Poly[[diaqua­caesium(I)]bis­(μ₃-3-carboxy­pyrazine-2-carboxyl­ato)]

The asymmetric unit of the title compound, [Cs(C₆H₃N₂O₄)₂(H₂O)₂]_n, contains one Cs^I cation on an inversion centre, one 3-carboxy­pyrazine-2-carboxyl­ate anion and one water mol­ecule. In the crystal structure, each anion is linked to three cations, while each cation is surrounded by six of the anions. In addition, each cation is coordinated by two water O atoms, raising the coordination number to ten. In the crystal structure, inter­molecular O—H...O and O—H...N hydrogen bonds contribute to the stabilization of the structure.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.019
• wR factor = 0.052
• Data-to-parameter ratio = 14.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT354_ALERT_3_C Short   O-H Bond (0.82A)   O3     -   H5     ...       0.64 Ang.

Alert level G
PLAT804_ALERT_5_G ARU-Pack Problem in PLATON Analysis ............          3 Times

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

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

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S1. Comment

Metal dicarboxylates are known to form structures with varying dimensionalities, e.g. chains or layers, linked by the dicarboxylate anions (Rao et al., 2004). Since the single-crystal X-ray analysis of pyrazine-2,3 dicarboxylic acid was first determined (Takusagawa & Shimada, 1973), a variety of metal-organic compounds of pyrazine-2,3-dicarboxylic acid have been characterized crystallographically, due to growing interest in supramolecular chemistry. These include the calcium (Ptasiewicz-Bak & Leciejewicz, 1997a; Starosta & Leciejewicz, 2005) and magnesium (Ptasiewicz-Bak & Leciejewicz, 1997b) complexes. The title compound (I), was obtained as a colorless powder during an attempt to synthesize a borate ester product from the reaction of Cs₂CO₃ with B(OH)₃ and pyrazine-2,3-dicarboxylic acid, akin to the result for the sodium complex reported previously by our group (Tombul et al., 2006). We herein report its crystal structure.

The asymmetric unit of the title compound, (I), contains one caesium cation, one pyrazine-2,3-dicarboxylate anion and one water molecule (Fig. 1). The pyrazine-2,3-dicarboxylic acid is deprotonated at one of the carboxylate groups so that the crystal structure consists of Cs+ cations and pyrazine-2,3-dicarboxylate anions. Taking a larger domain of the crystal structure, the anion is linked to three cations, while the cation is surrounded by six of the anions, two of which are coordinated by N and O atoms and the remaining four anions are coordinated solely by O atoms. In addition, each caesium atom is coordinated by two water molecules, reaching the coordination number to ten. The inner coordination sphere accommodates eight oxygen atoms (O3, O4, O1ⁱ, O1ⁱⁱ, O3ⁱⁱⁱ, O2^iv, O4^iv and O3^v), together with two nitrogen atoms (N1 and N1ⁱ) [Symmetry Codes: (i) 2 - x, -1 - y, 1 - z, (ii) 1 + x, y, z, (iii) 2 - x, -y, 1 - z, (iv) 1 + x, -1 + y, z, (v) 3 - x, -1 - y, 1 - z]. The Cs—O distances are in the range of 3.099 (1)–3.372 (2) Å, in which they are in accordance with the corresponding values reported for other caesium complexes (Harnish et al., 1999; Wiesbrock & Schmidbaur, 2003; Hu et al., 2005).

In the crystal structure, the intermolecular O—H···O and O—H···N hydrogen bonds (Table 2, Fig. 2) may be effective in the stabilization of the structure.

Related literature

For general background, see: Rao et al. (2004); Takusagawa & Shimada (1973); Ptasiewicz-Bak & Leciejewicz (1997a); Starosta & Leciejewicz (2005); Ptasiewicz-Bak & Leciejewicz (1997b). For related literature, see: Tombul et al. (2006); Harnish et al. (1999); Wiesbrock & Schmidbaur (2003); Hu et al. (2005).

S2. Experimental

For the preperation of the title compound, (I), Cs2CO₃ (882 mg, 2.7 mmol) was carefully added to an aqueous solution (20 ml) containing pyrazine-2,3-di- carboxylic acid (1680 mg, 10 mmol) and B(OH)₃ (5 mmol, 0.31 g), until no bubbles escapes. The reaction mixture produced a colorless and clear solution, which was stirred at 333 K for 5 h, until all became solid. The solid product was redissolved in water (10 ml) and allowed to stand for 10 min at room temperature, whereupon transparent and fine crystals were harvested.

S3. Refinement

The pyrazine H atoms were positioned geometrically with C—H = 0.94 Å and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C). H atoms of carboxylate and water molecules were located in difference syntheses and refined isotropically [O—H = 0.64 (4)–0.83 (4) Å and U_iso(H) = 0.057 (9)–0.066 (9) Ų].

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Figures

	Fig. 1. A segment of the structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level [symmetry codes: (i) 2 - x, -1 - y, 1 - z, (ii) 1 + x, y, z, (iii) 2 - x, -y, 1 - z, (iv) 1 + x, -1 + y, z, (v) 3 - x, -1 - y, 1 - z].
	Fig. 2. A packing diagram for (I). The hydrogen bonds are shown as dashed lines [(1) O3—H(4)..N2, (2) O3—H5..O1, (3) O5—H3..O3].

Poly[[diaquacaesium(II)]bis(µ₃-3-carboxypyrazine-2-carboxylato)]

Crystal data

[Cs(C6H3N2O4)2(H2O)2]	Z = 1
Mr = 503.15	F(000) = 245
Triclinic, P1	Dx = 1.968 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.4801 (9) Å	Cell parameters from 22636 reflections
b = 7.6352 (9) Å	θ = 2.5–28.0°
c = 8.6505 (11) Å	µ = 2.24 mm^−1
α = 70.031 (9)°	T = 296 K
β = 81.126 (10)°	Prism, colorless
γ = 66.128 (9)°	0.52 × 0.47 × 0.42 mm
V = 424.55 (10) Å^3

Data collection

Stoe IPDS2 diffractometer	1968 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	1949 reflections with I > 2σ(I)
Plane graphite monochromator	Rint = 0.057
Detector resolution: 6.67 pixels mm^-1	θmax = 27.7°, θmin = 2.5°
rotation method scans	h = −9→9
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −9→9
Tmin = 0.382, Tmax = 0.471	l = −11→11
7683 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.019	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.052	w = 1/[σ^2(Fo^2) + (0.0343P)^2 + 0.0717P] where P = (Fo^2 + 2Fc^2)/3
S = 0.98	(Δ/σ)max < 0.001
1968 reflections	Δρmax = 0.45 e Å^−3
137 parameters	Δρmin = −0.72 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.187 (6)

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
Cs1	1.5000	−0.5000	0.5000	0.04315 (10)
O1	0.7652 (2)	−0.1628 (2)	0.3351 (2)	0.0447 (3)
O2	0.54073 (19)	0.3193 (2)	0.2006 (2)	0.0464 (3)
O3	1.6315 (3)	−0.2774 (3)	0.1162 (2)	0.0545 (4)
H4	1.719 (5)	−0.381 (6)	0.118 (4)	0.059 (8)*
H5	1.659 (5)	−0.228 (6)	0.147 (4)	0.057 (9)*
O4	1.0625 (2)	−0.3669 (2)	0.4303 (2)	0.0500 (4)
O5	0.6999 (2)	0.1627 (3)	0.0154 (2)	0.0507 (3)
H3	0.589 (5)	0.202 (6)	−0.020 (5)	0.066 (9)*
N1	1.1830 (2)	−0.0606 (2)	0.34310 (19)	0.0342 (3)
N2	0.9390 (2)	0.3245 (2)	0.1696 (2)	0.0378 (3)
C1	1.2381 (2)	0.0943 (3)	0.3004 (2)	0.0376 (3)
H1	1.3639	0.0727	0.3275	0.045*
C2	1.1156 (3)	0.2872 (3)	0.2169 (3)	0.0403 (4)
H2	1.1579	0.3942	0.1930	0.048*
C3	0.8866 (2)	0.1668 (2)	0.20647 (19)	0.0297 (3)
C4	1.0056 (2)	−0.0248 (2)	0.29693 (19)	0.0286 (3)
C5	0.6880 (2)	0.2210 (2)	0.1433 (2)	0.0331 (3)
C6	0.9360 (2)	−0.1975 (3)	0.3563 (2)	0.0332 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cs1	0.03439 (11)	0.03736 (11)	0.04492 (12)	−0.00218 (7)	−0.00804 (6)	−0.00818 (7)
O1	0.0369 (6)	0.0391 (7)	0.0612 (8)	−0.0182 (6)	−0.0151 (6)	−0.0086 (6)
O2	0.0287 (6)	0.0499 (8)	0.0663 (9)	−0.0114 (6)	−0.0034 (6)	−0.0280 (7)
O3	0.0501 (8)	0.0445 (8)	0.0754 (11)	−0.0075 (7)	−0.0265 (8)	−0.0279 (8)
O4	0.0350 (6)	0.0290 (6)	0.0762 (10)	−0.0138 (5)	−0.0103 (7)	0.0014 (6)
O5	0.0401 (7)	0.0623 (9)	0.0481 (7)	−0.0066 (7)	−0.0147 (6)	−0.0247 (7)
N1	0.0282 (6)	0.0320 (6)	0.0403 (7)	−0.0109 (5)	−0.0050 (5)	−0.0073 (6)
N2	0.0341 (7)	0.0291 (6)	0.0481 (8)	−0.0135 (6)	−0.0073 (6)	−0.0049 (6)
C1	0.0286 (7)	0.0393 (9)	0.0472 (9)	−0.0163 (7)	−0.0045 (7)	−0.0101 (7)
C2	0.0349 (8)	0.0347 (8)	0.0539 (10)	−0.0185 (7)	−0.0047 (7)	−0.0084 (7)
C3	0.0275 (7)	0.0299 (7)	0.0315 (6)	−0.0110 (6)	−0.0027 (6)	−0.0083 (6)
C4	0.0277 (6)	0.0282 (7)	0.0310 (6)	−0.0116 (6)	−0.0018 (6)	−0.0088 (5)
C5	0.0305 (7)	0.0286 (7)	0.0394 (8)	−0.0109 (6)	−0.0069 (6)	−0.0073 (6)
C6	0.0338 (7)	0.0299 (7)	0.0378 (7)	−0.0145 (6)	−0.0042 (6)	−0.0084 (6)

Geometric parameters (Å, º)

Cs1—O1^i	3.188 (2)	O4—C6	1.268 (2)
Cs1—O1^ii	3.188 (2)	O5—C5	1.305 (2)
Cs1—O2^iii	3.249 (1)	O5—H3	0.83 (4)
Cs1—O2^iv	3.249 (2)	N1—C1	1.325 (2)
Cs1—O3	3.372 (2)	N1—C4	1.338 (2)
Cs1—O3^i	3.372 (2)	N2—C2	1.333 (2)
Cs1—O4	3.099 (1)	N2—C3	1.336 (2)
Cs1—O4^i	3.099 (1)	C1—C2	1.384 (3)
Cs1—N1	3.188 (2)	C1—H1	0.9400
Cs1—N1^i	3.188 (2)	C2—H2	0.9400
O1—C6	1.226 (2)	C4—C3	1.387 (2)
O2—C5	1.200 (2)	C5—C3	1.509 (2)
O3—H4	0.79 (4)	C6—C4	1.511 (2)
O3—H5	0.64 (4)
H4—O3—H5	109 (4)	N2—C3—C5	113.30 (14)
C5—O5—H3	109 (2)	C4—C3—C5	124.88 (13)
C1—N1—C4	117.24 (15)	N1—C4—C3	120.82 (14)
C2—N2—C3	116.75 (15)	N1—C4—C6	117.40 (15)
N1—C1—C2	121.84 (15)	C3—C4—C6	121.66 (14)
N1—C1—H1	119.1	O2—C5—O5	125.96 (17)
C2—C1—H1	119.1	O2—C5—C3	121.64 (15)
N2—C2—C1	121.40 (15)	O5—C5—C3	112.19 (14)
N2—C2—H2	119.3	O1—C6—O4	126.00 (15)
C1—C2—H2	119.3	O1—C6—C4	118.73 (16)
N2—C3—C4	121.81 (14)	O4—C6—C4	115.22 (14)
C4—N1—C1—C2	2.4 (3)	C6—C4—C3—C5	−6.3 (2)
C1—N1—C4—C3	0.7 (2)	O2—C5—C3—N2	−69.7 (2)
C1—N1—C4—C6	−175.48 (15)	O5—C5—C3—N2	105.33 (18)
C3—N2—C2—C1	−0.1 (3)	O2—C5—C3—C4	109.1 (2)
C2—N2—C3—C4	3.2 (2)	O5—C5—C3—C4	−75.9 (2)
C2—N2—C3—C5	−177.92 (16)	O1—C6—C4—N1	170.21 (16)
N1—C1—C2—N2	−2.8 (3)	O4—C6—C4—N1	−7.3 (2)
N1—C4—C3—N2	−3.7 (2)	O1—C6—C4—C3	−6.0 (2)
C6—C4—C3—N2	172.36 (15)	O4—C6—C4—C3	176.54 (16)
N1—C4—C3—C5	177.61 (15)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H3···O3^v	0.83 (1)	1.76 (1)	2.577 (1)	172.70 (3)
O3—H4···N2^iii	0.79 (1)	2.13 (1)	2.907 (1)	169.64 (3)
O3—H5···O1^ii	0.64 (1)	2.19 (1)	2.788 (1)	157.14 (3)

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