Poly[diaqua-μ3-4-nitro­phthalato-copper(II)]

Guo, M.-L.

doi:10.1107/S1600536810049792

metal-organic compounds

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ISSN: 2056-9890

Volume 67| Part 1| January 2011| Pages m21-m22

https://doi.org/10.1107/S1600536810049792

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Poly[diaqua-μ₃-4-nitrophthalato-copper(II)]

Ming-Lin Guo ^a ^*

^aSchool of Environment and Chemical Engineering and Key Laboratory of Hollow Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300160, People's Republic of China
^*Correspondence e-mail: guomlin@yahoo.com

(Received 17 November 2010; accepted 29 November 2010; online 4 December 2010)

In the title complex, [Cu(C₈H₃NO₆)(H₂O)₂]_n, the two carboxylate groups of the 4-nitrophthalate dianion ligands have monodentate and 1,3-bridging bonding modes, respectively. The Cu atom shows an approximate square-pyramidal coordination as it is bonded to O atoms from the carboxylate groups of three 4-nitrophthalate ligands and two O atoms of the non-equivalent coordinated water molecules. Other Cu atoms in the coordination polymer are connected into a two-dimensional layer in the ab plane. The layers are aggregated to a three-dimensional structure through interlayer hydrogen bonding involving an O atom of a nitro group. The whole three-dimensional structure is further maintained and stabilized by intralayer hydrogen bonds between the O atoms of the carboxylate groups and the coordinated water molecules.

Related literature

For τ value calculations in a square-pyramidal environment, see: Addison et al. (1984 ). For related structures, see: Baca et al. (2003 , 2004 ); Biagini Cingi et al. (1978 ); Fu et al. (2006 ); Guo & Guo (2007 ); Ma et al. (2004 ); Wang et al. (2009 ); Yang et al. (2003 ). For hydrogen bonds, see Bernstein et al. (1995 ); Brown (1976 ). For a comparison of Cu—O distances, see: Pasan et al. (2007 ).

Experimental

Crystal data

[Cu(C₈H₃NO₆)(H₂O)₂]
M_r = 308.69
Orthorhombic, P b c a
a = 14.208 (3) Å
b = 6.5159 (13) Å
c = 21.722 (4) Å
V = 2011.0 (7) Å³
Z = 8
Mo Kα radiation
μ = 2.21 mm⁻¹
T = 133 K
0.14 × 0.06 × 0.04 mm

Data collection

Rigaku Saturn diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005 ) T_min = 0.850, T_max = 0.917
11779 measured reflections
1974 independent reflections
1609 reflections with I > 2σ(I)
R_int = 0.079

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.144
S = 1.07
1974 reflections
163 parameters
H-atom parameters constrained
Δρ_max = 0.79 e Å⁻³
Δρ_min = −0.66 e Å⁻³

Table 1
Selected bond lengths (Å)

Cu1—O4ⁱ	1.917 (3)
Cu1—O1	1.945 (3)
Cu1—O8	1.991 (3)
Cu1—O7	1.991 (4)
Cu1—O3ⁱⁱ	2.263 (3)
Symmetry codes: (i) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H7A⋯O2ⁱⁱⁱ	0.85	2.19	2.862 (5)	136
O7—H7A⋯O3ⁱ	0.85	2.30	2.858 (5)	123
O7—H7B⋯O6^iv	0.85	2.15	2.959 (6)	158
O8—H8A⋯O1^v	0.85	1.98	2.787 (4)	160
O8—H8B⋯O2ⁱⁱ	0.85	1.85	2.692 (5)	170
Symmetry codes: (i) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, z]$ ; (iv) -x+1, -y, -z+1; (v) $[-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: CrystalClear (Rigaku/MSC, 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 (Sheldrick, 2008); software used to prepare material for publication: SHELXTL .

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536810049792/sj5060sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810049792/sj5060Isup2.hkl

checkCIF report

Comment top

Aromatic dicarboxylate ligands such as phthalate (phth) and substituted phthalatehave been used in the construction of polymeric metal complexes because they can act as a bis-monodentate, bis-bidentate and combined modes of coordination to form short bridges via one carboxylato end or long bridges via the benzene ring and lead to a great variety of structures (Biagini Cingi et al., 1978; Guo and Guo, 2007; Wang et al., 2009; Ma et al., 2004; Baca et al., 2003, 2004; Yang et al., 2003; Fu et al., 2006). We have used the 4-nitrophthalate dianion as a ligand, and have obtained the title novel five-coordinate 4-nitrophthalate-copper complex, (I), which forms a three-dimensional supramolecular network through O—H···O hydrogen bonding.

The asymmetric unit in the structure of (I) comprises one Cu atom, one complete 4-nitrophthate dianion and two non-equivalent water molecules, and is shown in Fig. 1 in a symmetry-expanded view, which displays the full coordination of the Cu atom. Selected geometric parameters are given in Table 1.

The Cu atom exhibits an approximate square pyramidal environment (the τ value being 0.171, Addison et al., 1984), with atoms O1, O4ⁱ (see Fig. 1 for symmetry codes) of two non-equivalent 4-nitrophthalate dianions and O7 and O8 atoms of coordinated water molecules in a planar arrangement, with the mean Cu–O(eq) bond distance being 1.961 (3) Å, which is comparable to that reported for poly[(µ₃-methylmalonato-O,O',O'',O''')-aqua-copper(II)] (Pasan, et al., 2007). The apical position is occupied by O3ⁱⁱ atom [Cu1–O3ⁱⁱ = 2.263 (3) Å]. The Cu atom is shifted by 0.0889 (5) A° toward the apical position. There is an additional weak Cu–O2 contact in (I), with a Cu···O distance of 2.821 (3) Å.

In the present structure, monodentate, bidentate 1,3-bridging bonding and 1,6-bridging bonding modes via the benzene ring are present (Fig. 2). The O1 atom binds in a monodentate fashion, while the O3 and O4 atoms display both monodentate and bidentate 1,3-bridge bonding to link two Cu atoms. The O1 and O3 (or O4) atoms adopt a 1,6-bridging bonding mode via the benzene ring to connect with two other Cu atoms.

The Cu atoms are further interconnected by three O atoms from three 4-nitrophthalate dianions into a two-dimensional layer in the ab plane. The mean planes of the carboxylate groups of O1/C1/O2 and the benzene ring make a dihedral angle of 72.4 (5)°, and the value of a dihedral angle for the carboxylate groups of O3/C8/O4 is 14.5 (5)°; the two C—O bond distances (O1—C1 and O2—C1) of the monodentate carboxylate group are 1.278 (5) and 1.241 (5) Å, respectively, and the two C—O bond distances (O3—C4 and O4—C4) of the 1,3-bridging bonding carboxylate group are 1.253 (5) and 1.266 (6) Å, respectively. These indicate that the mesomeric effect for the 1,3-bridging bonding carboxylate group is somewhat greater than that of the monodentate carboxylate group.

The two water molecules within the coordination sphere of the Cu atom, and the nitro group (O5/N1/O6) in the present structure engage in distinct hydrogen bonding interactions (see Table 2). Within each layer, the non-coordinated O2 atom is involved in forming strong O8—H8B···O2ⁱⁱ (Brown, 1976) and weak O7—H7A···O2^v hydrogen bonds. These play an important role in the propagation of the two-dimensional layer structure, due to the formation of different hydrogen bonded ring graph set motifs (Bernstein et al., 1995), such as an S(8), and two 10-membered R₂²(10) motifs (Fig.3). The neighbouring layers are linked together via weak O7—H7B···O6^vi hydrogen bonding interactions. These also result in the aryl rings of the 4-nitrophthalato ligands stacking weakly in an offset fashion along the c direction with centroid to centroid distances in the range 4.55 (4)Å - 4.97 (2)%A. Thus, the three-dimensional connectivity of the structure is achieved.

Related literature top

For τ value calculations in a square-pyramidal environment, see: Addison et al. (1984). For related structures, see: Baca et al. (2003, 2004); Biagini Cingi et al. (1978); Fu et al. (2006); Guo & Guo (2007); Ma et al. (2004); Wang et al. (2009); Yang et al. (2003). For hydrogen bonds, see Bernstein et al. (1995); Brown (1976). For a comparison of Cu—O distances, see: Pasan et al. (2007).

Experimental top

Copper(II) oxide (0.32 g 4 mmol) was added to a stirred solution of 4-nitrophthalic acid (0.53 g, 2.5 mmol) in boiling water (20.0 ml) over a period of 40 min. After filtration, slow evaporation over a period of a week at room temperature provided green needle-like crystals of (I).

Structure description top

For τ value calculations in a square-pyramidal environment, see: Addison et al. (1984). For related structures, see: Baca et al. (2003, 2004); Biagini Cingi et al. (1978); Fu et al. (2006); Guo & Guo (2007); Ma et al. (2004); Wang et al. (2009); Yang et al. (2003). For hydrogen bonds, see Bernstein et al. (1995); Brown (1976). For a comparison of Cu—O distances, see: Pasan et al. (2007).

Computing details top

Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear (Rigaku/MSC, 2005); data reduction: CrystalClear (Rigaku/MSC, 2005); 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. A view of the structure of (I), showing the atom-numbering scheme and coordination polyhedra for the Cu atoms; displacement ellipsoids were drawn at the 30% probability level [Symmetry codes: (i) x - 1/2, y, -z + 1/2; (ii) -x + 1, y - 1/2, -z + 1/2].
	Fig. 2. A view of the packing of (I), viewed down the c axis, showing the two-dimensional layer in the ab plane.
	Fig. 3. Packing diagram for (I), viewed down the b axis, showing the hydrogen bonding interactions as dashed lines.

Poly[diaqua-µ₃-4-nitrophthalato-copper(II)] top

Crystal data top

[Cu(C₈H₃NO₆)(H₂O)₂]	F(000) = 1240
M_r = 308.69	D_x = 2.039 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3445 reflections
a = 14.208 (3) Å	θ = 2.4–26.0°
b = 6.5159 (13) Å	µ = 2.21 mm⁻¹
c = 21.722 (4) Å	T = 133 K
V = 2011.0 (7) Å³	Needle, green
Z = 8	0.14 × 0.06 × 0.04 mm

Data collection top

Rigaku Saturn diffractometer	1974 independent reflections
Radiation source: rotating anode	1609 reflections with I > 2σ(I)
Confocal monochromator	R_int = 0.079
Detector resolution: 26.033 pixels mm^-1	θ_max = 26.1°, θ_min = 2.4°
ω scans	h = −17→15
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005)	k = −6→8
T_min = 0.850, T_max = 0.917	l = −26→26
11779 measured reflections

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.144	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0713P)² + 4.9336P] where P = (F_o² + 2F_c²)/3
1974 reflections	(Δ/σ)_max < 0.001
163 parameters	Δρ_max = 0.79 e Å⁻³
0 restraints	Δρ_min = −0.66 e Å⁻³

Crystal data top

[Cu(C₈H₃NO₆)(H₂O)₂]	V = 2011.0 (7) Å³
M_r = 308.69	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 14.208 (3) Å	µ = 2.21 mm⁻¹
b = 6.5159 (13) Å	T = 133 K
c = 21.722 (4) Å	0.14 × 0.06 × 0.04 mm

Data collection top

Rigaku Saturn diffractometer	1974 independent reflections
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005)	1609 reflections with I > 2σ(I)
T_min = 0.850, T_max = 0.917	R_int = 0.079
11779 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	0 restraints
wR(F²) = 0.144	H-atom parameters constrained
S = 1.07	Δρ_max = 0.79 e Å⁻³
1974 reflections	Δρ_min = −0.66 e Å⁻³
163 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
Cu1	0.35209 (4)	0.13735 (8)	0.24112 (3)	0.0228 (2)
O1	0.4485 (2)	0.1048 (4)	0.30394 (14)	0.0225 (7)
O2	0.4281 (2)	0.4401 (5)	0.31949 (14)	0.0268 (7)
O3	0.6351 (2)	0.2964 (5)	0.27688 (14)	0.0230 (7)
O4	0.7598 (2)	0.1491 (5)	0.32317 (15)	0.0274 (7)
N1	0.6821 (4)	0.1444 (7)	0.5486 (2)	0.0398 (11)
O5	0.7673 (3)	0.0995 (8)	0.5446 (2)	0.0547 (12)
O6	0.6397 (3)	0.1487 (6)	0.59882 (18)	0.0476 (11)
C1	0.4654 (3)	0.2731 (7)	0.33201 (19)	0.0226 (9)
C2	0.5298 (3)	0.2557 (6)	0.3875 (2)	0.0227 (9)
C3	0.4867 (4)	0.2677 (6)	0.4447 (2)	0.0266 (10)
H3	0.4226	0.2964	0.4470	0.032*
C4	0.5373 (4)	0.2375 (7)	0.4982 (2)	0.0295 (11)
H4	0.5086	0.2475	0.5366	0.035*
C5	0.6314 (4)	0.1923 (7)	0.4930 (2)	0.0306 (11)
C6	0.6779 (4)	0.1873 (7)	0.4368 (2)	0.0279 (10)
H6A	0.7423	0.1634	0.4350	0.034*
C7	0.6262 (3)	0.2185 (6)	0.3836 (2)	0.0222 (9)
C8	0.6772 (3)	0.2218 (6)	0.3224 (2)	0.0221 (9)
O7	0.2588 (3)	0.1002 (5)	0.30857 (16)	0.0318 (8)
H7A	0.2064	0.0748	0.2912	0.038*
H7B	0.2764	0.0051	0.3328	0.038*
O8	0.4457 (2)	0.2481 (5)	0.18154 (15)	0.0295 (8)
H8A	0.4672	0.3642	0.1921	0.035*
H8B	0.4877	0.1567	0.1770	0.035*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0185 (4)	0.0227 (3)	0.0271 (4)	0.0010 (2)	−0.0029 (2)	−0.00199 (19)
O1	0.0210 (17)	0.0233 (14)	0.0230 (14)	−0.0003 (13)	−0.0020 (13)	−0.0017 (11)
O2	0.0226 (18)	0.0240 (16)	0.0338 (17)	0.0017 (14)	−0.0012 (14)	0.0013 (13)
O3	0.0189 (17)	0.0227 (15)	0.0274 (16)	0.0001 (13)	−0.0008 (13)	0.0015 (12)
O4	0.0188 (18)	0.0333 (17)	0.0301 (17)	0.0047 (14)	0.0015 (14)	0.0047 (13)
N1	0.037 (3)	0.043 (3)	0.039 (3)	−0.006 (2)	0.000 (2)	−0.0008 (18)
O5	0.035 (3)	0.079 (3)	0.050 (3)	0.007 (2)	−0.007 (2)	0.002 (2)
O6	0.052 (3)	0.060 (3)	0.031 (2)	−0.009 (2)	0.0032 (19)	0.0028 (17)
C1	0.018 (2)	0.026 (2)	0.024 (2)	0.0005 (19)	0.0035 (18)	−0.0016 (16)
C2	0.020 (2)	0.0198 (19)	0.028 (2)	−0.0007 (18)	0.0003 (18)	−0.0004 (16)
C3	0.026 (3)	0.024 (2)	0.030 (2)	0.000 (2)	0.001 (2)	−0.0061 (17)
C4	0.034 (3)	0.028 (2)	0.027 (2)	−0.002 (2)	0.001 (2)	−0.0028 (17)
C5	0.041 (3)	0.025 (2)	0.026 (2)	0.000 (2)	−0.007 (2)	−0.0001 (17)
C6	0.023 (3)	0.029 (2)	0.032 (2)	0.002 (2)	−0.001 (2)	−0.0018 (18)
C7	0.022 (2)	0.019 (2)	0.026 (2)	0.0009 (18)	−0.0013 (18)	0.0004 (16)
C8	0.021 (2)	0.018 (2)	0.027 (2)	−0.0036 (18)	−0.0006 (19)	−0.0007 (16)
O7	0.0226 (19)	0.0408 (19)	0.0320 (17)	0.0000 (16)	−0.0039 (15)	−0.0032 (14)
O8	0.0263 (19)	0.0260 (16)	0.0361 (18)	−0.0035 (15)	−0.0035 (15)	0.0024 (13)

Geometric parameters (Å, º) top

Cu1—O4ⁱ	1.917 (3)	C2—C7	1.393 (7)
Cu1—O1	1.945 (3)	C3—C4	1.382 (7)
Cu1—O8	1.991 (3)	C3—H3	0.9300
Cu1—O7	1.991 (4)	C4—C5	1.373 (7)
Cu1—O3ⁱⁱ	2.263 (3)	C4—H4	0.9300
O1—C1	1.278 (5)	C5—C6	1.388 (7)
O2—C1	1.241 (5)	C6—C7	1.385 (7)
O3—C8	1.253 (5)	C6—H6A	0.9300
O4—C8	1.266 (6)	C7—C8	1.514 (6)
N1—O6	1.246 (6)	O7—H7A	0.8505
N1—O5	1.249 (7)	O7—H7B	0.8505
N1—C5	1.441 (7)	O8—H8A	0.8477
C1—C2	1.517 (6)	O8—H8B	0.8487
C2—C3	1.387 (6)

O4ⁱ—Cu1—O1	175.60 (13)	C4—C3—H3	119.5
O4ⁱ—Cu1—O8	88.20 (14)	C2—C3—H3	119.5
O1—Cu1—O8	91.45 (14)	C5—C4—C3	117.9 (4)
O4ⁱ—Cu1—O7	94.90 (15)	C5—C4—H4	121.1
O1—Cu1—O7	86.53 (14)	C3—C4—H4	121.1
O8—Cu1—O7	165.32 (14)	C4—C5—C6	122.8 (5)
O4ⁱ—Cu1—O3ⁱⁱ	88.18 (12)	C4—C5—N1	117.6 (5)
O1—Cu1—O3ⁱⁱ	87.58 (12)	C6—C5—N1	119.6 (5)
O8—Cu1—O3ⁱⁱ	100.93 (12)	C7—C6—C5	118.6 (5)
O7—Cu1—O3ⁱⁱ	93.51 (13)	C7—C6—H6A	120.7
C1—O1—Cu1	112.0 (3)	C5—C6—H6A	120.7
C8—O3—Cu1ⁱⁱⁱ	118.6 (3)	C6—C7—C2	119.7 (4)
C8—O4—Cu1^iv	129.7 (3)	C6—C7—C8	118.8 (4)
O6—N1—O5	122.4 (5)	C2—C7—C8	121.4 (4)
O6—N1—C5	119.2 (5)	O3—C8—O4	126.7 (4)
O5—N1—C5	118.4 (5)	O3—C8—C7	118.0 (4)
O2—C1—O1	124.6 (4)	O4—C8—C7	115.2 (4)
O2—C1—C2	119.8 (4)	Cu1—O7—H7A	106.3
O1—C1—C2	115.4 (4)	Cu1—O7—H7B	110.4
C3—C2—C7	119.9 (4)	H7A—O7—H7B	113.0
C3—C2—C1	116.1 (4)	Cu1—O8—H8A	112.9
C7—C2—C1	123.9 (4)	Cu1—O8—H8B	106.9
C4—C3—C2	121.0 (5)	H8A—O8—H8B	113.8

O8—Cu1—O1—C1	81.6 (3)	O5—N1—C5—C6	0.1 (7)
O7—Cu1—O1—C1	−83.9 (3)	C4—C5—C6—C7	−3.5 (7)
O3ⁱⁱ—Cu1—O1—C1	−177.6 (3)	N1—C5—C6—C7	175.2 (4)
Cu1—O1—C1—O2	−2.7 (6)	C5—C6—C7—C2	0.5 (7)
Cu1—O1—C1—C2	172.0 (3)	C5—C6—C7—C8	177.5 (4)
O2—C1—C2—C3	70.4 (5)	C3—C2—C7—C6	2.0 (6)
O1—C1—C2—C3	−104.5 (5)	C1—C2—C7—C6	−174.3 (4)
O2—C1—C2—C7	−113.1 (5)	C3—C2—C7—C8	−174.9 (4)
O1—C1—C2—C7	72.0 (6)	C1—C2—C7—C8	8.7 (6)
C7—C2—C3—C4	−1.8 (6)	Cu1ⁱⁱⁱ—O3—C8—O4	−90.7 (5)
C1—C2—C3—C4	174.8 (4)	Cu1ⁱⁱⁱ—O3—C8—C7	88.5 (4)
C2—C3—C4—C5	−1.0 (7)	Cu1^iv—O4—C8—O3	3.5 (7)
C3—C4—C5—C6	3.7 (7)	Cu1^iv—O4—C8—C7	−175.7 (3)
C3—C4—C5—N1	−175.0 (4)	C6—C7—C8—O3	−163.6 (4)
O6—N1—C5—C4	−1.1 (7)	C2—C7—C8—O3	13.3 (6)
O5—N1—C5—C4	178.8 (5)	C6—C7—C8—O4	15.7 (6)
O6—N1—C5—C6	−179.8 (5)	C2—C7—C8—O4	−167.4 (4)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H7A···O2^v	0.85	2.19	2.862 (5)	136
O7—H7A···O3ⁱ	0.85	2.30	2.858 (5)	123
O7—H7B···O6^vi	0.85	2.15	2.959 (6)	158
O8—H8A···O1ⁱⁱⁱ	0.85	1.98	2.787 (4)	160
O8—H8B···O2ⁱⁱ	0.85	1.85	2.692 (5)	170

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

Experimental details

Crystal data
Chemical formula	[Cu(C₈H₃NO₆)(H₂O)₂]
M_r	308.69
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	133
a, b, c (Å)	14.208 (3), 6.5159 (13), 21.722 (4)
V (Å³)	2011.0 (7)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	2.21
Crystal size (mm)	0.14 × 0.06 × 0.04

Data collection
Diffractometer	Rigaku Saturn
Absorption correction	Multi-scan (CrystalClear; Rigaku/MSC, 2005)
T_min, T_max	0.850, 0.917
No. of measured, independent and observed [I > 2σ(I)] reflections	11779, 1974, 1609
R_int	0.079
(sin θ/λ)_max (Å⁻¹)	0.618

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.144, 1.07
No. of reflections	1974
No. of parameters	163
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.79, −0.66

Computer programs: CrystalClear (Rigaku/MSC, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Cu1—O4ⁱ	1.917 (3)	O1—C1	1.278 (5)
Cu1—O1	1.945 (3)	O2—C1	1.241 (5)
Cu1—O8	1.991 (3)	O3—C8	1.253 (5)
Cu1—O7	1.991 (4)	O4—C8	1.266 (6)
Cu1—O3ⁱⁱ	2.263 (3)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H7A···O2ⁱⁱⁱ	0.85	2.19	2.862 (5)	136
O7—H7A···O3ⁱ	0.85	2.30	2.858 (5)	123
O7—H7B···O6^iv	0.85	2.15	2.959 (6)	158
O8—H8A···O1^v	0.85	1.98	2.787 (4)	160
O8—H8B···O2ⁱⁱ	0.85	1.85	2.692 (5)	170

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

Acknowledgements

The author thanks Tianjin Polytechnic University for financial support.

References

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