Bis[[(6-carb­oxy­pyridazine-3-carboxyl­ato-κ²N²,O³)lithium]-μ-penta­hydrogen­dioxy­gen(1+)]

The structure of the title compound, [Li(C₆H₃N₂O₄)₂(H₅O₂)], is composed of centrosymmetric monomers in which an Li^I ion is chelated by two N,O-bonding groups donated by two ligands. The Li^I ion and both ligand mol­ecules are coplanar [r.m.s. deviation 0.0047 (2) Å] and water O atoms are in the axial positions. The second carboxyl group of each ligand remains protonated. An additional H atom, located between adjacent coordinated water mol­ecules and observed on Fourier maps, maintains the charge balance within the monomers and bridges them by short symmetric hydrogen bonds of 2.518 (3) Å to form catenated ribbons. The monomers also inter­act via hydrogen bonds in which water and carboxyl O atoms act as donors.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.047
• wR factor = 0.117
• Data-to-parameter ratio = 16.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT241_ALERT_2_B Check High      Ueq as Compared to Neighbors for        Li1

Alert level C
RINTA01_ALERT_3_C  The value of Rint is greater than 0.12
            Rint given   0.160
PLAT213_ALERT_2_C Atom Li1             has ADP max/min Ratio .....       3.30 prola
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       3.98
PLAT313_ALERT_2_C Oxygen with three covalent bonds (rare) ........         O6
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          2

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n
PLAT180_ALERT_4_G Check Cell Rounding: # of Values Ending with 0 =          3
PLAT764_ALERT_4_G Overcomplete CIF Bond List Detected (Rep/Expd) .       1.29 Ratio

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

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

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S1. Comment

Studies of 3d metal complexes with pyridazine-3,6-dicarboxylate and water ligands revealed a variety of structures: from a monomeric anion in an ionic complex [Mg{C₆H₂N₂O₄)₂(H₂O)₂}]^2-(N₂H₆)²⁺ (Gryz et al., 2004) and dimeric molecules as in Ni, Co and Zn complexes (Escuer et al., 1997; Gryz et al., 2006; Sun et al., 2008) to coordination polymers as in Mn^II complexes (El Gueddi et al., 1996; Sun et al., 2007, 2008). The structure of a Pb^II complex shows also a polymeric pattern (Sobanska et al., 1999). The structure of the title compound is composed of monomers in which a Li^I ion located in a centre of symmetry is chelated by two N,O bonding groups donated by two symmetry related ligand molecules and by two symmetry related aqua O atoms in axial positions. The coordination is slightly distorted octahedral. The ligand molecules and a Li^I ion are coplanar [r.m.s. 0.0047 (2) Å]. The second carboxylic group of each ligand remains protonated and makes an angle of 5.9 (1)° with the pyridazine plane. Bond lengths and angles within the ligand ring are close to those reported earlier for both structures of the parent acid (Suecur et al., 1987; Starosta & Leciejewicz, 2004). An additional proton in a special position located between coordinated water molecules is clearly observed on Fourier maps. It maintains the charge balance within monomers and bridges them by short symmetric hydrogen bonds of 2.518 (3) Å with O6—H63—O6⁽ⁱⁱ⁾ angle of 180° to form catenated ribbons. Symmetry code: (ii) -x + 1, -y, -z + 2. The latter are held together via hydrogen bonds in which water and protonated carboxylate O atoms act as donors and carboxylate O atoms and hetero-N atoms in adjacent ribbons as acceptors.

Related literature

For the crystal structures of 3d metal complexes with pyridazine-3,6-dicarboxylate and water ligands, see: El Gueddi et al. (1996); Escuer et al. (1997); Gryz et al. (2006); Sun et al. (2007, 2008). For the structures of complexes with Mg^II, see: Gryz et al. (2004). For the structures of complexes with Pb^II, see: Sobanska et al. (1999). For the structures of both modifications of pyridazine-3,6-dicarboxylic acid, see: Suecur et al. (1987); Starosta & Leciejewicz (2004).

S2. Experimental

The title compound was synthesized by mixing of boiling aqueous solutions, one containing 1 mmol of pyridazine-3,6-dicarboxylic acid, the other - 1 mmol of lithium hydroxide (Aldrich). The mixture was boiled under reflux for 3 h and after cooling to room temperature, filtered and left to crystallize. Few days later, colourless single crystals in the form of thin plates were found after evaporation to dryness. They were extracted, washed with cold ethanol and dried in the air.

S3. Refinement

Water H atoms were located in a difference map and were allowed to ride on the parent atom with U_iso(H) = 1.5U_eq(O). H atoms attached to pyridazine-ring C atoms were located at calculated positions and treated as riding on the parent atoms, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: KM-4 (Kuma, 1996); cell refinement: KM-4 (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

	Fig. 1. A structural unit of title compound with atom labelling scheme. Displacement ellipsoids are drawn at 50% probability level. Symmetry codes: (i) -x, -y, -z + 1; (ii) -x + 1, -y, -z + 2.
	Fig. 2. Packing diagram of the structure.

Bis[[(6-carboxypyridazine-3-carboxylato- κ²N²,O³)lithium]-µ-pentahydrogendioxygen(1+)]

Crystal data

[Li(C6H3N2O4)2(H5O2)]	F(000) = 388
Mr = 378.19	Dx = 1.694 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 4.903 (1) Å	Cell parameters from 25 reflections
b = 24.640 (5) Å	θ = 6–15°
c = 6.6020 (13) Å	µ = 0.15 mm^−1
β = 111.60 (3)°	T = 295 K
V = 741.6 (3) Å^3	Plate, colourless
Z = 2	0.42 × 0.39 × 0.07 mm

Data collection

Kuma KM-4 four-circle diffractometer	1207 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.160
Graphite monochromator	θmax = 30.1°, θmin = 1.7°
profile data from ω/2θ–scans	h = −6→6
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008)	k = 0→34
Tmin = 0.961, Tmax = 0.999	l = −9→9
4355 measured reflections	3 standard reflections every 200 reflections
2181 independent reflections	intensity decay: 0.8%

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.117	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0251P)^2 + 0.0008P] where P = (Fo^2 + 2Fc^2)/3
2181 reflections	(Δ/σ)max < 0.001
135 parameters	Δρmax = 0.40 e Å^−3
3 restraints	Δρmin = −0.31 e Å^−3

Special details

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 > 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
N1	0.1189 (4)	0.08134 (5)	0.4137 (2)	0.0216 (3)
O1	−0.1491 (4)	0.04967 (4)	0.6760 (2)	0.0308 (3)
O3	0.5111 (3)	0.11620 (5)	0.0040 (2)	0.0288 (3)
O2	−0.2209 (3)	0.13593 (5)	0.7509 (2)	0.0297 (3)
C5	0.2683 (4)	0.14735 (6)	0.2292 (3)	0.0208 (4)
N2	0.2452 (4)	0.09550 (5)	0.2750 (2)	0.0215 (3)
C2	0.0209 (4)	0.11977 (6)	0.5110 (2)	0.0196 (3)
C7	−0.1279 (4)	0.10016 (6)	0.6606 (2)	0.0208 (4)
C8	0.4088 (4)	0.15946 (6)	0.0675 (3)	0.0226 (4)
O4	0.4208 (4)	0.20499 (4)	0.0057 (2)	0.0405 (4)
C4	0.1727 (5)	0.18911 (6)	0.3287 (3)	0.0264 (4)
H4	0.1930	0.2253	0.2965	0.032*
C3	0.0479 (5)	0.17513 (6)	0.4753 (3)	0.0253 (4)
H3	−0.0165	0.2014	0.5486	0.030*
Li1	0.0000	0.0000	0.5000	0.0588 (19)
O6	0.4949 (4)	−0.00562 (5)	0.8091 (2)	0.0415 (4)
H61	0.606 (6)	0.0181 (8)	0.792 (4)	0.062*
H62	0.558 (6)	−0.0364 (7)	0.807 (4)	0.062*
H31	0.617 (7)	0.1250 (8)	−0.089 (4)	0.042 (7)*
H63	0.5000	0.0000	1.0000	0.080 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0282 (8)	0.0198 (6)	0.0270 (7)	0.0007 (5)	0.0221 (6)	0.0017 (5)
O1	0.0433 (9)	0.0227 (5)	0.0420 (7)	−0.0012 (5)	0.0339 (6)	0.0023 (5)
O3	0.0415 (9)	0.0237 (5)	0.0362 (7)	0.0014 (5)	0.0319 (6)	0.0020 (5)
O2	0.0401 (9)	0.0289 (6)	0.0350 (7)	0.0004 (5)	0.0311 (5)	−0.0016 (4)
C5	0.0247 (9)	0.0204 (6)	0.0235 (7)	−0.0007 (7)	0.0160 (6)	0.0004 (5)
N2	0.0295 (9)	0.0200 (5)	0.0245 (7)	0.0004 (6)	0.0211 (6)	0.0018 (5)
C2	0.0234 (9)	0.0205 (6)	0.0215 (7)	−0.0009 (6)	0.0162 (6)	0.0000 (5)
C7	0.0215 (9)	0.0260 (7)	0.0221 (7)	−0.0010 (6)	0.0162 (6)	0.0000 (5)
C8	0.0289 (10)	0.0216 (7)	0.0243 (7)	−0.0016 (6)	0.0182 (7)	−0.0013 (5)
O4	0.0689 (11)	0.0230 (6)	0.0506 (8)	−0.0029 (7)	0.0465 (7)	0.0046 (5)
C4	0.0384 (12)	0.0187 (6)	0.0308 (9)	0.0008 (7)	0.0229 (8)	0.0013 (6)
C3	0.0352 (11)	0.0195 (7)	0.0312 (9)	0.0001 (7)	0.0239 (7)	−0.0029 (6)
Li1	0.108 (6)	0.0194 (19)	0.095 (4)	−0.006 (3)	0.091 (4)	−0.001 (2)
O6	0.0709 (13)	0.0209 (6)	0.0542 (9)	−0.0033 (6)	0.0484 (8)	0.0009 (5)

Geometric parameters (Å, º)

N1—N2	1.327 (2)	C2—C7	1.507 (3)
N1—C2	1.330 (2)	C8—O4	1.2024 (19)
N1—Li1	2.2194 (14)	C4—C3	1.366 (3)
O1—C7	1.2558 (18)	C4—H4	0.9300
O1—Li1	2.0019 (15)	C3—H3	0.9300
O3—C8	1.311 (2)	Li1—O1^i	2.0020 (15)
O3—H31	0.96 (4)	Li1—N1^i	2.2195 (14)
O2—C7	1.241 (2)	Li1—O6	2.535 (2)
C5—N2	1.3274 (19)	Li1—O6^i	2.535 (2)
C5—C4	1.392 (2)	O6—H61	0.836 (18)
C5—C8	1.498 (3)	O6—H62	0.822 (16)
C2—C3	1.399 (2)	O6—H63	1.2600
N2—N1—C2	119.32 (13)	C2—C3—H3	121.3
N2—N1—Li1	130.38 (11)	O1—Li1—O1^i	180.0
C2—N1—Li1	110.08 (12)	O1—Li1—N1	77.50 (6)
C7—O1—Li1	119.98 (14)	O1^i—Li1—N1	102.50 (6)
C8—O3—H31	112.3 (14)	O1—Li1—N1^i	102.50 (6)
N2—C5—C4	122.17 (19)	O1^i—Li1—N1^i	77.50 (6)
N2—C5—C8	117.00 (16)	N1—Li1—N1^i	180.0
C4—C5—C8	120.82 (14)	O1—Li1—O6	90.68 (6)
C5—N2—N1	120.70 (16)	O1^i—Li1—O6	89.32 (6)
N1—C2—C3	122.66 (18)	N1—Li1—O6	89.54 (5)
N1—C2—C7	115.88 (13)	N1^i—Li1—O6	90.46 (5)
C3—C2—C7	121.45 (17)	O1—Li1—O6^i	89.32 (6)
O2—C7—O1	127.48 (19)	O1^i—Li1—O6^i	90.68 (6)
O2—C7—C2	116.05 (14)	N1—Li1—O6^i	90.46 (5)
O1—C7—C2	116.45 (16)	N1^i—Li1—O6^i	89.54 (5)
O4—C8—O3	125.3 (2)	O6—Li1—O6^i	180.0
O4—C8—C5	121.33 (18)	Li1—O6—H61	109.5 (17)
O3—C8—C5	113.34 (14)	Li1—O6—H62	106.8 (17)
C3—C4—C5	117.69 (15)	H61—O6—H62	112 (3)
C3—C4—H4	121.2	Li1—O6—H63	117.00
C5—C4—H4	121.2	H61—O6—H63	107.00
C4—C3—C2	117.40 (17)	H62—O6—H63	104.00
C4—C3—H3	121.3

Symmetry code: (i) −x, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O6—H63···O6^ii	1.26	1.26	2.518 (3)	180
O6—H61···O1^iii	0.84 (2)	1.82 (2)	2.608 (2)	157 (3)
O3—H31···O2^iv	0.96 (4)	1.56 (4)	2.525 (2)	176 (2)
O6—H62···O3^v	0.82 (2)	2.42 (2)	2.9957 (19)	128 (3)
O6—H62···N2^v	0.82 (2)	1.93 (2)	2.712 (2)	159 (3)

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