Poly[μ2-aqua-μ2-(pyrazine-2-carboxyl­ato)-lithium]

Wojciech Starosta; Janusz Leciejewicz

doi:10.1107/S1600536812024683

. 2012 Jun 16;68(Pt 7):m933–m934. doi: 10.1107/S1600536812024683

Poly[μ₂-aqua-μ₂-(pyrazine-2-carboxylato)-lithium]

Wojciech Starosta ^a, Janusz Leciejewicz ^a,^*

PMCID: PMC3393196 PMID: 22807764

Abstract

The structure of the title compound, [Li(C₅H₃N₂O₂)(H₂O)]_n, contains an Li^I ion with a distorted trigonal–bipyramidal coordination environment involving the N and O atoms of pyrazine-2-carboxylate ligands with a bridging carboxylate group, and two aqua O atoms also in a bridging mode. The symmetry-related Li^I ions bridged by a carboxylate O atom and a coordinating water O atom form an Li₂O₂ unit with an Li⋯Li distance of 3.052 (4) Å, which generates molecular ribbons propagating in the c-axis direction. The ribbons are held together by a network of O—H⋯O hydrogen bonds in which the coordinating water molecules act as donors and the carboxylate O atoms as acceptors.

Related literature

For the crystal structure of an Li^I complex with a 3-aminopyrazine-2-carboxylate ligand, see: Starosta & Leciejewicz, (2010 ▶) and for the crystal structure of an Li^I complex with a 5-methylpyrazine-2-carboxylate ligand, see: Starosta & Leciejewicz, (2011a ▶). The structures of complexes with pyridazine-3-carboxylate and pyridazine-4-carboxylate ligands were reported by Starosta & Leciejewicz, (2011b ▶,c ▶). The structure of a complex with a pyrimidine-2-carboxylate ligand was also determined (Starosta & Leciejewicz, 2011d ▶).

Experimental

Crystal data

[Li(C₅H₃N₂O₂)(H₂O)]
M _r = 148.05
Orthorhombic,
a = 24.433 (5) Å
b = 4.7861 (10) Å
c = 5.6385 (11) Å
V = 659.4 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 293 K
0.35 × 0.18 × 0.13 mm

Data collection

Kuma KM-4 four-cricle diffractometer
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008 ▶) T _min = 0.972, T _max = 0.995
1586 measured reflections
1056 independent reflections
813 reflections with I > 2σ(I)
R _int = 0.078
3 standard reflections every 200 reflections intensity decay: 4.4%

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.116
S = 1.09
1056 reflections
108 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.30 e Å⁻³

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, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812024683/kp2421sup1.cif

e-68-0m933-sup1.cif^{(13.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812024683/kp2421Isup2.hkl

e-68-0m933-Isup2.hkl^{(52.3KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812024683/kp2421Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Li1—O1	2.080 (6)
Li1—N1	2.190 (6)
Li1—O3	2.013 (6)
Li1—O3ⁱ	2.032 (5)
Li1—O1ⁱ	2.237 (6)

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Symmetry code: (i) Inline graphic .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H31⋯O1ⁱⁱ	0.83 (5)	1.96 (5)	2.786 (3)	176 (5)
O3—H32⋯O2ⁱⁱⁱ	0.94 (4)	1.75 (4)	2.672 (3)	167 (4)

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Symmetry codes: (ii) Inline graphic ; (iii) .

supplementary crystallographic information

Comment

The structure of the title complex is built of Li^I ions, each coordinated by ligand with N1,O1 where O atom acts as bidentate and bridging to symmetry related Li1 and Li1ⁱ ions, whereas the O2 atom remains chelating inactive. The metal ions are also bridged by coordinated water O3 atom forming a Li1—O1—Li1ⁱ—O3—Li1 connectivity with Li1—Li1ⁱ distance of 3.052 (4) Å, (Fig.1). The observed bonding pathways –Li—O_carb—Li- and –Li—O_aqua—Li- give rise to molecular ribbon which propagates in the unit cell c direction (Fig. 2). The Li1 coordination polyhedron is distorted trigonal bipyramid (Fig. 1, Table 1) with an equatorial plane composed of O1, N1ⁱ and O3ⁱ; the Li1 ion is 0.0405 (2) Å out of the plane, O1 and O3 atoms are at the axial positions. The pyrazine ring is planar with r.m.s. of 0.0019 (1) Å; the dihedral angle between the pyrazine and the carboxylato group (C7/O1/O2) is 12.3 (1)°. Hydrogen bonds are realised through coordinated aqua O3 and carboxylato O2 atoms (Table 2, Fig. 2). Weak C—H···N interactions of 3.518 (5) Å and 3.651 (5) Å are observed. The structures of Li^I complexes with diazine monocarboxylate ligands show a variety of polymeric patterns. The structure of a complex with 3-aminopyrazine-2-carboxylato ligand shows a catenated pattern (Starosta & Leciejewicz, 2010) while the structure of a complex with 5-methylpyrazine-2-carboxylato ligand is composed of molecular columns (Starosta & Leciejewicz, 2011a). Molecular layers were reported in the structure of a complex with pyrimidine-2-carboxylato and nitrato ligands (Starosta & Leciejewicz, 2011d) and in the structure of a complex with pyridazine-4-carboxylato ligand (Starosta & Leciejewicz, 2011c). On the other hand, the structure of a complex with pyridazine-3-carboxylato ligand is built of monomeric molecules (Starosta & Leciejewicz, 2011b).

Experimental

50 mL of a solution containing 1 mmol of LiNO₃ and an excess of pyrazine-2-carboxylic acid dihydrate to mantain pH ca 5.1 was boiled under reflux with stirring for 10 h, then left to crystallise at room temperature. After a couple of days single-crystal blocks of the title compound were detected among polycrystalline material. They were washed with methanol and dried in the air.