trans-Diaqua­bis(pyridazine-3-carboxyl­ato-κ²N,O)magnesium(II) dihydrate

The title compound, [Mg(C₅H₃N₂O₂)₂(H₂O)₂]·2H₂O, contains centrosymmetric neutral complex mol­ecules. The pyridazine-3-carboxyl­ate ligands bond in an N,O-bidentate mode and the octa­hedral Mg coordination is completed by two trans water mol­ecules. There are also two non-coordinated water mol­ecules. O—H...O and O—H...N hydrogen bonds are present, resulting in a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.137
• Data-to-parameter ratio = 15.8

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT232_ALERT_2_B Hirshfeld Test Diff (M-X)  Mg1    -   O1      ..      17.61 su
PLAT232_ALERT_2_B Hirshfeld Test Diff (M-X)  Mg1    -   O3      ..      13.81 su
PLAT232_ALERT_2_B Hirshfeld Test Diff (M-X)  Mg1    -   N2      ..      16.87 su

Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.28
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C3     -   C7     ...       1.53 Ang.

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

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

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S1. Comment

The title compound, (I), is isostructural with the analogous complexes of manganese (Ardivinata et al., 1989) and zinc (Gryz et al., 2003) with the same ligands.

The structure of (I) is triclinic and its unit cell contains one monomeric [Mg(C₅H₃N₂O₂)₂(H₂O)₂] complex molecule and two non-coordinated water molecules. The Mg^II cation is located on an inversion centre and is coordinated by two equatorial bidentate-N,O ligand molecules. Two axial water O atoms complete a slightly distorted octahedron around the metal ion (Fig. 1 and Table 1). The pyridazine ring is almost planar (r.m.s. deviation 0.0106 Å) and the carboxylate entity is rotated from the ring best plane by 5.3(x)° [Please complete s.u.].

Fig. 2 shows the unit-cell packing diagram for (I) and the hydrogen-bonding scheme. Hydrogen bonds link the water molecules to uncoordinated carboxylate O atoms and uncoordinated hetero-ring N atoms in adjacent monomers, forming a three-dimensional network (Table 2). Monomeric molecules with octahedral coordination around the Mg^II cation have been also reported for magnesium(II) picolinate (Deloume et al., 1973) and magnesium aminopyrazinate (Ptasiewicz-Bąk et al., 1997). In both these compounds, the ligand molecules chelate the metal ion via an N,O-bonding mode. However, the ligand planes are in a cis arrangement, with a dihedral angle between the planes of 95° in the former complex and 67.3 (5)° in the latter.

S2. Experimental

A hot aqueous solution (50 ml) containing pyridazine-3-carboxylic acid (2 mmol) was added with constant stirring to a hot aqueous solution (50 ml) containing magnesium acetate tetrahydrate (1 mmol). After boiling for 1 h, the solution was left to crystallize at room temperature. After several days, single crystals of (I) in the form of colourless blocks deposited in the mother liquid. These were washed with cold water and ethanol and dried in air.

S3. Refinement

H atoms were located in difference maps and freely refined with isotropic displacement parameters. The largest electron-density peak is 0.47 Å from Mg1 and the deepest hole is 0.62 Å from O3.

Computing details

Data collection: KM-4 Software (Kuma, 1996); cell refinement: KM-4 Software; data reduction: DATAPROC (Kuma, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1992); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of (I), showing 50% displacement ellipsoids (arbitrary spheres for the H atoms). Unlabelled atoms are generated by the symmetry operation (1 − x, 1 − y, 1 − z).
	Fig. 2. The unit-cell packing for (I), with dashed lines indicating hydrogen bonds.

trans-Diaquabis(pyridazine-3-carboxylato-κ²N,O)magnesium(II) dihydrate

Crystal data

[Mg(C5H3N2O2)2(H2O)2]·2H2O	Z = 1
Mr = 342.56	F(000) = 178
Triclinic, P1	Dx = 1.586 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.3380 (11) Å	Cell parameters from 25 reflections
b = 7.4680 (15) Å	θ = 6–15°
c = 9.6410 (19) Å	µ = 0.18 mm^−1
α = 79.23 (3)°	T = 293 K
β = 88.91 (3)°	Rod, colourless
γ = 71.93 (3)°	0.40 × 0.09 × 0.07 mm
V = 358.63 (13) Å^3

Data collection

Kuma KM-4 four-circle diffractometer	1463 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.023
Graphite monochromator	θmax = 30.1°, θmin = 2.2°
ω/2θ scans	h = −7→0
Absorption correction: analytical (Please give details)	k = −10→10
Tmin = 0.978, Tmax = 0.986	l = −13→13
2327 measured reflections	3 standard reflections every 200 reflections
2117 independent reflections	intensity decay: 2.1%

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)] = 0.041	Hydrogen site location: difference Fourier map
wR(F^2) = 0.137	All H-atom parameters refined
S = 1.06	w = 1/[σ^2(Fo^2) + (0.089P)^2 + 0.0392P] where P = (Fo^2 + 2Fc^2)/3
2117 reflections	(Δ/σ)max < 0.001
134 parameters	Δρmax = 0.60 e Å^−3
0 restraints	Δρmin = −0.27 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Mg1	0.5000	0.5000	0.5000	0.01854 (18)
O3	0.3335 (2)	0.32486 (19)	0.41261 (15)	0.0348 (3)
N2	0.2316 (2)	0.75238 (18)	0.36709 (14)	0.0269 (3)
N1	−0.0111 (3)	0.8530 (2)	0.39952 (15)	0.0319 (3)
C4	0.2138 (4)	0.9778 (3)	0.1549 (2)	0.0400 (4)
C6	−0.1353 (3)	1.0153 (3)	0.3130 (2)	0.0383 (4)
C3	0.3386 (3)	0.8087 (2)	0.24865 (16)	0.0280 (3)
C5	−0.0306 (4)	1.0855 (3)	0.1899 (2)	0.0452 (5)
O2	0.7120 (3)	0.71295 (19)	0.11011 (13)	0.0417 (3)
C7	0.6101 (3)	0.6727 (2)	0.22408 (17)	0.0298 (3)
O1	0.7068 (2)	0.53239 (17)	0.32189 (12)	0.0331 (3)
H32	0.298 (6)	0.369 (4)	0.322 (3)	0.065 (8)*
H31	0.222 (7)	0.285 (5)	0.467 (4)	0.089 (11)*
O4	0.2412 (3)	0.4743 (3)	0.12985 (16)	0.0505 (4)
H5	−0.128 (5)	1.211 (4)	0.130 (3)	0.052 (7)*
H41	0.059 (7)	0.568 (4)	0.119 (3)	0.069 (8)*
H42	0.290 (6)	0.410 (4)	0.048 (3)	0.073 (9)*
H6	−0.310 (5)	1.092 (3)	0.343 (2)	0.040 (6)*
H4	0.309 (5)	1.022 (4)	0.069 (3)	0.053 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mg1	0.0146 (3)	0.0212 (3)	0.0152 (3)	−0.0020 (2)	0.0001 (2)	0.0019 (2)
O3	0.0303 (6)	0.0397 (6)	0.0339 (7)	−0.0114 (5)	0.0001 (5)	−0.0046 (5)
N2	0.0248 (6)	0.0283 (6)	0.0257 (6)	−0.0066 (5)	0.0012 (5)	−0.0032 (5)
N1	0.0260 (6)	0.0342 (7)	0.0334 (7)	−0.0056 (5)	0.0022 (5)	−0.0081 (5)
C4	0.0410 (9)	0.0382 (9)	0.0343 (8)	−0.0105 (7)	0.0011 (7)	0.0058 (7)
C6	0.0298 (8)	0.0343 (8)	0.0459 (10)	−0.0019 (6)	−0.0016 (7)	−0.0090 (7)
C3	0.0282 (7)	0.0292 (7)	0.0255 (7)	−0.0084 (6)	0.0018 (6)	−0.0034 (6)
C5	0.0427 (10)	0.0333 (9)	0.0479 (11)	−0.0019 (7)	−0.0051 (8)	0.0045 (8)
O2	0.0438 (7)	0.0455 (7)	0.0312 (6)	−0.0115 (6)	0.0136 (5)	−0.0018 (5)
C7	0.0283 (7)	0.0341 (8)	0.0274 (7)	−0.0109 (6)	0.0048 (6)	−0.0053 (6)
O1	0.0265 (5)	0.0364 (6)	0.0297 (6)	−0.0039 (5)	0.0042 (4)	−0.0006 (4)
O4	0.0403 (8)	0.0692 (10)	0.0415 (8)	−0.0117 (7)	−0.0035 (6)	−0.0185 (7)

Geometric parameters (Å, º)

Mg1—O1	2.0406 (13)	C4—C5	1.377 (3)
Mg1—O1^i	2.0406 (13)	C4—C3	1.389 (2)
Mg1—O3	2.0909 (14)	C4—H4	1.02 (3)
Mg1—O3^i	2.0909 (14)	C6—C5	1.385 (3)
Mg1—N2	2.1769 (16)	C6—H6	1.00 (2)
Mg1—N2^i	2.1769 (16)	C3—C7	1.534 (2)
O3—H32	0.88 (3)	C5—H5	1.00 (2)
O3—H31	0.87 (4)	O2—C7	1.245 (2)
N2—C3	1.324 (2)	C7—O1	1.252 (2)
N2—N1	1.3451 (19)	O4—H41	1.00 (3)
N1—C6	1.323 (2)	O4—H42	0.99 (3)
O1—Mg1—O1^i	180.0	N1—N2—Mg1	126.30 (10)
O1—Mg1—O3	89.63 (6)	C6—N1—N2	118.08 (14)
O1^i—Mg1—O3	90.37 (6)	C5—C4—C3	116.88 (17)
O1—Mg1—O3^i	90.37 (6)	C5—C4—H4	123.0 (15)
O1^i—Mg1—O3^i	89.63 (6)	C3—C4—H4	120.0 (15)
O3—Mg1—O3^i	180.0	N1—C6—C5	123.55 (17)
O1—Mg1—N2	77.39 (5)	N1—C6—H6	116.3 (13)
O1^i—Mg1—N2	102.61 (5)	C5—C6—H6	120.1 (13)
O3—Mg1—N2	89.87 (5)	N2—C3—C4	122.34 (15)
O3^i—Mg1—N2	90.13 (5)	N2—C3—C7	114.57 (13)
O1—Mg1—N2^i	102.61 (5)	C4—C3—C7	123.09 (15)
O1^i—Mg1—N2^i	77.39 (5)	C4—C5—C6	117.90 (16)
O3—Mg1—N2^i	90.13 (5)	C4—C5—H5	121.1 (15)
O3^i—Mg1—N2^i	89.87 (5)	C6—C5—H5	121.0 (15)
N2—Mg1—N2^i	180.0	O2—C7—O1	126.75 (15)
Mg1—O3—H32	110.6 (19)	O2—C7—C3	117.09 (14)
Mg1—O3—H31	113 (2)	O1—C7—C3	116.16 (13)
H32—O3—H31	121 (3)	C7—O1—Mg1	119.08 (10)
C3—N2—N1	121.16 (13)	H41—O4—H42	113 (3)
C3—N2—Mg1	112.42 (10)

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
O3—H32···O4	0.88 (3)	1.86 (3)	2.737 (2)	175 (3)
O3—H31···N1^ii	0.87 (4)	2.04 (4)	2.899 (2)	170 (3)
O4—H41···O2^iii	1.00 (3)	1.82 (3)	2.822 (2)	173 (3)
O4—H42···O2^iv	0.99 (3)	1.92 (3)	2.888 (2)	165 (3)

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