Diaqua­bis[5-(1H-tetra­zol-5-ylamino-κN⁴)-1H-tetra­zolato-κN¹]iron(II) dihydrate

The centrosymmetric title complex, [Fe(C₂H₂N₉)₂(H₂O)₂]·2H₂O, has been prepared by an in situ [2+3] cyclo­addition reaction of dicyanamide with sodium azide and ferrous sulfate, with heating and stirring. The Fe^II ion is coordinated by four N atoms from two 5-(1H-tetra­zol-5-ylamino)-1H-tetra­zolate ligands and two water mol­ecules in axial positions in an octa­hedral geometry. The complex is linked into a three-dimensional network by O—H...N, N—H...O and N—H...N hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](N-C) = 0.002 Å
• R factor = 0.025
• wR factor = 0.070
• Data-to-parameter ratio = 11.5

checkCIF/PLATON results

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Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Fe1         (2)       2.02

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
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   1 ALERT level G = General alerts; check

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S1. Comment

The complex of H₂BTA and its deprotonated anions have been not aroused sufficient attention (Friedrich et al., 2005). The H₂BTA and its deprotonated anions can show hundreds of different coordinating or bridging modes. The title complex, (I), consists of a Fe(II) cation, two HBTA^- anion ligands, two coordinated water molecules and two solvent water molecules (Table 1 and Fig. 1). The HBTA^- ligand acts as a chelatingbidentate and the Fe^II cation is coordinated to four N atoms from two HBTA^- ligands and two water molecules to form an octahedral mononuclear complex with the axial O—Mn—O bond angle of 180°. The complex is constructed 3-D networks through O—H···N, N—H···O and N—H···N hydrogen bonds between water molecule and HBTA^- ligands (Fig. 2 and Fig. 3).

Related literature

Reports of related bistetrazolylimine complexes are rare; see, for example, the copper(II) complex (Friedrich et al., 2005).

S2. Experimental

A solution of Ferrosi Sulfate (0.0139 g, 0.05 mmol) and L-Ascorbic acid (0.009 g, 0.05 mmol) in 5 ml of water was slowly added to a 10 mLaqueous solution of N,N-bis(1(2)H-tetrazol-5-yl)-amine) (0.0078 g, 0.05 mmol). The mixture was stirred and refluxed for an hour. After cooling, the resulting mixture was filtered and colourless crystals were obtained by slow evaporation of the filtrate after two weeks. The colourless crystal were collected and dried in air. Elemental analysis, calculated (%) for C₄H₁₂Fe₁N₁₈O₄: C 11.11, H 2.78, N 58.31; found (%): C 10.95, H 3.09, N 58.98.

S3. Refinement

All hydrogen atoms were found from difference Fourier mMaps and refined freely.

Computing details

Data collection: SMART (Bruker, 2001–2005); cell refinement: SAINT-Plus (Bruker, 2001–2005); data reduction: SAINT-Plus (Bruker, 2001–2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001–2005); software used to prepare material for publication: SHELXTL (Bruker, 2001–2005).

Figures

	Fig. 1. The molecular structure of the complex, with atom labels and 30% probability displacement ellipsoids for non-H atoms. [Ssymmetry code: (i) -x + 1, -y, -z].
	Fig. 2. The packing diagram of the complex, showing a three-dimensional network connected by O—H···N hydrogen bonds (dashed lines).

Diaquabis[5-(1H-tetrazol-5-ylamino-κN⁴)-1H-tetrazolato-κN¹]iron(II) dihydrate

Crystal data

[Fe(C4H4N18)(H2O)2]·2H2O	F(000) = 440.0
Mr = 432.17	Dx = 1.925 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1716 reflections
a = 7.6075 (4) Å	θ = 1.0–27.5°
b = 14.9759 (7) Å	µ = 1.08 mm^−1
c = 6.8285 (3) Å	T = 296 K
β = 106.585 (3)°	Block, colourless
V = 745.60 (6) Å^3	0.23 × 0.20 × 0.13 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	1717 independent reflections
Radiation source: fine-focus sealed tube	1479 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.030
phi and ω scans	θmax = 27.5°, θmin = 2.7°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.777, Tmax = 0.868	k = −19→19
11556 measured reflections	l = −8→8

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.025	All H-atom parameters refined
wR(F^2) = 0.070	w = 1/[σ^2(Fo^2) + (0.0382P)^2 + 0.306P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.032
1717 reflections	Δρmax = 0.28 e Å^−3
149 parameters	Δρmin = −0.24 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.005 (1)

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
Fe1	0.5000	0.0000	0.0000	0.01676 (12)
N9	0.25250 (19)	0.26170 (9)	−0.0636 (2)	0.0211 (3)
N1	0.78512 (18)	0.01838 (9)	0.1552 (2)	0.0199 (3)
N8	0.41760 (19)	0.28148 (9)	0.0682 (2)	0.0230 (3)
N6	0.39630 (18)	0.13691 (9)	0.0282 (2)	0.0194 (3)
N3	1.04020 (19)	0.08854 (9)	0.2765 (2)	0.0248 (3)
C1	0.9229 (2)	−0.03919 (10)	0.2181 (2)	0.0170 (3)
C2	0.2411 (2)	0.17333 (10)	−0.0869 (2)	0.0178 (3)
N5	0.90614 (19)	−0.13073 (9)	0.2088 (2)	0.0229 (3)
N2	0.8654 (2)	0.09916 (9)	0.1938 (2)	0.0260 (3)
N7	0.50155 (19)	0.20714 (9)	0.1231 (2)	0.0233 (3)
N4	1.08411 (19)	0.00108 (9)	0.2944 (2)	0.0216 (3)
O2	0.1478 (2)	0.76781 (11)	0.4968 (2)	0.0372 (4)
O1	0.4408 (2)	−0.04110 (10)	0.2711 (2)	0.0309 (3)
H3	0.177 (3)	0.3046 (16)	−0.117 (4)	0.045 (7)*
H1	0.340 (4)	−0.0296 (19)	0.286 (4)	0.061 (9)*
H2	0.478 (4)	−0.085 (2)	0.325 (4)	0.064 (9)*
H4	0.987 (3)	−0.1610 (14)	0.285 (3)	0.026 (5)*
H5	0.184 (4)	0.7216 (19)	0.460 (4)	0.049 (7)*
H6	0.232 (5)	0.792 (2)	0.579 (6)	0.099 (13)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.01274 (18)	0.01342 (18)	0.02238 (19)	0.00098 (11)	0.00220 (12)	0.00022 (12)
N9	0.0173 (7)	0.0133 (7)	0.0301 (7)	0.0021 (5)	0.0026 (6)	−0.0012 (6)
N1	0.0159 (7)	0.0133 (6)	0.0284 (7)	−0.0001 (5)	0.0028 (6)	−0.0013 (5)
N8	0.0168 (7)	0.0176 (7)	0.0326 (8)	−0.0005 (5)	0.0036 (6)	−0.0047 (6)
N6	0.0162 (6)	0.0152 (6)	0.0248 (7)	0.0007 (5)	0.0026 (5)	−0.0015 (5)
N3	0.0185 (7)	0.0174 (7)	0.0361 (8)	−0.0021 (6)	0.0039 (6)	−0.0017 (6)
C1	0.0156 (7)	0.0159 (8)	0.0185 (7)	−0.0003 (6)	0.0034 (6)	−0.0005 (6)
C2	0.0170 (7)	0.0142 (7)	0.0226 (8)	0.0009 (6)	0.0064 (6)	−0.0004 (6)
N5	0.0173 (7)	0.0133 (7)	0.0314 (8)	0.0028 (6)	−0.0039 (6)	0.0013 (6)
N2	0.0202 (7)	0.0143 (7)	0.0395 (8)	−0.0019 (5)	0.0021 (6)	−0.0019 (6)
N7	0.0188 (7)	0.0179 (7)	0.0309 (8)	−0.0001 (6)	0.0034 (6)	−0.0048 (6)
N4	0.0158 (7)	0.0170 (7)	0.0305 (8)	−0.0014 (5)	0.0043 (6)	−0.0019 (5)
O2	0.0345 (8)	0.0302 (8)	0.0384 (8)	0.0128 (6)	−0.0031 (6)	−0.0103 (6)
O1	0.0277 (7)	0.0345 (8)	0.0333 (7)	0.0107 (6)	0.0134 (6)	0.0124 (6)

Geometric parameters (Å, º)

Fe1—O1	2.1174 (14)	N6—N7	1.3680 (18)
Fe1—O1^i	2.1174 (14)	N3—N2	1.298 (2)
Fe1—N1	2.1427 (13)	N3—N4	1.3487 (19)
Fe1—N1^i	2.1427 (13)	C1—N4	1.332 (2)
Fe1—N6	2.2248 (13)	C1—N5	1.377 (2)
Fe1—N6^i	2.2248 (13)	C2—N5^i	1.350 (2)
N9—C2	1.333 (2)	N5—C2^i	1.350 (2)
N9—N8	1.3528 (19)	N5—H4	0.82 (2)
N9—H3	0.87 (2)	O2—H5	0.81 (3)
N1—C1	1.330 (2)	O2—H6	0.81 (4)
N1—N2	1.3469 (19)	O1—H1	0.82 (3)
N8—N7	1.2849 (19)	O1—H2	0.77 (3)
N6—C2	1.334 (2)
O1—Fe1—O1^i	180.00 (12)	N7—N8—N9	107.11 (13)
O1—Fe1—N1	92.45 (6)	C2—N6—N7	105.34 (12)
O1^i—Fe1—N1	87.55 (6)	C2—N6—Fe1	127.02 (11)
O1—Fe1—N1^i	87.55 (6)	N7—N6—Fe1	125.14 (10)
O1^i—Fe1—N1^i	92.45 (6)	N2—N3—N4	110.80 (13)
N1—Fe1—N1^i	180.00 (12)	N1—C1—N4	112.68 (14)
O1—Fe1—N6	91.33 (5)	N1—C1—N5	125.20 (14)
O1^i—Fe1—N6	88.67 (5)	N4—C1—N5	122.12 (14)
N1—Fe1—N6	99.95 (5)	N9—C2—N6	108.63 (14)
N1^i—Fe1—N6	80.05 (5)	N9—C2—N5^i	123.85 (14)
O1—Fe1—N6^i	88.67 (5)	N6—C2—N5^i	127.52 (15)
O1^i—Fe1—N6^i	91.33 (5)	C2^i—N5—C1	123.28 (14)
N1—Fe1—N6^i	80.05 (5)	C2^i—N5—H4	117.9 (14)
N1^i—Fe1—N6^i	99.95 (5)	C1—N5—H4	118.8 (14)
N6—Fe1—N6^i	180.00 (9)	N3—N2—N1	109.04 (13)
C2—N9—N8	108.25 (13)	N8—N7—N6	110.67 (13)
C2—N9—H3	132.3 (16)	C1—N4—N3	103.16 (13)
N8—N9—H3	119.5 (16)	H5—O2—H6	109 (3)
C1—N1—N2	104.33 (12)	Fe1—O1—H1	119 (2)
C1—N1—Fe1	132.04 (11)	Fe1—O1—H2	122 (2)
N2—N1—Fe1	123.41 (10)	H1—O1—H2	111 (3)

Symmetry code: (i) −x+1, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N9—H3···N3^ii	0.87 (2)	1.93 (2)	2.797 (2)	172 (2)
O1—H1···N4^iii	0.82 (3)	2.02 (3)	2.835 (2)	175 (3)
O1—H2···N8^iv	0.77 (3)	2.20 (3)	2.958 (2)	171 (3)
N5—H4···O2^v	0.82 (2)	1.93 (2)	2.737 (2)	169.6 (19)
O2—H5···N2^vi	0.81 (3)	2.09 (3)	2.830 (2)	151 (2)
O2—H5···N7^vi	0.81 (3)	2.62 (3)	3.140 (2)	124 (2)
O2—H6···N7^vii	0.81 (4)	2.43 (4)	3.169 (2)	153 (3)
O2—H6···N2^vii	0.81 (4)	2.50 (4)	2.926 (2)	114 (3)

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