supplementary materials


zl2495 scheme

Acta Cryst. (2012). E68, m1160-m1161    [ doi:10.1107/S1600536812034447 ]

Bis(4-aminopyridinium) tetraiodidocadmate monohydrate

Q. Sun, S. Liao, J. Yao, J. Wang and Q. Fang

Abstract top

The title compound, (C5H7N2)2[CdI4]·H2O, contains one [CdI4]2- anion, two prontonated 4-aminopyridine molecules and one water molecule in the asymmetric unit. In the anion, the CdII atom is coordinated by four I atoms in a slightly distorted tetrahedral geometry. The [CdI4]2- anion and the water molecule are bisected by a crystallographic mirror plane perpendicular to the c-axis direction, with the CdII atom, two of the I atoms and the atoms of the water molecule located on this plane. The crystal packing is stabilized by intermolecular N-H...I, N-H...O and O-H...I hydrogen bonds and by [pi]-[pi] stacking interactions [centroid-centroid distance = 3.798 (3) Å) between pyridine rings, which build up a three-dimensional network.

Comment top

Studies of hydrogen bonds connecting organic-inorganic hybrid compounds continue to be a topic of intense research in crystal engineering because such compounds not only allow for rational bottom-up construction but hydrogen bonds also effectively regulate the molecular architecture. Hydrogen bond connected organic-inorganic hybrid compounds can exhibit novel properties related to e.g magnetism, luminescence, antiviral activity and even multifunctional properties (Bauer et al., 2003; Cavicchioli et al., 2010; Li et al., 2007). The protonated form of 4-aminopyridine (4-AP) has hydrogen-bonding capability at both ends of the molecule, and it is also biologically active and can be used as a K+ and Ca2+ channel inhibitor (Picolo et al., 2003). Structures of 4-AP with the metals MnII, CoII, CuII, NiII, SnIV, SbV and PdII have been reported (Das et al., 2010; Ivanova et al., 2005; Jebas et al., 2009; Kulicka et al., 2006; Rademeyer et al., 2007; Zaouali Zgolli et al., 2009). Here we report the crystal structure of the title compound, which is a salt that comprises two symmetry related 4-AP cations and a complex [CdI4]2- anion, Fig. 1. The [CdI4]2- anion and the water molecule are bisected by a crystallographic mirror plane perpendicular to the c-axis direction, with the the atoms Cd1, I1, I3 and the water molecule located on this plane at x, y, 1/4. In the anion, the CdII ion is coordinated by four I atoms, exhibiting a slightly distorted tetrahedral geometry. The mean Cd···I bond distance is 2.78 Å, which is similar to that of related compounds reported in the literature (Hines et al., 2006).

In the cation, the nitrogen atom of the pyridine ring is protonated. Both of the nitrogen atoms of 4-AP are not metal coordinated, but are instead involved in an extensive hydrogen bonding network that includes the amine hydrogen atoms and the iodine atoms, the protonated pyridyl hydrogen atom, and the water molecule. The bond distances and bond angles of the 4-AP cation are comparable with values reported earlier for its uncomplexed form (Anderson et al., 2005).

Packing of the title complex (Fig. 2 and Fig. 3) is facilitated through ππ interactions between pyridine rings [ring centroid distance: 3.798 (3) Å], through the N—H···I hydrogen bonds between the [CdI4]2- anions and the 4-AP cations, and through O—H···I and N—H···O hydrogen bonds, which link the components of the structure into a three dimensional network.

Related literature top

For background literature on the magnetism, antiviral activity and luminescence of organic–inorganic hybrid compounds, see: Bauer et al. (2003); Cavicchioli et al. (2010); Li et al. (2007). For ion channel inhibitor properties of 4-aminopyridine, see: Picolo et al. (2003). For metal complexes of 4-aminopyridine, see: Das et al. (2010); Ivanova et al. (2005); Jebas et al. (2009); Kulicka et al. (2006); Rademeyer et al. (2007); Zaouali Zgolli et al. (2009). For bond-length data, see: Anderson et al. (2005); Hines et al. (2006).

Experimental top

A mixture of CdI2 (0.36 g, 0.98 mmol), pyridine-2,3-dicarboxylic acid (0.08 g, 0.48 mmol), and 4-aminopyridine (0.06 g, 0.64 mmol) in H2O (12.0 mL) was sealed in a 20 mL stainless-steal reactor with Teflon liner and heated at 423 K for 60 h under autogenous pressure. Colorless block crystals were collected after the reaction solution was cooled. Yield: 16%. IR: 3314(s), 1653(s), 1608(s), 1526(s), 1407(s), 1197(m), 993(m), 865(w), 806(m), 758(m), 715(w), 495(m).

Refinement top

All of the non-hydrogen atoms were refined with anisotropic thermal displacement parameters. The O—H distances of water molecules were restrained to 0.84 Å with a standard deviation of 0.001 Å. The other H atoms were not located in the difference map and placed in calculated positions using the riding model approximation with C—H distances of 0.93 Å and an N—H distances of 0.86 Å. Uiso(H) were set to 1.2Ueq(C, N) or 1.5Ueq(O).

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The title compound showing the atom-numbering scheme, with displacement ellipsoids shown at the 50% probability level; hydrogen atoms are drawn as spheres of arbitrary radius. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) x, y, -z+0.5; (ii) -x+1, -y+1, 0.5+z]
[Figure 2] Fig. 2. A packing diagram of the title compound, viewed in perspective along the a axis.
[Figure 3] Fig. 3. A view of the various N—H···I, N—H···O and O—H···I hydrogen bonds in the (1 1 2) plane, with hydrogen bonds shown as dashed lines. [Symmetry codes: (i) -x+1, -y+1, -z; (ii) -x+2, -y+1, -z; (iii) -x+2, -y+1, z-0.5; (iv) x-1, -y+0.5, z-0.5; (v) x-1, y, z.]
Bis(4-aminopyridinium) tetraiodidocadmate monohydrate top
Crystal data top
(C5H7N2)2[CdI4]·H2OF(000) = 1488
Mr = 828.27Dx = 2.694 Mg m3
Orthorhombic, PbcmMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P2c2bCell parameters from 7689 reflections
a = 7.3987 (2) Åθ = 2.6–28.2°
b = 14.7348 (4) ŵ = 7.12 mm1
c = 18.7286 (4) ÅT = 293 K
V = 2041.76 (9) Å3Block, colourless
Z = 40.40 × 0.24 × 0.20 mm
Data collection top
Bruker SMART CCD
diffractometer
1860 independent reflections
Radiation source: fine-focus sealed tube1755 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.052
φ and ω scansθmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 88
Tmin = 0.145, Tmax = 0.340k = 1714
11964 measured reflectionsl = 2222
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.025H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.064 w = 1/[σ2(Fo2) + (0.0406P)2 + 1.5671P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
1860 reflectionsΔρmax = 0.91 e Å3
102 parametersΔρmin = 0.72 e Å3
3 restraintsExtinction correction: SHELXTL (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.00433 (17)
Crystal data top
(C5H7N2)2[CdI4]·H2OV = 2041.76 (9) Å3
Mr = 828.27Z = 4
Orthorhombic, PbcmMo Kα radiation
a = 7.3987 (2) ŵ = 7.12 mm1
b = 14.7348 (4) ÅT = 293 K
c = 18.7286 (4) Å0.40 × 0.24 × 0.20 mm
Data collection top
Bruker SMART CCD
diffractometer
1860 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
1755 reflections with I > 2σ(I)
Tmin = 0.145, Tmax = 0.340Rint = 0.052
11964 measured reflectionsθmax = 25.0°
Refinement top
R[F2 > 2σ(F2)] = 0.025H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.064Δρmax = 0.91 e Å3
S = 1.02Δρmin = 0.72 e Å3
1860 reflectionsAbsolute structure: ?
102 parametersFlack parameter: ?
3 restraintsRogers parameter: ?
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cd11.01826 (6)0.20199 (3)0.25000.03793 (14)
I10.64576 (5)0.22518 (3)0.25000.03959 (14)
I21.14547 (4)0.28284 (2)0.125323 (15)0.04579 (13)
I31.11401 (5)0.01921 (3)0.25000.04403 (15)
N10.6396 (7)0.4593 (3)0.11682 (19)0.0606 (12)
H1B0.63710.48700.15720.073*
N20.6522 (6)0.3361 (3)0.0766 (2)0.0617 (11)
H2A0.55480.31450.09500.074*
H2B0.75260.33240.09960.074*
C10.4861 (8)0.4240 (3)0.0903 (2)0.0588 (13)
H1A0.37940.42820.11630.071*
C20.4861 (6)0.3821 (3)0.0254 (2)0.0467 (10)
H2C0.37970.35830.00670.056*
C30.6476 (6)0.3755 (3)0.0125 (2)0.0407 (9)
C40.8047 (7)0.4105 (3)0.0187 (3)0.0547 (11)
H4A0.91550.40480.00430.066*
C50.7938 (8)0.4524 (3)0.0821 (3)0.0626 (13)
H5A0.89770.47720.10210.075*
OW10.4000 (7)0.4442 (3)0.25000.0552 (11)
HW1A0.355 (5)0.3924 (19)0.25000.083*
HW1B0.514 (3)0.439 (3)0.25000.083*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.0368 (3)0.0395 (3)0.0375 (2)0.00051 (18)0.0000.000
I10.0341 (2)0.0429 (2)0.0418 (2)0.00329 (15)0.0000.000
I20.0395 (2)0.0539 (2)0.04392 (19)0.00186 (12)0.00688 (10)0.01025 (11)
I30.0430 (3)0.0383 (2)0.0508 (2)0.00445 (16)0.0000.000
N10.101 (4)0.046 (2)0.0349 (18)0.001 (2)0.0029 (19)0.0039 (16)
N20.059 (3)0.072 (3)0.054 (2)0.008 (2)0.0031 (17)0.022 (2)
C10.077 (4)0.049 (3)0.051 (2)0.002 (3)0.018 (2)0.009 (2)
C20.048 (3)0.044 (2)0.048 (2)0.002 (2)0.0030 (19)0.0044 (18)
C30.047 (3)0.033 (2)0.042 (2)0.0019 (17)0.0029 (16)0.0002 (16)
C40.048 (3)0.056 (3)0.061 (3)0.002 (2)0.008 (2)0.006 (2)
C50.071 (4)0.061 (3)0.056 (3)0.000 (3)0.023 (3)0.001 (2)
OW10.067 (3)0.051 (3)0.047 (2)0.001 (2)0.0000.000
Geometric parameters (Å, º) top
Cd1—I12.7771 (6)C1—C21.363 (6)
Cd1—I32.7849 (6)C1—H1A0.9300
Cd1—I2i2.7852 (4)C2—C31.394 (6)
Cd1—I22.7852 (4)C2—H2C0.9300
N1—C51.317 (7)C3—C41.400 (6)
N1—C11.345 (7)C4—C51.341 (7)
N1—H1B0.8600C4—H4A0.9300
N2—C31.333 (5)C5—H5A0.9300
N2—H2A0.8600OW1—HW1A0.83 (2)
N2—H2B0.8600OW1—HW1B0.85 (2)
I1—Cd1—I3111.805 (18)C2—C1—H1A119.8
I1—Cd1—I2i106.423 (13)C1—C2—C3119.1 (5)
I3—Cd1—I2i109.129 (13)C1—C2—H2C120.5
I1—Cd1—I2106.423 (13)C3—C2—H2C120.5
I3—Cd1—I2109.129 (13)N2—C3—C2120.8 (4)
I2i—Cd1—I2113.94 (2)N2—C3—C4121.0 (4)
C5—N1—C1121.2 (4)C2—C3—C4118.3 (4)
C5—N1—H1B119.4C5—C4—C3119.3 (5)
C1—N1—H1B119.4C5—C4—H4A120.3
C3—N2—H2A120.0C3—C4—H4A120.3
C3—N2—H2B120.0N1—C5—C4121.7 (5)
H2A—N2—H2B120.0N1—C5—H5A119.1
N1—C1—C2120.3 (5)C4—C5—H5A119.1
N1—C1—H1A119.8HW1A—OW1—HW1B108 (3)
Symmetry code: (i) x, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1B···OW1ii0.862.032.886 (5)173
N2—H2A···I2iii0.863.123.938 (4)161
N2—H2B···I20.863.043.843 (4)157
OW1—HW1A···I2iii0.83 (2)3.24 (1)3.828 (4)130 (1)
OW1—HW1A···I2iv0.83 (2)3.24 (1)3.828 (4)130 (1)
OW1—HW1A···I10.83 (2)3.27 (4)3.704 (5)116 (3)
OW1—HW1B···I3v0.85 (2)2.99 (2)3.761 (5)152 (4)
OW1—HW1A···I10.83 (2)3.27 (4)3.704 (5)116 (3)
Symmetry codes: (ii) x+1, y+1, z; (iii) x1, y, z; (iv) x1, y, z+1/2; (v) x+2, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1B···OW1i0.862.032.886 (5)173.2
N2—H2A···I2ii0.863.123.938 (4)160.5
N2—H2B···I20.863.043.843 (4)157.2
OW1—HW1A···I2ii0.83 (2)3.236 (14)3.828 (4)130.4 (12)
OW1—HW1A···I2iii0.83 (2)3.236 (14)3.828 (4)130.4 (12)
OW1—HW1A···I10.83 (2)3.27 (4)3.704 (5)116 (3)
OW1—HW1B···I3iv0.85 (2)2.99 (2)3.761 (5)152 (4)
OW1—HW1A···I10.83 (2)3.27 (4)3.704 (5)116 (3)
Symmetry codes: (i) x+1, y+1, z; (ii) x1, y, z; (iii) x1, y, z+1/2; (iv) x+2, y+1/2, z+1/2.
Acknowledgements top

The authors acknowledge financial support from the Postdoctoral Science Foundation of Central South University and the Fundamental Research Funds for the Central Universities.

references
References top

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