Poly[[hexa­aqua­bis­(μ3-pyrimidine-4,6-dicarboxyl­ato)dicalcium] dihydrate]

Starosta, W.; Leciejewicz, J.

doi:10.1107/S160053681204617X

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 12| December 2012| Pages m1478-m1479

doi:10.1107/S160053681204617X

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Poly[[hexaaquabis(μ₃-pyrimidine-4,6-dicarboxylato)dicalcium] dihydrate]

Wojciech Starosta ^a and Janusz Leciejewicz ^a ^*

^aInstitute of Nuclear Chemistry and Technology, ul.Dorodna 16, 03-195 Warszawa, Poland
^*Correspondence e-mail: j.leciejewicz@ichtj.waw.pl

(Received 7 November 2012; accepted 8 November 2012; online 14 November 2012)

The polymeric structure of the title compound, {[Ca₂(C₆H₂N₂O₄)₂(H₂O)₆]·2H₂O}_n, is built up of molecular layers composed of Ca^II ions bridged by both ligand N and O atoms with one of the O atoms being bis-monodentate. Two adjacent Ca^II ions are bridged by these O atoms, forming a centrosymmetric dimer which is the building unit of the structure. The dimers are nodes of a cross-linked molecular layer parallel to (101). The Ca^II ion is coordinated by two bidentate ligands, one monodentate ligand and three water molecules in the form of a distorted polyhedron with a coordination number of eight. Solvate water molecules located between adjacent layers participate as donors and acceptors in a system of hydrogen bonds in which coordinating water molecules also act as donors and non-coordinating carboxylate O atoms act as acceptors.

Related literature

For the crystal structures of Ca^II complexes with pyrazine-2,6-dicarboxylate and water ligands, see: Starosta et al. (2003 , 2004 ). The crystal structure of pyrimidine-4,6-dicarboxylic acid dihydrate was reported by Beobide et al. (2007 ).

Experimental

Crystal data

[Ca₂(C₆H₂N₂O₄)₂(H₂O)₆]·2H₂O
M_r = 278.24
Monoclinic, P 2₁ /n
a = 7.7053 (15) Å
b = 11.432 (2) Å
c = 11.916 (2) Å
β = 92.16 (3)°
V = 1048.9 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.64 mm⁻¹
T = 293 K
0.10 × 0.04 × 0.03 mm

Data collection

Kuma KM-4 four-circle diffractometer
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008 $[Oxford Diffraction (2008). CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ) T_min = 0.968, T_max = 0.982
3274 measured reflections
3065 independent reflections
1709 reflections with I > 2σ(I)
R_int = 0.049
3 standard reflections every 200 reflections intensity decay: 2.9%

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.107
S = 1.01
3065 reflections
186 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.59 e Å⁻³

Table 1
Selected bond lengths (Å)

Ca1—O5	2.398 (2)
Ca1—O7	2.420 (2)
Ca1—O3ⁱ	2.4361 (17)
Ca1—O1ⁱⁱ	2.4823 (16)
Ca1—O6	2.502 (2)
Ca1—O1	2.5061 (17)
Ca1—N1	2.563 (2)
Ca1—N3ⁱ	2.6133 (19)
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) -x, -y, -z+1.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H72⋯O2ⁱⁱⁱ	0.80 (6)	2.34 (6)	3.048 (3)	149 (6)
O6—H61⋯O2ⁱⁱ	0.85 (5)	1.88 (5)	2.698 (3)	163 (5)
O8—H81⋯O3^iv	0.76 (4)	2.04 (4)	2.793 (3)	170 (4)
O8—H82⋯O6^v	0.77 (5)	2.09 (5)	2.818 (3)	157 (5)
O5—H52⋯O8^vi	0.87 (4)	1.94 (4)	2.798 (3)	169 (4)
O6—H62⋯O4ⁱⁱⁱ	0.77 (4)	1.96 (4)	2.719 (2)	167 (4)
O7—H71⋯O4^vii	0.79 (4)	2.16 (4)	2.902 (3)	158 (3)
O5—H51⋯O8^iv	0.78 (4)	2.04 (4)	2.816 (3)	176 (4)
Symmetry codes: (ii) -x, -y, -z+1; (iii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iv) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (v) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (vi) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (vii) -x, -y+1, -z+1.

Data collection: KM-4 Software (Kuma, 1996 $[Kuma (1996). KM-4 Software. Kuma Diffraction Ltd, Wrocław, Poland.]$ ); cell refinement: KM-4 Software; data reduction: DATAPROC (Kuma, 2001 $[Kuma (2001). DATAPROC. Kuma Diffraction Ltd, Wrocław, Poland.]$ ); 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/S160053681204617X/qm2088sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681204617X/qm2088Isup2.hkl

checkCIF report

Comment top

The asymmetric unit of the title compound contains one Ca^II ion, one fully deprotonated pyrimidine-4,6-diarboxylate ligand molecule, three water molecules coordinated to the metal ion and one solvation water molecule. The ligand molecule acts in µ₃ mode and bridges Ca ^II ions using monodentate N and O atoms and another O atom which is bidentate. One of the O atoms in the carboxylate groups remains uncoordinated. Ca1 and Ca1ⁱⁱ ions are related by an inversion centre and bridged by bidentate carboxylato O1 and O1ⁱⁱ atoms to form a dimeric moiety (Fig.1). Due to the bridging action of the ligands the dimers are the nodes of a cross-linked two dimensional molecular network. The structure of the title compound can be thus visualized as built of molecular layers parallel to the crystal (101) plane (Fig.2). Solvation water molecules are located between adjacent layers. The Ca^II ion has a distorted eight coordinate geometry. The observed Ca—N and Ca—O bond distances are typical (Table 1). The pyrimidine ring is planar with an r.m.s. of 0.0079 (2) Å; carboxylate groups C7/O1/O2 and C8/O3/O4 make dihedral angles with the plane of 9.7 (1)° and 8.9 (1)°, respectively. Bond distances and bond angles within the pyrimidine ring do not differ from those reported for the parent acid (Beobide, et al., 2007). In a system of hydrogen bonds, which is responsible for structure stability, solvation and coordinated water molecules act as donors and as acceptors and coordination inactive carboxylato O atoms act as acceptors (Table 2). Centro-symmetric dimeric units in which two Ca^IIions are bridged by ligand bidentate carboxylato O atoms have been also observed in the structures of complexes with pyrazine-2,6-dicarboxylate and water ligands. In all, dimeric units bridged by pairs of coordinated aqua O atoms form "ladder" type molecular ribbons (Starosta, et al., 2003, 2004).

Related literature top

For the crystal structures of Ca^II complexes with pyrazine-2,6-dicarboxylate and water ligands, see: Starosta, et al. (2003, 2004). The crystal structure of pyrimidine-4,6-dicarboxylic acid dihydrate was reported by Beobide et al. (2007).

Experimental top

An aqueous solution containing 1 mmol of calcium acetate hydrate and 1 mmol of pyrimidine-4,6-diarboxylic acid dihydrate was refluxed with constant stirring for 6 h. After cooling to room temperature, the solution was left to evaporate. Well formed single-crystal blocks appeared overnight at the bottom of the reaction pot. They were separated from the mother liquid, washed with cold water and dried in air.

Computing details top

Data collection: KM-4 Software (Kuma, 1996); cell refinement: KM-4 Software (Kuma, 1996); data reduction: DATAPROC (Kuma, 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. A fragment of the molecular layer showing a dimeric moiety with atom labelling scheme and 50% probability displacement ellipsoids. Symmetry code: ⁱ -x + 1/2, y - 1/2, -z + 3/2; ⁱⁱ -x, -y,-z + 1; ⁱⁱⁱ x - 1/2, -y + 1/2, z + 1/2.
	Fig. 2. The alignment of molecular layers in the structure of a Ca^II complex with pyrimidine-4,6-carboxylate and water ligands viewed along [010].

Poly[[hexaaquabis(µ₃-pyrimidine-4,6-dicarboxylato)dicalcium] dihydrate] top

Crystal data top

[Ca₂(C₆H₂N₂O₄)₂(H₂O)₆]·2H₂O	F(000) = 576
M_r = 278.24	D_x = 1.762 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 25 reflections
a = 7.7053 (15) Å	θ = 6–15°
b = 11.432 (2) Å	µ = 0.64 mm⁻¹
c = 11.916 (2) Å	T = 293 K
β = 92.16 (3)°	Blocks, colourless
V = 1048.9 (4) Å³	0.10 × 0.04 × 0.03 mm
Z = 4

Data collection top

Kuma KM-4 four-circle diffractometer	1709 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.049
Graphite monochromator	θ_max = 30.1°, θ_min = 2.5°
profile data from ω/2θ scans	h = 0→10
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008)	k = −16→0
T_min = 0.968, T_max = 0.982	l = −16→16
3274 measured reflections	3 standard reflections every 200 reflections
3065 independent reflections	intensity decay: 2.9%

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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.107	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ²(F_o²) + (0.0572P)² + 0.0532P] where P = (F_o² + 2F_c²)/3
3065 reflections	(Δ/σ)_max = 0.001
186 parameters	Δρ_max = 0.44 e Å⁻³
0 restraints	Δρ_min = −0.59 e Å⁻³

Crystal data top

[Ca₂(C₆H₂N₂O₄)₂(H₂O)₆]·2H₂O	V = 1048.9 (4) Å³
M_r = 278.24	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 7.7053 (15) Å	µ = 0.64 mm⁻¹
b = 11.432 (2) Å	T = 293 K
c = 11.916 (2) Å	0.10 × 0.04 × 0.03 mm
β = 92.16 (3)°

Data collection top

Kuma KM-4 four-circle diffractometer	1709 reflections with I > 2σ(I)
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008)	R_int = 0.049
T_min = 0.968, T_max = 0.982	3 standard reflections every 200 reflections
3274 measured reflections	intensity decay: 2.9%
3065 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	0 restraints
wR(F²) = 0.107	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	Δρ_max = 0.44 e Å⁻³
3065 reflections	Δρ_min = −0.59 e Å⁻³
186 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
Ca1	0.03092 (6)	0.05117 (4)	0.65920 (3)	0.01409 (11)
O1	0.0060 (2)	0.12495 (14)	0.46120 (13)	0.0195 (3)
O2	0.0320 (3)	0.27178 (16)	0.33877 (13)	0.0261 (4)
N1	0.1313 (3)	0.26241 (16)	0.63011 (14)	0.0163 (4)
C6	0.1190 (3)	0.30679 (18)	0.52650 (17)	0.0148 (4)
C5	0.1834 (3)	0.41685 (18)	0.50185 (18)	0.0174 (4)
H5	0.1705	0.4487	0.4302	0.021*
C7	0.0438 (3)	0.22887 (19)	0.43434 (18)	0.0165 (4)
O4	0.3231 (3)	0.64500 (15)	0.48018 (14)	0.0313 (5)
O7	−0.2529 (3)	0.14194 (19)	0.6459 (2)	0.0342 (5)
O6	−0.1678 (3)	−0.08219 (17)	0.76038 (16)	0.0267 (4)
N3	0.2839 (3)	0.43217 (16)	0.69222 (14)	0.0169 (4)
O5	0.3228 (3)	0.0407 (2)	0.59679 (18)	0.0348 (5)
C2	0.2132 (3)	0.32771 (19)	0.70832 (18)	0.0180 (4)
H2	0.2216	0.2974	0.7807	0.022*
C4	0.2679 (3)	0.47703 (19)	0.58880 (17)	0.0152 (4)
C8	0.3517 (3)	0.59611 (18)	0.57191 (18)	0.0170 (4)
O8	0.9331 (3)	0.35726 (19)	0.89833 (19)	0.0303 (4)
H51	0.390 (5)	−0.010 (4)	0.601 (3)	0.047 (11)*
O3	0.4436 (2)	0.63449 (14)	0.65273 (13)	0.0199 (3)
H71	−0.285 (4)	0.187 (3)	0.600 (3)	0.031 (9)*
H62	−0.174 (5)	−0.090 (3)	0.824 (3)	0.038 (10)*
H52	0.358 (5)	0.081 (4)	0.540 (3)	0.055 (12)*
H82	0.882 (6)	0.384 (5)	0.847 (4)	0.076 (16)*
H81	0.957 (5)	0.293 (3)	0.888 (3)	0.036 (9)*
H61	−0.120 (6)	−0.146 (4)	0.743 (4)	0.081 (16)*
H72	−0.324 (8)	0.138 (5)	0.693 (5)	0.10 (2)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ca1	0.0198 (2)	0.01036 (17)	0.01203 (17)	−0.00052 (18)	−0.00070 (13)	−0.00012 (16)
O1	0.0290 (9)	0.0126 (7)	0.0168 (7)	−0.0043 (6)	−0.0002 (6)	−0.0028 (6)
O2	0.0448 (10)	0.0193 (8)	0.0135 (7)	−0.0052 (8)	−0.0076 (7)	0.0006 (6)
N1	0.0223 (9)	0.0135 (8)	0.0131 (8)	−0.0017 (7)	−0.0013 (7)	−0.0006 (7)
C6	0.0180 (10)	0.0128 (9)	0.0135 (9)	−0.0005 (8)	−0.0010 (8)	−0.0012 (7)
C5	0.0266 (11)	0.0124 (9)	0.0130 (8)	−0.0024 (8)	−0.0019 (8)	0.0011 (7)
C7	0.0205 (10)	0.0135 (9)	0.0155 (9)	−0.0016 (8)	−0.0009 (8)	−0.0038 (8)
O4	0.0595 (14)	0.0183 (8)	0.0154 (8)	−0.0108 (9)	−0.0070 (8)	0.0064 (6)
O7	0.0323 (11)	0.0327 (11)	0.0378 (11)	0.0116 (9)	0.0063 (9)	0.0124 (9)
O6	0.0394 (11)	0.0236 (9)	0.0172 (8)	−0.0052 (8)	0.0030 (8)	0.0011 (7)
N3	0.0241 (9)	0.0149 (9)	0.0117 (7)	−0.0054 (7)	0.0003 (7)	0.0005 (6)
O5	0.0301 (10)	0.0360 (12)	0.0389 (11)	0.0114 (9)	0.0109 (8)	0.0158 (9)
C2	0.0264 (12)	0.0164 (10)	0.0112 (8)	−0.0030 (9)	−0.0013 (8)	0.0013 (8)
C4	0.0206 (10)	0.0123 (9)	0.0125 (9)	−0.0006 (8)	0.0001 (8)	−0.0001 (7)
C8	0.0257 (12)	0.0116 (9)	0.0136 (9)	−0.0029 (9)	0.0013 (8)	−0.0012 (7)
O8	0.0296 (10)	0.0219 (10)	0.0392 (11)	0.0042 (8)	0.0005 (8)	−0.0076 (8)
O3	0.0298 (9)	0.0132 (7)	0.0164 (7)	−0.0064 (7)	−0.0026 (6)	−0.0015 (6)

Geometric parameters (Å, º) top

Ca1—O5	2.398 (2)	C5—H5	0.9300
Ca1—O7	2.420 (2)	O4—C8	1.240 (3)
Ca1—O3ⁱ	2.4361 (17)	O7—H71	0.79 (4)
Ca1—O1ⁱⁱ	2.4823 (16)	O7—H72	0.80 (6)
Ca1—O6	2.502 (2)	O6—H62	0.77 (4)
Ca1—O1	2.5061 (17)	O6—H61	0.85 (5)
Ca1—N1	2.563 (2)	N3—C2	1.330 (3)
Ca1—N3ⁱ	2.6133 (19)	N3—C4	1.336 (3)
Ca1—Ca1ⁱⁱ	3.9817 (11)	N3—Ca1ⁱⁱⁱ	2.6133 (19)
Ca1—H61	2.74 (5)	O5—H51	0.78 (4)
O1—C7	1.267 (3)	O5—H52	0.87 (4)
O1—Ca1ⁱⁱ	2.4823 (16)	C2—H2	0.9300
O2—C7	1.240 (3)	C4—C8	1.523 (3)
N1—C2	1.334 (3)	C8—O3	1.253 (3)
N1—C6	1.335 (3)	O8—H82	0.77 (5)
C6—C5	1.388 (3)	O8—H81	0.76 (4)
C6—C7	1.512 (3)	O3—Ca1ⁱⁱⁱ	2.4361 (17)
C5—C4	1.385 (3)

O5—Ca1—O7	148.95 (7)	N1—Ca1—H61	163.4 (11)
O5—Ca1—O3ⁱ	105.11 (8)	N3ⁱ—Ca1—H61	63.5 (11)
O7—Ca1—O3ⁱ	86.21 (7)	Ca1ⁱⁱ—Ca1—H61	93.9 (11)
O5—Ca1—O1ⁱⁱ	82.45 (7)	C7—O1—Ca1ⁱⁱ	129.56 (14)
O7—Ca1—O1ⁱⁱ	103.09 (7)	C7—O1—Ca1	122.89 (13)
O3ⁱ—Ca1—O1ⁱⁱ	148.46 (6)	Ca1ⁱⁱ—O1—Ca1	105.91 (6)
O5—Ca1—O6	135.80 (7)	C2—N1—C6	116.67 (19)
O7—Ca1—O6	74.03 (7)	C2—N1—Ca1	124.75 (14)
O3ⁱ—Ca1—O6	79.90 (6)	C6—N1—Ca1	118.15 (14)
O1ⁱⁱ—Ca1—O6	74.06 (6)	N1—C6—C5	121.77 (19)
O5—Ca1—O1	76.37 (7)	N1—C6—C7	117.37 (19)
O7—Ca1—O1	75.95 (7)	C5—C6—C7	120.70 (19)
O3ⁱ—Ca1—O1	137.32 (5)	C4—C5—C6	116.97 (19)
O1ⁱⁱ—Ca1—O1	74.09 (6)	C4—C5—H5	121.5
O6—Ca1—O1	129.21 (6)	C6—C5—H5	121.5
O5—Ca1—N1	73.37 (7)	O2—C7—O1	126.4 (2)
O7—Ca1—N1	82.17 (7)	O2—C7—C6	116.52 (19)
O3ⁱ—Ca1—N1	75.03 (6)	O1—C7—C6	117.02 (19)
O1ⁱⁱ—Ca1—N1	135.61 (6)	Ca1—O7—H71	126 (2)
O6—Ca1—N1	146.35 (7)	Ca1—O7—H72	125 (4)
O1—Ca1—N1	64.43 (5)	H71—O7—H72	109 (5)
O5—Ca1—N3ⁱ	71.93 (7)	Ca1—O6—H62	127 (3)
O7—Ca1—N3ⁱ	137.41 (7)	Ca1—O6—H61	97 (3)
O3ⁱ—Ca1—N3ⁱ	63.72 (6)	H62—O6—H61	101 (4)
O1ⁱⁱ—Ca1—N3ⁱ	90.98 (6)	C2—N3—C4	116.97 (18)
O6—Ca1—N3ⁱ	71.62 (7)	C2—N3—Ca1ⁱⁱⁱ	125.87 (14)
O1—Ca1—N3ⁱ	146.45 (6)	C4—N3—Ca1ⁱⁱⁱ	117.02 (14)
N1—Ca1—N3ⁱ	114.97 (6)	Ca1—O5—H51	131 (3)
O5—Ca1—Ca1ⁱⁱ	76.69 (6)	Ca1—O5—H52	122 (3)
O7—Ca1—Ca1ⁱⁱ	89.33 (6)	H51—O5—H52	103 (4)
O3ⁱ—Ca1—Ca1ⁱⁱ	173.73 (4)	N3—C2—N1	126.0 (2)
O1ⁱⁱ—Ca1—Ca1ⁱⁱ	37.25 (4)	N3—C2—H2	117.0
O6—Ca1—Ca1ⁱⁱ	103.10 (5)	N1—C2—H2	117.0
O1—Ca1—Ca1ⁱⁱ	36.84 (4)	N3—C4—C5	121.6 (2)
N1—Ca1—Ca1ⁱⁱ	100.01 (4)	N3—C4—C8	116.09 (18)
N3ⁱ—Ca1—Ca1ⁱⁱ	122.36 (5)	C5—C4—C8	122.31 (18)
O5—Ca1—H61	119.2 (10)	O4—C8—O3	126.6 (2)
O7—Ca1—H61	88.9 (10)	O4—C8—C4	117.21 (19)
O3ⁱ—Ca1—H61	90.5 (11)	O3—C8—C4	116.20 (18)
O1ⁱⁱ—Ca1—H61	60.1 (11)	H82—O8—H81	112 (4)
O6—Ca1—H61	17.9 (10)	C8—O3—Ca1ⁱⁱⁱ	126.43 (14)
O1—Ca1—H61	126.9 (11)

Symmetry codes: (i) −x+1/2, y−1/2, −z+3/2; (ii) −x, −y, −z+1; (iii) −x+1/2, y+1/2, −z+3/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H72···O2^iv	0.80 (6)	2.34 (6)	3.048 (3)	149 (6)
O6—H61···O2ⁱⁱ	0.85 (5)	1.88 (5)	2.698 (3)	163 (5)
O8—H81···O3^v	0.76 (4)	2.04 (4)	2.793 (3)	170 (4)
O8—H82···O6ⁱⁱⁱ	0.77 (5)	2.09 (5)	2.818 (3)	157 (5)
O5—H52···O8^vi	0.87 (4)	1.94 (4)	2.798 (3)	169 (4)
O6—H62···O4^iv	0.77 (4)	1.96 (4)	2.719 (2)	167 (4)
O7—H71···O4^vii	0.79 (4)	2.16 (4)	2.902 (3)	158 (3)
O5—H51···O8^v	0.78 (4)	2.04 (4)	2.816 (3)	176 (4)

Symmetry codes: (ii) −x, −y, −z+1; (iii) −x+1/2, y+1/2, −z+3/2; (iv) x−1/2, −y+1/2, z+1/2; (v) −x+3/2, y−1/2, −z+3/2; (vi) x−1/2, −y+1/2, z−1/2; (vii) −x, −y+1, −z+1.

Experimental details

Crystal data
Chemical formula	[Ca₂(C₆H₂N₂O₄)₂(H₂O)₆]·2H₂O
M_r	278.24
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	7.7053 (15), 11.432 (2), 11.916 (2)
β (°)	92.16 (3)
V (Å³)	1048.9 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.64
Crystal size (mm)	0.10 × 0.04 × 0.03

Data collection
Diffractometer	Kuma KM-4 four-circle diffractometer
Absorption correction	Analytical (CrysAlis RED; Oxford Diffraction, 2008)
T_min, T_max	0.968, 0.982
No. of measured, independent and observed [I > 2σ(I)] reflections	3274, 3065, 1709
R_int	0.049
(sin θ/λ)_max (Å⁻¹)	0.705

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.107, 1.01
No. of reflections	3065
No. of parameters	186
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.44, −0.59

Computer programs: KM-4 Software (Kuma, 1996), DATAPROC (Kuma, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

Ca1—O5	2.398 (2)	Ca1—O6	2.502 (2)
Ca1—O7	2.420 (2)	Ca1—O1	2.5061 (17)
Ca1—O3ⁱ	2.4361 (17)	Ca1—N1	2.563 (2)
Ca1—O1ⁱⁱ	2.4823 (16)	Ca1—N3ⁱ	2.6133 (19)

Symmetry codes: (i) −x+1/2, y−1/2, −z+3/2; (ii) −x, −y, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O7—H72···O2ⁱⁱⁱ	0.80 (6)	2.34 (6)	3.048 (3)	149 (6)
O6—H61···O2ⁱⁱ	0.85 (5)	1.88 (5)	2.698 (3)	163 (5)
O8—H81···O3^iv	0.76 (4)	2.04 (4)	2.793 (3)	170 (4)
O8—H82···O6^v	0.77 (5)	2.09 (5)	2.818 (3)	157 (5)
O5—H52···O8^vi	0.87 (4)	1.94 (4)	2.798 (3)	169 (4)
O6—H62···O4ⁱⁱⁱ	0.77 (4)	1.96 (4)	2.719 (2)	167 (4)
O7—H71···O4^vii	0.79 (4)	2.16 (4)	2.902 (3)	158 (3)
O5—H51···O8^iv	0.78 (4)	2.04 (4)	2.816 (3)	176 (4)

Symmetry codes: (ii) −x, −y, −z+1; (iii) x−1/2, −y+1/2, z+1/2; (iv) −x+3/2, y−1/2, −z+3/2; (v) −x+1/2, y+1/2, −z+3/2; (vi) x−1/2, −y+1/2, z−1/2; (vii) −x, −y+1, −z+1.

References

Beobide, G., Castillo, O., Luque, A., Garcia-Couceiro, U., Garcia-Teran, J. P. & Roman, P. (2007). Dalton Trans. pp. 2668–2680. Google Scholar
Kuma (1996). KM-4 Software. Kuma Diffraction Ltd, Wrocław, Poland. Google Scholar
Kuma (2001). DATAPROC. Kuma Diffraction Ltd, Wrocław, Poland. Google Scholar
Oxford Diffraction (2008). CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Starosta, W., Ptasiewicz-Bąk, H. & Leciejewicz, J. (2003). J. Coord. Chem. 56, 677–682. Web of Science CSD CrossRef CAS Google Scholar
Starosta, W., Ptasiewicz-Bąk, H. & Leciejewicz, J. (2004). J. Coord. Chem. 57, 167–173. Web of Science CSD CrossRef CAS Google Scholar

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Volume 68| Part 12| December 2012| Pages m1478-m1479

doi:10.1107/S160053681204617X

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