trans-Di­aqua­bis­(pyridazine-3-carboxyl­ato-κ²N²,O)copper(II)

In the title compound, [Cu(C₅H₃N₂O₂)₂(H₂O)₂], the Cu^II ion, located on an inversion center, exhibits an octa­hedral coordination geometry. The equatorial plane is defined by two trans-related N,O-bidentate pyridazine-3-carboxyl­ate ligands and the axial positions are occupied by two water mol­ecules. In the crystal, mol­ecules are connected by O—H...O hydrogen bonds between the water mol­ecules and the noncoordinating carboxyl­ate O atoms, forming layers parallel to the bc plane. The layers are stacked along the a axis by further O—H...O hydrogen bonds between the water mol­ecules and the coordinating carboxyl­ate O atoms. Weak C—H...O hydrogen bonds are also observed between the pyridazine rings and the water mol­ecules and between the pyridazine rings and the non-coordinating carboxyl­ate O atoms.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.027
• wR factor = 0.065
• Data-to-parameter ratio = 11.6

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S1. Comment

The metal ion, the pyridazine ring and carboxylate atoms are coplanar. As expected, the Cu—O and Cu—N distances (Table 1) are similar to the Zn(II) and Co(II) analogue compounds (Gryz et al., 2004; Artetxe et al., 2013). Table 2 summarizes the geometrical parameters of the O—H···O and C—H···O hydrogen bonding interactions.

Related literature

For an isotypic zinc(II) complex, see: Gryz et al. (2004). For a related cobalt(II) complex which contains two non-coordinating water molecules, see: Artetxe et al. (2013).

S2. Experimental

To a solution of CuCl₂.2H₂O (34 mg, 0.2 mmol) in water (10 mL) 3-pyridazine carboxylic acid (48 mg, 0.4 mmol) was dropwise added and the resulting solution was stirred for 1 h at 80 °C. Blue prismatic crystals suitable for single-crystal X-ray diffraction were obtained by slow evaporation of the resulting solution after six days.

S3. Refinement

H atoms of the water molecules were located in a Fourier difference map and refined isotropically with O—H bond lengths restrained to 0.88 (1) Å. All H atoms of the pyridazine ring were positioned geometrically and refined using a riding model with standard SHELXL parameters.

Computing details

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis RED (Agilent, 2012); program(s) used to solve structure: OLEX2 (Dolomanov et al., 2009); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2010); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures

	Fig. 1. Molecular structure of the title compound, showing atom labelling and 50% probability displacement ellipsoids. [Symmetry code: (i) 1 - x, 1 - y, 1 - z.]
	Fig. 2. Left: View of the crystal packing along the b axis. Right: Projection of a layer along the a axis (O—H···O hydrogen bonds represented as dotted red lines and weak C—H···O interactions as dotted green lines).

trans-Diaquabis(pyridazine-3-carboxylato-κ²N²,O)copper(II)

Crystal data

[Cu(C5H3N2O2)2(H2O)2]	F(000) = 350
Mr = 345.76	Dx = 1.951 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1663 reflections
a = 5.4014 (1) Å	θ = 2.8–28.4°
b = 11.5633 (3) Å	µ = 1.89 mm^−1
c = 9.6283 (2) Å	T = 100 K
β = 101.837 (3)°	Prism, blue
V = 588.58 (2) Å^3	0.19 × 0.09 × 0.06 mm
Z = 2

Data collection

Agilent SuperNova diffractometer	1216 independent reflections
Radiation source: Nova (Mo) X-ray micro-source	1077 reflections with I > 2σ(I)
Multilayer optics monochromator	Rint = 0.022
Detector resolution: 16.2439 pixels mm^-1	θmax = 26.5°, θmin = 2.8°
ω scans	h = −6→6
Absorption correction: numerical (CrysAlis PRO; Agilent, 2012)	k = −13→14
Tmin = 0.772, Tmax = 0.898	l = −12→9
2532 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.065	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0235P)^2 + 0.6643P] where P = (Fo^2 + 2Fc^2)/3
1216 reflections	(Δ/σ)max < 0.001
105 parameters	Δρmax = 0.44 e Å^−3
3 restraints	Δρmin = −0.45 e Å^−3

Special details

Experimental. IR (cm^-1): 3554(s), 3315(s), 3233(s), 1628(s), 1571(m), 1578(s), 1365(w), 1231(w), 1152(w), 1091(w), 1072(w), 1039(w), 978(m), 851(m), 785(m), 722(m), 669(w), 536(w), 440(w).

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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 (Ų)

	x	y	z	Uiso*/Ueq
C3	0.4961 (4)	0.27046 (19)	0.4096 (2)	0.0083 (4)
C4	0.4421 (4)	0.15278 (19)	0.3920 (2)	0.0107 (4)
H4	0.5153	0.1071	0.3318	0.013*
C5	0.2754 (4)	0.10781 (19)	0.4680 (2)	0.0106 (5)
H5	0.2313	0.03	0.4606	0.013*
C6	0.1737 (4)	0.18136 (19)	0.5564 (2)	0.0111 (5)
H6	0.0632	0.1503	0.6089	0.013*
C7	0.6781 (4)	0.33471 (19)	0.3358 (2)	0.0097 (4)
Cu1	0.5	0.5	0.5	0.00820 (13)
N1	0.2267 (3)	0.29375 (16)	0.5696 (2)	0.0101 (4)
N2	0.3890 (3)	0.33637 (16)	0.49462 (18)	0.0084 (4)
O1	0.7022 (3)	0.44303 (13)	0.36438 (16)	0.0100 (3)
O2	0.7873 (3)	0.28108 (13)	0.25561 (17)	0.0135 (4)
O1W	0.1555 (3)	0.53934 (14)	0.30161 (17)	0.0121 (3)
H1WA	0.014 (3)	0.514 (2)	0.321 (3)	0.024 (8)*
H1WB	0.149 (6)	0.6143 (9)	0.292 (4)	0.051 (11)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C3	0.0088 (10)	0.0095 (11)	0.0063 (10)	0.0001 (8)	0.0005 (8)	0.0003 (8)
C4	0.0128 (11)	0.0094 (11)	0.0094 (10)	0.0035 (9)	0.0014 (9)	−0.0004 (8)
C5	0.0107 (10)	0.0082 (11)	0.0117 (11)	−0.0007 (8)	−0.0007 (9)	0.0019 (8)
C6	0.0106 (10)	0.0125 (11)	0.0106 (11)	−0.0011 (9)	0.0028 (9)	0.0014 (9)
C7	0.0091 (10)	0.0120 (11)	0.0080 (10)	−0.0007 (8)	0.0018 (9)	0.0001 (9)
Cu1	0.0111 (2)	0.0052 (2)	0.0101 (2)	−0.00061 (14)	0.00618 (15)	−0.00061 (14)
N1	0.0107 (9)	0.0099 (9)	0.0104 (9)	−0.0019 (7)	0.0039 (8)	−0.0002 (7)
N2	0.0091 (9)	0.0092 (9)	0.0072 (9)	0.0007 (7)	0.0021 (7)	0.0013 (7)
O1	0.0112 (7)	0.0071 (8)	0.0128 (8)	−0.0012 (6)	0.0052 (6)	0.0004 (6)
O2	0.0158 (8)	0.0120 (8)	0.0152 (8)	−0.0009 (6)	0.0094 (7)	−0.0033 (6)
O1W	0.0101 (8)	0.0105 (8)	0.0161 (8)	0.0006 (6)	0.0037 (7)	0.0023 (7)

Geometric parameters (Å, º)

C3—N2	1.334 (3)	C7—C3	1.520 (3)
C3—C4	1.395 (3)	Cu1—O1^i	1.9792 (15)
C3—C7	1.520 (3)	Cu1—O1	1.9792 (15)
C4—C5	1.374 (3)	Cu1—N2	1.9822 (18)
C4—H4	0.93	Cu1—N2^i	1.9822 (18)
C5—C6	1.393 (3)	Cu1—O1W	2.4207 (16)
C5—H5	0.93	Cu1—O1W^i	2.4207 (16)
C6—N1	1.331 (3)	N1—N2	1.339 (3)
C6—H6	0.93	O1W—H1WA	0.872 (10)
C7—O2	1.231 (3)	O1W—H1WB	0.872 (10)
C7—O1	1.283 (3)
N2—C3—C4	121.7 (2)	O1^i—Cu1—N2^i	82.52 (7)
N2—C3—C7	114.28 (19)	N2—Cu1—N2^i	180
C4—C3—C7	124.0 (2)	O1—Cu1—O1W	88.90 (6)
C5—C4—C3	116.6 (2)	O1^i—Cu1—O1W	91.10 (6)
C5—C4—H4	121.7	N2—Cu1—O1W	88.82 (6)
C3—C4—H4	121.7	N2^i—Cu1—O1W	91.18 (6)
C4—C5—C6	118.6 (2)	O1—Cu1—O1W^i	91.10 (6)
C4—C5—H5	120.7	O1^i—Cu1—O1W^i	88.90 (6)
C6—C5—H5	120.7	N2—Cu1—O1W^i	91.18 (6)
N1—C6—C5	123.4 (2)	N2^i—Cu1—O1W^i	88.82 (6)
N1—C6—H6	118.3	O1W—Cu1—O1W^i	180
C5—C6—H6	118.3	C6—N1—N2	117.37 (19)
O2—C7—O1	125.8 (2)	C3—N2—N1	122.33 (19)
O2—C7—C3	119.1 (2)	C3—N2—Cu1	113.24 (15)
O1—C7—C3	115.06 (19)	N1—N2—Cu1	124.43 (14)
O1^i—Cu1—O1	180	C7—O1—Cu1	114.89 (13)
O1—Cu1—N2	82.52 (7)	Cu1—O1W—H1WA	109.8 (19)
O1^i—Cu1—N2	97.48 (7)	Cu1—O1W—H1WB	106 (2)
O1—Cu1—N2^i	97.48 (7)	H1WA—O1W—H1WB	109 (2)
N2—C3—C4—C5	−0.8 (3)	O1W—Cu1—N2—C3	89.46 (15)
C7—C3—C4—C5	179.22 (19)	O1W^i—Cu1—N2—C3	−90.54 (15)
C3—C4—C5—C6	−0.2 (3)	O1—Cu1—N2—N1	179.32 (17)
C4—C5—C6—N1	1.1 (3)	O1^i—Cu1—N2—N1	−0.68 (17)
C5—C6—N1—N2	−0.9 (3)	O1W—Cu1—N2—N1	−91.63 (16)
C4—C3—N2—N1	1.0 (3)	O1W^i—Cu1—N2—N1	88.37 (16)
C7—C3—N2—N1	−179.04 (18)	O2—C7—O1—Cu1	−179.34 (18)
C4—C3—N2—Cu1	179.92 (16)	C3—C7—O1—Cu1	0.8 (2)
C7—C3—N2—Cu1	−0.1 (2)	N2—Cu1—O1^i—C7^i	−179.30 (15)
C6—N1—N2—C3	−0.1 (3)	N2—Cu1—O1—C7	−0.70 (15)
C6—N1—N2—Cu1	−178.91 (15)	O1W—Cu1—O1—C7	−89.65 (15)
O1—Cu1—N2—C3	0.41 (14)	O1W^i—Cu1—O1—C7	90.35 (15)
O1^i—Cu1—N2—C3	−179.59 (14)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O1^ii	0.87 (2)	1.99 (2)	2.865 (2)	175 (2)
O1W—H1WB···O2^iii	0.87 (1)	2.03 (2)	2.878 (2)	165 (3)
C4—H4···O1W^iv	0.93	2.52	3.403 (3)	158
C6—H6···O2^v	0.93	2.39	3.141 (3)	138

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