Bis(1H-imidazole-κN3)bis­(2-methyl­benzoato-κO)bis­(2-methyl­benzoic acid-κO)copper(II)

Ni, S.-L.; Zhao, M.-X.; Ge, H.-X.

doi:10.1107/S160053681102839X

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 8| August 2011| Pages m1123-m1124

doi:10.1107/S160053681102839X

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Bis(1H-imidazole-κN³)bis(2-methylbenzoato-κO)bis(2-methylbenzoic acid-κO)copper(II)

Sheng-Liang Ni,^a ^* Ming-Xing Zhao ^a and Hai-Xia Ge ^a

^aDepartment of Chemistry, Huzhou Teachers College, Huzhou, Zhejiang 313000, People's Republic of China
^*Correspondence e-mail: shengliangni@163.com

(Received 3 July 2011; accepted 15 July 2011; online 23 July 2011)

The structure of the title compound, [Cu(C₈H₇O₂)₂(C₃H₄N₂)₂(C₈H₈O₂)₂], consists of centrosymmetric monomeric units, in which the Cu^II atom has a tetragonally distorted octahedral coordination involving two imidazole N atoms and two carboxylate O atoms in the square plane [Cu—N = 1.964 (3) and Cu—O = 1.960 (2) Å] and 2-methylbenzoic acid O atoms in axial sites [Cu—O = 2.753 (3) Å]. Within the complex, the carboxylic acid forms intramolecular O—H⋯O hydrogen bonds, while the molecules are assembled through N—H⋯O(carboxyl) hydrogen bonds into chains extending along the a-axis direction. These chains are further linked by weak π–π interactions [centroid–centroid separation = 3.930 (2) Å].

Related literature

For applications of transition metal complexes, see: Aakeröy & Seddon (1993 ). For the use of carboxylate ligands in the construction of supramolecular complexes, see: Moulton & Zaworotko (2001 ). For Cu—O/N distances in other tetragonally distorted octahedral copper(II) complexes, see: Bonamartini et al. (1993 ); Chen et al. (2010 ); Su et al. (1991 ).

Experimental

Crystal data

[Cu(C₈H₇O₂)₂(C₃H₄N₂)₂(C₈H₈O₂)₂]
M_r = 742.27
Monoclinic, P 2₁ /c
a = 8.0866 (16) Å
b = 12.193 (2) Å
c = 18.887 (4) Å
β = 101.90 (3)°
V = 1822.2 (6) Å³
Z = 2
Mo Kα radiation
μ = 0.66 mm⁻¹
T = 298 K
0.51 × 0.20 × 0.15 mm

Data collection

Rigaku R-AXIS RAPID CCD diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ) T_min = 0.846, T_max = 0.901
17516 measured reflections
4135 independent reflections
2654 reflections with I > 2σ(I)
R_int = 0.035

Refinement

R[F² > 2σ(F²)] = 0.046
wR(F²) = 0.164
S = 1.14
4135 reflections
236 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.61 e Å⁻³
Δρ_min = −0.95 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H2⋯O2	0.85	1.67	2.516 (3)	168.9
N2—H1⋯O4ⁱ	0.89 (5)	1.97 (5)	2.786 (4)	152 (5)
Symmetry code: (i) -x, -y+1, -z.

Data collection: RAPID-AUTO (Rigaku, 1998 ); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004 ); 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/S160053681102839X/zs2128sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681102839X/zs2128Isup2.hkl

checkCIF report

Comment top

In the past decade, a variety of supramolecular architectures based on non-covalent intermolecular interactions such as hydrogen bonding, van der Waals forces and π–π stacking interactions have been achieved by using transition metal centers and organic ligands. Such complexes may have interesting structural topologies and have potential applications in catalysis, ion exchange, gas storage, and molecular-based magnetic materials (Aakeröy & Seddon, 1993). Carboxylate ligands have been commonly utilized as construction units to obtain a number of supramolecular complexes (Moulton & Zaworotko, 2001). We obtained the mononuclear title complex, [Cu(C₃H₄N₂)₂(C₈H₇O₂)₂(C₈H₈O₂)₂] from the reaction of imidazole and 2-methylbenzoic acid with CuCO₃ in an aqueous ethanolic solution and its crystal structure is reported here.

The centrosymmetric title complex (Fig. 1) has tetragonally distorted octahedral stereochemistry, the coordination sphere about copper(II) comprising two two imidazole N donors and two carboxylate O donors in the square plane [Cu—N, 1.964 (3) Å; Cu—O, 1.960 (2) Å] and two O donors from the 2–methylbenzoic acid molecules in the axial sites [Cu—O, 2.753 (3) Å]. The Cu–O/N distances are similar to those found in other tetragonally distorted octahedral copper(II) complexes (Chen et al., 2010, Bonamartini et al., 1993, Su et al., 1991). Within the complex the carboxylic acid forms intramolecular O—H···O hydrogen bonds (Table 1) while the molecules are assembled through N—H···O(carboxyl) hydrogen bonds into one-dimensional chains extending along the a cell direction (Fig. 2) and are further linked by weak π–π stacking [ring centroid separation, 3.930 (2) Å] giving layers extending across (110).

Related literature top

For applications of transition metal complexes, see: Aakeröy & Seddon (1993). For the use of carboxylate ligands in the construction of supramolecular complexes, see: Moulton & Zaworotko (2001). For Cu—O/N distances in other tetragonally distorted octahedral copper(II) complexes, see: Bonamartini et al. (1993); Chen et al. (2010); Su et al. (1991).

Experimental top

Freshly prepared CuCO₃ was essential for an optimal synthesis. An aqueous solution of aqueous Na₂CO₃ (1.0 cm³; 1M) was added dropwise to 4 cm³ of a stirred aqueous solution of CuSO₄. 5H₂O (0.2490 g, 1.0 mmol), giving a precipitate of Cu(OH)_2–2x(CO₃)_x.yH₂O, which was centrifuged and washed with double distilled water until no SO₄^2- anions were detected in the washings. The precipitate was subsequently added to a stirred solution of 2-methylbenzoic acid (0.5450 g, 4.0 mmol) and imidazole (0.069 g, 1.0 mmol) in 20 cm³ of 1:1 ethanol–water. The mixture was stirred for 1 h and the solid was removed by filtration, the resulting solution (pH = 4.10) was allowed to stand at room temperature, slow evaporation of the solvent forming blue block crystals after a week (yield: 43%).

Computing details top

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2004); 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. An ORTEP view of the title compound showing atom numbering, with displacement ellipsoids drawn at the 45% probability level. For symmetry code (#1): -x + 1, -y + 1, -z.
	Fig. 2. The structure of the title compound formed through hydrogen bonding and weak π–π packing interactions

Bis(1H-imidazole-κN³)bis(2-methylbenzoato-κO)bis(2- methylbenzoic acid-κO)copper(II) top

Crystal data top

[Cu(C₈H₇O₂)₂(C₃H₄N₂)₂(C₈H₈O₂)₂]	F(000) = 774
M_r = 742.27	D_x = 1.353 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 8.0866 (16) Å	θ = 3.0–27.4°
b = 12.193 (2) Å	µ = 0.66 mm⁻¹
c = 18.887 (4) Å	T = 298 K
β = 101.90 (3)°	Block, blue
V = 1822.2 (6) Å³	0.51 × 0.20 × 0.15 mm
Z = 2

Data collection top

Rigaku R-AXIS RAPID CCD diffractometer	4135 independent reflections
Radiation source: fine-focus sealed tube	2654 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
ω scans	θ_max = 27.4°, θ_min = 3.0°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	h = −9→10
T_min = 0.846, T_max = 0.901	k = −15→15
17516 measured reflections	l = −24→24

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.164	H atoms treated by a mixture of independent and constrained refinement
S = 1.14	w = 1/[σ²(F_o²) + (0.0599P)² + 1.5834P] where P = (F_o² + 2F_c²)/3
4135 reflections	(Δ/σ)_max < 0.001
236 parameters	Δρ_max = 0.61 e Å⁻³
0 restraints	Δρ_min = −0.95 e Å⁻³

Crystal data top

[Cu(C₈H₇O₂)₂(C₃H₄N₂)₂(C₈H₈O₂)₂]	V = 1822.2 (6) Å³
M_r = 742.27	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.0866 (16) Å	µ = 0.66 mm⁻¹
b = 12.193 (2) Å	T = 298 K
c = 18.887 (4) Å	0.51 × 0.20 × 0.15 mm
β = 101.90 (3)°

Data collection top

Rigaku R-AXIS RAPID CCD diffractometer	4135 independent reflections
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	2654 reflections with I > 2σ(I)
T_min = 0.846, T_max = 0.901	R_int = 0.035
17516 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.046	0 restraints
wR(F²) = 0.164	H atoms treated by a mixture of independent and constrained refinement
S = 1.14	Δρ_max = 0.61 e Å⁻³
4135 reflections	Δρ_min = −0.95 e Å⁻³
236 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
Cu	0.5000	0.5000	0.0000	0.0496 (2)
O1	0.4213 (3)	0.64617 (17)	0.02095 (14)	0.0596 (6)
O2	0.2854 (4)	0.6947 (2)	−0.08906 (16)	0.0783 (8)
C1	0.3427 (4)	0.7153 (2)	−0.0237 (2)	0.0513 (8)
C2	0.3180 (4)	0.8272 (2)	0.00562 (19)	0.0511 (8)
C3	0.3655 (6)	0.8403 (3)	0.0799 (2)	0.0726 (11)
H3A	0.4116	0.7813	0.1085	0.087*
C4	0.3455 (7)	0.9400 (4)	0.1122 (3)	0.0979 (17)
H4A	0.3769	0.9477	0.1622	0.117*
C5	0.2799 (7)	1.0264 (3)	0.0705 (3)	0.0948 (16)
H5A	0.2671	1.0938	0.0918	0.114*
C6	0.2329 (7)	1.0143 (3)	−0.0021 (3)	0.0848 (14)
H6A	0.1882	1.0745	−0.0297	0.102*
C7	0.2485 (5)	0.9156 (3)	−0.0373 (2)	0.0640 (10)
C8	0.1914 (8)	0.9123 (4)	−0.1184 (2)	0.1054 (18)
H8A	0.1491	0.9831	−0.1356	0.158*
H8B	0.1035	0.8586	−0.1314	0.158*
H8C	0.2852	0.8931	−0.1399	0.158*
O3	0.3580 (3)	0.51870 (19)	−0.14514 (16)	0.0670 (7)
H2	0.3217	0.5742	−0.1255	0.080*
O4	0.0849 (4)	0.4803 (2)	−0.16537 (18)	0.0801 (9)
C9	0.2279 (5)	0.4565 (3)	−0.17091 (18)	0.0536 (8)
C10	0.2697 (4)	0.3551 (3)	−0.20755 (17)	0.0510 (8)
C11	0.4218 (5)	0.3531 (3)	−0.2315 (2)	0.0611 (9)
H11A	0.4940	0.4132	−0.2227	0.073*
C12	0.4669 (6)	0.2638 (3)	−0.2680 (2)	0.0715 (11)
H12A	0.5672	0.2642	−0.2848	0.086*
C13	0.3628 (6)	0.1750 (3)	−0.2791 (2)	0.0772 (12)
H13A	0.3924	0.1143	−0.3037	0.093*
C14	0.2145 (6)	0.1743 (3)	−0.2545 (2)	0.0746 (11)
H14A	0.1468	0.1119	−0.2616	0.089*
C15	0.1622 (5)	0.2648 (3)	−0.21914 (19)	0.0599 (9)
C16	−0.0046 (6)	0.2574 (4)	−0.1956 (3)	0.0896 (14)
H16A	−0.0250	0.3245	−0.1723	0.134*
H16B	−0.0014	0.1974	−0.1624	0.134*
H16C	−0.0935	0.2455	−0.2372	0.134*
N1	0.2954 (3)	0.4336 (2)	0.02226 (15)	0.0499 (6)
N2	0.0739 (4)	0.4079 (3)	0.06931 (18)	0.0614 (8)
H1	−0.003 (6)	0.426 (4)	0.095 (3)	0.101 (16)*
C17	0.1960 (5)	0.4773 (3)	0.0623 (2)	0.0553 (8)
H17A	0.2098	0.5470	0.0828	0.066*
C18	0.0930 (5)	0.3148 (3)	0.0321 (2)	0.0677 (10)
H18A	0.0249	0.2527	0.0272	0.081*
C19	0.2311 (5)	0.3312 (3)	0.0036 (2)	0.0606 (9)
H19A	0.2757	0.2808	−0.0243	0.073*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu	0.0522 (3)	0.0276 (3)	0.0718 (4)	0.0049 (2)	0.0195 (3)	0.0006 (2)
O1	0.0704 (16)	0.0301 (11)	0.0816 (16)	0.0099 (11)	0.0236 (13)	0.0000 (11)
O2	0.109 (2)	0.0432 (14)	0.0782 (19)	0.0115 (14)	0.0089 (16)	−0.0148 (13)
C1	0.0493 (18)	0.0308 (15)	0.077 (2)	0.0002 (13)	0.0212 (17)	−0.0053 (15)
C2	0.0526 (18)	0.0305 (15)	0.071 (2)	−0.0009 (13)	0.0140 (16)	−0.0058 (14)
C3	0.094 (3)	0.0404 (19)	0.076 (3)	0.0172 (19)	−0.001 (2)	−0.0058 (17)
C4	0.136 (4)	0.062 (3)	0.082 (3)	0.028 (3)	−0.009 (3)	−0.026 (2)
C5	0.123 (4)	0.043 (2)	0.105 (4)	0.024 (2)	−0.006 (3)	−0.026 (2)
C6	0.111 (4)	0.038 (2)	0.097 (3)	0.019 (2)	0.002 (3)	−0.005 (2)
C7	0.081 (3)	0.0335 (16)	0.075 (2)	0.0052 (16)	0.011 (2)	−0.0013 (16)
C8	0.178 (6)	0.059 (3)	0.074 (3)	0.023 (3)	0.012 (3)	0.007 (2)
O3	0.0695 (17)	0.0451 (14)	0.0900 (19)	−0.0034 (12)	0.0250 (15)	−0.0162 (12)
O4	0.0636 (17)	0.0740 (19)	0.104 (2)	0.0116 (14)	0.0206 (16)	−0.0226 (16)
C9	0.062 (2)	0.0457 (17)	0.0527 (19)	0.0034 (16)	0.0119 (16)	0.0010 (15)
C10	0.062 (2)	0.0423 (17)	0.0481 (17)	0.0031 (15)	0.0102 (15)	−0.0023 (14)
C11	0.069 (2)	0.052 (2)	0.064 (2)	0.0015 (17)	0.0177 (18)	−0.0044 (17)
C12	0.076 (3)	0.070 (3)	0.071 (2)	0.015 (2)	0.023 (2)	−0.009 (2)
C13	0.097 (3)	0.060 (2)	0.071 (3)	0.017 (2)	0.009 (2)	−0.017 (2)
C14	0.094 (3)	0.052 (2)	0.071 (3)	−0.009 (2)	0.003 (2)	−0.0131 (19)
C15	0.068 (2)	0.055 (2)	0.054 (2)	−0.0033 (17)	0.0062 (17)	−0.0018 (16)
C16	0.080 (3)	0.094 (3)	0.097 (3)	−0.029 (3)	0.025 (3)	−0.017 (3)
N1	0.0511 (15)	0.0373 (14)	0.0620 (17)	0.0039 (11)	0.0133 (13)	0.0012 (12)
N2	0.0509 (17)	0.066 (2)	0.070 (2)	0.0089 (15)	0.0193 (15)	0.0117 (16)
C17	0.058 (2)	0.0468 (19)	0.062 (2)	0.0105 (15)	0.0143 (17)	0.0008 (15)
C18	0.060 (2)	0.051 (2)	0.095 (3)	−0.0049 (17)	0.023 (2)	0.005 (2)
C19	0.062 (2)	0.0398 (17)	0.083 (3)	−0.0035 (15)	0.0226 (19)	−0.0059 (17)

Geometric parameters (Å, º) top

Cu—O1ⁱ	1.960 (2)	O4—C9	1.217 (4)
Cu—O1	1.960 (2)	C9—C10	1.489 (5)
Cu—O3ⁱ	2.753 (3)	C10—C15	1.392 (5)
Cu—O3	2.753 (3)	C10—C11	1.396 (5)
Cu—N1ⁱ	1.964 (3)	C11—C12	1.377 (5)
Cu—N1	1.964 (3)	C11—H11A	0.9300
O1—C1	1.267 (4)	C12—C13	1.360 (6)
O2—C1	1.252 (4)	C12—H12A	0.9300
C1—C2	1.501 (4)	C13—C14	1.373 (6)
C2—C3	1.385 (5)	C13—H13A	0.9300
C2—C7	1.395 (5)	C14—C15	1.400 (5)
C3—C4	1.385 (5)	C14—H14A	0.9300
C3—H3A	0.9300	C15—C16	1.507 (6)
C4—C5	1.356 (6)	C16—H16A	0.9600
C4—H4A	0.9300	C16—H16B	0.9600
C5—C6	1.353 (7)	C16—H16C	0.9600
C5—H5A	0.9300	N1—C17	1.325 (4)
C6—C7	1.393 (5)	N1—C19	1.371 (4)
C6—H6A	0.9300	N2—C17	1.327 (5)
C7—C8	1.506 (6)	N2—C18	1.361 (5)
C8—H8A	0.9600	N2—H1	0.89 (5)
C8—H8B	0.9600	C17—H17A	0.9300
C8—H8C	0.9600	C18—C19	1.350 (5)
O3—C9	1.307 (4)	C18—H18A	0.9300
O3—H2	0.8519	C19—H19A	0.9300

O1ⁱ—Cu—O1	180.00 (15)	C15—C10—C9	122.4 (3)
O1ⁱ—Cu—N1ⁱ	90.49 (10)	C11—C10—C9	117.7 (3)
O1—Cu—N1ⁱ	89.51 (10)	C12—C11—C10	121.2 (4)
O1ⁱ—Cu—N1	89.51 (10)	C12—C11—H11A	119.4
O1—Cu—N1	90.49 (10)	C10—C11—H11A	119.4
N1ⁱ—Cu—N1	180.0	C13—C12—C11	119.2 (4)
C1—O1—Cu	127.6 (2)	C13—C12—H12A	120.4
O2—C1—O1	123.8 (3)	C11—C12—H12A	120.4
O2—C1—C2	119.7 (3)	C12—C13—C14	120.6 (4)
O1—C1—C2	116.5 (3)	C12—C13—H13A	119.7
C3—C2—C7	119.6 (3)	C14—C13—H13A	119.7
C3—C2—C1	116.6 (3)	C13—C14—C15	121.8 (4)
C7—C2—C1	123.8 (3)	C13—C14—H14A	119.1
C2—C3—C4	121.0 (4)	C15—C14—H14A	119.1
C2—C3—H3A	119.5	C10—C15—C14	117.3 (4)
C4—C3—H3A	119.5	C10—C15—C16	124.7 (4)
C5—C4—C3	119.6 (4)	C14—C15—C16	118.0 (4)
C5—C4—H4A	120.2	C15—C16—H16A	109.5
C3—C4—H4A	120.2	C15—C16—H16B	109.5
C6—C5—C4	119.9 (4)	H16A—C16—H16B	109.5
C6—C5—H5A	120.1	C15—C16—H16C	109.5
C4—C5—H5A	120.1	H16A—C16—H16C	109.5
C5—C6—C7	123.0 (4)	H16B—C16—H16C	109.5
C5—C6—H6A	118.5	C17—N1—C19	105.7 (3)
C7—C6—H6A	118.5	C17—N1—Cu	126.5 (2)
C6—C7—C2	117.1 (4)	C19—N1—Cu	127.8 (2)
C6—C7—C8	118.0 (4)	C17—N2—C18	108.3 (3)
C2—C7—C8	124.9 (3)	C17—N2—H1	121 (3)
C7—C8—H8A	109.5	C18—N2—H1	131 (3)
C7—C8—H8B	109.5	N1—C17—N2	110.6 (3)
H8A—C8—H8B	109.5	N1—C17—H17A	124.7
C7—C8—H8C	109.5	N2—C17—H17A	124.7
H8A—C8—H8C	109.5	C19—C18—N2	105.8 (3)
H8B—C8—H8C	109.5	C19—C18—H18A	127.1
C9—O3—H2	107.4	N2—C18—H18A	127.1
O4—C9—O3	122.4 (3)	C18—C19—N1	109.5 (3)
O4—C9—C10	123.3 (3)	C18—C19—H19A	125.2
O3—C9—C10	114.3 (3)	N1—C19—H19A	125.2
C15—C10—C11	119.9 (3)

Symmetry code: (i) −x+1, −y+1, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H2···O2	0.85	1.67	2.516 (3)	168.9
N2—H1···O4ⁱⁱ	0.89 (5)	1.97 (5)	2.786 (4)	152 (5)

Symmetry code: (ii) −x, −y+1, −z.

Experimental details

Crystal data
Chemical formula	[Cu(C₈H₇O₂)₂(C₃H₄N₂)₂(C₈H₈O₂)₂]
M_r	742.27
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	8.0866 (16), 12.193 (2), 18.887 (4)
β (°)	101.90 (3)
V (Å³)	1822.2 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.66
Crystal size (mm)	0.51 × 0.20 × 0.15

Data collection
Diffractometer	Rigaku R-AXIS RAPID CCD diffractometer
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995)
T_min, T_max	0.846, 0.901
No. of measured, independent and observed [I > 2σ(I)] reflections	17516, 4135, 2654
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.648

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.164, 1.14
No. of reflections	4135
No. of parameters	236
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.61, −0.95

Computer programs: RAPID-AUTO (Rigaku, 1998), CrystalStructure (Rigaku/MSC, 2004), 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
O3—H2···O2	0.85	1.67	2.516 (3)	168.9
N2—H1···O4ⁱ	0.89 (5)	1.97 (5)	2.786 (4)	152 (5)

Symmetry code: (i) −x, −y+1, −z.

Acknowledgements

This project was supported by the Foundation of the Education Department of Zhejiang Province (ZC200805662).

References

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