Tetraaquabis-[5-(3-pyrid-yl-κN)pyrimi-dine]zinc(II) bis-(trifluoromethanesulfonate): A novel cationic complex and three-dimensional hydrogen-bonded network

Article abstract of DOI:10.1107/S0108270111036274

The title compound, [Zn(C₉H₇N₃) ₂(H₂O)₄](CF₃O₃S) ₂, con-tains an octa-hedral [ZnL 2(H₂O)4]²⁺ cationic complex with trans geometry (Zn site symmetry ), and each 5-(3-pyridyl)pyrimidine (L) ligand is coordinated in a monodentate fashion through the pyridine N atom. In the extended structure, these complexes, with both hydrogen-bond acceptor (pyrimidine) and donor (H₂O) functions, are linked to each other by inter-molecular water-pyrimidine O - H...N hydrogen-bonding inter-actions, resulting in a double chain along the crystallographic a axis. The trifluoro-methane-sulfonate anions are integrated into the chains via O - H...O hydrogen bonds between the coordinated water and sulfonate O atoms. These double chains are associated into a novel three-dimensional network through inter-chain water-pyrimidine O - H...N hydrogen bonds. The asymmetric ligand plays an important role in constructing this unusual supra-molecular structure.

Full text of DOI:10.1107/S0108270111036274

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
tives have occasionally been used in supramolecular chemistry
and coordination polymers with versatile structures, and
potential properties have been reported. For example,
Champness and co-workers have reported a highly unusual
three-dimensional polymer, [Cu3I3{5-(4-pyridyl)pyrimidine}]n,
in which the 5-(4-pyridyl)pyrimidine ligand bridges two-
ISSN 0108-2701
Tetraaquabis[5-(3-pyridyl-jN)pyrimi-
dine]zinc(II) bis(trifluoromethane-
sulfonate): a novel cationic complex
and three-dimensional hydrogen-
bonded network
´
dimensional brick-wall (CuI)n sheets (Thebault et al., 2006).
Fujita et al. (2005) reported two M8L4 cages controlled by the
guest molecules, based on the tridentate ligand 3,5-bis(3-
pyridyl)-1-(pyrimidin-5-yl)benzene. In addition, some pyri-
midine derivatives employed as nucleophilic linkers have
received much attention in self-assembly with various
hydrogen-bond donors (Georgiev et al. 2004). In this contri-
bution, a new asymmetric organic ligand, 5-(3-pyridyl)-
pyrimidine (L), has been synthesized and used to create a
novel ZnII complex salt, [ZnL2(H2O)4](CF3SO3)2, (I), the
structure of which is reported.
Gui-Ge Hou,* Li-Ying Ma and Xian-Ping Dai
College of Pharmacy, Binzhou Medical University, Yantai 264003, People’s
Republic of China
Correspondence e-mail: guigehou@163.com
Received 25 July 2011
Accepted 5 September 2011
Online 15 September 2011
The title compound, [Zn(C9H7N3)2(H2O)4](CF3O3S)2, con-
tains an octahedral [ZnL2(H2O)4]2+ cationic complex with
trans geometry (Zn site symmetry 1), and each 5-(3-
pyridyl)pyrimidine (L) ligand is coordinated in a monodentate
fashion through the pyridine N atom. In the extended
structure, these complexes, with both hydrogen-bond acceptor
(pyrimidine) and donor (H2O) functions, are linked to each
other by intermolecular water–pyrimidine O—Hꢀ ꢀ ꢀN
hydrogen-bonding interactions, resulting in a double chain
along the crystallographic a axis. The trifluoromethane-
sulfonate anions are integrated into the chains via O—
Hꢀ ꢀ ꢀO hydrogen bonds between the coordinated water and
sulfonate O atoms. These double chains are associated into a
novel three-dimensional network through interchain water–
pyrimidine O—Hꢀ ꢀ ꢀN hydrogen bonds. The asymmetric
ligand plays an important role in constructing this unusual
supramolecular structure.
Compound (I) crystallizes in the monoclinic space group
P21/n with one half of a [ZnL2(H2O)4]2+ complexꢁcation (Zn is
on a centre of inversion) and one CF3SO3 (trifluoro-
methanesulfonate) counter-anion in the asymmetric unit. The
ZnII centre lies in a highly regular octahedral {ZnN2O4}
coordination environment, which is composed of two pyridine
N-atom donors from two L ligands in the axial positions and
four O-atom donors from four coordinated water molecules in
Comment
Asymmetric organic ligands with various topologies and
coordination natures are widely used by chemists in the
construction of coordination polymers and supramolecular
complexes. Some of the resulting materials exhibit encoura-
ging potential for applications in magnetism (He et al., 2006),
luminescence (Allendorf et al., 2009; Hou et al., 2010) and
nonlinear optics (Evans & Lin, 2002; Ye et al., 2005). The
geometry of the organic ligands is one of the most important
factors in determining the structure of the framework. It is
well known that the inclusion of different functional groups,
such as pyrimidine and pyridine, can lead to different coor-
dination modes and may play a crucial role in the construction
of supramolecular complexes driven by coordinate inter-
actions and hydrogen bonds. Previously, pyrimidine deriva-
Figure 1
The ZnII coordination environment of (I), showing the atom-numbering
scheme. Displacement ellipsoids are drawn at the 20% probability level.
Hydrogen bonds are shown as dashed lines. [Symmetry code: (iv) ꢁx + 1,
ꢁy + 1, ꢁz + 1.]
Acta Cryst. (2011). C67, m321–m323
doi:10.1107/S0108270111036274
# 2011 International Union of Crystallography m321

metal-organic compounds
Figure 2
The hydrogen-bond-driven double chain formed along the crystallographic a direction of (I). Hydrogen bonds are shown as dashed lines. [Symmetry
codes: (i) x ꢁ 1, y, z; (iii) x + 1, y, z.]
the equatorial positions (Fig. 1). The fact that L acts as a
monodentate ligand in this fashion proves that the pyridine
group has a stronger coordination ability than the pyrimidine
group in this case. The pyrimidine and pyridine rings in the
ligand are significantly twisted. The dihedral angle between
the twoꢂrings [42.36 (15)ꢂ] is distinctly larger than the value of
(L1 is 1,2-bis{1-[1-(pyridin-3-ylmethyl)benzimidazol-2-yl]ethyl-
idene}hydrazine; Zheng et al., 2009) in which a (Zn com-
plex)ꢀ ꢀ ꢀp-CH3C6H4SO3ꢁꢀ ꢀ ꢀ(Zn complex) chain is constructed
only by water–sulfonate O—Hꢀ ꢀ ꢀO hydrogen bonds, without
the participation of ligand L1. In (I), the chain is generated
from a combination of water–pyrimidine O—Hꢀ ꢀ ꢀN and
water–sulfonate O—Hꢀ ꢀ ꢀO hydrogen bonds. Viewed along
the crystallographic a direction, all the hydrogen-bond-driven
chains are parallel and further extend into a three-dimensional
framework via O5—H5Bꢀ ꢀ ꢀN3ii hydrogen bonds between
´
34.0 (1) in [Cu3I3{5-(4-pyridyl)pyrimidine}]n (Thebault et al.,
2006). For [ML2(H2O)4] complexes with this type of asym-
metric ligand, the two terminal groups of the ligand can be
located on either the same or opposite sides of the central
pyridine–M–pyridine unit, resulting in cis or trans conforma-
tions (Dong et al., 2007; Zheng et al., 2009), which is distinctly
different from some [ML2(H2O)4] complexes with non-
asymmetric ligands (Khanpour & Morsali, 2009; Peedikakkal
& Vittal, 2008; Chen et al., 2008). In (I), the two terminal
pyrimidine groups of the [ZnL2(H2O)4]2+ complex cation give
rise to a trans conformation with respect to the central pyri-
dine–Zn–pyridine unit, as required by the inversion symmetry.
Though some similar trans-conformation complexes have been
reported (Chen et al., 2004; Cakir et al., 2003; Zhu et al., 2009),
the specific combination of interacting groups in (I) leads to a
novel three-dimensional network of interactions.
1
2
double chains (Fig. 3) [symmetry code: (ii) x ꢁ , ꢁy + 32, z + 21].
In summary, the introduction of both pyrimidinyl and
pyridyl donor groups in the 5-(3-pyridyl)pyrimidine ligand
leads to a [ZnL2(H2O)4]2+ complex cation with multiple
hydrogeꢁn-bonding capabilities which combines with the
CF3SO3 counter-anions to generate a novel three-dimen-
sional network. This study demonstrates that such an asym-
metric ligand plays an important role in constructing unusual
supramolecular compounds, which may provide a new method
for constructing novel functional materials in the future.
Given the strong hydrogen-bond capability of the uncoor-
dinated pyrimidine groups (Horikoshi et al., 2004; Georgiev et
al., 2004), it is not surprising that the [ZnL2(H2O)4]2+ complex
cation displays a robust hydrogen-bonding framework. The
uncoordinated pyrimidine groups act as hydrogen-bond
acceptors to link the complexes into double chains along the
crystallographic a direction via O5—H5Aꢀ ꢀ ꢀN2i hydrogen
bonds between coordinated water molecules and pyrimidine
N atoms (Fig. 2) [symmetry code: (i) x ꢁ 1, y, z]. In the double
˚
chain, the Znꢀ ꢀ ꢀZn separation is 9.360 (2) A and this space is
ꢁ
large enough to accommodate two uncoordinated CF3SO3
anions, which are locked in the chain through O5—H5Bꢀ ꢀ ꢀO1
and O4—H4Aꢀ ꢀ ꢀO3iii hydrogen bonds between the coordi-
ꢁ
nated water molecules and the CF3SꢁO3 anions [symmetry
code: (iii) x + 1, y, z]. The CF3SO3 anions thus play an
important role in constructing the hydrogen-bonded supra-
molecular chain. Notably, the hydrogen-bond-driven chain
here is distinctly different from that observed in the related
compound {[Zn(L1)2(CH3CH2OH)2(H2O)2](p-CH3C6H4SO3)2}n,
Figure 3
The three-dimensional framework of (I) formed via O4—H4Bꢀ ꢀ ꢀN3ii
interactions (dashed lines) between double chains. [Symmetry code: (ii)
1
2
1
2
x ꢁ , ꢁy + 32, z + .]
ꢃ
m322 Hou et al. [Zn(C9H7N3)2(H2O)4](CF3O3S)2
Acta Cryst. (2011). C67, m321–m323

metal-organic compounds
Table 1
Hydrogen-bond geometry (A, ).
Experimental
ꢂ
˚
5-Bromopyrimidine (0.32 g, 2.0 mmol), 3-pyridylboronic acid (0.27 g,
2.2 mmol), [Pd(PPh3)4] (0.076 g, 0.066 mmol) and K2CO3 (0.83 g,
6.0 mmol) in EtOH–H2O (3:1 v/v, 20 ml) were heated under reflux for
48 h. After removal of the solvents under vacuum, the residue was
purified on silica gel using column chromatography with CH2Cl2–
THF (10:1 v/v) as the eluent to give 5-(3-pyridyl)pyrimidine (L) as a
colourless crystalline solid (yield 85%). IR (KBr pellet, ꢀ, cmꢁ1): 3026
(m), 1638 (m), 1592 (s), 1574 (s), 1443 (s), 1418 (s), 1400 (m), 1354
(m), 1233 (m), 1026 (m), 994 (m), 805 (m), 729 (s), 708 (s), 634 (s); 1H
NMR (300 MHz, DMSO-d6, TMS): ꢁ 9.27 (s, 1H, C4H4N2), 8.97 (s,
2H, C4H4N2), 8.87 (s, 1H, C5H4N), 8.74–8.72 (d, 1H, C5H4N), 7.95–
7.92 (d, 1H, C5H4N), 7.52–7.48 (t, 1H, C5H4N). Elemental analysis
calculated for C9H7N3: C 68.77, H 4.49, N 26.74%; found: C 68.54, H
4.57, N 26.83%.
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
O5—H5Bꢀ ꢀ ꢀO1
O5—H5Aꢀ ꢀ ꢀN2i
O4—H4Bꢀ ꢀ ꢀN3ii
O4—H4Aꢀ ꢀ ꢀO3iii
0.81
0.82
0.82
0.82
1.89
2.07
2.02
1.96
2.677 (7)
2.762 (5)
2.812 (5)
2.755 (7)
162
142
162
164
1
2
3
2
1
2
Symmetry codes: (i) x ꢁ 1; y; z; (ii) x ꢁ ; ꢁy þ ; z þ ; (iii) x þ 1; y; z.
Data collection: SMART (Bruker, 2003); cell refinement: SMART;
data reduction: SAINT (Bruker, 2003); program(s) used to solve
structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine
structure: SHELXL97 (Sheldrick, 2008); molecular graphics:
SHELXTL (Sheldrick, 2008); software used to prepare material for
publication: SHELXTL.
A solution of Zn(CF3SO3)2 (9.0 mg, 0.025 mmol) in CH3CN (2 ml)
was layered onto a solution of L (7.8 mg, 0.050 mmol) in CH2Cl2
(2 ml). The system was left for about three weeks at room
temperature, after which time colourless crystals of (I) were obtained
(yield 80%).
The authors are grateful for financial support from the
National Natural Science Foundation of China (grant No.
30970298).
Crystal data
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SQ3296). Services for accessing these data are
described at the back of the journal.
3
˚
[Zn(C9H7N3)2(H2O)4](CF3O3S)2
Mr = 749.93
V = 1534.5 (4) A
Z = 2
Monoclinic, P21=n
Mo Kꢃ radiation
ꢄ = 1.03 mmꢁ1
T = 298 K
0.30 ꢄ 0.25 ꢄ 0.22 mm
˚
a = 9.3597 (15) A
˚
b = 17.198 (3) A
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˚
c = 9.6857 (16) A
ꢂ = 100.187 (2)ꢂ
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˚
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ꢁ3
˚
Áꢆmin = ꢁ0.93 e A
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˚
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˚
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´
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˚
˚
˚
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distance restraints were used.
ꢃ
Acta Cryst. (2011). C67, m321–m323
Hou et al.
[Zn(C9H7N3)2(H2O)4](CF3O3S)2 m323