Dipotassium aquabis(pyrazine-2,3-dicarboxylato-κ2N,O)cuprate(II) hexahydrate

Castillo, O.; Beobide, G.; Luque, A.; Román, P.

doi:10.1107/S160053680301732X

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Dipotassium aquabis(pyrazine-2,3-dicarboxylato-κ²N,O)cuprate(II) hexahydrate

O. Castillo, G. Beobide, A. Luque and P. Román

The crystal structure of the title compound, K₂[Cu(C₆H₂N₂O₄)₂(H₂O)]·6H₂O, consists of mononuclear [Cu(pzdc)₂(H₂O)]²⁻ complex anions (pzdc is pyrazine-2,3-dicarboxylate), K⁺ cations and water molecules, held together by means of K—O/OW bonds and an extended OW—H

O/OW and OW—H

N hydrogen-bond network. The distorted square-pyramidal coordination of the Cu atom is achieved by two N and two O donor atoms from two bidentate pzdc ligands in the basal plane, while a water molecule occupies the apical position with a longer metal–O distance.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680301732X/ci6247sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S160053680301732X/ci6247Isup2.hkl Contains datablock I

CCDC reference: 222825

checkCIF report

Key indicators

Single-crystal X-ray study
T = 294 K
Mean (C-C) = 0.004 Å
R factor = 0.054
wR factor = 0.158
Data-to-parameter ratio = 19.1

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT420_ALERT_2_B D-H Without Acceptor       O5W    -   H52W   ...          ?

Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.99
PLAT241_ALERT_2_C Check High   U(eq) as Compared to Neighbors ....       O172

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

Pyrazine-2,3-dicarboxylic acid (H₂pzdc; Takusagawa & Shimada, 1973) and its dianion (Richard et al., 1973; Nepveu & Berkaoui, 1993) have proved to be well suited for the construction of multidimensional frameworks (nD, n = 1–3), due to the presence of two adjacent carboxylate groups (O donor atoms) as substituents in the N-heterocyclic pyrazine ring (N donor atoms). This permits multiple coordination modes and the usual non-coplanarity of these carboxylate groups, which favours the construction of high-dimensional covalent networks (O'Connor et al., 1982; Kondo et al., 1999; Zou et al., 1999; Kitaura et al., 2002). One approach to the design of extended homo- and heterometallic coordination polymers is to use mononuclear transition metal complexes possessing multidentate terminal ligands with free coordination sites, which can further connect a second metal centre, increasing the dimensionality of the coordination network (Pilkington et al., 2001; Ciurtin et al., 2003). This paper reports the synthesis and crystal structure of the potassium salt of one of these complexes, namely, K₂[Cu(C₆H₂N₂O₄)₂(H₂O)]·6H₂O, (I). This compound is a potential building block in the design of extended metal-organic networks, by replacing the K⁺ cations by transition metal ions.

As shown in Fig. 1, the Cu^II atom of (I), located on a general position, is surrounded by two N,O-bidentate pzdc ligands and a water molecule, which imposes a distorted square-pyramidal CuN₂O₃ environment. The two pzdc anions coordinate to the metal centre via one N-pyrazine atom and one O atom from the adjacent carboxylate group, forming a five-membered ring. These four donor atoms form the basal plane [maximum deviation from the mean plane 0.074 (3) Å for atom N21], while the Cu atom is displaced by 0.1612 (4) Å from this plane towards the apical position filled by a water molecule. The Cu—O1W bond distance of 2.203 (3) Å is substantially longer than the equatorial Cu—O/N distances (<2.00 Å). The coordination distances (Table 1) are similar to those reported for analogous Cu^II complexes containing the pzdc ligand (Kondo et al., 1999; Kitaura et al., 2002; Wang et al., 2003). The remaining O atoms of the carboxylate groups are connected to K⁺ cations (Fig. 2). The C—O bond distances of the K-bound O atoms are somewhat shorter (<1.25 Å) than those involving the O atoms attached to the Cu centres (>1.28 Å).

For both pzdc ligands, the carboxylate group coordinated to the Cu atoms is nearly coplanar with the pyrazine ring [dihedral angles 5.5 (1) and 4.5 (1)°], while the remaining one is twisted by 85.0 (1) and 82.5 (1)°, respectively. Both K⁺ cations are surrounded by nine O atoms, six from four carboxylate groups and three from free water molecules, with K—O distances ranging from 2.688 (3) to 3.221 (3) Å. An extensive OW—H···O, OW—H···N and OW—H···OW hydrogen-bond network involving the water molecules and the heteroatoms of the pzdc ligands further stabilizes the crystal packing (Table 2).

Experimental top

Blue crystals of (I) suitable for X-ray analysis were obtained by slow diffusion of a water-methanol mixture of pyrazine-2,3-dicarboxylic acid (84 mg, 0.5 mmol), adjusted to pH ca 7 with 1 N KOH, into an aqueous solution containing Cu(NO₃)₂·3H₂O (60 mg, 0.25 mmol) (yield 60–70%, based on metal). Elemental analysis (C/H/N/Cu), found: 24.32, 3.08, 9.28, 10.50%; calculated for C₁₂H₁₈Cu K₂N₄O₁₅: 24.02, 3.02, 9.34, 10.59%.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis RED (Oxford Diffraction, 2002); data reduction: CrysAlis RED; program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. A view of the trans-[Cu(C₆H₂N₂O₄)₂(H₂O)]²⁻ complex anion in (I). Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The crystal structure of (I), viewed along the a axis. H atoms have been omitted for clarity. The coordination environment of the K⁺ cations is shown by dotted lines.

Dipotassium aquabis(pyrazine-2,3-dicarboxylato-κ²N,O)cuprate(II) hexahydrate top

Crystal data top

K₂[Cu(C₆H₂N₂O₄)₂(H₂O)]·6H₂O	Z = 2
M_r = 600.05	F(000) = 610
Triclinic, P1	D_x = 1.822 Mg m⁻³ D_m = 1.82 (1) Mg m⁻³ D_m measured by flotation in ?
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.830 (1) Å	Cell parameters from 6673 reflections
b = 11.339 (2) Å	θ = 3.2–30.6°
c = 14.627 (2) Å	µ = 1.46 mm⁻¹
α = 94.58 (1)°	T = 294 K
β = 95.92 (1)°	Hexagonal plate, blue
γ = 102.54 (2)°	0.4 × 0.4 × 0.1 mm
V = 1093.8 (3) Å³

Data collection top

Oxford Diffraction Xcalibur diffractometer	6673 independent reflections
Radiation source: Fine-focus sealed tube	3580 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.091
Detector resolution: 1024 × 1024 with blocks 2 × 2 pixels mm^-1	θ_max = 30.6°, θ_min = 3.2°
ω scans	h = −9→8
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2002)	k = −16→16
T_min = 0.572, T_max = 0.854	l = −20→20
11367 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)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.158	H-atom parameters constrained
S = 0.94	w = 1/[σ²(F_o²) + (0.0638P)²] where P = (F_o² + 2F_c²)/3
6673 reflections	(Δ/σ)_max = 0.002
349 parameters	Δρ_max = 1.01 e Å⁻³
21 restraints	Δρ_min = −0.94 e Å⁻³

Crystal data top

K₂[Cu(C₆H₂N₂O₄)₂(H₂O)]·6H₂O	γ = 102.54 (2)°
M_r = 600.05	V = 1093.8 (3) Å³
Triclinic, P1	Z = 2
a = 6.830 (1) Å	Mo Kα radiation
b = 11.339 (2) Å	µ = 1.46 mm⁻¹
c = 14.627 (2) Å	T = 294 K
α = 94.58 (1)°	0.4 × 0.4 × 0.1 mm
β = 95.92 (1)°

Data collection top

Oxford Diffraction Xcalibur diffractometer	6673 independent reflections
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2002)	3580 reflections with I > 2σ(I)
T_min = 0.572, T_max = 0.854	R_int = 0.091
11367 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.054	21 restraints
wR(F²) = 0.158	H-atom parameters constrained
S = 0.94	Δρ_max = 1.01 e Å⁻³
6673 reflections	Δρ_min = −0.94 e Å⁻³
349 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	0.72941 (6)	0.76290 (4)	0.00097 (2)	0.03097 (14)
K1	0.71404 (12)	0.91836 (8)	0.57449 (5)	0.0363 (2)
K2	0.78333 (12)	0.59087 (8)	0.42584 (5)	0.0387 (2)
N11	0.7634 (4)	0.8876 (3)	0.10899 (17)	0.0266 (6)
C12	0.7786 (4)	0.8404 (3)	0.1874 (2)	0.0238 (6)
C13	0.7792 (4)	0.9073 (3)	0.2724 (2)	0.0241 (6)
N14	0.7657 (4)	1.0234 (3)	0.27433 (18)	0.0316 (6)
C15	0.7512 (5)	1.0702 (3)	0.1945 (2)	0.0346 (8)
H15	0.743	1.151	0.195	0.042*
C16	0.7479 (5)	1.0034 (3)	0.1110 (2)	0.0318 (7)
H16	0.735	1.039	0.056	0.038*
C17	0.7946 (5)	0.7098 (3)	0.1788 (2)	0.0292 (7)
C18	0.7914 (5)	0.8557 (3)	0.3643 (2)	0.0307 (7)
O171	0.7748 (4)	0.6575 (2)	0.09650 (15)	0.0386 (6)
O172	0.8253 (5)	0.6578 (3)	0.24852 (17)	0.0509 (7)
O181	0.6285 (4)	0.8018 (2)	0.38902 (16)	0.0382 (6)
O182	0.9604 (4)	0.8747 (3)	0.40944 (17)	0.0476 (7)
N21	0.7221 (4)	0.6405 (2)	−0.10539 (16)	0.0264 (6)
C22	0.7245 (5)	0.6866 (3)	−0.1851 (2)	0.0259 (7)
C23	0.7155 (4)	0.6150 (3)	−0.26820 (19)	0.0241 (6)
N24	0.7041 (4)	0.4952 (3)	−0.26812 (18)	0.0338 (7)
C25	0.7016 (6)	0.4498 (3)	−0.1871 (2)	0.0387 (8)
H25	0.693	0.367	−0.186	0.046*
C26	0.7113 (5)	0.5213 (3)	−0.1045 (2)	0.0335 (8)
H26	0.710	0.487	−0.049	0.04*
C27	0.7372 (5)	0.8209 (3)	−0.1773 (2)	0.0346 (8)
C28	0.7137 (5)	0.6605 (3)	−0.3620 (2)	0.0302 (7)
O271	0.7542 (4)	0.8736 (2)	−0.09497 (15)	0.0419 (7)
O272	0.7243 (5)	0.8741 (2)	−0.24745 (16)	0.0495 (7)
O281	0.8783 (4)	0.7053 (2)	−0.38860 (15)	0.0357 (6)
O282	0.5452 (4)	0.6447 (3)	−0.40796 (17)	0.0475 (7)
O1w	0.4000 (4)	0.7380 (3)	−0.0011 (2)	0.0556 (9)
H11w	0.335 (4)	0.783 (3)	0.026 (2)	0.067*
H12w	0.318 (4)	0.699 (4)	−0.047 (2)	0.067*
O2w	0.2980 (4)	0.8800 (3)	0.54471 (18)	0.0448 (7)
H21w	0.188 (3)	0.839 (4)	0.515 (2)	0.054*
H22w	0.280 (5)	0.877 (4)	0.601 (1)	0.054*
O3w	0.2812 (5)	0.8380 (4)	0.3008 (2)	0.0609 (9)
H31w	0.259 (5)	0.804 (4)	0.246 (1)	0.073*
H32w	0.372 (5)	0.807 (4)	0.328 (2)	0.073*
O4w	1.1987 (4)	0.6086 (3)	0.4458 (2)	0.0474 (7)
H41w	1.214 (5)	0.604 (4)	0.389 (1)	0.057*
H42w	1.303 (4)	0.659 (3)	0.473 (2)	0.057*
O5w	0.7859 (4)	0.3586 (3)	0.3117 (2)	0.0562 (8)
H51w	0.880 (3)	0.331 (4)	0.339 (3)	0.067*
H52w	0.680 (3)	0.329 (4)	0.336 (2)	0.067*
O6w	0.2406 (5)	0.8764 (3)	0.1177 (2)	0.0537 (8)
H61w	0.264 (5)	0.953 (1)	0.130 (3)	0.064*
H62w	0.114 (1)	0.855 (3)	0.100 (3)	0.064*
O7w	0.8228 (5)	0.4139 (3)	0.1378 (2)	0.0552 (8)
H71w	0.819 (7)	0.396 (3)	0.193 (1)	0.066*
H72w	0.804 (7)	0.486 (2)	0.139 (3)	0.066*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0497 (3)	0.0267 (2)	0.0163 (2)	0.00715 (18)	0.00730 (16)	0.00070 (15)
K1	0.0429 (4)	0.0387 (5)	0.0260 (4)	0.0065 (3)	0.0034 (3)	0.0054 (3)
K2	0.0491 (5)	0.0396 (5)	0.0272 (4)	0.0104 (4)	0.0044 (3)	0.0027 (3)
N11	0.0337 (14)	0.0286 (14)	0.0174 (12)	0.0054 (12)	0.0039 (10)	0.0057 (10)
C12	0.0271 (15)	0.0250 (16)	0.0192 (14)	0.0053 (12)	0.0034 (11)	0.0028 (12)
C13	0.0229 (14)	0.0311 (17)	0.0168 (14)	0.0032 (13)	0.0011 (11)	0.0029 (12)
N14	0.0416 (16)	0.0307 (16)	0.0209 (13)	0.0057 (13)	0.0036 (11)	−0.0011 (11)
C15	0.050 (2)	0.0228 (17)	0.0312 (18)	0.0086 (15)	0.0037 (15)	0.0014 (14)
C16	0.0439 (19)	0.0308 (18)	0.0217 (15)	0.0083 (15)	0.0046 (13)	0.0092 (13)
C17	0.0400 (18)	0.0249 (17)	0.0236 (16)	0.0101 (14)	0.0034 (13)	0.0019 (13)
C18	0.0372 (18)	0.0327 (19)	0.0204 (15)	0.0068 (15)	0.0048 (13)	−0.0053 (13)
O171	0.0649 (16)	0.0291 (13)	0.0224 (12)	0.0124 (12)	0.0077 (11)	−0.0012 (10)
O172	0.094 (2)	0.0420 (16)	0.0219 (12)	0.0272 (16)	0.0048 (13)	0.0047 (11)
O181	0.0435 (14)	0.0457 (16)	0.0299 (12)	0.0102 (12)	0.0116 (11)	0.0224 (11)
O182	0.0402 (14)	0.064 (2)	0.0331 (14)	0.0045 (13)	−0.0113 (11)	0.0126 (13)
N21	0.0382 (15)	0.0277 (15)	0.0145 (12)	0.0085 (12)	0.0048 (10)	0.0047 (10)
C22	0.0292 (16)	0.0286 (17)	0.0207 (15)	0.0079 (13)	0.0063 (12)	0.0003 (12)
C23	0.0233 (14)	0.0329 (17)	0.0156 (13)	0.0059 (13)	0.0011 (11)	0.0022 (12)
N24	0.0474 (17)	0.0289 (16)	0.0246 (14)	0.0070 (13)	0.0089 (12)	−0.0005 (12)
C25	0.061 (2)	0.0261 (18)	0.0300 (18)	0.0086 (17)	0.0112 (16)	0.0035 (14)
C26	0.052 (2)	0.0302 (18)	0.0194 (15)	0.0087 (16)	0.0077 (14)	0.0064 (13)
C27	0.046 (2)	0.036 (2)	0.0238 (16)	0.0118 (16)	0.0098 (14)	−0.0010 (14)
C28	0.0365 (18)	0.0307 (18)	0.0228 (15)	0.0090 (14)	0.0054 (14)	−0.0074 (13)
O271	0.0808 (19)	0.0254 (13)	0.0209 (12)	0.0117 (13)	0.0138 (12)	0.0016 (10)
O272	0.101 (2)	0.0324 (15)	0.0216 (12)	0.0242 (15)	0.0140 (13)	0.0091 (11)
O281	0.0402 (13)	0.0429 (15)	0.0273 (12)	0.0096 (11)	0.0102 (10)	0.0157 (11)
O282	0.0366 (14)	0.076 (2)	0.0288 (13)	0.0118 (14)	−0.0031 (11)	0.0126 (13)
O1w	0.0404 (15)	0.065 (2)	0.0546 (19)	0.0106 (14)	0.0018 (13)	−0.0247 (16)
O2w	0.0441 (14)	0.059 (2)	0.0294 (13)	0.0103 (13)	0.0058 (11)	−0.0028 (13)
O3w	0.0501 (17)	0.087 (3)	0.0527 (19)	0.0225 (17)	0.0085 (14)	0.0261 (18)
O4w	0.0464 (15)	0.058 (2)	0.0315 (14)	0.0035 (14)	0.0053 (12)	−0.0104 (13)
O5w	0.0443 (15)	0.074 (2)	0.0568 (19)	0.0191 (16)	0.0136 (14)	0.0237 (16)
O6w	0.0675 (19)	0.0380 (17)	0.0583 (19)	0.0159 (14)	0.0185 (16)	−0.0043 (15)
O7w	0.0716 (19)	0.0437 (18)	0.0459 (17)	0.0144 (16)	−0.0052 (15)	−0.0091 (14)

Geometric parameters (Å, º) top

Cu1—O171	1.953 (3)	C17—O172	1.240 (4)
Cu1—O271	1.953 (2)	C17—O171	1.279 (4)
Cu1—N11	1.994 (3)	C18—O182	1.235 (4)
Cu1—N21	1.990 (2)	C18—O181	1.251 (4)
Cu1—O1w	2.203 (3)	N21—C22	1.315 (4)
K1—O181	2.866 (3)	N21—C26	1.338 (4)
K1—O182	3.148 (3)	C22—C23	1.396 (4)
K1—O182ⁱ	2.836 (3)	C22—C27	1.500 (5)
K1—O272ⁱⁱ	2.688 (3)	C23—N24	1.344 (4)
K1—O281ⁱⁱ	2.941 (3)	C23—C28	1.504 (5)
K1—O282ⁱⁱ	3.108 (3)	N24—C25	1.329 (4)
K1—O2w	2.762 (3)	C25—C26	1.388 (4)
K1—O2wⁱⁱⁱ	2.994 (3)	C25—H25	0.93
K1—O3wⁱⁱⁱ	3.179 (4)	C26—H26	0.93
K2—O172	2.785 (3)	C27—O272	1.236 (5)
K2—O181	2.884 (3)	C27—O271	1.283 (4)
K2—O182	3.221 (3)	C28—O282	1.241 (4)
K2—O281ⁱⁱ	2.860 (2)	C28—O281	1.244 (4)
K2—O282^iv	3.067 (3)	O1w—H11w	0.85 (3)
K2—O282ⁱⁱ	3.153 (3)	O1w—H12w	0.85 (3)
K2—O4w	2.783 (3)	O2w—H21w	0.85 (3)
K2—O4w^v	3.067 (3)	O2w—H22w	0.85 (1)
K2—O5w	3.008 (4)	O3w—H31w	0.85 (1)
N11—C12	1.307 (4)	O3w—H32w	0.86 (4)
N11—C16	1.338 (4)	O4w—H41w	0.85 (1)
C12—C13	1.403 (4)	O4w—H42w	0.85 (3)
C12—C17	1.505 (4)	O5w—H51w	0.85 (3)
C13—N14	1.338 (4)	O5w—H52w	0.85 (3)
C13—C18	1.510 (5)	O6w—H61w	0.85 (1)
N14—C15	1.324 (4)	O6w—H62w	0.85 (1)
C15—C16	1.381 (4)	O7w—H71w	0.85 (1)
C15—H15	0.93	O7w—H72w	0.85 (3)
C16—H16	0.93

O271—Cu1—O171	166.16 (11)	O281ⁱⁱ—K2—O182	74.13 (7)
O271—Cu1—N21	82.35 (10)	O181—K2—O182	42.15 (7)
O171—Cu1—N21	95.72 (10)	O5w—K2—O182	134.49 (8)
O271—Cu1—N11	97.54 (10)	O4w^v—K2—O182	142.44 (7)
O171—Cu1—N11	83.16 (10)	O282^iv—K2—O182	155.49 (8)
N21—Cu1—N11	174.92 (11)	O282ⁱⁱ—K2—O182	93.19 (8)
O271—Cu1—O1w	95.64 (13)	C12—N11—C16	118.3 (3)
O171—Cu1—O1w	98.20 (13)	C12—N11—Cu1	111.8 (2)
N21—Cu1—O1w	96.93 (10)	C16—N11—Cu1	129.4 (2)
N11—Cu1—O1w	88.14 (10)	N11—C12—C13	122.1 (3)
O272ⁱⁱ—K1—O2w	94.47 (9)	N11—C12—C17	114.8 (3)
O272ⁱⁱ—K1—O182ⁱ	99.67 (9)	C13—C12—C17	123.1 (3)
O2w—K1—O182ⁱ	134.84 (9)	N14—C13—C12	119.6 (3)
O272ⁱⁱ—K1—O181	142.90 (8)	N14—C13—C18	116.6 (3)
O2w—K1—O181	78.45 (8)	C12—C13—C18	123.9 (3)
O182ⁱ—K1—O181	111.15 (8)	C15—N14—C13	117.8 (3)
O272ⁱⁱ—K1—O281ⁱⁱ	67.11 (7)	N14—C15—C16	122.4 (3)
O2w—K1—O281ⁱⁱ	116.42 (9)	N14—C15—H15	118.8
O182ⁱ—K1—O281ⁱⁱ	108.59 (8)	C16—C15—H15	118.8
O181—K1—O281ⁱⁱ	83.40 (7)	N11—C16—C15	120.0 (3)
O272ⁱⁱ—K1—O2wⁱⁱⁱ	140.94 (8)	N11—C16—H16	120.0
O2w—K1—O2wⁱⁱⁱ	83.70 (9)	C15—C16—H16	120.0
O182ⁱ—K1—O2wⁱⁱⁱ	58.83 (8)	O172—C17—O171	123.1 (3)
O181—K1—O2wⁱⁱⁱ	75.09 (7)	O172—C17—C12	120.8 (3)
O281ⁱⁱ—K1—O2wⁱⁱⁱ	147.03 (7)	O171—C17—C12	116.1 (3)
O272ⁱⁱ—K1—O282ⁱⁱ	68.73 (8)	O182—C18—O181	126.3 (3)
O2w—K1—O282ⁱⁱ	73.66 (9)	O182—C18—C13	116.8 (3)
O182ⁱ—K1—O282ⁱⁱ	151.15 (8)	O181—C18—C13	116.9 (3)
O181—K1—O282ⁱⁱ	74.36 (7)	C17—O171—Cu1	113.6 (2)
O281ⁱⁱ—K1—O282ⁱⁱ	42.76 (7)	C17—O172—K2	157.4 (3)
O2wⁱⁱⁱ—K1—O282ⁱⁱ	144.92 (7)	C18—O181—K1	94.85 (19)
O272ⁱⁱ—K1—O182	136.70 (9)	C18—O181—K2	92.5 (2)
O2w—K1—O182	120.34 (7)	K1—O181—K2	96.59 (8)
O182ⁱ—K1—O182	74.61 (9)	K1ⁱ—O182—K1	105.39 (9)
O181—K1—O182	42.96 (6)	K1ⁱ—O182—K2	151.47 (10)
O281ⁱⁱ—K1—O182	74.18 (7)	K1—O182—K2	84.74 (7)
O2wⁱⁱⁱ—K1—O182	73.04 (8)	C22—N21—C26	118.7 (3)
O282ⁱⁱ—K1—O182	95.49 (8)	C22—N21—Cu1	113.2 (2)
O272ⁱⁱ—K1—O3wⁱⁱⁱ	70.85 (8)	C26—N21—Cu1	128.2 (2)
O2w—K1—O3wⁱⁱⁱ	87.94 (8)	N21—C22—C23	121.9 (3)
O182ⁱ—K1—O3wⁱⁱⁱ	57.68 (8)	N21—C22—C27	113.8 (3)
O181—K1—O3wⁱⁱⁱ	143.76 (8)	C23—C22—C27	124.2 (3)
O281ⁱⁱ—K1—O3wⁱⁱⁱ	132.30 (8)	N24—C23—C22	119.8 (3)
O2wⁱⁱⁱ—K1—O3wⁱⁱⁱ	70.09 (8)	N24—C23—C28	115.1 (3)
O282ⁱⁱ—K1—O3wⁱⁱⁱ	133.63 (8)	C22—C23—C28	125.1 (3)
O182—K1—O3wⁱⁱⁱ	129.94 (8)	C25—N24—C23	117.6 (3)
O4w—K2—O172	86.29 (9)	N24—C25—C26	122.5 (3)
O4w—K2—O281ⁱⁱ	81.48 (7)	N24—C25—H25	118.8
O172—K2—O281ⁱⁱ	137.36 (8)	C26—C25—H25	118.8
O4w—K2—O181	119.59 (9)	N21—C26—C25	119.5 (3)
O172—K2—O181	66.56 (8)	N21—C26—H26	120.2
O281ⁱⁱ—K2—O181	84.54 (7)	C25—C26—H26	120.2
O4w—K2—O5w	81.54 (8)	O272—C27—O271	123.5 (4)
O172—K2—O5w	75.43 (9)	O272—C27—C22	120.5 (3)
O281ⁱⁱ—K2—O5w	141.36 (9)	O271—C27—C22	116.0 (3)
O181—K2—O5w	133.84 (8)	O282—C28—O281	125.7 (3)
O4w—K2—O4w^v	81.24 (9)	O282—C28—C23	115.9 (3)
O172—K2—O4w^v	145.44 (8)	O281—C28—C23	118.3 (3)
O281ⁱⁱ—K2—O4w^v	72.33 (7)	C27—O271—Cu1	114.3 (2)
O181—K2—O4w^v	146.53 (7)	C27—O272—K1^vi	160.7 (2)
O5w—K2—O4w^v	70.94 (8)	K2^vi—O281—K1^vi	95.45 (7)
O4w—K2—O282^iv	126.06 (9)	K2^iv—O282—K1^vi	155.15 (10)
O172—K2—O282^iv	107.62 (8)	K2^iv—O282—K2^vi	100.65 (8)
O281ⁱⁱ—K2—O282^iv	112.60 (7)	K1^vi—O282—K2^vi	86.58 (7)
O181—K2—O282^iv	113.62 (8)	Cu1—O1w—H11w	129 (2)
O5w—K2—O282^iv	54.44 (7)	Cu1—O1w—H12w	122 (2)
O4w^v—K2—O282^iv	57.63 (7)	H11w—O1w—H12w	105 (3)
O4w—K2—O282ⁱⁱ	123.19 (7)	K1—O2w—K1ⁱⁱⁱ	96.30 (9)
O172—K2—O282ⁱⁱ	138.79 (9)	H21w—O2w—H22w	105 (3)
O281ⁱⁱ—K2—O282ⁱⁱ	42.80 (6)	H31w—O3w—H32w	105 (3)
O181—K2—O282ⁱⁱ	73.43 (8)	K2—O4w—K2^v	98.76 (9)
O5w—K2—O282ⁱⁱ	131.79 (8)	H41w—O4w—H42w	105 (3)
O4w^v—K2—O282ⁱⁱ	73.16 (8)	H51w—O5w—H52w	106 (3)
O282^iv—K2—O282ⁱⁱ	79.35 (8)	H61w—O6w—H62w	105 (3)
O4w—K2—O182	77.54 (9)	H71w—O7w—H72w	105 (4)
O172—K2—O182	63.35 (8)

C16—N11—C12—C13	0.0 (5)	C26—N21—C22—C23	0.2 (5)
Cu1—N11—C12—C13	−172.2 (2)	Cu1—N21—C22—C23	−178.5 (2)
C16—N11—C12—C17	179.8 (3)	C26—N21—C22—C27	−179.9 (3)
Cu1—N11—C12—C17	7.6 (3)	Cu1—N21—C22—C27	1.4 (4)
N11—C12—C13—N14	−0.6 (5)	N21—C22—C23—N24	−0.1 (5)
C17—C12—C13—N14	179.6 (3)	C27—C22—C23—N24	−179.9 (3)
N11—C12—C13—C18	178.4 (3)	N21—C22—C23—C28	178.8 (3)
C17—C12—C13—C18	−1.3 (5)	C27—C22—C23—C28	−1.0 (5)
C12—C13—N14—C15	0.3 (5)	C22—C23—N24—C25	0.1 (5)
C18—C13—N14—C15	−178.8 (3)	C28—C23—N24—C25	−178.9 (3)
C13—N14—C15—C16	0.6 (5)	C23—N24—C25—C26	−0.4 (5)
C12—N11—C16—C15	0.9 (5)	C22—N21—C26—C25	−0.4 (5)
Cu1—N11—C16—C15	171.5 (2)	Cu1—N21—C26—C25	178.1 (2)
N14—C15—C16—N11	−1.2 (5)	N24—C25—C26—N21	0.5 (6)
N11—C12—C17—O172	174.4 (3)	N21—C22—C27—O272	−174.2 (3)
C13—C12—C17—O172	−5.8 (5)	C23—C22—C27—O272	5.7 (5)
N11—C12—C17—O171	−5.5 (4)	N21—C22—C27—O271	3.4 (4)
C13—C12—C17—O171	174.3 (3)	C23—C22—C27—O271	−176.8 (3)
N14—C13—C18—O182	−84.0 (4)	N24—C23—C28—O282	80.7 (4)
C12—C13—C18—O182	96.9 (4)	C22—C23—C28—O282	−98.3 (4)
N14—C13—C18—O181	93.3 (4)	N24—C23—C28—O281	−96.3 (4)
C12—C13—C18—O181	−85.8 (4)	C22—C23—C28—O281	84.8 (4)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1w—H11w···O6w	0.85 (3)	1.89 (3)	2.714 (4)	163 (3)
O1w—H12w···O7w^iv	0.85 (3)	1.81 (4)	2.639 (4)	165 (4)
O2w—H21w···O182^vii	0.85 (3)	2.20 (3)	2.866 (4)	136 (4)
O2w—H22w···N14ⁱⁱⁱ	0.85 (1)	2.15 (2)	2.894 (4)	146 (4)
O3w—H31w···O6w	0.85 (1)	2.11 (3)	2.743 (4)	132 (4)
O3w—H32w···O181	0.86 (4)	1.90 (3)	2.708 (4)	158 (4)
O4w—H41w···N24^viii	0.85 (1)	2.20 (3)	2.964 (4)	149 (4)
O4w—H42w···O282^ix	0.85 (3)	2.32 (3)	2.956 (4)	132 (3)
O5w—H51w···O281^viii	0.85 (3)	1.87 (3)	2.715 (4)	168 (4)
O5w—H52w···O282^iv	0.85 (3)	2.02 (3)	2.779 (4)	149 (4)
O6w—H61w···O271^x	0.85 (1)	2.10 (2)	2.873 (4)	152 (4)
O6w—H61w···O272^x	0.85 (1)	2.48 (3)	3.228 (4)	147 (3)
O6w—H62w···N11^vii	0.85 (1)	2.52 (1)	3.279 (5)	149 (3)
O7w—H71w···O5w	0.85 (1)	1.85 (2)	2.692 (4)	175 (5)
O7w—H72w···O171	0.85 (3)	2.13 (3)	2.953 (4)	161 (4)
O7w—H72w···O172	0.85 (3)	2.39 (3)	3.087 (5)	139 (4)

Symmetry codes: (iii) −x+1, −y+2, −z+1; (iv) −x+1, −y+1, −z; (vii) x−1, y, z; (viii) −x+2, −y+1, −z; (ix) x+1, y, z+1; (x) −x+1, −y+2, −z.

Experimental details

Crystal data
Chemical formula	K₂[Cu(C₆H₂N₂O₄)₂(H₂O)]·6H₂O
M_r	600.05
Crystal system, space group	Triclinic, P1
Temperature (K)	294
a, b, c (Å)	6.830 (1), 11.339 (2), 14.627 (2)
α, β, γ (°)	94.58 (1), 95.92 (1), 102.54 (2)
V (Å³)	1093.8 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	1.46
Crystal size (mm)	0.4 × 0.4 × 0.1

Data collection
Diffractometer	Oxford Diffraction Xcalibur diffractometer
Absorption correction	Analytical (CrysAlis RED; Oxford Diffraction, 2002)
T_min, T_max	0.572, 0.854
No. of measured, independent and observed [I > 2σ(I)] reflections	11367, 6673, 3580
R_int	0.091
(sin θ/λ)_max (Å⁻¹)	0.716

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.054, 0.158, 0.94
No. of reflections	6673
No. of parameters	349
No. of restraints	21
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.01, −0.94

Computer programs: CrysAlis CCD (Oxford Diffraction, 2002), CrysAlis RED (Oxford Diffraction, 2002), CrysAlis RED, SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected bond lengths (Å) top

Cu1—O171	1.953 (3)	K1—O2wⁱⁱⁱ	2.994 (3)
Cu1—O271	1.953 (2)	K1—O3wⁱⁱⁱ	3.179 (4)
Cu1—N11	1.994 (3)	K2—O172	2.785 (3)
Cu1—N21	1.990 (2)	K2—O181	2.884 (3)
Cu1—O1w	2.203 (3)	K2—O182	3.221 (3)
K1—O181	2.866 (3)	K2—O281ⁱⁱ	2.860 (2)
K1—O182	3.148 (3)	K2—O282^iv	3.067 (3)
K1—O182ⁱ	2.836 (3)	K2—O282ⁱⁱ	3.153 (3)
K1—O272ⁱⁱ	2.688 (3)	K2—O4w	2.783 (3)
K1—O281ⁱⁱ	2.941 (3)	K2—O4w^v	3.067 (3)
K1—O282ⁱⁱ	3.108 (3)	K2—O5w	3.008 (4)
K1—O2w	2.762 (3)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1w—H11w···O6w	0.85 (3)	1.89 (3)	2.714 (4)	163 (3)
O1w—H12w···O7w^iv	0.85 (3)	1.81 (4)	2.639 (4)	165 (4)
O2w—H21w···O182^vi	0.85 (3)	2.20 (3)	2.866 (4)	136 (4)
O2w—H22w···N14ⁱⁱⁱ	0.85 (1)	2.15 (2)	2.894 (4)	146 (4)
O3w—H31w···O6w	0.85 (1)	2.11 (3)	2.743 (4)	132 (4)
O3w—H32w···O181	0.86 (4)	1.90 (3)	2.708 (4)	158 (4)
O4w—H41w···N24^vii	0.85 (1)	2.20 (3)	2.964 (4)	149 (4)
O4w—H42w···O282^viii	0.85 (3)	2.32 (3)	2.956 (4)	132 (3)
O5w—H51w···O281^vii	0.85 (3)	1.87 (3)	2.715 (4)	168 (4)
O5w—H52w···O282^iv	0.85 (3)	2.02 (3)	2.779 (4)	149 (4)
O6w—H61w···O271^ix	0.85 (1)	2.10 (2)	2.873 (4)	152 (4)
O6w—H61w···O272^ix	0.85 (1)	2.48 (3)	3.228 (4)	147 (3)
O6w—H62w···N11^vi	0.85 (1)	2.52 (1)	3.279 (5)	149 (3)
O7w—H71w···O5w	0.85 (1)	1.85 (2)	2.692 (4)	175 (5)
O7w—H72w···O171	0.85 (3)	2.13 (3)	2.953 (4)	161 (4)
O7w—H72w···O172	0.85 (3)	2.39 (3)	3.087 (5)	139 (4)

Symmetry codes: (iii) −x+1, −y+2, −z+1; (iv) −x+1, −y+1, −z; (vi) x−1, y, z; (vii) −x+2, −y+1, −z; (viii) x+1, y, z+1; (ix) −x+1, −y+2, −z.

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