glide plane at y = 34. However, there
are no direction-speci®c interactions between adjacent sheets;
in particular, there are neither XÐHÁ Á Áꢀ(arene) hydrogen
bonds (X = C, N or O) nor aromatic ꢀ±ꢀ stacking interactions
in the structure.
Figure 6
Part of the crystal structure of (II), showing the formation of a chain of
rings along [001] built from hard hydrogen bonds. For the sake of clarity,
H atoms bonded to C atoms have been omitted. Atoms marked with an
asterisk (*), a hash (#) or an ampersand (&) are at the symmetry positions
1
(
x, 1 y, 12 + z), (21 x, 1 y, 12 + z) and (x, y, 1 + z), respectively.
2
three-centre NÐHÁ Á Á(N,O) bond and one two-centre CÐ
HÁ Á ÁO bond, both of which utilize the same O acceptor atom
(Table 2). Amino atom N4 in the molecule at (x, y, z) acts as a
hydrogen-bond donor, via atom H42, to imino atom N2 and to
carbonyl atom O5, both in the molecule at (12 x, 1 y,
12 + z), thereby producing a C(4)C(7)[R21(5)] chain of rings
running parallel to the [001] direction and generated by the 21
In summary, the overall conformations adopted by (I)±(III)
are similar to those of the analogues reported previously. This
conformation appears to be independent of the presence or
absence of intermolecular hydrogen bonding involving the
carbonyl O atom, a mechanism that was previously suggested
as a contributory factor in the determination of molecular
conformation (Tucker et al., 2000).
Figure 7
Part of the crystal structure of (II), showing the formation of a C(8) chain
Figure 8
along [100] built from soft hydrogen bonds. Atoms marked with an
1
A stereoview of part of the crystal structure of (III), showing the
formation of a (010) sheet of S(6) and R45(22) rings. For the sake of clarity,
H atoms bonded to C atoms have been omitted.
asterisk (*) or a hash (#) are at the symmetry positions (12 + x, y,
z)
2
1
and ( 12 + x, y,
z), respectively.
2
ꢂ
o30 Carlos E. M. Carvalho et al.
C14H12N2O2, C14H12N2O3 and C14H12N2O3
Acta Cryst. (2004). C60, o28±o32

organic compounds
Re®nement
Experimental
Re®nement on F2
R[F2 > 2ꢆ(F2)] = 0.039
wR(F2) = 0.105
S = 0.97
2758 re¯ections
w = 1/[ꢆ2(F2o) + (0.0581P)2
+ 1.0166P]
Samples of (I)±(III) were prepared by heating under re¯ux for 1 h a
mixture containing equimolar quantities of the appropriate acyl
chloride and the appropriate benzamidoxime in dry tetrahydrofuran
solution, in the presence of triethylamine. After removal of
triethylammonium chloride and evaporation of the solvent, the solid
products were crystallized from acetonitrile.
where P = (F2o + 2Fc2)/3
(Á/ꢆ)max = 0.001
3
Ê
Áꢇmax = 0.23 e A
3
Ê
0.28 e A
175 parameters
H-atom parameters constrained
Áꢇmin
=
Table 2
Hydrogen-bonding geometry (A, ) for (II).
Compound (I)
ꢀ
Ê
Crystal data
Cg1 is the centroid of the C21±C26 ring.
3
C14H12N2O2
Mr = 240.26
Dx = 1.381 Mg m
Mo Kꢂ radiation
Cell parameters from 2614
re¯ections
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
Monoclinic, P21=n
Ê
a = 7.0415 (2) A
O22ÐH22Á Á ÁO5
N4ÐH42Á Á ÁO5ii
N4ÐH42Á Á ÁN2ii
C12ÐH12Á Á ÁO5iii
C16ÐH16Á Á ÁCg1iv
0.84
0.91
0.91
0.95
0.95
1.90
2.31
2.46
2.46
2.68
2.632 (2)
3.146 (2)
3.190 (2)
3.405 (2)
3.529 (2)
144
154
138
173
149
ꢃ = 3.2±27.5ꢀ
ꢄ = 0.09 mm
T = 120 (2) K
Ê
b = 21.4704 (7) A
1
Ê
c = 8.0570 (3) A
ꢁ = 108.4804 (16)ꢀ
3
Ê
V = 1155.27 (7) A
Z = 4
Plate, colourless
0.25 Â 0.20 Â 0.08 mm
1
2
Symmetry codes: (ii)
x; 1 y; z 12; (iii) 21 ‡ x; y; 12 z; (iv) x; 1 y; z.
Data collection
Nonius KappaCCD diffractometer
' scans, and ! scans with ꢅ offsets
Absorption correction: multi-scan
(DENZO±SMN; Otwinowski &
Minor, 1997)
2614 independent re¯ections
1708 re¯ections with I > 2ꢆ(I)
Rint = 0.056
Compound (III)
Crystal data
3
ꢃ
max = 27.5ꢀ
C14H12N2O3
Mr = 256.26
Dx = 1.403 Mg m
Mo Kꢂ radiation
Cell parameters from 2549
re¯ections
h = 9 ! 9
Monoclinic, P21=n
Tmin = 0.967, Tmax = 0.993
10 316 measured re¯ections
k = 27 ! 27
l = 10 ! 10
Ê
a = 4.6463 (3) A
ꢃ = 3.3±27.5ꢀ
ꢄ = 0.10 mm
T = 120 (2) K
Ê
b = 22.1280 (13) A
1
Ê
c = 11.9551 (9) A
Re®nement
ꢁ = 99.202 (3)ꢀ
V = 1213.33 (14) A
Z = 4
Re®nement on F2
R[F2 > 2ꢆ(F2)] = 0.049
wR(F2) = 0.129
S = 0.96
2614 re¯ections
w = 1/[ꢆ2(F2o) + (0.0719P)2
+ 0.0022P]
3
Ê
Plate, colourless
0.25 Â 0.10 Â 0.01 mm
where P = (F2o + 2Fc2)/3
(Á/ꢆ)max < 0.001
Data collection
3
Ê
Áꢇmax = 0.21 e A
3
Ê
0.27 e A
Nonius KappaCCD diffractometer
' scans, and ! scans with ꢅ offsets
Absorption correction: multi-scan
(DENZO±SMN; Otwinowski &
Minor, 1997)
2549 independent re¯ections
1412 re¯ections with I > 2ꢆ(I)
Rint = 0.065
165 parameters
H-atom parameters constrained
Áꢇmin
=
ꢃmax = 27.5ꢀ
h = 5 ! 5
Table 1
Hydrogen-bonding geometry (A, ) for (I).
ꢀ
Ê
Tmin = 0.970, Tmax = 0.998
8910 measured re¯ections
k = 27 ! 28
l = 15 ! 15
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
Re®nement
N4ÐH41Á Á ÁN2i
Symmetry code: (i) ‡ x; 12 y; 21 ‡ z.
0.95
2.15
3.029 (2)
153
Re®nement on F2
R[F2 > 2ꢆ(F2)] = 0.056
wR(F2) = 0.133
S = 0.98
2549 re¯ections
173 parameters
H-atom parameters constrained
w = 1/[ꢆ2(F2o) + (0.0626P)2]
where P = (F2o + 2Fc2)/3
(Á/ꢆ)max < 0.001
1
2
3
Ê
Áꢇmax = 0.32 e A
3
Ê
0.22 e A
Áꢇmin
=
Compound (II)
Crystal data
Table 3
Hydrogen-bonding geometry (A, ) for (III).
ꢀ
Ê
C14H12N2O3
Mr = 256.26
Orthorhombic, Pbca
Ê
a = 9.3808 (1) A
b = 24.9553 (4) A
c = 10.3277 (1) A
Ê
V = 2417.72 (5) A
Z = 8
Dx = 1.408 Mg m
Mo Kꢂ radiation
Cell parameters from 2758
re¯ections
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
ꢃ = 3.1±27.5ꢀ
ꢄ = 0.10 mm
T = 120 (2) K
N4ÐH41Á Á ÁO121v
0.88
0.88
0.84
2.26
2.10
1.82
2.975 (2)
2.954 (2)
2.550 (2)
138
163
144
1
Ê
Ê
N4ÐH42Á Á ÁO5i
3
O121ÐH121Á Á ÁN2
Block, colourless
0.55 Â 0.32 Â 0.28 mm
1
2
1 1
Symmetry codes: (i) ‡ x; 12 y; 21 ‡ z; (v) x
;
2 2
y; 12 ‡ z.
3
Data collection
For compounds (I) and (III), space group P21/n was uniquely
assigned from the systematic absences; space group Pbca was likewise
assigned for (II). All H atoms were located from difference maps,
which showed clearly that the NH2 groups are all pyramidal; all H
atoms were then treated as riding atoms with CÐH distances of
Nonius KappaCCD diffractometer
' scans, and ! scans with ꢅ offsets
Absorption correction: multi-scan
(DENZO±SMN; Otwinowski &
Minor, 1997)
2758 independent re¯ections
2308 re¯ections with I > 2ꢆ(I)
Rint = 0.065
ꢃ
max = 27.5ꢀ
h = 12 ! 9
k = 32 ! 32
l = 13 ! 12
Tmin = 0.966, Tmax = 0.972
17 440 measured re¯ections
Ê
0.95 A, NÐH distances of 0.88±0.95 A and OÐH distances of 0.84 A.
Ê
Ê
ꢂ
Acta Cryst. (2004). C60, o28±o32
Carlos E. M. Carvalho et al.
C14H12N2O2, C14H12N2O3 and C14H12N2O3 o31

organic compounds
Table 4
Selected geometric parameters (A, ) for compounds (I)±(III).
thanks NCR Self-Service, Dundee, for grants that have
provided computing facilities for this work. CEMC, SMSVW
and JLW thank CNPq for ®nancial support.
ꢀ
Ê
Parameter
(I)
1.297 (2)
(II)
(III)
C3ÐN2
C3ÐN4
N2ÐO1
O1ÐC5
C5ÐO5
1.302 (2)
1.354 (2)
1.460 (2)
1.340 (2)
1.222 (2)
1.303 (2)
1.344 (2)
1.442 (2)
1.351 (2)
1.208 (2)
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SK1677). Services for accessing these data are
described at the back of the journal.
1.352 (2)
1.452 (2)
1.356 (2)
1.206 (2)
C11ÐC3ÐN2ÐO1
C3ÐN2ÐO1ÐC5
N2ÐO1ÐC5ÐC21
179.8 (2)
160.0 (2)
175.0 (2)
174.47 (9)
152.4 (2)
171.77 (9)
180.0 (2)
178.8 (2)
176.3 (2)
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ꢂ
o32 Carlos E. M. Carvalho et al.
C14H12N2O2, C14H12N2O3 and C14H12N2O3
Acta Cryst. (2004). C60, o28±o32