Structures of protonated bis(pyridine-2-yl) ketone arylhydrazone derivatives: [(C5H4N)(C5H4NH)C= NNHC6H4Y]+[X]- (Y,X = 3-O 2N,Cl: 4-Me,Cl:)

Article abstract of DOI:10.1007/s10870-012-0384-8

The crystal structures of two salts of protonated bis(pyridine-2-yl) ketone arylhydrazone derivatives, [(C₅H₄N)(C₅H ₄NH)C=NNHC₆H₄Y]⁺[X]^-, 2 (Y,X = 3-O₂N,Cl), and the trihydrate of 3 (X,Y = 4-Me,Cl), are reported from data collected at 120 K. The cations in 2 and 3 exhibit different conformations, which have consequences in the type and number of intra- and intermolecular interactions exhibited. Three dimensional arrays are generated for both compounds by different combinations of intermolecular interactions. In 2, the cations are linked directly by π-π stacking interactions and by C-H...O hydrogen bonds, as well as by bridging chloride ions. The cations in [(3)·3H₂O] are directly again linked by π-π stacking and also by C-H...π interactions, and indirectly via chloride ions and water molecules. Compound 2 crystallises in the monoclinic space group P21/c, with a = 14.4210(4) A, b = 9.1543(3) A, c = 12.3365(3) A, β, 104.583(2)^o and Z = 4. Compound 3 crystallises in the triclinic space group P-1, with a = 8.1352(2) A, b = 10.0278(3) A, c = 12.1482(4) A, α = 106.4290(14)^o, β = 92.8080(18)^o, 90.3920(18)^o, Z = 2. Graphical Abstract: [Different three dimensional arrays are generated by different combinations of intermolecular interactions in [(C₅H₄N)(C ₅H₄NH)C = NNHC₆H₄Y] ⁺[X]^-, 2 (Y,X = 3-O₂N,Cl), and the trihydrate of 3 (X,Y = 4-Me, Cl.][Figure not available: see fulltext.].

Full text of DOI:10.1007/s10870-012-0384-8

J Chem Crystallogr (2013) 43:36–43
DOI 10.1007/s10870-012-0384-8
ORIGINAL PAPER
Structures of Protonated Bis(pyridine-2-yl) Ketone
Arylhydrazone Derivatives: [(C5H4N)(C5H4NH)C=NNHC6
H4Y]+[X]2 (Y,X 5 3-O2N,Cl: 4-Me,Cl:)
•
Geraldo M. de Lima James L. Wardell
•
•
R. Alan Howie Solange M. S. V. Wardell
Received: 7 June 2012 / Accepted: 6 November 2012 / Published online: 23 November 2012
Ó Springer Science+Business Media New York 2012
o
o
˚
Abstract The crystal structures of two salts of protonated
bis(pyridine-2-yl) ketone arylhydrazone derivatives, [(C5H4N)
(C5H4NH)C=NNHC6H4Y]?[X]-, 2 (Y,X = 3-O2N,Cl), and
the trihydrate of 3 (X,Y = 4-Me,Cl), are reported from data
collected at 120 K. The cations in 2 and 3 exhibit different
conformations, which have consequences in the type and
number of intra- and intermolecular interactions exhibited.
Three dimensional arrays are generated for both compounds by
different combinations of intermolecular interactions. In 2, the
cations are linked directly by p-p stacking interactions and by
C-HÁÁÁO hydrogen bonds, as well as by bridging chloride ions.
The cations in [(3)Á3H2O] are directly again linked by p-p
stacking and also by C-HÁÁÁp interactions, and indirectly via
chloride ions and water molecules. Compound 2 crystallises in
c = 12.1482(4) A, a = 106.4290(14) , b = 92.8080(18) ,
90.3920(18)o, Z = 2.
Keywords Hydrazones Á Supramolecular arrangements Á
Crystal structures Á Dipyridyl ketone
Introduction
We have been interested in the crystal structures of bio-
logically active nitrogen heterocycles for some time. In
particular, series of hydrazone derivatives have attracted
our attention [1–7]. The aim in our structural work has
been to identify common modes of intermolecular inter-
action within each series of compounds as well as varia-
tions in the patterns of the supramolecular aggregation
arising from different substituents. We recently turned our
attention to hydrazone derivatives, obtained from
bis(pyridin-2-yl) ketone (py2CO), and arylhydrazines [7].
Such compounds have been reported to have useful bio-
logical activities, e.g., bis(pyridn-2-yl) ketone isonicotinoyl
hydrazone has been shown to be an orally effective iron
chelator for the treatment of iron overload diseases [8–10].
As well as potential biological interests, such compounds
as well as oxime, semicarbazone and thiosemicarbazone
derivatives of 2-pyridyl ketone, have found use as ligands
for metal complexation. Of paramount interest in the
coordination studies has been the use in analytical chem-
istry for the extraction and spectrophotometric determina-
tion of metal ions in solution, see [11].
˚
the monoclinic space group P21/c, with a = 14.4210(4) A,
o
˚
˚
b = 9.1543(3) A, c = 12.3365(3) A, b, 104.583(2) and
Z = 4. Compound 3 crystallises in the triclinic space
˚
group P-1, with a = 8.1352(2) A, b = 10.0278(3) A,
˚
G. M. de Lima
Departamento de Quimica, ICEx, Universidade Federal de
Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
J. L. Wardell (&)
´
´
Centro de Desenvolvimento Tecnologico em Saude (CDTS),
Fundac¸a˜o Oswaldo Cruz (FIOCRUZ), Casa Amarela, Campus de
Manguinhos, Av. Brasil 4365, Rio de Janeiro, RJ 21040-900,
Brazil
e-mail: j.wardell@abdn.ac.uk
J. L. Wardell Á R. A. Howie
Our recent report on the crystal structures of bis(pyridin-
2-yl) ketone X-phenylhydrazine derivatives, (1: X = H, 2-O2N,
4-O2N and 4-I), [7], followed on from earlier articles by
Bakir and co-workers on other polymorphic forms of (1: X =
4-O2N) [12, 13]. It was noticeable how different were the
Department of Chemistry, University of Aberdeen,
Old Aberdeen AB24 3UE, Scotland, UK
S. M. S. V. Wardell
CHEMSOL, 1 Harcourt Road, Aberdeen AB15 5NY,
Scotland, UK
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J Chem Crystallogr (2013) 43:36–43
37
Fig. 1 Bis(pyridine-2-yl)
ketone arylhydrazones: a non-
protonated; b mono-protonated
(a)
(b)
N
Y
NH
2 (X,Y = 3-O2N, Cl)
3 (X,Y = 4-Me, Cl)
N
-
X
NH+
(1)
conformations adopted by the derivatives of 1: such differences
included the orientations of the pyridine rings. In continuation of
the structural studies of bis(pyridin-2-yl) ketone X-phenylhydr-
azines, we have investigated the crystal structures of a protonated
anhydrous derivative of 1, namely [(C5H4N)(C5H4NH)C=NNH
C6H4NO2-3]?[Cl]-, 2, and a protonated trihydrated derivative,
{[(C5H4N)(C5H4NH)C=NNHC6H4Me-4]?[Cl]-[(H2O)3]} [(3)Á
(H2O)3], see Fig. 1. In each case, the protonation site in the cation
is a pyridine nitrogen atom. The structure of pyridinio 2-pyridyl
ketone phenyl hydrazone chloride trihydrate, [(4)Á(H2O)3], was
reported earlier [14].
IR (KBr, cm-1): v: 3100-2800(br), 1616,1583, 1570,
1520, 1466, 1429, 1344, 1298, 1242, 1132, 1088, 1051,
995, 978, 955, 916, 873, 831, 800, 758, 741, 702, 673, 652,
637, 615, 565, 542, 486, 453, 430.
Calcd for C117H10ClN5O2: C, 57.39; H, 3.97; N, 19.68.
Found: C, 57.57; H, 4.03; N, 19.49 %.
Compound 3: yield: 79 % after first recrystallisation
from EtOH. The crystal used in the X-ray determination
was grown from EtOH and was found to be the trihydrate.
1H NMR (DMSO-d6, 400 Mz) d: 2.50(s,3H,Me),
7.45(m,1H), 7.55(m,1H), 7.64(d,1H, J = 8 Hz), 7.67(m,1H),
7.67(m,1H), 8.04(m, 2H), 8.13(d, 1H, J = 8 Hz), 8.27(d, 1H,
J = 9 Hz), 8.47(br,d, 1H, J = 9 Hz), 8.66(d, 1H, J = 4.6 Hz),
8.94(m, 2H), 15.61(s,1H, NH).
IR (KBr, cm-1): v; 3000-2800(br), 1611, 1584, 1564,
1520, 1462, 1425, 1331, 1304, 1277, 1258, 1240, 1211,
1146, 1105, 1090, 1049, 993, 970, 818, 800, 741, 729, 673,
629, 613, 523, 507, 467, 409.
Experimental
General
Melting points were determined on a Griffin melting point
apparatus and are uncorrected. IR spectra were recorded on
a Nicolet Magna 760 FTIR instrument. NMR spectra were
recorded on Bruker Avance 400 and Bruker Avance 500
spectrometers.
Calcd for C18H23ClN4O3: C, 57.06; H, 6.12; N, 7.39.
Found: C, 56.91; H, 6.34; N, 7.28 %.
X-Ray Crystallography
General Synthesis
Data for 2 and 3 were obtained at 120 (2) K with Mo-Ka
radiation by means of the Bruker-Nonius 95 mm CCD
camera on kappa-goniostat of the EPSRC crystallographic
service, based at the University of Southampton. Data
collection was carried out under the control of the program
COLLECT [15] and data reduction and unit cell refinement
were achieved with the COLLECT and DENZO [16]
programs.
Solutions of py2CO (2 mmol) in MeOH (15 ml) and the
arylhydrazine.hydrochloride (2 mmol) in MeOH (20 ml)
were mixed. The reaction mixture was heated for 3-4 h
and rotary evaporated. The solid residues were recrystal-
lised twice from the solvents indicated below.
Specific Compounds
After assignment of the atoms in what became the major
component of the cation of 2, five peaks ([0.9 e A-3) in
˚
Compound (2): yield: 87 %, after the first recrystallisation
from EtOH, m.p. 448–450 K. The crystals used in the
X-ray determination were grown from EtOH.
1H NMR (Me2CO-66, 500 Mz) d: 7.58(m, 2H), 7.77(m,
3H), 8.03(br.t, 1H, J = 8 Hz), 8.13(br.d, 1H, J = 8 Hz),
8.16(br.d, 1H), 8.31(br.t, 1H, J = 7.5 Hz), 8.32(m, 1H),
8.83(d, 1H, J = 5 Hz), 8.89(d, 1H, J = 5 Hz), 13.78(s,1H,
NH).
the in the difference map (A1-A5) were observed super-
imposed upon the major component of the nitrophenyl
moiety, O1, O2, N3 and C1-C6. It is clear that A1, A2 and
A3 provide a reasonable representation of a minor com-
ponent nitro group, and with A3 to A5 the benzene ring of
the minor component was initially made up by C1, C6, A5,
C3, A4 and C2. Refinement of the minor component ben-
zene ring was carried out after labelling the atoms of the
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J Chem Crystallogr (2013) 43:36–43
minor ring as C1A, C2A, C3A, C4A, C5A and C6A. The
occupancies of all of the atoms of the major component,
including all of the C and H atoms of the benzene ring,
were set to 21 (FVAR 2 having been set) and the occu-
pancies of all of the minor component atoms to -21. The
disorder in 2 was dealt with by assigning SHELXL97
PART numbers to the atoms, O1,O2, N3, C1-C6,] of the
major component (PART 1) and [O1A,O2A, N3A, C1A-
C6A] of the minor component (PART 2) [17].
Table 1 Crystal data and structure refinement
2
[(3): (H2O)3]
Empirical formula
Formula weight
Temperature, (K)
C17H14ClN5O2
355.78
C18H23ClN4O3
378.85
120(2)
298(2)
˚
Wavelength, (A)
0.71073
0.71073
Triclinic
P-1
Crystal system
Space group
Monoclinic
P21/c
Correction for absorption was achieved in each case by a
semi-empirical method based upon the variation of equiv-
alent reflections with the program SADABS [18]. The
programs ORTEP-3 for Windows [19] and MERCURY
[20] were used in the preparation of the Figures. SHEL-
XL97 [17] and PLATON [21] were used in the calculation
of molecular geometry. The structures were solved by
direct methods using SHELXS-97 [17] and fully refined by
means of the program SHELXL-97 [17]. All hydrogen
atoms were placed in calculated positions. Crystal data and
structure refinement details are listed in Table 1.
Unit cell dimensions
˚
a, (A)
14.4210(4)
9.1543(3)
12.3365(3)
90
8.1352(2)
10.0278(3)
12.1482(4)
106.4290(14)
92.8080(18)
90.3920(18)
949.20(5)
2
˚
b, (A)
˚
c, (A)
a, (°)
b, (°)
c, (°)
104.583(2)
90
3
˚
Volume, (A )
1576.13(8)
4
Z
Density (calculated),
(Mg m-3
1.499
1.326
)
Absorption
coefficient, (mm-1
0.265
736
0.227
400
)
F(000)
Results and Discussion
Crystal size, (mm)
0.90 9 0.70 9 0.40 0.32 9 0.14 9 0.12
Theta range for data
collection
2.96 to 27.52
3.11 to 27.61
Synthesis
Index ranges
-18 B h B 18
-11 B k B 11
-16 B l B 15
17958
-10 B h B 10
-13 B k B 13
-15 B l B 15
21061
The salts, 2 and 3, were isolated from reaction mixtures con-
taining py2CO and the appropriate substituted-phenylhydrazine
hydrochloride in methanol solution, Scheme 1. Despite the
same batch of methanol being used, 3 was isolated as a trihy-
drated salt in contrast to anhydrous 2.
Reflections collected
Independent
reflections
3611
4353
[R(int) = 0.0725]
2521
[R(int) = 0.0431]
3194
Reflections observed
([2r)
Data Completeness
Crystallography
0.998
0.989
Molecular Structures
Max. and min.
transmission
0.9013 and 0.7962
Absorption correction None
None
The asymmetric unit of 2 consists of the two disordered
cations, in a ratio of 82.5:17.5 and a single chloride ion,
and that for [(3)Á(H2O)3], a cation ion, chloride ion and
three hydrate molecules. The disorder in 2 concerns the
orienatation of the nitrophenyl moiety and results in for-
mation of conformational isomers. Protonation occurs on a
pyridinyl nitrogen, which is numbered N12 and N12a in the
major and minor components of 2 and N12 in [(3)Á(H2O)3].
Figures 2a,2b and 3a show the atom arrangements and
numbering schemes for the major and minor components
of 2, and of [(3)Á(H2O)3], respectively. Superimposition of
the major and minor components of 2 is shown in Fig. 2c.
The bond lengths and angles are in the expected regions
and are not commented on further.
Refinement method
Full-matrix least-
squares on F2
Full-matrix least-
squares on F2
Data/restraints/
parameters
3611/0/252
4353/9/261
Goodness-of-fit on F2 1.059
1.055
Final R indices
[I [ 2r(I)]
R1 = 0.047
R1 = 0.047
wR2 = 0.105
R1 = 0.083
wR * 2 = 0.124
R1 = 0.070
R indices (all data)
wR2 = 0.118
wR2 = 0.136
0.253 and -0.207
Largest diff. peak and 0.311 and -0.324
3
˚
hole, e A
isometric compounds satisfy the criteria proposed by
Kalman and co-workers [22] for isotructural compounds,
e.g., in terms of orthogonized lattice parameters and the
isostructurality index.
It is clear that [(3)Á(H2O)3] and the previously reported
[(4)Á(H2O)3] [14] are isostructural: indeed the two
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J Chem Crystallogr (2013) 43:36–43
39
Fig. 2 Features of 2. a, b Atom arrangements and atom numbering
scheme for the major and minor cations, respectively: probability
ellipsoids are drawn at the 50 % level and hydrogen atoms are drawn
as spheres of arbitrary radius; c superimposition of the two cations;
d p-p stacking interactions involving the major cations, drawn as
dashed lines between centroids of the aromatic rings: red, blue and
black spheres are centroids of [C1-C6], [N(22),C(21),C(23)-C(26)]
and [N(12),C(11),C(13)-C(16)] rings, respectively; e a partial chain
of major cations formed from C(23)—H(23)ÁÁÁO(1) intermolecular
hydrogen bonds; f packing diagram looking down the c axis.
Hydrogen bonds are drawn as dotted lines: symmetry operations are
listed in Tables 3, 4, 5. Atom colours: oxygen red; nitrogen blue,
chlorine green, carbon grey (Color figure online)
There are significant differences in the conformations of
the cations in 2 and [(3)Á(H2O)3], as indicated by the angles
between the best planes through the aromatic rings, see
Table 2. Furthermore, differences in the orientations of the
non-protonated pyridinyl ring are noted between the cations
of 2 and [(3)Á(H2O)3]. In the case of the latter, the pyridinyl
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J Chem Crystallogr (2013) 43:36–43
Fig. 3 Features of (3ÁH2O)3]. a Atom arrangements and atom
numbering scheme for the cation: probability ellipsoids are drawn
at the 50 % level and hydrogen atoms are drawn as spheres of
arbitrary radius; b cation dimers generated from p–p stacking
interactions; (c) cations and hydrate molecules linked via OW(2)-
HW(3)ÁÁÁN(22) and N(12)-H(12N)ÁÁÁOW(2) hydrogen bonds into
dimeric units; d links between cations formed from combinations of
N(12)-H(12N)ÁÁÁOW(2),
OW(2)-HW(4)ÁÁÁOW(1),
OW(1)-
HW(2)ÁÁÁOW(3), OW(3)-HW(6)ÁÁÁCl and OW(3)-HW(5)ÁÁÁCl
hydrogen bonds; e packing diagram, looking down the b axis.
Hydrogen bonds and p-p stacking interactions are drawn as dotted
lines: symmetry operations are listed in Tables 3, 4, 5. Atom colours:
oxygen red; nitrogen blue, chlorine green, carbon grey (Color figure
online)
nitrogen is sited away from the hydrazonyl moiety, see
Figs. 2a, and 3a. Consequently, there are differences in the
hydrogen bonding and other interactions associated with
these cations, see Tables 3, 4,5. As found in the structures of
the unprotonated compounds, 1, differences were also
observed in the orienatations of pyridine rings [6].
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J Chem Crystallogr (2013) 43:36–43
41
Table 2 Angles between least square planes through the aromatic rings
Planes through rings
2
3
Major conformer
Minor conformation
[C1-C6] and [C11, N12,C13-C16]
47.26(7)
4.87(14)
52.10(5)
46.4(8)a
6.2(6)a
6.29(9)
[C1-C6] and [C21, N22,C23-C26]
67.71(6)
61.48(6)
[C11, N12,C13-C16 and [C21, N22,C23-C26]
52.10(5)
a
C1-C6 replaced by C1a-C6a
˚
Table 3 Hydrogen-bond parameters (A, 8)
Compound
D-HÁÁÁA
D-H
HÁÁÁA
DÁÁÁA
D-HÁÁÁA
a. Intra-cation hydrogen-bonds
2
N(1)-H(1)ÁÁÁN(22)
0.88
2.00
2.651(3)
2.6686(19)
3.135(2)
130
[(3)Á(H2O)3]
[(3)Á(H2O)3]
b. Inter-species hydrogen-bonds
N(12)-H(12N)ÁÁÁN(2)
C(16)-H(16)ÁÁÁN(22)
0.923(19)
0.93
2.312(19)
2.55
102.5(14)
121
2a
N(12)-H(12)ÁÁÁCl
0.88
2.19
3.0356(18)
3.195(3)
162
2
C(23)-H(23)ÁÁÁO(1)i
N(1)-H(1)ÁÁÁCl(1)
0.95
2.38
144
[(3)Á(H2O)3]b
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
[(3)Á(H2O)3]
0.82(2)
0.85(3)
0.860(16)
0.853(16)
0.849(16)
0.855(19)
0.851(15)
0.923(19)
0.93
2.591(19)
1.96(3)
2.442(16)
2.019(17)
1.969(16)
2.36(2)
2.322(15)
1.96(2)
2.49
3.3604(15)
2.803(2)
156.9(18)
170(2)
169(2)
173(2)
172(3)
171(3)
179(4)
145.9(16)
169
OW(1)-HW(2)ÁÁ OW(3)
OW(1)-HW(2)ÁÁ Cli
OW(2)-HW(3)ÁÁÁN(22)ii
OW(2)-HW(4)ÁÁ OW(1)ii
OW(3)-HW(5)ÁÁÁCliii
OW(3)-HW(6)ÁÁ Cl
3.2899(17)
2.868(2)
2.812(2)
3.2080(19)
3.1727(16)
2.776(2)
N(12)-H(12 N)ÁÁÁOW(2)
C(6)-H(6)ÁÁÁOW(2)
3.411(2)
C(13)-H(13)ÁÁÁOW(2)ii
0.93
2.50
3.366(2)
155
a
i = -x,1/2 ? y,-1/2 - z
b
i = 1 ? x,y,z: ii = 1 - x,1 - y,1 - z; iii = 1 - x,1 - y,2 - z
The major cation of 2 possesses an intra-cation hydrogen
interactions is illustrated in Fig. 2d, while Fig. 2e shows a
partial zig-zag chain, [C(12)] [23], directed along the
a axis, arising from the C(23)-H(23)ÁÁÁO(1) hydrogen
bonds. The minor cations are also connected by p-p
stacking interactions between all three rings, supplemented
by N-OÁÁp(phenyl) interactions [24], but, in contrast to the
situation found for the major cations, there are no C(23)-
H(23)ÁÁO(1) inter-cation hydrogen bonds: the interactions
involving the minor cation are not illustrated. Apart from
the strong N(12)ÁÁÁH(12)ÁÁÁCl hydrogen bond, each chloride
ion has four C-H-Cl contacts with different cations,
bond, N(1)-H(1)ÁÁÁN(22) and an N-HÁÁÁCl hydrogen bonded
link with the chloride ion within the asymmetric unit, see Fig. 2a.
This is a very different situation to that in [(3)Á(H2O)3], where the
cation-chloride ion hydrogen bond involves N(1)-H(1)ÁÁÁCl(1),
with N(12)-H(12 N)ÁÁÁN(2) C(16)-H(16)ÁÁÁN(22) intra-cation
hydrogen bonds also present, see Fig. 3a.
Crystal Structures
Compound 2
˚
between 2.899 and 2.922 A.
The major cations in 2 are linked by p-p stacking inter-
actions, involving all three aryl rings, C(23)—H(23)ÁÁÁO(1)
hydrogen bonds, and chloride ions, see Tables 3-5 for
details including symmetry operations. For clarity, the p-p
stacking interactions and the C(23)ÁÁÁH(23)ÁÁÁO(1) hydro-
gen bonds are considered separately. A partial arrangement
of cations arising from the three distinct p-p stacking
All in all, a three dimensional array is obtained.
Figure 2f illustrates the packing arrangement in 2.
Compound [(3)Á(H2O)3]
The cations in [(3)Á(H2O)3] are directly linked by p-p
stacking interactions, involving protonated pyridyl rings,
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˚
Table 4 Geometric parameters (A, °) for p-p contacts
Cpd
Cg(I)ÁÁÁCg(J)
CgÁÁÁCg
a
b
c
CgIperp
CgJperp
2
Cg(1)ÁÁÁCg(2i)
Cg(2)ÁÁÁCg(1ii)
Cg(2)ÁÁÁCg(3iii)
Cg(3)ÁÁÁCg(2iv)
Cg(3)ÁÁÁCg(4v)
Cg(4)ÁÁÁCg(3v)
Cg(4)ÁÁÁCg(4v)
Cg(I)ÁÁÁCg(J)
3.8527(12)
3.8529(12)
3.8205(16)
3.8207(16)
3.797(4)
6.71(11)
6.71(11)
4.86(13)
4.86(13)
1.9(4)
1.9(4)
0
32.10
26.15
25.91
29.85
31.32
30.59
22.26
b
26.15
32.10
29.85
25.91
30.59
31.32
22.26
c
3.4585(8)
3.2638(9)
3.3137(9)
3.4366(13)
3.2686(12)
3.243(4)
3.260(4)
CgIperp
3.2637(9)
3.4585(8)
3.4366(13)
3.3138(9
3.243(4)
3.2686(12)
3.259(4)
CgJperp
2
2
2
2
2
3.798(4)
2
3.522
Cpd
CgÁÁÁCg
3.7958(9)
a
[(3)Á(H2O)3]
[(3)Á(H2O)3]
Cg(1)ÁÁÁCg(3i)
6.30
29.47
24.24
24.24
29.47
3.461
3.305
Cg(3)ÁÁÁCg(1i)
3.7958(9)
6.30
3.305
3.461
Cg(1), Cg(2), Cg(3) and Cg(4) are the centroids of the rings defined by [N(12),C(11),C(13)-C(16)], [N(22),C(21),C(23)-C(26)], [C(1)-C(6)]
and [C(1a)-C(6a)]. Symmetry codes: i = x,3/2 - y,1/2 ? z; ii = x,3/2 - y,-1/2 ? z; iii = x,1 ? y,z; iv = x,-1 ? y,z; v = -x,1 - y,-z.
Cg(1) and Cg(3) are the centroids of the rings defined by [N(12),C(11),C(13)-C(16)] and [C(1)-C(6)], respectively. Symmetry codes: i:
-x,1 - y,1 - z. The angle a is the dihedral angle between the overlapping rings and is identically zero when the rings are parallel to one another
as a consequence of being related to one another by the operation of a crystallographic centre of symmetry. The angles b and c are the angles at
Cg(I) and Cg(J), respectively, between the vectors CgÁÁÁCg and the appropriate Cgperp; CgÁÁÁCg is the distance between the ring centroids; Cgperp
is the perpendicular distance between the ring planes and slippage, or lateral displacement, is the distance, averaged where necessary, between
Cg(I) and perpendicular projection of Cg(J) on ring I or vice versa
˚
Table 5 Parameters (A, °) for Y—XÁÁÁp interactions
Y-XÁÁÁCg
XÁÁÁCg
Xperp
c
Y-XÁÁÁCg
YÁÁÁCg
Y-X, p
2
2
N(3A)-O(1A)ÁÁÁCg(2i)
3.374(10)
3.843(9)
3.045
25.53
3.436
77.5(7)
26.61
3.334(11)
56.6(6)
10.68
N(3A)-O(1A)ÁÁÁCg(2i)
2.9456
56.6(6)
Cg(2) is the centroid of the rings defined by [C1A-C6A]
Symmetry operations: i: x, - 1 ? y,z
and indirectly via chloride ions and water molecules, see
Tables 3, 4, 5 for details. Figure 3b shows the direct for-
mation of cation dimers arising from p-p stacking inter-
actions. Other dimeric units including cations and water
molecules are generated from OW(2)-HW(3)ÁÁÁN(22) and
N(12)-H(12N)ÁÁÁOW(2) hydrogen bonds, as shown in
Fig. 3c. A more elaborate link between cations is that
generated from a combination of N(12)-H(12N)ÁÁÁOW(2),
OW(2)-HW(4)ÁÁÁOW(1), OW(1)-HW(2)ÁÁÁOW(3), OW
(3)-HW(6)ÁÁÁCl and OW(3)-HW(5)ÁÁÁCl hydrogen bonds,
as shown in Fig. 3d. All in all, a three dimensional array is
generated for 4. The packing arrangement, looking down
the b axis is illustrated in Fig. 3e.
pyridyl rings Consequently, there are differences, both in the
intra- and intermolecular interactions present in the crystal of
each series, see Table 2. Three dimensional arrays are gen-
erated for 2 and 3 by the combined intermolecular interac-
tions, in contrast to the different dimensionalities exhibited
by the members of the unprotonated series 1. For 2, the
cations are linked directly by p-p stacking interactions and
by C-HÁÁÁO hydrogen bonds, as well as by bridging chloride
ions. Interactions involving the water solvate molecules in
[(3)Á(H2O)3] result in more elaborate supramolecular arrays.
The cations in [(3)Á(H2O)3] are directly linked by p-p
stacking and C-HÁÁÁp interactions, and indirectly via chlo-
ride ions and water molecules.
Conclusions and Comparison with the Structures
of Non-protonated Forms
Supplementary material
Full details of the crystal structure determinations in CIF
format have been deposited with the Cambridge Crystal-
lographic Data Centre with deposition numbers CCDC
873364 and 875047, respectively. Copies of these can be
As found with the non-protonated forms 1 ([7]), different
conformations are found in 2 and 3 as indicated by the dif-
ferences in the inter-planar angles and by the orientations of
123

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