4-Amino-3,5-dimethyl-4H1-,2,4-triazole–water (2/3)

Cheng, L.; Zhang, Y.-W.; Sun, Y.-Y.; Xu, G.

doi:10.1107/S1600536808028146

organic compounds

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ISSN: 2056-9890

Volume 64| Part 10| October 2008| Page o1893

doi:10.1107/S1600536808028146

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4-Amino-3,5-dimethyl-4H1-,2,4-triazole–water (2/3)

Lin Cheng,^a ^* Ya-Wen Zhang,^a Yan-Yan Sun ^a and Gang Xu ^a

^aDepartment of Chemistry and Chemical Engineering, Southeast University, Nanjing, People's Republic of China
^*Correspondence e-mail: cep02chl@yahoo.com.cn

(Received 2 September 2008; accepted 3 September 2008; online 6 September 2008)

The asymmetric unit of the title compound, 2C₄H₈N₄·3H₂O, contains two crystallographically independent 4-amino-3,5-dimethyl-1,2,4-triazole molecules and three water molecules. The structure exhibits N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds.

Related literature

For related structures, see: Wang et al. (2006 ); Zachara et al. 2004 ). For related literature, see: Beckmann & Brooker (2003 ); Bentiss et al. (1999 ); Collin et al. (2003 ); Curtis (2004 ).

Experimental

Crystal data

2C₄H₈N₄·3H₂O
M_r = 278.34
Triclinic, $[P \overline 1]$
a = 7.194 (4) Å
b = 8.680 (4) Å
c = 13.592 (7) Å
α = 72.332 (8)°
β = 84.993 (8)°
γ = 68.936 (7)°
V = 754.5 (6) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 293 (2) K
0.20 × 0.18 × 0.17 mm

Data collection

Bruker APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2000 ) T_min = 0.981, T_max = 0.984
5166 measured reflections
2904 independent reflections
2447 reflections with I > 2σ(I)
R_int = 0.014

Refinement

R[F² > 2σ(F²)] = 0.049
wR(F²) = 0.137
S = 1.03
2904 reflections
213 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N4—H4D⋯O1W	0.93 (2)	2.00 (2)	2.924 (3)	170.9 (18)
N4—H4E⋯O3Wⁱ	0.88 (2)	2.21 (2)	3.078 (3)	168.3 (18)
N8—H8E⋯O2Wⁱⁱ	0.93 (3)	2.23 (3)	3.104 (3)	156 (2)
O1W—H1WA⋯O2Wⁱⁱⁱ	0.84 (3)	1.95 (3)	2.793 (3)	173 (3)
O1W—H1WB⋯O3W^iv	0.92 (3)	1.93 (3)	2.810 (2)	160 (3)
O2W—H2WA⋯N2	0.87 (3)	2.02 (3)	2.885 (2)	171 (2)
O2W—H2WB⋯N5	0.90 (3)	1.93 (3)	2.816 (2)	168 (2)
O3W—H3WA⋯N1	0.88 (2)	1.92 (2)	2.787 (2)	168 (2)
O3W—H3WB⋯N6	0.89 (3)	1.93 (3)	2.827 (2)	176 (2)
Symmetry codes: (i) -x+1, -y, -z; (ii) -x+1, -y+1, -z-1; (iii) -x, -y+1, -z; (iv) -x, -y, -z.

Data collection: SMART (Bruker, 2000 ); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808028146/bt2782sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808028146/bt2782Isup2.hkl

checkCIF report

Comment top

The derivatives of 4-amino-1,2,4-triazoles have considerable importance in medicinal chemistry, agricultural and industrial chemistry (Bentiss et al. 1999; Collin et al. 2003; Curtis et al. 2004). They have also been used as multidentate ligands in coordination chemistry (Beckmann et al. 2003). Here, we report a hydrated 4-amino-1,2,4-triazole (mta)₂.3H₂O (mta = 4-amino-3,5-dimethyl-1,2,4-triazole).

The asymmetric unit of the title compound contains two crystallographically independent mta molecules and three water molecules. The C═N—N—C fragments of the tetrazine rings have the C═N distances of 1.299 (2), 1.300 (2) and 1.304 (2) Å, and the N—N distances of 1.392 (2) and 1.389 (2) Å. All other C—N distances are between 1.352 (2) and 1.362 (2) Å, which are considered to have part double-bond character. In the crystalline state, the mta and crystal water molecules are linked together by N—H···O, O—H···N and O—H···O hydrogen bonding.

Related literature top

For related structures, see: Wang et al. (2006); Zachara et al. 2004). For related literature, see: Beckmann & Brooker (2003); Bentiss et al. (1999); Collin et al. (2003); Curtis (2004).

Experimental top

To a solution of mta (mta = 4-amino-3,5-dimethyl-1,2,4-triazole) (0.0228 g, 0.2 mmol) in CH₃OH (5 ml), an aqueous solution (5 ml) of MnSO₄.H₂O (0.0169 g, 0.1 mmol) was added. The mixture was stirred for half an hour and filtered. The filtrate was allowed to evaporate slowly at room temperature. After several days, colorless block crystals were obtained in 5% yield (0.0007 g) based on mta.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART (Bruker, 2000); data reduction: SAINT (Bruker, 2000); 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 (Sheldrick, 2008).

Figures top

	Fig. 1. The asymmetric unit of the title compound with 30% thermal ellipsoids.
	Fig. 2. The three-dimensional supramolecular network of the title compound. The H atoms bonded to C atoms are omitted for clarity.

4-Amino-3,5-dimethyl-4H-1,2,4-triazole–water (2/3) top

Crystal data top

2C₄H₈N₄·3H₂O	Z = 2
M_r = 278.34	F(000) = 300
Triclinic, P1	D_x = 1.225 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.194 (4) Å	Cell parameters from 785 reflections
b = 8.680 (4) Å	θ = 2.4–28.0°
c = 13.592 (7) Å	µ = 0.10 mm⁻¹
α = 72.332 (8)°	T = 293 K
β = 84.993 (8)°	Block, colourless
γ = 68.936 (7)°	0.20 × 0.18 × 0.17 mm
V = 754.5 (6) Å³

Data collection top

Bruker APEX CCD diffractometer	2904 independent reflections
Radiation source: fine-focus sealed tube	2447 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.014
ϕ and ω scan	θ_max = 26.0°, θ_min = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	h = −8→8
T_min = 0.981, T_max = 0.984	k = −10→10
5166 measured reflections	l = −16→12

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.049	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.137	w = 1/[σ²(F_o²) + (0.0782P)² + 0.0952P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max < 0.001
2904 reflections	Δρ_max = 0.27 e Å⁻³
213 parameters	Δρ_min = −0.22 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.151 (12)

Crystal data top

2C₄H₈N₄·3H₂O	γ = 68.936 (7)°
M_r = 278.34	V = 754.5 (6) Å³
Triclinic, P1	Z = 2
a = 7.194 (4) Å	Mo Kα radiation
b = 8.680 (4) Å	µ = 0.10 mm⁻¹
c = 13.592 (7) Å	T = 293 K
α = 72.332 (8)°	0.20 × 0.18 × 0.17 mm
β = 84.993 (8)°

Data collection top

Bruker APEX CCD diffractometer	2904 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	2447 reflections with I > 2σ(I)
T_min = 0.981, T_max = 0.984	R_int = 0.014
5166 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.049	0 restraints
wR(F²) = 0.137	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	Δρ_max = 0.27 e Å⁻³
2904 reflections	Δρ_min = −0.22 e Å⁻³
213 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.2307 (2)	0.21698 (19)	0.03818 (12)	0.0464 (4)
C2	0.2155 (3)	0.3435 (2)	0.09351 (15)	0.0675 (5)
H2A	0.2195	0.4487	0.0448	0.101*
H2B	0.3249	0.2973	0.1422	0.101*
H2C	0.0922	0.3666	0.1295	0.101*
C3	0.2508 (2)	−0.02273 (19)	0.01050 (12)	0.0450 (4)
C4	0.2584 (3)	−0.2021 (2)	0.02881 (14)	0.0574 (4)
H4A	0.2743	−0.2287	−0.0357	0.086*
H4B	0.1369	−0.2134	0.0596	0.086*
H4C	0.3691	−0.2805	0.0744	0.086*
C5	0.2491 (2)	0.3310 (2)	−0.54342 (13)	0.0518 (4)
C6	0.2507 (4)	0.2018 (3)	−0.59340 (17)	0.0790 (6)
H6A	0.2633	0.0947	−0.5416	0.119*
H6B	0.3612	0.1843	−0.6389	0.119*
H6C	0.1286	0.2421	−0.6324	0.119*
C7	0.2362 (2)	0.5735 (2)	−0.52294 (12)	0.0500 (4)
C8	0.2197 (3)	0.7564 (2)	−0.54624 (15)	0.0691 (5)
H8A	0.2259	0.7821	−0.4830	0.104*
H8B	0.0951	0.8304	−0.5817	0.104*
H8C	0.3274	0.7752	−0.5892	0.104*
N1	0.2638 (2)	0.08533 (18)	−0.07827 (10)	0.0528 (4)
N2	0.2508 (2)	0.23853 (17)	−0.06052 (10)	0.0533 (4)
N3	0.22893 (18)	0.05496 (15)	0.08561 (9)	0.0433 (3)
N4	0.2136 (3)	−0.02566 (19)	0.19138 (10)	0.0543 (4)
H4D	0.100 (3)	0.047 (3)	0.2139 (15)	0.071 (6)*
H4E	0.320 (3)	−0.030 (3)	0.2220 (15)	0.071 (6)*
N5	0.2546 (2)	0.46293 (18)	−0.43183 (10)	0.0568 (4)
N6	0.2637 (2)	0.30785 (18)	−0.44498 (11)	0.0579 (4)
N7	0.2326 (2)	0.49581 (17)	−0.59485 (9)	0.0511 (4)
N8	0.2096 (4)	0.5651 (3)	−0.70320 (12)	0.0790 (6)
H8D	0.105 (4)	0.659 (4)	−0.710 (2)	0.109 (10)*
H8E	0.325 (5)	0.589 (4)	−0.726 (2)	0.119 (10)*
O1W	−0.1595 (3)	0.1723 (3)	0.26863 (18)	0.1022 (7)
H1WA	−0.219 (5)	0.280 (4)	0.254 (2)	0.132 (12)*
H1WB	−0.248 (5)	0.128 (4)	0.254 (2)	0.131 (11)*
O2W	0.3524 (2)	0.47375 (18)	−0.23848 (12)	0.0706 (4)
H2WA	0.308 (4)	0.412 (3)	−0.186 (2)	0.090 (7)*
H2WB	0.308 (4)	0.466 (3)	−0.296 (2)	0.101 (8)*
O3W	0.3962 (2)	0.02300 (16)	−0.26616 (11)	0.0610 (4)
H3WA	0.341 (3)	0.055 (3)	−0.2121 (18)	0.079 (6)*
H3WB	0.349 (4)	0.114 (3)	−0.321 (2)	0.093 (8)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0471 (8)	0.0429 (8)	0.0438 (8)	−0.0139 (6)	−0.0002 (6)	−0.0069 (6)
C2	0.0849 (13)	0.0529 (10)	0.0645 (11)	−0.0241 (9)	−0.0015 (10)	−0.0161 (9)
C3	0.0393 (7)	0.0485 (8)	0.0455 (8)	−0.0143 (6)	0.0017 (6)	−0.0128 (7)
C4	0.0574 (10)	0.0543 (10)	0.0636 (11)	−0.0213 (8)	0.0020 (8)	−0.0198 (8)
C5	0.0514 (9)	0.0550 (9)	0.0478 (9)	−0.0184 (7)	0.0075 (7)	−0.0152 (7)
C6	0.0942 (15)	0.0765 (13)	0.0778 (14)	−0.0334 (11)	0.0145 (11)	−0.0378 (11)
C7	0.0513 (9)	0.0539 (9)	0.0444 (9)	−0.0212 (7)	0.0050 (7)	−0.0115 (7)
C8	0.0833 (13)	0.0610 (11)	0.0660 (12)	−0.0345 (10)	0.0060 (10)	−0.0129 (9)
N1	0.0571 (8)	0.0584 (8)	0.0431 (7)	−0.0227 (6)	0.0055 (6)	−0.0134 (6)
N2	0.0589 (8)	0.0512 (8)	0.0455 (8)	−0.0221 (6)	0.0029 (6)	−0.0053 (6)
N3	0.0445 (7)	0.0430 (7)	0.0374 (7)	−0.0144 (5)	0.0013 (5)	−0.0060 (5)
N4	0.0632 (9)	0.0543 (8)	0.0378 (7)	−0.0206 (7)	0.0038 (7)	−0.0034 (6)
N5	0.0697 (9)	0.0578 (8)	0.0427 (8)	−0.0249 (7)	0.0031 (6)	−0.0119 (6)
N6	0.0709 (9)	0.0516 (8)	0.0467 (8)	−0.0213 (7)	0.0030 (6)	−0.0086 (6)
N7	0.0565 (8)	0.0584 (8)	0.0368 (7)	−0.0242 (6)	0.0045 (6)	−0.0080 (6)
N8	0.1082 (16)	0.0910 (14)	0.0374 (8)	−0.0448 (13)	0.0018 (9)	−0.0062 (8)
O1W	0.0737 (10)	0.0831 (12)	0.170 (2)	−0.0312 (9)	0.0195 (10)	−0.0655 (13)
O2W	0.1040 (11)	0.0668 (9)	0.0514 (8)	−0.0482 (8)	−0.0005 (7)	−0.0090 (6)
O3W	0.0781 (9)	0.0496 (7)	0.0488 (7)	−0.0161 (6)	0.0067 (6)	−0.0143 (6)

Geometric parameters (Å, º) top

C1—N2	1.300 (2)	C7—N7	1.352 (2)
C1—N3	1.362 (2)	C7—C8	1.483 (2)
C1—C2	1.478 (2)	C8—H8A	0.9600
C2—H2A	0.9600	C8—H8B	0.9600
C2—H2B	0.9600	C8—H8C	0.9600
C2—H2C	0.9600	N1—N2	1.391 (2)
C3—N1	1.304 (2)	N3—N4	1.4091 (18)
C3—N3	1.355 (2)	N4—H4D	0.93 (2)
C3—C4	1.482 (2)	N4—H4E	0.88 (2)
C4—H4A	0.9600	N5—N6	1.389 (2)
C4—H4B	0.9600	N7—N8	1.411 (2)
C4—H4C	0.9600	N8—H8D	0.88 (3)
C5—N6	1.299 (2)	N8—H8E	0.93 (3)
C5—N7	1.354 (2)	O1W—H1WA	0.84 (3)
C5—C6	1.474 (3)	O1W—H1WB	0.92 (3)
C6—H6A	0.9600	O2W—H2WA	0.87 (3)
C6—H6B	0.9600	O2W—H2WB	0.90 (3)
C6—H6C	0.9600	O3W—H3WA	0.88 (2)
C7—N5	1.299 (2)	O3W—H3WB	0.89 (3)

N2—C1—N3	109.30 (14)	N5—C7—C8	126.38 (16)
N2—C1—C2	126.85 (15)	N7—C7—C8	124.62 (15)
N3—C1—C2	123.85 (15)	C7—C8—H8A	109.5
C1—C2—H2A	109.5	C7—C8—H8B	109.5
C1—C2—H2B	109.5	H8A—C8—H8B	109.5
H2A—C2—H2B	109.5	C7—C8—H8C	109.5
C1—C2—H2C	109.5	H8A—C8—H8C	109.5
H2A—C2—H2C	109.5	H8B—C8—H8C	109.5
H2B—C2—H2C	109.5	C3—N1—N2	107.78 (13)
N1—C3—N3	109.02 (14)	C1—N2—N1	107.36 (12)
N1—C3—C4	126.61 (15)	C3—N3—C1	106.55 (13)
N3—C3—C4	124.37 (14)	C3—N3—N4	124.23 (13)
C3—C4—H4A	109.5	C1—N3—N4	129.20 (13)
C3—C4—H4B	109.5	N3—N4—H4D	106.6 (12)
H4A—C4—H4B	109.5	N3—N4—H4E	105.8 (13)
C3—C4—H4C	109.5	H4D—N4—H4E	109.1 (17)
H4A—C4—H4C	109.5	C7—N5—N6	107.56 (14)
H4B—C4—H4C	109.5	C5—N6—N5	107.64 (13)
N6—C5—N7	108.89 (15)	C7—N7—C5	106.91 (14)
N6—C5—C6	126.70 (17)	C7—N7—N8	129.47 (15)
N7—C5—C6	124.41 (16)	C5—N7—N8	123.59 (15)
C5—C6—H6A	109.5	N7—N8—H8D	102.0 (18)
C5—C6—H6B	109.5	N7—N8—H8E	105.6 (17)
H6A—C6—H6B	109.5	H8D—N8—H8E	112 (3)
C5—C6—H6C	109.5	H1WA—O1W—H1WB	106 (3)
H6A—C6—H6C	109.5	H2WA—O2W—H2WB	107 (2)
H6B—C6—H6C	109.5	H3WA—O3W—H3WB	107 (2)
N5—C7—N7	109.00 (15)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4D···O1W	0.93 (2)	2.00 (2)	2.924 (3)	170.9 (18)
N4—H4E···O3Wⁱ	0.88 (2)	2.21 (2)	3.078 (3)	168.3 (18)
N8—H8E···O2Wⁱⁱ	0.93 (3)	2.23 (3)	3.104 (3)	156 (2)
O1W—H1WA···O2Wⁱⁱⁱ	0.84 (3)	1.95 (3)	2.793 (3)	173 (3)
O1W—H1WB···O3W^iv	0.92 (3)	1.93 (3)	2.810 (2)	160 (3)
O2W—H2WA···N2	0.87 (3)	2.02 (3)	2.885 (2)	171 (2)
O2W—H2WB···N5	0.90 (3)	1.93 (3)	2.816 (2)	168 (2)
O3W—H3WA···N1	0.88 (2)	1.92 (2)	2.787 (2)	168 (2)
O3W—H3WB···N6	0.89 (3)	1.93 (3)	2.827 (2)	176 (2)

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

Experimental details

Crystal data
Chemical formula	2C₄H₈N₄·3H₂O
M_r	278.34
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	7.194 (4), 8.680 (4), 13.592 (7)
α, β, γ (°)	72.332 (8), 84.993 (8), 68.936 (7)
V (Å³)	754.5 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.20 × 0.18 × 0.17

Data collection
Diffractometer	Bruker APEX CCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2000)
T_min, T_max	0.981, 0.984
No. of measured, independent and observed [I > 2σ(I)] reflections	5166, 2904, 2447
R_int	0.014
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.137, 1.03
No. of reflections	2904
No. of parameters	213
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.27, −0.22

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4D···O1W	0.93 (2)	2.00 (2)	2.924 (3)	170.9 (18)
N4—H4E···O3Wⁱ	0.88 (2)	2.21 (2)	3.078 (3)	168.3 (18)
N8—H8E···O2Wⁱⁱ	0.93 (3)	2.23 (3)	3.104 (3)	156 (2)
O1W—H1WA···O2Wⁱⁱⁱ	0.84 (3)	1.95 (3)	2.793 (3)	173 (3)
O1W—H1WB···O3W^iv	0.92 (3)	1.93 (3)	2.810 (2)	160 (3)
O2W—H2WA···N2	0.87 (3)	2.02 (3)	2.885 (2)	171 (2)
O2W—H2WB···N5	0.90 (3)	1.93 (3)	2.816 (2)	168 (2)
O3W—H3WA···N1	0.88 (2)	1.92 (2)	2.787 (2)	168 (2)
O3W—H3WB···N6	0.89 (3)	1.93 (3)	2.827 (2)	176 (2)

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

Acknowledgements

The authors thank the Program for Young Excellent Talents in Southeast University for financial support.

References

Beckmann, U. & Brooker, S. (2003). Coord. Chem. Rev. 245, 17–29. Web of Science CrossRef CAS Google Scholar
Bentiss, F., Lagrenee, M., Traisnel, M. & Hornez, J. C. (1999). Corros. Sci. 41, 789–803. Web of Science CrossRef CAS Google Scholar
Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Collin, X., Sauleau, A. & Coulon, J. (2003). Bioorg. Med. Chem. Lett. 13, 2601–2605. Web of Science CrossRef PubMed CAS Google Scholar
Curtis, A. D. M. (2004). Sci. Synth., 13, 603–605. CAS Google Scholar
Sheldrick, G. M. (2000). SADABS., University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wang, P., Ma, J. P., Huang, R.-Q. & Dong, Y.-B. (2006). Acta Cryst. E62, o2791–o2792. Web of Science CSD CrossRef IUCr Journals Google Scholar
Zachara, J., Madura, I. & Włostowski, M. (2004). Acta Cryst. C60, o57–o59. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar