catena-Poly[[diaqua­rubidium(I)](μ2-3-carboxy­pyrazine-2-carboxyl­ato)(μ2-pyrazine-2,3-dicarboxylic acid)]

Tombul, M.; Guven, K.

doi:10.1107/S1600536809002001

metal-organic compounds

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ISSN: 2056-9890

Volume 65| Part 2| February 2009| Pages m213-m214

doi:10.1107/S1600536809002001

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catena-Poly[[diaquarubidium(I)](μ₂-3-carboxypyrazine-2-carboxylato)(μ₂-pyrazine-2,3-dicarboxylic acid)]

Mustafa Tombul ^a ^* and Kutalmis Guven ^b

^aDepartment of Chemistry, Faculty of Art and Science, University of Kırıkkale, Campus, Yahsihan, 71450 Kırıkkale, Turkey, and ^bDepartment of Physics, Faculty of Art and Science, University of Kirikkale, Campus, Yahsihan, 71450 Kırıkkale, Turkey
^*Correspondence e-mail: mustafatombul38@gmail.com

(Received 25 November 2008; accepted 15 January 2009; online 23 January 2009)

The structural unit of the title compound, [Rb(C₆H₃N₂O₄)(C₆H₄N₂O₄)(H₂O)₂]_n, consists of one rubidium cation, one hydrogen pyrazine-2,3-dicarboxylate anion, one pyrazine-2,3-dicarboxylic acid molecule and two water molecules. This formulation is repeated twice in the asymmetric unit as the rubidium cation lies on an inversion centre. Each anion or acid molecule is linked to two rubidium cations, while the rubidium cation has close contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each rubidium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid holds its H atom, which forms a hydrogen bond to a coordinated water molecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O—H⋯O hydrogen bond disordered over an inversion centre. The stabilization of the crystal structure is further assisted by O—H⋯O and O—H⋯N hydrogen-bonding interactions involving the water molecules and carboxylate O atoms.

Related literature

Pyrazine-2,3-dicarboxylic acid (Takusagawa & Shimada, 1973 ) and its dianion (Richard et al., 1973 ; Nepveu et al., 1993 ) have been used in the construction of multi-dimensional frameworks. A variety of metal–pyrazine-2,3-dicarboxylic acid complexes have been characterized, including the calcium (Ptasiewicz-Bak & Leciejewicz, 1997a ; Starosta & Leciejewicz, 2005 ), magnesium (Ptasiewicz-Bak & Leciejewicz, 1997b ), sodium (Tombul et al., 2006 ), caesium (Tombul et al., 2007 ), potassium (Tombul et al., 2008a ) and lithium (Tombul et al., 2008b ) complexes. For Rb—N bond lengths, see: Yang et al. (2008 ); Cametti et al. (2005 ); Wiesbrock & Schmidbaur (2003 ); Shannon (1976 ); Devi & Vidyasagar (2000 ).

Experimental

Crystal data

[Rb(C₆H₃N₂O₄)(C₆H₄N₂O₄)(H₂O)₂]
M_r = 456.72
Triclinic, $[P \overline 1]$
a = 7.452 (2) Å
b = 7.8640 (15) Å
c = 8.3280 (12) Å
α = 69.111 (12)°
β = 81.424 (19)°
γ = 65.322 (18)°
V = 414.32 (16) Å³
Z = 1
Mo Kα radiation
μ = 3.05 mm⁻¹
T = 298 (2) K
0.20 × 0.15 × 0.06 mm

Data collection

Rigaku AFC-7S diffractometer
Absorption correction: numerical (Clark & Reid, 1995 ) T_min = 0.581, T_max = 0.838
5329 measured reflections
5057 independent reflections
1604 reflections with I > 2σ(I)
R_int = 0.048
3 standard reflections every 150 reflections intensity decay: none

Refinement

R[F² > 2σ(F²)] = 0.053
wR(F²) = 0.219
S = 0.98
5057 reflections
133 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.35 e Å⁻³
Δρ_min = −1.91 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

Rb1—O3ⁱ	2.987 (3)
Rb1—N2ⁱⁱ	3.007 (3)
Rb1—O5	3.096 (4)
Rb1—O1	3.137 (3)
Symmetry codes: (i) -x+1, -y+1, -z; (ii) x+1, y-1, z.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1⋯O3^iv	0.93	1.55 (1)	2.468 (3)	170 (1)
O5—H5A⋯N1	0.84 (9)	2.07 (9)	2.888 (3)	168 (7)
O5—H5B⋯O4^v	0.82 (6)	1.94 (6)	2.753 (3)	170.39 (5)
O2—H2⋯O5^vi	0.82	1.79	2.596 (6)	166 (1)
Symmetry codes: (iv) -x+1, -y+2, -z; (v) x, y-1, z; (vi) -x+2, -y, -z+1.

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1997 $[Molecular Structure Corporation (1997). TEXSAN for Windows and MSC/AFC Diffractometer Control Software. MSC, The Woodlands, Texas, USA.]$ ); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1997 $[Molecular Structure Corporation (1997). TEXSAN for Windows and MSC/AFC Diffractometer Control Software. MSC, The Woodlands, Texas, USA.]$ ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006 ); software used to prepare material for publication: publCIF (Westrip, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809002001/hg2450sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809002001/hg2450Isup2.hkl

checkCIF report

Comment top

Pyrazine-2,3-dicarboxylic acid (Takusagawa & Shimada, 1973) and its dianion (Richard et al., 1973; Nepveu et al., 1993) have been reported to be well suited for the construction of multidimensional frameworks (nD, n = 1–3), owing to the presence of two adjacent carboxylate groups (O donor atoms) as substituents on the N-heterocyclic pyrazine ring (N donor atoms). In recent years, a variety of metal-organic compound of pyrazine-2,3-dicarboxylic acid have been characterized crystallographically owing to growing interest in supramolecular chemistry. Examples are including the calcium (Ptasiewicz-Bak & Leciejewicz, 1997a; Starosta & Leciejewicz, 2005), magnesium (Ptasiewicz-Bak & Leciejewicz, 1997b), sodium (Tombul et al., 2006), caesium (Tombul et al., 2007) and potassium (Tombul et al., 2008a) and lithium (Tombul et al., 2008b) complexes. Continuation our research on Group I dicarboxylates, we present here the synthesis and crystal structure of the hydrated polymeric rubidium complex, (I), formed with pyrazine-2,3-dicarboxylic acid.

The structural unit of the title compound, (I), contains one rubidium cation, one hydrogen pyrazine-2,3-dicarboxylate anion, one pyrazine-2,3-dicarboxylic acid molecule and two water molecules; this is twice in the asymmetric unit, since the rubidium ion lies on an inversion centre. This compound is isostructural with the corresponding potassium and caesium complexes, which are fully described previously (Tombul et al., 2008a; Tombul et al., 2007). Pyrazine-2,3-dicarboxylic acid is, on average, only half deprotonated at one of the carboxylate groups (O3ⁱⁱ and O3ⁱⁱⁱ) complete the charge balance of the cation. Taking a larger domain of the crystal structure, the anion or acid molecule is linked to two rubidium cations, while the Rb⁺ cation is surrounded by four organic ligands, two of which are coordinated by employing both N and O atoms and the other two are coordinated solely by O atoms. In addition, each rubidium cation is coordinated by two water molecules, raising a coordination number of eight. The inner coordination sphere accommodates comprises six oxygen atoms (O1, O1ⁱ, O3ⁱⁱ, O3ⁱⁱⁱ, O5 and O5ⁱ), together with two nitrogen atoms (N2ⁱⁱ and N2ⁱⁱⁱ). The planes of the carboxylic/carboxylate groups (O1/C1/C2/O2) and (O3/C6/C5/O4) form dihedral angles with the ring (C2/C3/C4/C5/N1/N2) plane of 75.87 (16) and 6.65 (21), respectively. The Rb—O distances are in the range from 2.987 (3) Å to 3.137 (3) Å, which are well within the range reported in the literature for other rubidium complexes (Yang et al. 2008; Cametti et al., 2005; Wiesbrock & Schmidbaur, 2003; Shannon, 1976; Devi & Vidyasagar, 2000). Rb—N bond lengths also lie within the normal ranges found for similar bonds in the literature (Yang et al. 2008).

In the crystal structure, an asymmetric strong hydrogen bond occurs, linking carboxylate O atoms O—H···O [O···O = 2.468 (3) 2.596 (2) Å respectively]. Atom H1 is involved in this bond and maintains the charge balance within the structure. The water molecules are involved in normal, slightly bent, hydrogen bonds with hydrogen pyrazine-2,3-dicarboxylate (Table 2); the acceptors are carboxylate O atoms and N atoms of the aromatic ring. The polymeric complex is linked in a three-dimensional manner by further numerous intermolecular O—H···O and O—H···N hydrogen bonds (Fig. 2 and Table 2)

Related literature top

Pyrazine-2,3-dicarboxylic acid (Takusagawa & Shimada, 1973) and its dianion (Richard et al., 1973; Nepveu et al., 1993) Forhave been used in the construction of multi-dimensional frameworks. A variety of metal–pyrazine-2,3-dicarboxylic acid complexes have been characterized, including the calcium (Ptasiewicz-Bak & Leciejewicz, 1997a; Starosta & Leciejewicz, 2005), magnesium (Ptasiewicz-Bak & Leciejewicz, 1997b), sodium (Tombul et al., 2006), caesium (Tombul et al., 2007), potassium (Tombul et al., 2008a) and lithium (Tombul et al., 2008b) complexes. For Rb—N bond lengths, see: Yang et al. (2008); Cametti et al. (2005); Wiesbrock & Schmidbaur (2003); Shannon (1976); Devi & Vidyasagar (2000).

Experimental top

Rb~2~CO~3~ (462 mg, 2 mmol) was carefully added to an aqueous solution (20 ml) of pyrazine 2,3-dicarboxylic acid (672 mg, 4 mmol), until no further bubbles formed. The reaction mixture produced a colourless and clear solution which was stirred at 323 K for 200 min., until it solidified. The solid product was then redissolved in water (5 ml) and allowed to stand for three days at ambient temperature, after which transparent fine crystals were harvested.

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1997); cell refinement: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1997); data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2009).

Figures top

	Fig. 1. A perspective view diagram of the structure of (I) together with asymmetric units. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) 1 - x, 1 - y, -z, (ii) 1 + x, y - 1, z, (iii) -x + 2, -y, -z, (vii) x - 1, y + 1, z].
	Fig. 2. Hydrogen bongd diagram of (I). Dashed lines indicate hydrogen bonds. (H atoms of carbons were ommited for clarity).

catena-Poly[[diaquarubidium(I)](µ₂-3-carboxypyrazine-2- carboxylato)(µ₂-pyrazine-2,3-dicarboxylic acid)] top

Crystal data top

[Rb(C₆H₃N₂O₄)(C₆H₄N₂O₄)(H₂O)₂]	Z = 1
M_r = 456.72	F(000) = 228
Triclinic, P1	D_x = 1.830 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.452 (2) Å	Cell parameters from 25 reflections
b = 7.8640 (15) Å	θ = 2.6–9.2°
c = 8.3280 (12) Å	µ = 3.05 mm⁻¹
α = 69.111 (12)°	T = 298 K
β = 81.424 (19)°	Prism, colourless
γ = 65.322 (18)°	0.20 × 0.15 × 0.06 mm
V = 414.32 (16) Å³

Data collection top

Rigaku AFC-7S diffractometer	1604 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.048
Graphite monochromator	θ_max = 40.0°, θ_min = 2.6°
ω–2θ scans	h = −13→13
Absorption correction: numerical (Clark & Reid, 1995)	k = −12→13
T_min = 0.581, T_max = 0.838	l = 0→15
5329 measured reflections	3 standard reflections every 150 reflections
5057 independent reflections	intensity decay: none

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.053	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.219	w = 1/[σ²(F_o²) + (0.0711P)² + 0.5448P] where P = (F_o² + 2F_c²)/3
S = 0.98	(Δ/σ)_max = 0.002
5057 reflections	Δρ_max = 1.35 e Å⁻³
133 parameters	Δρ_min = −1.91 e Å⁻³
1 restraint	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.093 (11)

Crystal data top

[Rb(C₆H₃N₂O₄)(C₆H₄N₂O₄)(H₂O)₂]	γ = 65.322 (18)°
M_r = 456.72	V = 414.32 (16) Å³
Triclinic, P1	Z = 1
a = 7.452 (2) Å	Mo Kα radiation
b = 7.8640 (15) Å	µ = 3.05 mm⁻¹
c = 8.3280 (12) Å	T = 298 K
α = 69.111 (12)°	0.20 × 0.15 × 0.06 mm
β = 81.424 (19)°

Data collection top

Rigaku AFC-7S diffractometer	1604 reflections with I > 2σ(I)
Absorption correction: numerical (Clark & Reid, 1995)	R_int = 0.048
T_min = 0.581, T_max = 0.838	3 standard reflections every 150 reflections
5329 measured reflections	intensity decay: none
5057 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.053	1 restraint
wR(F²) = 0.219	H atoms treated by a mixture of independent and constrained refinement
S = 0.98	Δρ_max = 1.35 e Å⁻³
5057 reflections	Δρ_min = −1.91 e Å⁻³
133 parameters

Special details top

Experimental. [analytical numeric absorption correction using a multifaceted crystal model based on expressions derived (Clark & Reid, 1995)]

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 (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Rb1	1.0000	0.0000	0.0000	0.0474 (3)
O1	0.9512 (4)	0.1940 (5)	0.2826 (4)	0.0451 (7)
O2	0.8035 (5)	0.3205 (6)	0.4927 (4)	0.0555 (9)
H2	0.9157	0.2906	0.5229	0.083*
O3	0.4264 (4)	0.8765 (4)	0.0673 (4)	0.0472 (7)
H1	0.4742	0.9762	0.0256	0.071*	0.50
O4	0.7256 (4)	0.6622 (5)	0.1716 (5)	0.0497 (8)
O5	0.8582 (5)	−0.1900 (5)	0.3618 (5)	0.0520 (8)
N1	0.5456 (5)	0.1950 (5)	0.3236 (4)	0.0367 (7)
N2	0.2959 (4)	0.5834 (5)	0.1521 (4)	0.0333 (6)
C1	0.8065 (5)	0.2816 (5)	0.3520 (5)	0.0335 (7)
C2	0.6004 (5)	0.3460 (5)	0.2892 (4)	0.0307 (7)
C3	0.3632 (6)	0.2399 (6)	0.2753 (5)	0.0390 (8)
H3	0.3190	0.1392	0.2980	0.047*
C4	0.2388 (6)	0.4346 (6)	0.1918 (5)	0.0372 (8)
H4	0.1117	0.4612	0.1629	0.045*
C5	0.4790 (5)	0.5392 (5)	0.1997 (4)	0.0297 (7)
C6	0.5508 (6)	0.7044 (5)	0.1459 (5)	0.0344 (8)
H5A	0.761 (12)	−0.087 (12)	0.364 (10)	0.10 (3)*
H5B	0.816 (8)	−0.243 (8)	0.316 (6)	0.057 (16)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Rb1	0.0433 (4)	0.0367 (3)	0.0434 (4)	−0.0028 (2)	−0.0063 (2)	−0.0051 (2)
O1	0.0316 (14)	0.0510 (17)	0.0607 (19)	−0.0160 (13)	−0.0025 (13)	−0.0265 (15)
O2	0.0423 (16)	0.079 (2)	0.0460 (17)	−0.0112 (16)	−0.0128 (13)	−0.0312 (17)
O3	0.0395 (15)	0.0302 (13)	0.069 (2)	−0.0180 (12)	−0.0093 (14)	−0.0036 (13)
O4	0.0393 (15)	0.0428 (16)	0.075 (2)	−0.0207 (13)	−0.0172 (14)	−0.0157 (15)
O5	0.0471 (18)	0.0489 (18)	0.066 (2)	−0.0120 (15)	−0.0233 (15)	−0.0253 (16)
N1	0.0360 (16)	0.0293 (14)	0.0426 (17)	−0.0139 (12)	−0.0078 (13)	−0.0053 (12)
N2	0.0290 (14)	0.0350 (15)	0.0375 (16)	−0.0144 (12)	−0.0070 (12)	−0.0088 (12)
C1	0.0304 (17)	0.0321 (17)	0.0395 (19)	−0.0143 (14)	−0.0057 (14)	−0.0089 (14)
C2	0.0299 (16)	0.0340 (17)	0.0304 (17)	−0.0148 (14)	−0.0030 (13)	−0.0093 (13)
C3	0.040 (2)	0.0370 (19)	0.046 (2)	−0.0223 (16)	−0.0045 (16)	−0.0094 (16)
C4	0.0324 (17)	0.043 (2)	0.041 (2)	−0.0219 (16)	−0.0042 (15)	−0.0096 (16)
C5	0.0307 (16)	0.0325 (16)	0.0300 (16)	−0.0147 (13)	−0.0050 (13)	−0.0100 (13)
C6	0.0397 (19)	0.0314 (17)	0.0400 (19)	−0.0200 (15)	−0.0049 (15)	−0.0113 (14)

Geometric parameters (Å, º) top

Rb1—O3ⁱ	2.987 (3)	O4—C6	1.234 (5)
Rb1—O3ⁱⁱ	2.987 (3)	O5—H5A	0.84 (9)
Rb1—N2ⁱⁱ	3.007 (3)	O5—H5B	0.82 (6)
Rb1—N2ⁱ	3.007 (3)	N1—C2	1.336 (5)
Rb1—O5	3.096 (4)	N1—C3	1.340 (5)
Rb1—O5ⁱⁱⁱ	3.096 (4)	N2—C4	1.326 (5)
Rb1—O1ⁱⁱⁱ	3.137 (3)	N2—C5	1.344 (4)
Rb1—O1	3.137 (3)	N2—Rb1^iv	3.007 (3)
Rb1—H5B	3.16 (5)	C1—C2	1.513 (5)
O1—C1	1.204 (5)	C2—C5	1.389 (5)
O2—C1	1.307 (5)	C3—C4	1.391 (6)
O2—H2	0.8210	C3—H3	0.9300
O3—C6	1.274 (5)	C4—H4	0.9300
O3—Rb1^iv	2.987 (3)	C5—C6	1.506 (5)
O3—H1	0.9299

O3ⁱ—Rb1—O3ⁱⁱ	180.00 (14)	O5ⁱⁱⁱ—Rb1—H5B	165.0 (3)
O3ⁱ—Rb1—N2ⁱⁱ	126.56 (8)	O1ⁱⁱⁱ—Rb1—H5B	104.1 (4)
O3ⁱⁱ—Rb1—N2ⁱⁱ	53.44 (8)	O1—Rb1—H5B	76.0 (10)
O3ⁱ—Rb1—N2ⁱ	53.44 (8)	C1—O1—Rb1	131.4 (2)
O3ⁱⁱ—Rb1—N2ⁱ	126.56 (8)	C1—O2—H2	111.2
N2ⁱⁱ—Rb1—N2ⁱ	180.0	C6—O3—Rb1^iv	128.1 (2)
O3ⁱ—Rb1—O5	78.94 (9)	C6—O3—H1	116.0
O3ⁱⁱ—Rb1—O5	101.06 (9)	Rb1^iv—O3—H1	115.9
N2ⁱⁱ—Rb1—O5	70.89 (9)	Rb1—O5—H5A	95 (5)
N2ⁱ—Rb1—O5	109.11 (9)	Rb1—O5—H5B	87 (4)
O3ⁱ—Rb1—O5ⁱⁱⁱ	101.06 (9)	H5A—O5—H5B	104 (6)
O3ⁱⁱ—Rb1—O5ⁱⁱⁱ	78.94 (9)	C2—N1—C3	116.8 (3)
N2ⁱⁱ—Rb1—O5ⁱⁱⁱ	109.11 (9)	C4—N2—C5	117.1 (3)
N2ⁱ—Rb1—O5ⁱⁱⁱ	70.89 (9)	C4—N2—Rb1^iv	119.0 (2)
O5—Rb1—O5ⁱⁱⁱ	180.00 (13)	C5—N2—Rb1^iv	123.5 (2)
O3ⁱ—Rb1—O1ⁱⁱⁱ	81.24 (8)	O1—C1—O2	126.2 (3)
O3ⁱⁱ—Rb1—O1ⁱⁱⁱ	98.76 (8)	O1—C1—C2	121.8 (3)
N2ⁱⁱ—Rb1—O1ⁱⁱⁱ	76.07 (8)	O2—C1—C2	111.8 (3)
N2ⁱ—Rb1—O1ⁱⁱⁱ	103.93 (8)	N1—C2—C5	121.9 (3)
O5—Rb1—O1ⁱⁱⁱ	118.29 (9)	N1—C2—C1	113.0 (3)
O5ⁱⁱⁱ—Rb1—O1ⁱⁱⁱ	61.71 (9)	C5—C2—C1	125.1 (3)
O3ⁱ—Rb1—O1	98.76 (8)	N1—C3—C4	121.2 (3)
O3ⁱⁱ—Rb1—O1	81.24 (8)	N1—C3—H3	119.4
N2ⁱⁱ—Rb1—O1	103.93 (8)	C4—C3—H3	119.4
N2ⁱ—Rb1—O1	76.07 (8)	N2—C4—C3	122.0 (3)
O5—Rb1—O1	61.71 (9)	N2—C4—H4	119.0
O5ⁱⁱⁱ—Rb1—O1	118.29 (9)	C3—C4—H4	119.0
O1ⁱⁱⁱ—Rb1—O1	180.00 (14)	N2—C5—C2	120.9 (3)
O3ⁱ—Rb1—H5B	70.4 (9)	N2—C5—C6	117.8 (3)
O3ⁱⁱ—Rb1—H5B	109.6 (9)	C2—C5—C6	121.2 (3)
N2ⁱⁱ—Rb1—H5B	69.3 (10)	O4—C6—O3	125.3 (3)
N2ⁱ—Rb1—H5B	110.7 (10)	O4—C6—C5	118.4 (3)
O5—Rb1—H5B	15.1 (10)	O3—C6—C5	116.1 (3)

O3ⁱ—Rb1—O1—C1	4.0 (4)	Rb1^iv—N2—C4—C3	−174.7 (3)
O3ⁱⁱ—Rb1—O1—C1	−176.0 (4)	N1—C3—C4—N2	1.8 (7)
N2ⁱⁱ—Rb1—O1—C1	−127.2 (4)	C4—N2—C5—C2	−1.2 (5)
N2ⁱ—Rb1—O1—C1	52.8 (4)	Rb1^iv—N2—C5—C2	171.6 (3)
O5—Rb1—O1—C1	−68.3 (4)	C4—N2—C5—C6	176.2 (3)
O5ⁱⁱⁱ—Rb1—O1—C1	111.7 (4)	Rb1^iv—N2—C5—C6	−11.0 (4)
Rb1—O1—C1—O2	164.6 (3)	N1—C2—C5—N2	3.7 (6)
Rb1—O1—C1—C2	−10.4 (6)	C1—C2—C5—N2	−178.5 (3)
C3—N1—C2—C5	−3.4 (6)	N1—C2—C5—C6	−173.6 (3)
C3—N1—C2—C1	178.7 (3)	C1—C2—C5—C6	4.2 (6)
O1—C1—C2—N1	72.3 (5)	Rb1^iv—O3—C6—O4	−179.2 (3)
O2—C1—C2—N1	−103.3 (4)	Rb1^iv—O3—C6—C5	5.3 (5)
O1—C1—C2—C5	−105.6 (5)	N2—C5—C6—O4	−171.9 (4)
O2—C1—C2—C5	78.8 (5)	C2—C5—C6—O4	5.5 (6)
C2—N1—C3—C4	0.7 (6)	N2—C5—C6—O3	3.9 (5)
C5—N2—C4—C3	−1.5 (6)	C2—C5—C6—O3	−178.7 (4)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1···O3^v	0.93	1.55 (1)	2.468 (3)	170 (1)
O5—H5A···N1	0.84 (9)	2.07 (9)	2.888 (3)	168 (7)
O5—H5B···O4^vi	0.82 (6)	1.94 (6)	2.753 (3)	170 (1)
O2—H2···O5^vii	0.82	1.79	2.596 (6)	166 (1)

Symmetry codes: (v) −x+1, −y+2, −z; (vi) x, y−1, z; (vii) −x+2, −y, −z+1.

Experimental details

Crystal data
Chemical formula	[Rb(C₆H₃N₂O₄)(C₆H₄N₂O₄)(H₂O)₂]
M_r	456.72
Crystal system, space group	Triclinic, P1
Temperature (K)	298
a, b, c (Å)	7.452 (2), 7.8640 (15), 8.3280 (12)
α, β, γ (°)	69.111 (12), 81.424 (19), 65.322 (18)
V (Å³)	414.32 (16)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	3.05
Crystal size (mm)	0.20 × 0.15 × 0.06

Data collection
Diffractometer	Rigaku AFC-7S diffractometer
Absorption correction	Numerical (Clark & Reid, 1995)
T_min, T_max	0.581, 0.838
No. of measured, independent and observed [I > 2σ(I)] reflections	5329, 5057, 1604
R_int	0.048
(sin θ/λ)_max (Å⁻¹)	0.904

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.219, 0.98
No. of reflections	5057
No. of parameters	133
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.35, −1.91

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1997), TEXSAN for Windows (Molecular Structure Corporation, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2006), publCIF (Westrip, 2009).

Selected geometric parameters (Å, º) top

Rb1—O3ⁱ	2.987 (3)	Rb1—O5	3.096 (4)
Rb1—N2ⁱⁱ	3.007 (3)	Rb1—O1	3.137 (3)

O3ⁱ—Rb1—N2ⁱⁱ	126.56 (8)	O5—Rb1—O1ⁱⁱⁱ	118.29 (9)
O3ⁱ—Rb1—O5	78.94 (9)	O3ⁱ—Rb1—O1	98.76 (8)
N2ⁱⁱ—Rb1—O5	70.89 (9)	N2ⁱ—Rb1—O1	76.07 (8)
O3ⁱ—Rb1—O1ⁱⁱⁱ	81.24 (8)	O5—Rb1—O1	61.71 (9)
N2ⁱⁱ—Rb1—O1ⁱⁱⁱ	76.07 (8)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1···O3^iv	0.930	1.5470 (10)	2.468 (3)	169.81 (12)
O5—H5A···N1	0.84 (9)	2.07 (9)	2.888 (3)	168 (7)
O5—H5B···O4^v	0.82 (6)	1.94 (6)	2.753 (3)	170.39 (5)
O2—H2···O5^vi	0.820	1.790	2.596 (6)	165.68 (11)

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

Acknowledgements

The authors gratefully acknowledge Kırıkkale University Scientific Research Centre for financial support of this work.

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