catena-Poly[[tetra­aqua-μ-aqua-bis­(μ4-pyrimidine-2-carboxyl­ato)tetra­lithium] dichloride]

Wojciech Starosta; Janusz Leciejewicz

doi:10.1107/S1600536812041955

. 2012 Oct 20;68(Pt 11):m1369–m1370. doi: 10.1107/S1600536812041955

catena-Poly[[tetraaqua-μ-aqua-bis(μ₄-pyrimidine-2-carboxylato)tetralithium] dichloride]

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

PMCID: PMC3515122 PMID: 23284349

Abstract

The asymmetric unit of the title compound, [Li₄(C₅H₃N₂O₂)₂(H₂O)₅]Cl₂, contains two Li^I cations, one with a distorted trigonal–bipyramidal and the other with a distorted tetrahedral coordination geometry. Two symmetry-related asymmetric units constitute a building block of the structure, in which both ligand carboxylate O atoms are bidentate and bridge the metal ions, forming a divalent cation. Charge balance is maintained by two chloride anions. The building blocks, bridged by Li^I cations, form cationic ribbons with chloride anions in the space between them. The ribbons propagate in [010] and are held together by a network of weak O—H⋯O hydrogen bonds which operate in the space between adjacent ribbons.

Related literature

For the structure of a Li complex with pyrimidine-2-carboxylate and nitrate ligands, see: Starosta & Leciejewicz (2011 ▶). The structure of a Li^I complex with pyrimidine-4-carboxylate and water ligands was reported recently by Starosta & Leciejewicz (2012 ▶).

Experimental

Crystal data

[Li₄(C₅H₃N₂O₂)₂(H₂O)₅]Cl₂
M _r = 434.93
Monoclinic,
a = 22.084 (4) Å
b = 8.0773 (16) Å
c = 10.814 (2) Å
β = 94.08 (3)°
V = 1924.1 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.39 mm⁻¹
T = 293 K
0.37 × 0.24 × 0.18 mm

Data collection

Kuma KM4 four-circle diffractometer
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008 ▶) T _min = 0.917, T _max = 0.935
2964 measured reflections
2819 independent reflections
1781 reflections with I > 2σ(I)
R _int = 0.029
3 standard reflections every 200 reflections intensity decay: 2.3%

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.147
S = 1.02
2819 reflections
152 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.36 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

Click here for additional data file.^{(16.7KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812041955/qm2084sup1.cif

e-68-m1369-sup1.cif^{(16.7KB, cif)}

Click here for additional data file.^{(138.5KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812041955/qm2084Isup2.hkl

e-68-m1369-Isup2.hkl^{(138.5KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Li1—O1	2.069 (3)
Li1—N1	2.175 (4)
Li1—O3	1.987 (4)
Li1—O2ⁱ	2.029 (4)
Li1—N3ⁱ	2.221 (4)
Li2—O21	2.140 (6)
Li2—O22	1.915 (4)
Li2—O2ⁱⁱ	1.968 (4)
Li2—O1	1.993 (4)

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O22—H222⋯O3	0.89 (2)	2.16 (3)	2.841 (3)	133 (3)
O22—H221⋯Cl1ⁱⁱⁱ	0.87 (2)	2.36 (2)	3.212 (2)	167 (3)
O3—H31⋯Cl1	0.83 (4)	2.35 (4)	3.1381 (19)	158 (3)
O3—H32⋯Cl1^iv	0.86 (4)	2.29 (4)	3.1429 (19)	168 (4)
O21—H211⋯Cl1^v	0.84 (3)	2.45 (3)	3.288 (2)	175 (3)

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Symmetry codes: (iii) Inline graphic ; (iv) ; (v) .

supplementary crystallographic information

Comment

The asymmetric cell of the title compound contains two symmetry independent Li^I ions, one deprotonated pyramidine-2-carboxylatato ligand molecule, three symmetry independent water molecules which are coordinated to metal ions and one chloride anion. The latter maintains charge balance in the cell. Two symmetry related cells form a molecular moiety which can be visualized as a building unit of the structure (Fig. 1).The ligand bridges Li ions in a µ₄ mode using both its carboxylate O atoms which act as bidentate. Ligand bonding groups N1,O1 and N3,O2 chelate Li1 and Liⁱⁱ ions; the O1 and O2 atoms are also bonded to Li2 and Li2ⁱ ions, respectively. Since the Li1 and Li1ⁱⁱ ions are also coordinated by bonding groups from adjacent symmetry related ligands, a –Li1ⁱⁱ—O2—O1—Li1—O2ⁱⁱⁱO1ⁱⁱⁱ—Li1ⁱⁱⁱ– bridging pathway is formed. Apart from two N,O bonding groups, Li1 coordination is completed by an aqua O3 atom. On the other hand, pairs of adjacent symmetry related Li2 and Li2ⁱ ions are bridged by an aqua O21 atom while the other coordinated to them aqua O22 and O22ⁱ atoms are not bridging. Symmetry code: ⁱ -x, y, -z + 1/2; ⁱⁱx, -y + 2, z - 1/2; ⁱⁱⁱx, -y + 2, z + 1/2. Adjacent moieties linked along the Li1 bridging pathway form a cationic ribbon propagating in the unit cell b direction (Fig. 2). Chloride anions are located in the space between adjacent ribbons. Fig. 1 shows, that a ribbon can be visualized as built of centro-symmetric molecular clusters in which Li ions form a tetrameric entities additionally connected by Li2—O21—Li2ⁱ bridges. The Li1 ion exhibits a distorted trigonal bipyramidal coordination environment in which O1, O3 and N3ⁱⁱⁱ atoms form an equatorial plane with a Li1 ion 0.0619 (2) Å out of it; N1 and O2ⁱⁱⁱ atoms are at apical positions. The coordination of the Li2 ion is strongly distorted tetrahedral. The Li—O and Li—N bond distances (Table 1) are close to those reported in the structures of a Li complex with the title and nitrate ligands (Starosta & Leciejewicz, 2011) and pyrimidine-4-carboxylate and water ligands (Starosta & Leciejewicz, 2012). The pyrimidine ring is planar with r.m.s. of 0.0071 (1) Å; the C7/O1/O2 makes with it a dihedral angle of 5.8 (1)°. Weak hydrogen bonds in which water O atoms are as donors and chloride anions act as acceptors operate between adjacent ribbons (Table 2).

Experimental

1 mmol of methyl pyrimidine-2-carboxylate and ca2 mmol s of lithium hydroxide dissolved in 50 ml of hot, doubly distilled water were boiled under reflux with stirring for twenty hours. After evaporation to dryness at room temperature the polycrystalline material was dissolved in 50 ml of water. The solution was titrated with 1 N HCl until the pH reached 6.0 and then stirred for 3 h at ca 320 K. Left to crystallize at room temperature, colourless single-crystal blocks deposited after a week. They were washed with cold methanol and dried in the air.