Poly­[disodium bis(μ-malonato)­zincate(II) dihydrate]

The title compound, {Na₂[Zn(C₃H₂O₄)₂]·2H₂O}_n, is a three-dimensional polymeric complex bridged by malonate dianions. The malonate ligand exhibits versatile coordination modes and links two Zn^II and four Na^I atoms. The Zn atom occupies a special position in an inversion centre and is chelated by two malonate ligands [Zn—O = 2.0230 (10) and 2.0875 (11) Å]; two other malonates are involved in monodentate coordin­ation of the Zn atom [Zn—O = 2.2789 (12) Å], thus completing its octahedral coordination environment. The Na atom also has a distorted octahedral coordination, formed by four carboxyl­ate O atoms of four malonate ligands [2.4328 (15)–2.5493 (13) Å] and two water mol­ecules [2.3749 (15) and 2.4144 (14) Å].

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.023
• wR factor = 0.056
• Data-to-parameter ratio = 13.7

checkCIF/PLATON results

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PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?

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Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC and Rigaku, 2002); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

(I)

Crystal data

Na2[Zn(C3H2O4)2]·2H2O	F(000) = 704
Mr = 351.49	Dx = 2.198 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 8742 reflections
a = 6.8359 (10) Å	θ = 2.5–24.5°
b = 9.3875 (13) Å	µ = 2.44 mm^−1
c = 16.5518 (14) Å	T = 295 K
V = 1062.2 (2) Å^3	Prism, colorless
Z = 4	0.26 × 0.20 × 0.19 mm

Data collection

Rigaku R-AXIS RAPID diffractometer	1206 independent reflections
Radiation source: fine-focus sealed tube	1089 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
Detector resolution: 10.00 pixels mm^-1	θmax = 27.4°, θmin = 2.5°
ω scans	h = −8→8
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −12→12
Tmin = 0.530, Tmax = 0.626	l = −21→21
8878 measured reflections

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)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.056	H-atom parameters constrained
S = 1.17	w = 1/[σ^2(Fo^2) + (0.026P)^2 + 0.6078P] where P = (Fo^2 + 2Fc^2)/3
1206 reflections	(Δ/σ)max = 0.001
88 parameters	Δρmax = 0.30 e Å^−3
0 restraints	Δρmin = −0.37 e Å^−3

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
Zn	0.5000	0.0000	0.0000	0.01881 (10)
Na	0.49869 (10)	−0.13327 (8)	0.20158 (4)	0.02557 (17)
O1	0.61212 (17)	0.06455 (11)	0.10703 (6)	0.0194 (2)
O2	0.7021 (2)	0.22662 (12)	0.19722 (7)	0.0268 (3)
O3	0.56485 (19)	0.19501 (12)	−0.05437 (6)	0.0204 (2)
O4	0.71367 (17)	0.40542 (12)	−0.04577 (7)	0.0213 (2)
O5	0.7003 (2)	−0.00375 (12)	0.29618 (7)	0.0263 (3)
C1	0.6344 (2)	0.19311 (16)	0.12926 (9)	0.0166 (3)
C2	0.5712 (2)	0.31520 (16)	0.07490 (9)	0.0168 (3)
H2A	0.6296	0.4021	0.0955	0.020*
H2B	0.4304	0.3254	0.0797	0.020*
C3	0.6212 (2)	0.30374 (16)	−0.01457 (9)	0.0164 (3)
H5A	0.7172	0.0692	0.2637	0.050*
H5B	0.6926	0.0253	0.3455	0.050*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn	0.02894 (17)	0.01336 (15)	0.01414 (15)	−0.00364 (10)	−0.00306 (10)	0.00003 (8)
Na	0.0270 (4)	0.0255 (4)	0.0242 (4)	0.0026 (3)	0.0007 (3)	0.0004 (3)
O1	0.0270 (6)	0.0135 (5)	0.0175 (5)	0.0007 (5)	−0.0036 (4)	−0.0013 (4)
O2	0.0429 (7)	0.0210 (6)	0.0167 (5)	−0.0065 (5)	−0.0077 (5)	−0.0010 (4)
O3	0.0291 (6)	0.0156 (5)	0.0165 (5)	−0.0040 (5)	−0.0004 (5)	−0.0006 (4)
O4	0.0264 (6)	0.0177 (5)	0.0199 (5)	−0.0055 (5)	−0.0008 (5)	0.0040 (4)
O5	0.0382 (7)	0.0233 (6)	0.0174 (6)	0.0017 (5)	−0.0013 (5)	0.0000 (4)
C1	0.0173 (7)	0.0163 (7)	0.0162 (7)	−0.0024 (6)	0.0016 (6)	−0.0004 (6)
C2	0.0214 (7)	0.0130 (7)	0.0160 (7)	−0.0014 (6)	0.0005 (6)	−0.0016 (5)
C3	0.0175 (7)	0.0145 (7)	0.0171 (7)	0.0020 (6)	−0.0015 (6)	0.0010 (5)

Geometric parameters (Å, º)

Zn—O1	2.0230 (10)	O1—C1	1.2709 (18)
Zn—O3	2.0875 (11)	O2—C1	1.2564 (19)
Zn—O4^i	2.2789 (12)	O3—C3	1.2746 (18)
Zn—Na	3.5634 (7)	O4—C3	1.2558 (19)
Na—O1	2.5493 (13)	O5—H5A	0.878
Na—O2^ii	2.5338 (15)	O5—H5B	0.862
Na—O2^iii	2.4328 (15)	C1—C2	1.520 (2)
Na—O3^iv	2.5419 (13)	C2—C3	1.524 (2)
Na—O5	2.4144 (14)	C2—H2A	0.9700
Na—O5^v	2.3749 (15)	C2—H2B	0.9700
Na—Na^v	3.7751 (7)
O1—Zn—O3	91.97 (4)	Na^vi—O2—Na^vii	98.93 (5)
O1—Zn—O4^iii	94.73 (4)	C3—O3—Zn	122.93 (9)
O3—Zn—O4^iii	90.91 (4)	C3—O3—Na^iv	136.87 (9)
O5^v—Na—O5	102.85 (5)	Zn—O3—Na^iv	100.20 (4)
O5^v—Na—O2^iii	177.90 (6)	C3—O4—Zn^viii	126.27 (10)
O5—Na—O2^iii	79.14 (5)	Na^ix—O5—Na	104.04 (5)
O5^v—Na—O2^ii	77.88 (5)	Na^ix—O5—H5A	107.2
O5—Na—O2^ii	98.16 (5)	Na—O5—H5A	94.1
O2^iii—Na—O2^ii	101.21 (5)	Na^ix—O5—H5B	101.5
O5^v—Na—O3^iv	89.14 (5)	Na—O5—H5B	137.6
O5—Na—O3^iv	146.51 (5)	H5A—O5—H5B	109.92
O2^iii—Na—O3^iv	89.54 (5)	O2—C1—O1	122.76 (14)
O2^ii—Na—O3^iv	115.01 (5)	O2—C1—C2	116.48 (13)
O5^v—Na—O1	84.14 (5)	O1—C1—C2	120.71 (13)
O5—Na—O1	81.82 (4)	C1—C2—C3	117.26 (13)
O2^iii—Na—O1	96.89 (5)	C1—C2—H2A	108.0
O2^ii—Na—O1	161.58 (5)	C3—C2—H2A	108.0
O3^iv—Na—O1	68.26 (4)	C1—C2—H2B	108.0
C1—O1—Zn	125.69 (10)	C3—C2—H2B	108.0
C1—O1—Na	123.40 (9)	H2A—C2—H2B	107.2
Zn—O1—Na	101.78 (5)	O4—C3—O3	123.25 (14)
C1—O2—Na^vi	118.14 (11)	O4—C3—C2	117.33 (13)
C1—O2—Na^vii	121.49 (11)	O3—C3—C2	119.41 (13)

Symmetry codes: (i) x−1/2, −y+1/2, −z; (ii) −x+1, y−1/2, −z+1/2; (iii) −x+3/2, y−1/2, z; (iv) −x+1, −y, −z; (v) x−1/2, y, −z+1/2; (vi) −x+3/2, y+1/2, z; (vii) −x+1, y+1/2, −z+1/2; (viii) x+1/2, −y+1/2, −z; (ix) x+1/2, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5A···O2	0.88	1.85	2.7129 (17)	169
O5—H5B···O4^x	0.86	1.92	2.7756 (17)	172

Symmetry code: (x) x, −y+1/2, z+1/2.