Diaqua­bis­{5-(pyridin-2-yl-κN)-3-[4-(pyridin-4-yl)phen­yl]-1H-1,2,4-triazol-1-ido-κN1}iron(II)

Li, B.

doi:10.1107/S1600536813004601

metal-organic compounds

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Volume 69| Part 3| March 2013| Page m168

doi:10.1107/S1600536813004601

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Diaquabis{5-(pyridin-2-yl-κN)-3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-1-ido-κN¹}iron(II)

Bin Li ^a ^*

^aAdvanced Material Institute of Research, Department of Chemistry and Chemical Engineering, Qilu Normal University, Shandong 250013, People's Republic of China
^*Correspondence e-mail: libin_qlnu@yahoo.com.cn

(Received 8 February 2013; accepted 16 February 2013; online 23 February 2013)

In the centrosymmetric title complex, [Fe(C₁₈H₁₂N₅)₂(H₂O)₂], the Fe^II ion, lying on an inversion centre, is coordinated by two N,N′-bidentate 5-(pyridin-2-yl)-3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-1-ide ligands and two water molecules in a trans-FeO₂N₄ geometry. In the ligand, the triazole ring makes dihedral angles of 5.21 (18) and 6.7 (2)°, respectively, with the adjacent pyridine and benzene rings. In the crystal, molecules are linked by O—H⋯N hydrogen bonds, generating a three-dimensional network.

Related literature

For background to coordination complexes, see: Zhang, Sun et al. (2012 ); Zhang, Fan et al. (2012 ); Fan et al. (2013 ).

Experimental

Crystal data

[Fe(C₁₈H₁₂N₅)₂(H₂O)₂]
M_r = 688.53
Monoclinic, P 2₁ /c
a = 13.1965 (17) Å
b = 12.0279 (16) Å
c = 9.9006 (13) Å
β = 100.998 (1)°
V = 1542.6 (4) Å³
Z = 2
Mo Kα radiation
μ = 0.54 mm⁻¹
T = 296 K
0.12 × 0.10 × 0.08 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.938, T_max = 0.958
7711 measured reflections
2722 independent reflections
2214 reflections with I > 2σ(I)
R_int = 0.035

Refinement

R[F² > 2σ(F²)] = 0.059
wR(F²) = 0.184
S = 1.00
2722 reflections
231 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.14 e Å⁻³
Δρ_min = −0.42 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1W⋯N4ⁱ	0.81 (4)	1.99 (4)	2.784 (4)	168 (4)
O1—H2W⋯N5ⁱⁱ	0.85 (5)	2.39 (5)	3.165 (6)	152 (5)
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) x-1, y, z-1.

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; 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 global, I. DOI: 10.1107/S1600536813004601/is5245sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813004601/is5245Isup2.hkl

checkCIF report

Comment top

The design and synthesis of coordination complexes have attracted upsurging research interest not only because of their appealing structural and topological novelty but also owing to their tremendous potential applications in gas storage, microelectronics, ion exchange, chemical separations, nonlinear optics and heterogeneous catalysis (Zhang, Sun et al., 2012; Zhang, Fan et al., 2012; Fan et al., 2013). Here, we report one new compound, [Fe(H₂O)₂(C₁₈H₁₂N₅)₂], obtained from the solvothermal reaction of 2-{3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-5-yl}pyridine and iron(II) chloride tetrahydrate.

The asymmetric unit of the title compound consists of a half of Fe(II), one deprotonated 2-{3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-5-}pyridine, and one water molecule. The Fe atom owns a distorted octahedral coordination geometry, completed by four N atoms from two deprotonated 2-{3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-5-yl}pyridine and two O atoms from two water molecules (Fig. 1). The Fe—O distance is 2.205 (3) Å. The Fe—N distances are 2.103 (3) and 2.171 (3) Å. The O—H···N hydrogen bonds (Table 1) in the crystal lead to a consolidation of the structure (Fig. 2) .

Related literature top

For background to coordination complexes, see: Zhang, Sun et al. (2012); Zhang, Fan et al. (2012); Fan et al. (2013).

Experimental top

A mixture of 2-{3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-5-yl}pyridine (0.20 mmol, 0.060 g), iron(II) chloride tetrahydrate (0.40 mmol, 0.078 g), NaOH (0.20 mmol, 0.008 g) and 12 mL H₂O was placed in a Teflon-lined stainless steel vessel, heated to 170 °C for 3 days, followed by slow cooling (a descent rate of 10 °C/h) to room temperature. Red crystals suitable for the X-ray experiment were obtained. Anal. Calc. for C₃₆H₂₈FeN₁₀O₂: C 62.80, H 4.10, N 20.34%; Found: C 62.72, H 4.03, N 20.18%.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); 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 molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are given as spheres of arbitrary radius.
	Fig. 2. A crystal packing view of the title compound, displayed with hydrogen bonds as dashed lines.

Diaquabis{5-(pyridin-2-yl-κN)-3-[4-(pyridin-4-yl)phenyl]-1H-1,2,4-triazol-1-ido-κN¹}iron(II) top

Crystal data top

[Fe(C₁₈H₁₂N₅)₂(H₂O)₂]	F(000) = 712
M_r = 688.53	D_x = 1.482 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 425 reflections
a = 13.1965 (17) Å	θ = 2.3–16.0°
b = 12.0279 (16) Å	µ = 0.54 mm⁻¹
c = 9.9006 (13) Å	T = 296 K
β = 100.998 (1)°	Block, colorless
V = 1542.6 (4) Å³	0.12 × 0.10 × 0.08 mm
Z = 2

Data collection top

Bruker APEXII CCD diffractometer	2722 independent reflections
Radiation source: fine-focus sealed tube	2214 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
ϕ and ω scans	θ_max = 25.0°, θ_min = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −11→15
T_min = 0.938, T_max = 0.958	k = −13→14
7711 measured reflections	l = −11→11

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.059	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.184	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ²(F_o²) + (0.120P)² + 1.3369P] where P = (F_o² + 2F_c²)/3
2722 reflections	(Δ/σ)_max = 0.007
231 parameters	Δρ_max = 1.14 e Å⁻³
1 restraint	Δρ_min = −0.42 e Å⁻³

Crystal data top

[Fe(C₁₈H₁₂N₅)₂(H₂O)₂]	V = 1542.6 (4) Å³
M_r = 688.53	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 13.1965 (17) Å	µ = 0.54 mm⁻¹
b = 12.0279 (16) Å	T = 296 K
c = 9.9006 (13) Å	0.12 × 0.10 × 0.08 mm
β = 100.998 (1)°

Data collection top

Bruker APEXII CCD diffractometer	2722 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	2214 reflections with I > 2σ(I)
T_min = 0.938, T_max = 0.958	R_int = 0.035
7711 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.059	1 restraint
wR(F²) = 0.184	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	Δρ_max = 1.14 e Å⁻³
2722 reflections	Δρ_min = −0.42 e Å⁻³
231 parameters

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

	x	y	z	U_iso*/U_eq
C1	0.3747 (3)	0.2112 (3)	−0.1244 (4)	0.0363 (8)
H1	0.3428	0.1627	−0.1925	0.044*
C2	0.3486 (3)	0.3216 (3)	−0.1351 (4)	0.0412 (9)
H2	0.3004	0.3476	−0.2095	0.049*
C3	0.3951 (3)	0.3931 (3)	−0.0334 (4)	0.0425 (9)
H3	0.3786	0.4683	−0.0383	0.051*
C4	0.4663 (3)	0.3527 (3)	0.0757 (4)	0.0377 (9)
H4	0.4977	0.4000	0.1455	0.045*
C5	0.4900 (2)	0.2410 (3)	0.0795 (3)	0.0285 (7)
C6	0.5674 (2)	0.1872 (3)	0.1860 (3)	0.0280 (7)
C7	0.6842 (3)	0.1449 (3)	0.3520 (3)	0.0310 (8)
C8	0.7662 (3)	0.1451 (3)	0.4768 (3)	0.0357 (8)
C9	0.7863 (3)	0.2334 (4)	0.5670 (4)	0.0468 (10)
H9	0.7465	0.2976	0.5507	0.056*
C10	0.8648 (3)	0.2276 (4)	0.6809 (4)	0.0512 (11)
H10	0.8764	0.2881	0.7403	0.061*
C11	0.9267 (3)	0.1348 (4)	0.7094 (4)	0.0456 (10)
C12	0.9037 (4)	0.0443 (4)	0.6214 (5)	0.0576 (12)
H12	0.9421	−0.0207	0.6395	0.069*
C13	0.8253 (4)	0.0489 (3)	0.5086 (5)	0.0557 (12)
H13	0.8112	−0.0132	0.4522	0.067*
C14	1.0144 (3)	0.1269 (4)	0.8279 (4)	0.0515 (11)
C15	1.0280 (5)	0.1932 (7)	0.9391 (6)	0.124 (3)
H15	0.9809	0.2496	0.9455	0.149*
C16	1.1133 (6)	0.1770 (8)	1.0451 (6)	0.132 (4)
H16	1.1206	0.2259	1.1191	0.158*
C17	1.1777 (5)	0.0489 (6)	0.9320 (7)	0.0927 (19)
H17	1.2319	0.0018	0.9229	0.111*
C18	1.0973 (5)	0.0595 (6)	0.8208 (6)	0.0885 (19)
H18	1.0993	0.0205	0.7403	0.106*
Fe1	0.5000	0.0000	0.0000	0.0319 (3)
N1	0.4444 (2)	0.1702 (2)	−0.0198 (3)	0.0300 (6)
N2	0.5878 (2)	0.0804 (2)	0.1719 (3)	0.0335 (7)
N3	0.6647 (2)	0.0523 (2)	0.2789 (3)	0.0371 (7)
N4	0.6261 (2)	0.2328 (2)	0.2991 (3)	0.0307 (7)
N5	1.1827 (3)	0.1012 (5)	1.0503 (4)	0.0787 (14)
O1	0.3849 (2)	−0.0453 (3)	0.1252 (3)	0.0406 (6)
H1W	0.374 (3)	−0.110 (4)	0.140 (5)	0.063 (15)*
H2W	0.336 (4)	−0.002 (3)	0.136 (5)	0.055 (15)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.040 (2)	0.0363 (18)	0.0265 (18)	−0.0005 (16)	−0.0088 (15)	−0.0023 (15)
C2	0.044 (2)	0.038 (2)	0.034 (2)	0.0095 (17)	−0.0115 (16)	0.0047 (16)
C3	0.054 (2)	0.0281 (18)	0.040 (2)	0.0084 (17)	−0.0064 (17)	0.0031 (15)
C4	0.047 (2)	0.0277 (17)	0.0325 (19)	−0.0005 (15)	−0.0077 (16)	−0.0042 (15)
C5	0.0304 (17)	0.0278 (16)	0.0244 (17)	−0.0019 (13)	−0.0024 (13)	−0.0018 (13)
C6	0.0319 (17)	0.0238 (16)	0.0248 (17)	−0.0027 (13)	−0.0036 (13)	0.0009 (13)
C7	0.0350 (18)	0.0304 (17)	0.0234 (17)	−0.0018 (14)	−0.0046 (14)	−0.0003 (14)
C8	0.0352 (19)	0.0381 (19)	0.0283 (18)	0.0013 (15)	−0.0077 (14)	−0.0014 (15)
C9	0.044 (2)	0.051 (2)	0.038 (2)	0.0121 (18)	−0.0089 (17)	−0.0124 (18)
C10	0.044 (2)	0.063 (3)	0.039 (2)	0.012 (2)	−0.0115 (17)	−0.022 (2)
C11	0.038 (2)	0.064 (3)	0.0303 (19)	0.0060 (19)	−0.0057 (16)	−0.0057 (19)
C12	0.058 (3)	0.049 (2)	0.054 (3)	0.013 (2)	−0.020 (2)	0.000 (2)
C13	0.062 (3)	0.040 (2)	0.052 (3)	0.007 (2)	−0.023 (2)	−0.009 (2)
C14	0.036 (2)	0.075 (3)	0.038 (2)	0.008 (2)	−0.0067 (17)	−0.005 (2)
C15	0.088 (4)	0.196 (8)	0.064 (4)	0.067 (5)	−0.048 (3)	−0.063 (5)
C16	0.094 (5)	0.225 (10)	0.056 (4)	0.048 (6)	−0.038 (3)	−0.061 (5)
C17	0.063 (4)	0.120 (5)	0.080 (4)	0.018 (4)	−0.024 (3)	0.002 (4)
C18	0.071 (4)	0.107 (5)	0.072 (4)	0.028 (3)	−0.025 (3)	−0.016 (3)
Fe1	0.0380 (5)	0.0226 (4)	0.0274 (4)	0.0003 (3)	−0.0131 (3)	−0.0020 (3)
N1	0.0311 (15)	0.0258 (14)	0.0277 (14)	−0.0008 (11)	−0.0080 (11)	−0.0002 (11)
N2	0.0377 (16)	0.0274 (14)	0.0278 (15)	0.0006 (12)	−0.0127 (12)	0.0005 (12)
N3	0.0397 (17)	0.0308 (15)	0.0317 (16)	0.0013 (13)	−0.0158 (13)	−0.0009 (13)
N4	0.0320 (15)	0.0299 (14)	0.0260 (14)	0.0000 (12)	−0.0054 (12)	−0.0047 (12)
N5	0.050 (2)	0.130 (4)	0.045 (2)	0.010 (3)	−0.0188 (18)	0.004 (3)
O1	0.0414 (16)	0.0322 (15)	0.0438 (15)	0.0010 (13)	−0.0031 (12)	0.0047 (13)

Geometric parameters (Å, º) top

C1—N1	1.341 (4)	C11—C12	1.391 (6)
C1—C2	1.371 (5)	C11—C14	1.485 (5)
C1—H1	0.9300	C12—C13	1.371 (6)
C2—C3	1.376 (5)	C12—H12	0.9300
C2—H2	0.9300	C13—H13	0.9300
C3—C4	1.378 (5)	C14—C15	1.344 (7)
C3—H3	0.9300	C14—C18	1.374 (7)
C4—C5	1.378 (5)	C15—C16	1.398 (7)
C4—H4	0.9300	C15—H15	0.9300
C5—N1	1.352 (4)	C16—N5	1.287 (9)
C5—C6	1.470 (4)	C16—H16	0.9300
C6—N2	1.325 (4)	C17—N5	1.320 (8)
C6—N4	1.350 (4)	C17—C18	1.381 (7)
C7—N3	1.327 (4)	C17—H17	0.9300
C7—N4	1.351 (4)	C18—H18	0.9300
C7—C8	1.479 (4)	Fe1—N2	2.103 (3)
C8—C9	1.380 (5)	Fe1—N1	2.171 (3)
C8—C13	1.397 (5)	Fe1—O1	2.205 (3)
C9—C10	1.380 (5)	N2—N3	1.363 (4)
C9—H9	0.9300	O1—H1W	0.81 (4)
C10—C11	1.381 (6)	O1—H2W	0.85 (5)
C10—H10	0.9300

N1—C1—C2	122.8 (3)	C18—C14—C11	120.4 (4)
N1—C1—H1	118.6	C14—C15—C16	119.6 (6)
C2—C1—H1	118.6	C14—C15—H15	120.2
C1—C2—C3	118.5 (3)	C16—C15—H15	120.2
C1—C2—H2	120.7	N5—C16—C15	126.4 (6)
C3—C2—H2	120.7	N5—C16—H16	116.8
C2—C3—C4	119.7 (3)	C15—C16—H16	116.8
C2—C3—H3	120.1	N5—C17—C18	124.3 (6)
C4—C3—H3	120.1	N5—C17—H17	117.8
C5—C4—C3	118.9 (3)	C18—C17—H17	117.8
C5—C4—H4	120.6	C14—C18—C17	120.8 (6)
C3—C4—H4	120.6	C14—C18—H18	119.6
N1—C5—C4	121.8 (3)	C17—C18—H18	119.6
N1—C5—C6	113.3 (3)	N2—Fe1—N2ⁱ	180.0 (2)
C4—C5—C6	124.9 (3)	N2—Fe1—N1ⁱ	103.68 (10)
N2—C6—N4	112.6 (3)	N2ⁱ—Fe1—N1ⁱ	76.32 (10)
N2—C6—C5	118.6 (3)	N2—Fe1—N1	76.32 (10)
N4—C6—C5	128.8 (3)	N2ⁱ—Fe1—N1	103.68 (10)
N3—C7—N4	114.1 (3)	N1ⁱ—Fe1—N1	180.00 (14)
N3—C7—C8	119.4 (3)	N2—Fe1—O1ⁱ	90.52 (11)
N4—C7—C8	126.4 (3)	N2ⁱ—Fe1—O1ⁱ	89.48 (11)
C9—C8—C13	117.5 (3)	N1ⁱ—Fe1—O1ⁱ	91.52 (11)
C9—C8—C7	124.1 (3)	N1—Fe1—O1ⁱ	88.48 (11)
C13—C8—C7	118.4 (3)	N2—Fe1—O1	89.48 (11)
C10—C9—C8	120.7 (4)	N2ⁱ—Fe1—O1	90.52 (11)
C10—C9—H9	119.6	N1ⁱ—Fe1—O1	88.48 (11)
C8—C9—H9	119.6	N1—Fe1—O1	91.52 (11)
C9—C10—C11	122.1 (4)	O1ⁱ—Fe1—O1	180.00 (19)
C9—C10—H10	119.0	C1—N1—C5	118.3 (3)
C11—C10—H10	119.0	C1—N1—Fe1	125.9 (2)
C10—C11—C12	117.0 (3)	C5—N1—Fe1	115.6 (2)
C10—C11—C14	123.7 (4)	C6—N2—N3	107.2 (3)
C12—C11—C14	119.3 (4)	C6—N2—Fe1	116.1 (2)
C13—C12—C11	121.3 (4)	N3—N2—Fe1	136.7 (2)
C13—C12—H12	119.4	C7—N3—N2	104.7 (3)
C11—C12—H12	119.4	C6—N4—C7	101.4 (3)
C12—C13—C8	121.3 (4)	C16—N5—C17	112.8 (5)
C12—C13—H13	119.4	Fe1—O1—H1W	121 (3)
C8—C13—H13	119.4	Fe1—O1—H2W	123 (3)
C15—C14—C18	114.1 (4)	H1W—O1—H2W	113 (4)
C15—C14—C11	124.8 (4)

Symmetry code: (i) −x+1, −y, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1W···N4ⁱⁱ	0.81 (4)	1.99 (4)	2.784 (4)	168 (4)
O1—H2W···N5ⁱⁱⁱ	0.85 (5)	2.39 (5)	3.165 (6)	152 (5)

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

Experimental details

Crystal data
Chemical formula	[Fe(C₁₈H₁₂N₅)₂(H₂O)₂]
M_r	688.53
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	13.1965 (17), 12.0279 (16), 9.9006 (13)
β (°)	100.998 (1)
V (Å³)	1542.6 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.54
Crystal size (mm)	0.12 × 0.10 × 0.08

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2001)
T_min, T_max	0.938, 0.958
No. of measured, independent and observed [I > 2σ(I)] reflections	7711, 2722, 2214
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.059, 0.184, 1.00
No. of reflections	2722
No. of parameters	231
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.14, −0.42

Computer programs: APEX2 (Bruker, 2004), SAINT-Plus (Bruker, 2001), 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
O1—H1W···N4ⁱ	0.81 (4)	1.99 (4)	2.784 (4)	168 (4)
O1—H2W···N5ⁱⁱ	0.85 (5)	2.39 (5)	3.165 (6)	152 (5)

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

References

Bruker (2001). SAINT-Plus and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Fan, L. M., Zhang, X.-T., Li, D.-C., Sun, D., Zhang, W. & Dou, J.-M. (2013). CrystEngComm, 15, 349–355. Web of Science CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zhang, X.-T., Fan, L.-M., Zhao, X., Sun, D., Li, D.-C. & Dou, J.-M. (2012). CrystEngComm, 14, 2053–2061. Web of Science CSD CrossRef CAS Google Scholar
Zhang, X.-T., Sun, D., Li, B., Fan, L.-M., Li, B. & Wei, P.-H. (2012). Cryst. Growth Des. 12, 3845–3848. Web of Science CSD CrossRef CAS Google Scholar

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