Poly[[diaqua-μ4-pyrazine-2,3-dicarboxyl­ato-κ6N,O2:O2′:O3,O3′:O3-strontium(II)] monohydrate]

Abedi, A.; Mousavi Mirkolaei, M.; Amani, V.

doi:10.1107/S1600536808015316

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 7| July 2008| Pages m888-m889

doi:10.1107/S1600536808015316

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Poly[[diaqua-μ₄-pyrazine-2,3-dicarboxylato-κ⁶N,O²:O^2′:O³,O^3′:O³-strontium(II)] monohydrate]

Anita Abedi,^a Maryam Mousavi Mirkolaei ^a and Vahid Amani ^b ^*

^aDepartment of Chemistry, Islamic Azad University, North Tehran Branch, Tehran, Iran, and ^bDepartment of Chemistry, Islamic Azad University, Shahr-e-Rey Branch, Tehran, Iran
^*Correspondence e-mail: v_amani2002@yahoo.com

(Received 26 April 2008; accepted 21 May 2008; online 7 June 2008)

In the title compound, {[Sr(C₆H₂N₂O₄)(H₂O)₂]·H₂O}_n, the Sr^II ions are bridged by the pyrazine-2,3-dicarboxylate ligands with the formation of two-dimensional polymeric layers parallel to the ac plane. Each Sr^II ion is eight-coordinated by one N and five O atoms from the four ligands and two water molecules. The coordination polyhedron is derived from a pentagonal bipyramid with an O atom at the apex on one side of the equatorial plane and two O atoms sharing the apical site on the other side. The coordinated and uncoordinated water molecules are involved in O—H⋯O and O—H⋯N hydrogen bonds, which consolidate the crystal structure.

Related literature

For related literature, see: Takusagawa & Shimada (1973 ); Richard et al. (1973 ); Zou et al. (1999 ); Konar et al. (2004 ); Li et al. (2003 ); Xu et al. (2008 ); Ma et al. (2006 ); Ptasiewicz-Bak & Leciejewicz (1997a ,b ); Starosta & Leciejewicz (2005 ); Tombul et al. (2006 ).

Experimental

Crystal data

[Sr(C₆H₂N₂O₄)(H₂O)₂]·H₂O
M_r = 307.76
Monoclinic, P 2₁ /n
a = 10.4931 (7) Å
b = 6.9839 (4) Å
c = 13.5208 (8) Å
β = 94.2670 (10)°
V = 988.10 (10) Å³
Z = 4
Mo Kα radiation
μ = 5.48 mm⁻¹
T = 120 (2) K
0.28 × 0.25 × 0.10 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1998 ) T_min = 0.240, T_max = 0.568
8338 measured reflections
1934 independent reflections
1595 reflections with I > 2σ(I)
R_int = 0.040

Refinement

R[F² > 2σ(F²)] = 0.024
wR(F²) = 0.054
S = 1.00
1934 reflections
145 parameters
H-atom parameters constrained
Δρ_max = 0.92 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Table 1
Selected bond lengths (Å)

Sr1—O2ⁱ	2.4887 (18)
Sr1—O2W	2.5106 (18)
Sr1—O4ⁱⁱ	2.5533 (18)
Sr1—O1W	2.5937 (19)
Sr1—O3	2.6145 (18)
Sr1—O1ⁱⁱⁱ	2.6155 (18)
Sr1—N1	2.714 (2)
Sr1—O2ⁱⁱⁱ	2.8517 (18)
Symmetry codes: (i) $[-x-{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-x-{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W1⋯O3Wⁱ	0.85	1.87	2.713 (3)	170
O1W—H2W1⋯O3W^iv	0.85	1.90	2.744 (3)	171
O2W—H1W2⋯O1ⁱⁱ	0.85	1.85	2.696 (3)	174
O2W—H2W2⋯O1W^v	0.85	2.01	2.857 (3)	178
O3W—H1W3⋯O4	0.85	1.94	2.781 (3)	170
O3W—H2W3⋯N2^vi	0.85	1.96	2.792 (3)	168
Symmetry codes: (i) $[-x-{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-x-{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) x-1, y, z; (v) -x-1, -y, -z+1; (vi) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: SMART (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 1998); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808015316/cv2408sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808015316/cv2408Isup2.hkl

checkCIF report

Comment top

Takusagawa & Shimada (1973) first determined the structure of pyrazine-2,3-dicarboxlic acid by single-crystal X-ray analysis. Almost at the same time, the first metal-organic compound of pyrazine-2,3-dicarboxylic acid was reported (Richard et al., 1973). Among many reported compounds containing pyrazine-2,3-dicarboxylic acid, most are complexes of transition metal ions, including manganese (Zou et al., 1999), copper (Konar et al., 2004), zinc (Li et al., 2003), iron (Xu et al., 2008) and cadmium (Ma et al., 2006). Also, there are many reported compounds of pyrazine-2,3-dicarboxylic acid with main group metals such as calcium (Ptasiewicz-Bak & Leciejewicz, 1997a; Starosta & Leciejewicz, 2005), magnesium (Ptasiewicz-Bak & Leciejewicz, 1997b) and sodium (Tombul et al., 2006) complexes. For further investigation of pyrazine-2,3-dicarboxylic acid, we synthesized the title compound, (I).

The asymmetric unit of the title compound, (Fig. 1), contains molecular sheets in which Sr^II ions are bridged by the carboxylate groups of the ligand molecules. Two bridging paths are evident. In the first, an N,O-bonding moiety formed by a hetero-ring nitrogen atom and the carboxylate oxygen atom nearest to it and both oxygen atoms of the second carboxylic group are active. The second path is formed by the other oxygen atom from the carboxylic group involved in the N,O-bonding moiety and an oxygen atom from the second carboxylic group. The latter atom is bidentate. A two-dimensional molecular pattern is formed. Each Sr^II ion is also coordinated by two water oxygen atoms, making the number of coordinated atoms eight. The coordination polyhedron is a distorted pentagonal bipyramid with an oxygen atom at the apex on one side of the equatorial plane and two oxygen atoms forming the apices on the other side. There is also one non-coordinated water molecule in the asymmetric unit. The Sr—O and Sr—N bond lengths are collected in Table 1.

Intermolecular O—H···O and O—H···N hydrogen bonds (Table 2) help to consolidate the crystal packing (Fig. 2).

Related literature top

For related literature, see: Takusagawa & Shimada (1973); Richard et al. (1973); Zou et al. (1999); Konar et al. (2004); Li et al. (2003); Xu et al. (2008); Ma et al. (2006); Ptasiewicz-Bak & Leciejewicz (1997a,b); Starosta & Leciejewicz (2005); Tombul et al. (2006).

Experimental top

A solution of pyrazine-2,3-dicarboxlic acid (0.5 g, 2.91 mmol) in methanol (40 ml) was added to a solution of Sr(NO₃)₂ (0.31 g, 1.46 mmol) in water (10 ml) and the resulting colourless solution was stirred for 10 min at room temperature. This solution was left to evaporate slowly at room temperature. After one week, colourless plate crystals of the title compound were isolated (yield 0.35 g, 78.03%).

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 1998); data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. A portion of the polymeric structure of (I) with the atom-numbering scheme and displacement ellipsoids drawn at the 40% probability level [symmetry codes: (i) -x - 1/2,y - 1/2,-z + 1/2, (ii) -x - 1/2, y + 1/2,-z + 1/2, (iii) x - 1/2,-y + 1/2,z + 1/2].
	Fig. 2. A packing diagram for (I). Hydrogen bonds are shown as dashed lines.

Poly[[diaqua-µ₄-pyrazine-2,3-dicarboxylato- κ⁶N,O²:O^2':O³,O^3':O³-strontium(II)] monohydrate] top

Crystal data top

[Sr(C₆H₂N₂O₄)(H₂O)₂]·H₂O	F(000) = 608
M_r = 307.76	D_x = 2.069 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 156 reflections
a = 10.4931 (7) Å	θ = 3–26°
b = 6.9839 (4) Å	µ = 5.48 mm⁻¹
c = 13.5208 (8) Å	T = 120 K
β = 94.267 (1)°	Plate, colorless
V = 988.10 (10) Å³	0.28 × 0.25 × 0.10 mm
Z = 4

Data collection top

Bruker SMART 1000 CCD area-detector diffractometer	1934 independent reflections
Radiation source: fine-focus sealed tube	1595 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.040
ϕ and ω scans	θ_max = 26.0°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 1998)	h = −12→12
T_min = 0.240, T_max = 0.568	k = −8→8
8338 measured reflections	l = −16→16

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)] = 0.024	Hydrogen site location: mixed
wR(F²) = 0.054	H-atom parameters constrained
S = 1.01	w = 1/[σ²(F_o²) + (0.026P)²] where P = (F_o² + 2F_c²)/3
1934 reflections	(Δ/σ)_max = 0.002
145 parameters	Δρ_max = 0.92 e Å⁻³
0 restraints	Δρ_min = −0.45 e Å⁻³

Crystal data top

[Sr(C₆H₂N₂O₄)(H₂O)₂]·H₂O	V = 988.10 (10) Å³
M_r = 307.76	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 10.4931 (7) Å	µ = 5.48 mm⁻¹
b = 6.9839 (4) Å	T = 120 K
c = 13.5208 (8) Å	0.28 × 0.25 × 0.10 mm
β = 94.267 (1)°

Data collection top

Bruker SMART 1000 CCD area-detector diffractometer	1934 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 1998)	1595 reflections with I > 2σ(I)
T_min = 0.240, T_max = 0.568	R_int = 0.040
8338 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.024	0 restraints
wR(F²) = 0.054	H-atom parameters constrained
S = 1.01	Δρ_max = 0.92 e Å⁻³
1934 reflections	Δρ_min = −0.45 e Å⁻³
145 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
Sr1	−0.44206 (2)	0.17756 (3)	0.375530 (17)	0.01058 (9)
N1	−0.4291 (2)	0.1488 (3)	0.17632 (16)	0.0137 (5)
N2	−0.3958 (2)	0.2550 (3)	−0.01781 (16)	0.0138 (5)
O1	−0.14140 (18)	0.1344 (3)	−0.07125 (13)	0.0154 (4)
O2	−0.09707 (18)	0.3655 (3)	0.03862 (13)	0.0148 (4)
O3	−0.21964 (18)	0.1162 (3)	0.30617 (13)	0.0164 (4)
O4	−0.10633 (16)	0.0171 (3)	0.18088 (13)	0.0131 (4)
C1	−0.3115 (2)	0.1518 (4)	0.14221 (19)	0.0114 (6)
C2	−0.2956 (3)	0.2059 (4)	0.04464 (19)	0.0117 (6)
C3	−0.5114 (3)	0.2480 (4)	0.0166 (2)	0.0156 (6)
H3A	−0.5841	0.2794	−0.0264	0.019*
C4	−0.5277 (3)	0.1963 (4)	0.11335 (19)	0.0150 (6)
H4A	−0.6115	0.1945	0.1356	0.018*
C5	−0.2037 (3)	0.0901 (4)	0.21630 (19)	0.0123 (6)
C6	−0.1670 (3)	0.2340 (4)	0.00239 (19)	0.0114 (6)
O1W	−0.64324 (17)	−0.0101 (3)	0.30768 (13)	0.0161 (4)
H1W1	−0.6382	−0.1106	0.2727	0.019*
H2W1	−0.7174	0.0355	0.2932	0.019*
O2W	−0.31193 (17)	0.2633 (3)	0.53262 (13)	0.0150 (4)
H1W2	−0.3220	0.3802	0.5478	0.018*
H2W2	−0.3246	0.1853	0.5791	0.018*
O3W	0.11689 (17)	0.1471 (3)	0.28299 (13)	0.0161 (4)
H1W3	0.0444	0.1203	0.2540	0.019*
H2W3	0.1011	0.1787	0.3415	0.019*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sr1	0.00953 (13)	0.01224 (14)	0.01019 (13)	0.00004 (11)	0.00220 (9)	0.00048 (11)
N1	0.0110 (12)	0.0183 (13)	0.0119 (11)	0.0000 (10)	0.0026 (9)	−0.0003 (10)
N2	0.0112 (12)	0.0163 (12)	0.0140 (11)	0.0013 (9)	0.0021 (9)	0.0000 (10)
O1	0.0168 (10)	0.0174 (10)	0.0125 (9)	−0.0015 (8)	0.0050 (8)	−0.0024 (8)
O2	0.0123 (10)	0.0160 (11)	0.0163 (10)	−0.0026 (8)	0.0029 (8)	−0.0017 (8)
O3	0.0142 (10)	0.0245 (11)	0.0106 (9)	0.0028 (8)	0.0022 (8)	−0.0006 (8)
O4	0.0084 (9)	0.0159 (10)	0.0154 (9)	0.0020 (8)	0.0033 (8)	−0.0022 (8)
C1	0.0086 (13)	0.0133 (14)	0.0124 (13)	−0.0008 (11)	0.0016 (10)	−0.0041 (11)
C2	0.0137 (14)	0.0095 (13)	0.0123 (13)	−0.0030 (11)	0.0024 (11)	−0.0016 (11)
C3	0.0119 (15)	0.0185 (14)	0.0161 (14)	0.0013 (11)	−0.0009 (11)	−0.0008 (12)
C4	0.0096 (14)	0.0195 (15)	0.0157 (14)	−0.0006 (11)	0.0005 (11)	−0.0008 (12)
C5	0.0126 (14)	0.0099 (13)	0.0144 (14)	−0.0027 (11)	0.0017 (11)	0.0027 (11)
C6	0.0115 (14)	0.0108 (13)	0.0118 (13)	0.0017 (11)	−0.0001 (11)	0.0027 (11)
O1W	0.0123 (10)	0.0176 (10)	0.0184 (10)	0.0009 (8)	0.0016 (8)	−0.0007 (8)
O2W	0.0161 (10)	0.0145 (10)	0.0142 (10)	−0.0007 (8)	0.0010 (8)	0.0013 (8)
O3W	0.0112 (10)	0.0257 (11)	0.0113 (9)	−0.0009 (8)	0.0012 (8)	−0.0013 (8)

Geometric parameters (Å, º) top

Sr1—O2ⁱ	2.4887 (18)	O2—Sr1ⁱⁱ	2.4887 (18)
Sr1—O2W	2.5106 (18)	O2—Sr1^v	2.8517 (18)
Sr1—O4ⁱⁱ	2.5533 (18)	O3—C5	1.252 (3)
Sr1—O1W	2.5937 (19)	O4—C5	1.267 (3)
Sr1—O3	2.6145 (18)	O4—Sr1ⁱ	2.5533 (18)
Sr1—O1ⁱⁱⁱ	2.6155 (18)	C1—C2	1.394 (4)
Sr1—N1	2.714 (2)	C1—C5	1.517 (4)
Sr1—O2ⁱⁱⁱ	2.8517 (18)	C2—C6	1.516 (4)
Sr1—C6ⁱⁱⁱ	3.082 (3)	C3—C4	1.381 (4)
Sr1—Sr1^iv	4.4235 (5)	C3—H3A	0.9500
Sr1—H1W2	2.9292	C4—H4A	0.9500
Sr1—H2W2	2.9320	C6—Sr1^v	3.082 (3)
N1—C4	1.332 (3)	O1W—H1W1	0.8500
N1—C1	1.349 (3)	O1W—H2W1	0.8500
N2—C3	1.331 (3)	O2W—H1W2	0.8500
N2—C2	1.343 (3)	O2W—H2W2	0.8500
O1—C6	1.260 (3)	O3W—H1W3	0.8501
O1—Sr1^v	2.6155 (18)	O3W—H2W3	0.8499
O2—C6	1.252 (3)

O2ⁱ—Sr1—O2W	75.75 (6)	O2ⁱⁱⁱ—Sr1—H1W2	70.9
O2ⁱ—Sr1—O4ⁱⁱ	157.35 (6)	C6ⁱⁱⁱ—Sr1—H1W2	76.3
O2W—Sr1—O4ⁱⁱ	85.61 (6)	Sr1^iv—Sr1—H1W2	78.0
O2ⁱ—Sr1—O1W	79.88 (6)	O2ⁱ—Sr1—H2W2	62.3
O2W—Sr1—O1W	142.83 (6)	O2W—Sr1—H2W2	15.6
O4ⁱⁱ—Sr1—O1W	122.57 (6)	O4ⁱⁱ—Sr1—H2W2	100.6
O2ⁱ—Sr1—O3	84.44 (6)	O1W—Sr1—H2W2	128.0
O2W—Sr1—O3	84.19 (6)	O3—Sr1—H2W2	90.9
O4ⁱⁱ—Sr1—O3	80.93 (6)	O1ⁱⁱⁱ—Sr1—H2W2	91.2
O1W—Sr1—O3	121.00 (6)	N1—Sr1—H2W2	152.2
O2ⁱ—Sr1—O1ⁱⁱⁱ	114.76 (6)	O2ⁱⁱⁱ—Sr1—H2W2	60.0
O2W—Sr1—O1ⁱⁱⁱ	92.48 (6)	C6ⁱⁱⁱ—Sr1—H2W2	76.1
O4ⁱⁱ—Sr1—O1ⁱⁱⁱ	78.28 (6)	Sr1^iv—Sr1—H2W2	54.3
O1W—Sr1—O1ⁱⁱⁱ	72.81 (6)	H1W2—Sr1—H2W2	28.2
O3—Sr1—O1ⁱⁱⁱ	159.14 (6)	C4—N1—C1	117.7 (2)
O2ⁱ—Sr1—N1	112.29 (6)	C4—N1—Sr1	121.46 (17)
O2W—Sr1—N1	142.46 (6)	C1—N1—Sr1	116.91 (16)
O4ⁱⁱ—Sr1—N1	75.33 (6)	C3—N2—C2	117.5 (2)
O1W—Sr1—N1	73.21 (6)	C6—O1—Sr1^v	99.33 (16)
O3—Sr1—N1	61.32 (6)	C6—O2—Sr1ⁱⁱ	153.65 (17)
O1ⁱⁱⁱ—Sr1—N1	114.22 (6)	C6—O2—Sr1^v	88.36 (15)
O2ⁱ—Sr1—O2ⁱⁱⁱ	68.33 (6)	Sr1ⁱⁱ—O2—Sr1^v	111.67 (6)
O2W—Sr1—O2ⁱⁱⁱ	71.13 (6)	C5—O3—Sr1	124.02 (17)
O4ⁱⁱ—Sr1—O2ⁱⁱⁱ	117.81 (5)	C5—O4—Sr1ⁱ	132.10 (16)
O1W—Sr1—O2ⁱⁱⁱ	73.99 (5)	N1—C1—C2	120.3 (2)
O3—Sr1—O2ⁱⁱⁱ	146.69 (6)	N1—C1—C5	115.2 (2)
O1ⁱⁱⁱ—Sr1—O2ⁱⁱⁱ	47.66 (5)	C2—C1—C5	124.4 (2)
N1—Sr1—O2ⁱⁱⁱ	146.41 (6)	N2—C2—C1	121.3 (2)
O2ⁱ—Sr1—C6ⁱⁱⁱ	91.29 (7)	N2—C2—C6	114.0 (2)
O2W—Sr1—C6ⁱⁱⁱ	82.66 (6)	C1—C2—C6	124.4 (2)
O4ⁱⁱ—Sr1—C6ⁱⁱⁱ	99.08 (6)	N2—C3—C4	121.4 (3)
O1W—Sr1—C6ⁱⁱⁱ	70.19 (6)	N2—C3—H3A	119.3
O3—Sr1—C6ⁱⁱⁱ	166.80 (6)	C4—C3—H3A	119.3
O1ⁱⁱⁱ—Sr1—C6ⁱⁱⁱ	23.79 (6)	N1—C4—C3	121.7 (3)
N1—Sr1—C6ⁱⁱⁱ	131.61 (7)	N1—C4—H4A	119.1
O2ⁱⁱⁱ—Sr1—C6ⁱⁱⁱ	23.97 (6)	C3—C4—H4A	119.1
O2ⁱ—Sr1—Sr1^iv	36.81 (4)	O3—C5—O4	126.5 (2)
O2W—Sr1—Sr1^iv	69.70 (4)	O3—C5—C1	116.9 (2)
O4ⁱⁱ—Sr1—Sr1^iv	145.08 (4)	O4—C5—C1	116.6 (2)
O1W—Sr1—Sr1^iv	73.93 (4)	O2—C6—O1	124.1 (2)
O3—Sr1—Sr1^iv	118.96 (4)	O2—C6—C2	117.4 (2)
O1ⁱⁱⁱ—Sr1—Sr1^iv	78.55 (4)	O1—C6—C2	118.3 (2)
N1—Sr1—Sr1^iv	138.62 (5)	O2—C6—Sr1^v	67.67 (14)
O2ⁱⁱⁱ—Sr1—Sr1^iv	31.52 (4)	O1—C6—Sr1^v	56.88 (13)
C6ⁱⁱⁱ—Sr1—Sr1^iv	54.80 (5)	C2—C6—Sr1^v	167.25 (17)
O2ⁱ—Sr1—H1W2	90.3	Sr1—O1W—H1W1	122.1
O2W—Sr1—H1W2	15.7	Sr1—O1W—H2W1	126.8
O4ⁱⁱ—Sr1—H1W2	72.9	H1W1—O1W—H2W1	105.9
O1W—Sr1—H1W2	144.7	Sr1—O2W—H1W2	111.4
O3—Sr1—H1W2	91.3	Sr1—O2W—H2W2	111.6
O1ⁱⁱⁱ—Sr1—H1W2	81.0	H1W2—O2W—H2W2	114.0
N1—Sr1—H1W2	140.8	H1W3—O3W—H2W3	104.9

O2ⁱ—Sr1—N1—C4	121.4 (2)	C3—N2—C2—C1	−0.7 (4)
O2W—Sr1—N1—C4	−143.01 (19)	C3—N2—C2—C6	−175.0 (2)
O4ⁱⁱ—Sr1—N1—C4	−81.1 (2)	N1—C1—C2—N2	−0.4 (4)
O1W—Sr1—N1—C4	50.2 (2)	C5—C1—C2—N2	178.5 (2)
O3—Sr1—N1—C4	−168.7 (2)	N1—C1—C2—C6	173.3 (2)
O1ⁱⁱⁱ—Sr1—N1—C4	−11.5 (2)	C5—C1—C2—C6	−7.8 (4)
O2ⁱⁱⁱ—Sr1—N1—C4	37.4 (3)	C2—N2—C3—C4	1.3 (4)
C6ⁱⁱⁱ—Sr1—N1—C4	8.1 (2)	C1—N1—C4—C3	−0.3 (4)
Sr1^iv—Sr1—N1—C4	89.0 (2)	Sr1—N1—C4—C3	156.5 (2)
O2ⁱ—Sr1—N1—C1	−81.51 (18)	N2—C3—C4—N1	−0.8 (4)
O2W—Sr1—N1—C1	14.0 (2)	Sr1—O3—C5—O4	−162.37 (19)
O4ⁱⁱ—Sr1—N1—C1	75.96 (18)	Sr1—O3—C5—C1	17.6 (3)
O1W—Sr1—N1—C1	−152.72 (19)	Sr1ⁱ—O4—C5—O3	96.7 (3)
O3—Sr1—N1—C1	−11.61 (17)	Sr1ⁱ—O4—C5—C1	−83.2 (3)
O1ⁱⁱⁱ—Sr1—N1—C1	145.59 (17)	N1—C1—C5—O3	−27.8 (3)
O2ⁱⁱⁱ—Sr1—N1—C1	−165.53 (15)	C2—C1—C5—O3	153.3 (3)
C6ⁱⁱⁱ—Sr1—N1—C1	165.13 (16)	N1—C1—C5—O4	152.2 (2)
Sr1^iv—Sr1—N1—C1	−113.97 (17)	C2—C1—C5—O4	−26.8 (4)
O2ⁱ—Sr1—O3—C5	115.1 (2)	Sr1ⁱⁱ—O2—C6—O1	148.1 (3)
O2W—Sr1—O3—C5	−168.7 (2)	Sr1^v—O2—C6—O1	7.3 (3)
O4ⁱⁱ—Sr1—O3—C5	−82.2 (2)	Sr1ⁱⁱ—O2—C6—C2	−26.3 (5)
O1W—Sr1—O3—C5	40.4 (2)	Sr1^v—O2—C6—C2	−167.1 (2)
O1ⁱⁱⁱ—Sr1—O3—C5	−87.1 (3)	Sr1ⁱⁱ—O2—C6—Sr1^v	140.8 (4)
N1—Sr1—O3—C5	−4.08 (19)	Sr1^v—O1—C6—O2	−8.1 (3)
O2ⁱⁱⁱ—Sr1—O3—C5	149.62 (18)	Sr1^v—O1—C6—C2	166.25 (19)
C6ⁱⁱⁱ—Sr1—O3—C5	−173.4 (3)	N2—C2—C6—O2	110.2 (3)
Sr1^iv—Sr1—O3—C5	128.36 (19)	C1—C2—C6—O2	−63.9 (4)
C4—N1—C1—C2	0.9 (4)	N2—C2—C6—O1	−64.5 (3)
Sr1—N1—C1—C2	−157.03 (19)	C1—C2—C6—O1	121.4 (3)
C4—N1—C1—C5	−178.1 (2)	N2—C2—C6—Sr1^v	−0.2 (9)
Sr1—N1—C1—C5	24.0 (3)	C1—C2—C6—Sr1^v	−174.3 (7)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O3Wⁱ	0.85	1.87	2.713 (3)	170
O1W—H2W1···O3W^vi	0.85	1.90	2.744 (3)	171
O2W—H1W2···O1ⁱⁱ	0.85	1.85	2.696 (3)	174
O2W—H2W2···O1W^iv	0.85	2.01	2.857 (3)	178
O3W—H1W3···O4	0.85	1.94	2.781 (3)	170
O3W—H2W3···N2^vii	0.85	1.96	2.792 (3)	168

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

Experimental details

Crystal data
Chemical formula	[Sr(C₆H₂N₂O₄)(H₂O)₂]·H₂O
M_r	307.76
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	120
a, b, c (Å)	10.4931 (7), 6.9839 (4), 13.5208 (8)
β (°)	94.267 (1)
V (Å³)	988.10 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	5.48
Crystal size (mm)	0.28 × 0.25 × 0.10

Data collection
Diffractometer	Bruker SMART 1000 CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 1998)
T_min, T_max	0.240, 0.568
No. of measured, independent and observed [I > 2σ(I)] reflections	8338, 1934, 1595
R_int	0.040
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.024, 0.054, 1.01
No. of reflections	1934
No. of parameters	145
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.92, −0.45

Computer programs: SMART (Bruker, 1998), SAINT-Plus (Bruker, 1998), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Sr1—O2ⁱ	2.4887 (18)	Sr1—O3	2.6145 (18)
Sr1—O2W	2.5106 (18)	Sr1—O1ⁱⁱⁱ	2.6155 (18)
Sr1—O4ⁱⁱ	2.5533 (18)	Sr1—N1	2.714 (2)
Sr1—O1W	2.5937 (19)	Sr1—O2ⁱⁱⁱ	2.8517 (18)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W1···O3Wⁱ	0.85	1.872	2.713 (3)	170
O1W—H2W1···O3W^iv	0.85	1.901	2.744 (3)	171
O2W—H1W2···O1ⁱⁱ	0.85	1.849	2.696 (3)	174
O2W—H2W2···O1W^v	0.85	2.007	2.857 (3)	178
O3W—H1W3···O4	0.85	1.941	2.781 (3)	170
O3W—H2W3···N2^vi	0.85	1.955	2.792 (3)	168

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

Acknowledgements

We are grateful to the Islamic Azad University, North Tehran Branch, for financial support.

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