trans-Di­aqua­bis­[5-(1H-imidazol-4-yl-κN³)-1H-tetra­zolato-κN¹]zinc(II)

In the title complex, [Zn(C₄H₃N₆)₂(H₂O)₂], the metal centre lies on an inversion centre and displays a distorted octa­hedral ZnN₄O₂ coordination geometry. The organic ligand is not planar; the dihedral angle between the imidazole and tetra­zole rings is 8.39 (9)°. An extended network of inter­molecular N—H⋯N and O—H⋯N hydrogen bonds stabilizes the crystal structure.

Related literature

For the synthesis and properties of tetra­zole compounds, see: Demko & Sharpless (2001, 2002); Zhao et al. (2008).

Experimental

Crystal data

• [Zn(C₄H₃N₆)₂(H₂O)₂]

• M_r = 371.65

• Monoclinic, P 2₁ /c

• a = 5.9068 (10) Å

• b = 17.408 (3) Å

• c = 7.091 (2) Å

• β = 110.70 (2)°

• V = 682.1 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 1.84 mm⁻¹

• T = 291 K

• 0.20 × 0.18 × 0.15 mm

Data collection

• Rigaku SCXmini diffractometer

• Absorption correction: multi-scan (CrystalClear; Rigaku, 2005) T_min = 0.753, T_max = 0.762

• 6793 measured reflections

• 1555 independent reflections

• 1429 reflections with I > 2σ(I)

• R_int = 0.025

Refinement

• R[F² > 2σ(F²)] = 0.028

• wR(F²) = 0.113

• S = 1.30

• 1555 reflections

• 106 parameters

• H-atom parameters constrained

• Δρ_max = 0.59 e Å⁻³

• Δρ_min = −0.64 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯N6^i	0.86	2.01	2.803 (3)	153
O1—H1B⋯N5^ii	0.86	2.00	2.837 (3)	164
O1—H1A⋯N4^iii	0.79	2.08	2.841 (2)	164
Symmetry codes: (i) ; (ii) -x+1, -y+1, -z; (iii) x+1, y, z.

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: SHELXTL/PC.

Supporting information

S1. Comment

Tetrazole ligands have found a wide range of applications in medicine chemistry, coordination chemistry and material chemistry (Demko & Sharpless, 2001). Recently, the tetrazole synthesis in water has attracted intense attention. For example, a safe, convenient, and environmentally friendly procedure for the synthesis of 5-substituted 1H-tetrazoles, which were prepared by the addition of azides to nitriles in water using zinc salts as catalysts, has been reported (Demko & Sharpless, 2002). Our group has been interested in the construction of novel supramolecular motifs through in situ hydrothermal reactions (Zhao et al., 2008). In particular, we have combined metal salts with potentially bridging organic ligands under hydrothermal conditions to produce a range of new materials in order to investigate the Demko-Sharpless reaction. Herein we report on the synthesis and structure of the title compound, which was obtained by the hydrothermal reaction of ZnCl₂ with (4-cyano)-imidazole and NaN₃ in water.

Figure 1 shows the monomeric complex molecule along with the atom-labelling scheme. The zinc(II) metal lies on an inversion centre, and displays a distorted octahedral coordination geometry provided by the N atoms of two chelating ligands at the equatorial plane and by the oxygen atoms of two trans-arranged water molecules at the axial positions. The bond distances and angles within the coordination octahedron have normal values. The organic ligand is not planar, the dihedral angle formed by the imidazole and tetrazole rings is 8.39 (9)°. The five-membered chelating ring assumes an approximately planar conformation (maximum deviation 0.030 (2) Å for atom C4). The crystal structure is stabilized by intermolecular N—H···N and O—H···N hydrogen bonds (Table 1), forming an extended three-dimensional network (Fig. 2).

Related literature

For the synthesis and properties of tetrazole compounds, see: Demko & Sharpless (2001, 2002); Zhao et al. (2008).

S2. Experimental

Colourless single crystals of title compound were obtained by hydrothermal treatment of ZnCl₂ (1 mmol), NaN₃ (3 mmol), (4-cyano)-imidazole (1 mmol) and water (7 ml) over 1 day at 398 K. Yield: 53% (based on ZnCl₂).

S3. Refinement

The water H atoms were located from a difference Fourier map but not refined [U_iso(H) = 1.5 U_eq(O)]. All other H atoms were placed at calculated positions and refined as riding, with C—H = 0.93 Å, N—H = 0.86 Å, and with U_iso(H) = 1.2 U_eq(C, N).

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: SHELXTL/PC (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Atoms labelled with suffix A are generated by the symmetry operation (2-x, 1-y, 1-z).
	Fig. 2. Packing diagram of the title compound viewed along the b axis. Intermolecular hydrogen bonds are shown as dashed lines.

trans-Diaquabis[5-(1H-imidazol-4-yl-κN³)-1H- tetrazolato-κN¹]zinc(II)

Crystal data

[Zn(C4H3N6)2(H2O)2]	F(000) = 376
Mr = 371.65	Dx = 1.809 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2098 reflections
a = 5.9068 (10) Å	θ = 2.3–27.5°
b = 17.408 (3) Å	µ = 1.84 mm^−1
c = 7.091 (2) Å	T = 291 K
β = 110.70 (2)°	Prism, colourless
V = 682.1 (3) Å^3	0.20 × 0.18 × 0.15 mm
Z = 2

Data collection

Rigaku SCXmini diffractometer	1555 independent reflections
Radiation source: fine-focus sealed tube	1429 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.5°, θmin = 2.3°
ω scans	h = −7→7
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −22→22
Tmin = 0.753, Tmax = 0.762	l = −9→9
6793 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H-atom parameters constrained
S = 1.30	w = 1/[σ^2(Fo^2) + (0.0683P)^2 + 0.021P] where P = (Fo^2 + 2Fc^2)/3
1555 reflections	(Δ/σ)max < 0.001
106 parameters	Δρmax = 0.59 e Å^−3
0 restraints	Δρmin = −0.64 e Å^−3

Special details

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

	x	y	z	Uiso*/Ueq
Zn1	1.0000	0.5000	0.5000	0.02202 (18)
C1	0.9503 (4)	0.34932 (12)	0.3008 (3)	0.0212 (4)
C2	1.0396 (4)	0.27845 (13)	0.2890 (4)	0.0287 (5)
H2	0.9581	0.2376	0.2090	0.034*
C3	1.3185 (4)	0.34887 (13)	0.5063 (4)	0.0262 (5)
H3	1.4657	0.3635	0.6021	0.031*
C4	0.7145 (4)	0.38475 (12)	0.2122 (3)	0.0207 (4)
N1	1.1269 (3)	0.39332 (10)	0.4390 (3)	0.0223 (4)
N2	1.2733 (4)	0.27947 (11)	0.4186 (3)	0.0292 (4)
H2A	1.3746	0.2421	0.4404	0.035*
N3	0.6743 (3)	0.45320 (10)	0.2795 (3)	0.0208 (4)
N4	0.4411 (3)	0.46893 (11)	0.1772 (3)	0.0242 (4)
N5	0.3469 (3)	0.41230 (11)	0.0538 (3)	0.0272 (4)
N6	0.5162 (3)	0.35808 (11)	0.0704 (3)	0.0258 (4)
O1	1.0962 (3)	0.56118 (9)	0.2680 (2)	0.0285 (4)
H1B	0.9793	0.5753	0.1617	0.043*
H1A	1.1972	0.5434	0.2327	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0195 (3)	0.0171 (2)	0.0251 (3)	0.00042 (11)	0.00252 (17)	−0.00441 (12)
C1	0.0214 (10)	0.0190 (10)	0.0211 (10)	−0.0010 (7)	0.0049 (8)	−0.0013 (8)
C2	0.0301 (12)	0.0212 (11)	0.0323 (12)	0.0020 (9)	0.0081 (9)	−0.0019 (9)
C3	0.0198 (10)	0.0270 (11)	0.0287 (11)	0.0035 (8)	0.0045 (9)	0.0030 (9)
C4	0.0210 (10)	0.0175 (9)	0.0216 (10)	−0.0022 (7)	0.0052 (8)	0.0008 (8)
N1	0.0186 (9)	0.0194 (8)	0.0256 (9)	0.0007 (7)	0.0039 (7)	−0.0019 (7)
N2	0.0271 (10)	0.0233 (9)	0.0356 (11)	0.0098 (8)	0.0089 (8)	0.0035 (8)
N3	0.0169 (9)	0.0214 (9)	0.0217 (9)	0.0030 (7)	0.0037 (7)	−0.0004 (7)
N4	0.0177 (9)	0.0277 (10)	0.0254 (10)	0.0021 (7)	0.0051 (7)	0.0028 (8)
N5	0.0192 (9)	0.0297 (10)	0.0286 (10)	−0.0008 (7)	0.0031 (7)	0.0028 (8)
N6	0.0215 (9)	0.0214 (9)	0.0282 (10)	−0.0031 (7)	0.0011 (7)	−0.0021 (8)
O1	0.0226 (8)	0.0344 (9)	0.0259 (8)	0.0058 (6)	0.0055 (6)	0.0016 (7)

Geometric parameters (Å, º)

Zn1—N1^i	2.1042 (18)	C3—N1	1.313 (3)
Zn1—N1	2.1042 (18)	C3—N2	1.342 (3)
Zn1—N3^i	2.1641 (19)	C3—H3	0.9300
Zn1—N3	2.1641 (19)	C4—N6	1.329 (3)
Zn1—O1	2.1966 (17)	C4—N3	1.336 (3)
Zn1—O1^i	2.1966 (17)	N2—H2A	0.8600
C1—C2	1.356 (3)	N3—N4	1.339 (3)
C1—N1	1.383 (3)	N4—N5	1.305 (3)
C1—C4	1.448 (3)	N5—N6	1.350 (3)
C2—N2	1.362 (3)	O1—H1B	0.8585
C2—H2	0.9300	O1—H1A	0.7874
N1^i—Zn1—N1	180.0	N1—C3—N2	110.9 (2)
N1^i—Zn1—N3^i	79.02 (7)	N1—C3—H3	124.5
N1—Zn1—N3^i	100.98 (7)	N2—C3—H3	124.5
N1^i—Zn1—N3	100.98 (7)	N6—C4—N3	111.23 (19)
N1—Zn1—N3	79.02 (7)	N6—C4—C1	129.4 (2)
N3^i—Zn1—N3	180.00 (8)	N3—C4—C1	119.34 (19)
N1^i—Zn1—O1	86.07 (7)	C3—N1—C1	105.58 (19)
N1—Zn1—O1	93.93 (7)	C3—N1—Zn1	140.26 (16)
N3^i—Zn1—O1	87.66 (7)	C1—N1—Zn1	113.59 (14)
N3—Zn1—O1	92.34 (7)	C3—N2—C2	108.22 (18)
N1^i—Zn1—O1^i	93.93 (7)	C3—N2—H2A	125.9
N1—Zn1—O1^i	86.07 (7)	C2—N2—H2A	125.9
N3^i—Zn1—O1^i	92.34 (7)	C4—N3—N4	105.51 (17)
N3—Zn1—O1^i	87.66 (7)	C4—N3—Zn1	111.67 (14)
O1—Zn1—O1^i	180.00 (7)	N4—N3—Zn1	142.77 (14)
C2—C1—N1	109.58 (19)	N5—N4—N3	108.77 (18)
C2—C1—C4	134.1 (2)	N4—N5—N6	110.06 (17)
N1—C1—C4	116.14 (18)	C4—N6—N5	104.42 (19)
C1—C2—N2	105.7 (2)	Zn1—O1—H1B	117.1
C1—C2—H2	127.2	Zn1—O1—H1A	118.2
N2—C2—H2	127.2	H1B—O1—H1A	107.4

Symmetry code: (i) −x+2, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···N6^ii	0.86	2.01	2.803 (3)	153
O1—H1B···N5^iii	0.86	2.00	2.837 (3)	164
O1—H1A···N4^iv	0.79	2.08	2.841 (2)	164

Symmetry codes: (ii) x+1, −y+1/2, z+1/2; (iii) −x+1, −y+1, −z; (iv) x+1, y, z.