A second modification of poly[diaquadi-μ-citrato(3-)-trizinc(II)].

A second modification of the zinc(II) coordination polymer with citric acid, [Zn(3)(C(6)H(5)O(7))(2)(H(2)O)(2)](n) or [Zn(citrate)(2)(H(2)O)(2)], has been synthesized under hydro-thermal conditions by reacting zinc acetate with citric acid. The structure contains two unique Zn atoms, one with a distorted octa-hedral coordination and located on an inversion centre, and one with a distorted tetra-hedral coordination. The ZnO(6) and ZnO(4) units are linked into layers extending parallel to (010).

Related literature

For the structure of the first polymorph, see: Wu (2008 ▶). For general background, see Bourne et al. (2001 ▶); Yaghi et al. (1996 ▶). Biologically relevant transition-metal citrate compounds have bee reported by Liu et al. (2005 ▶) and Xie et al. (2005 ▶).

Experimental

Crystal data

[Zn3(C6H5O7)2(H2O)2]

M = 610.34

Triclinic,

a = 6.4649 (13) Å

b = 7.2666 (15) Å

c = 9.6951 (19) Å

α = 85.27 (3)°

β = 77.31 (3)°

γ = 80.99 (3)°

V = 438.29 (15) Å3

Z = 1

Mo Kα radiation

μ = 4.16 mm−1

T = 298 (2) K

0.28 × 0.26 × 0.22 mm

Data collection

Rigaku R-AXIS RAPID IP diffractometer

Absorption correction: multi-scan ABSCOR (Higashi, 1995 ▶) T min = 0.389, T max = 0.461 (expected range = 0.337–0.400)

4339 measured reflections

2004 independent reflections

1763 reflections with I > 2σ(I)

R int = 0.029

Refinement

R[F 2 > 2σ(F 2)] = 0.027

wR(F 2) = 0.066

S = 1.04

2004 reflections

146 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.87 e Å−3

Δρmin = −0.60 e Å−3

Data collection: RAPID-AUTO (Rigaku, 1998 ▶); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL-Plus (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808028456/rk2084sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808028456/rk2084Isup2.hkl

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

[Zn3(C6H5O7)2(H2O)2]	Z = 1
Mr = 610.34	F(000) = 304
Triclinic, P1	Dx = 2.312 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.4649 (13) Å	Cell parameters from 2026 reflections
b = 7.2666 (15) Å	θ = 3.3–27.5°
c = 9.6951 (19) Å	µ = 4.16 mm−1
α = 85.27 (3)°	T = 298 K
β = 77.31 (3)°	Block, yellow
γ = 80.99 (3)°	0.28 × 0.26 × 0.22 mm
V = 438.29 (15) Å3

Rigaku R-AXIS RAPID IP diffractometer	2004 independent reflections
Radiation source: fine-focus sealed tube	1763 reflections with I > 2σ(I)
graphite	Rint = 0.029
ω–scans	θmax = 27.5°, θmin = 3.3°
Absorption correction: multi-scan ABSCOR (Higashi, 1995)	h = −8→8
Tmin = 0.389, Tmax = 0.461	k = −9→9
4339 measured reflections	l = −12→12

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.066	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ2(Fo2) + (0.0291P)2 + 0.3186P] where P = (Fo2 + 2Fc2)/3
2004 reflections	(Δ/σ)max < 0.001
146 parameters	Δρmax = 0.87 e Å−3
0 restraints	Δρmin = −0.60 e Å−3

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.The highest residual peak, 0.871 e A3, is close to O (1) (with the distance of ca 0.967 A), to C(1) with the distance of ca 1.296 A, but featureless. The deepest hole is -0.604 e A3.

	x	y	z	Uiso*/Ueq
Zn1	0.0000	0.0000	0.0000	0.02280 (11)
Zn2	0.43151 (4)	−0.21372 (4)	0.32805 (3)	0.02389 (10)
C1	−0.1926 (4)	0.3065 (4)	0.4125 (2)	0.0263 (5)
C2	−0.0112 (4)	0.3838 (3)	0.3087 (2)	0.0220 (5)
H2A	0.1033	0.3924	0.3569	0.026*
H2B	−0.0624	0.5087	0.2756	0.026*
C3	0.0768 (3)	0.2625 (3)	0.1818 (2)	0.0179 (4)
C4	0.2481 (4)	0.3533 (3)	0.0755 (2)	0.0224 (5)
H4A	0.1908	0.4827	0.0582	0.027*
H4B	0.3698	0.3527	0.1189	0.027*
C5	0.3282 (4)	0.2647 (3)	−0.0660 (2)	0.0213 (5)
C6	0.1701 (4)	0.0658 (3)	0.2287 (2)	0.0198 (4)
O1	−0.2934 (4)	0.1977 (5)	0.3701 (2)	0.0669 (9)
O2	−0.2314 (3)	0.3509 (3)	0.53876 (18)	0.0344 (5)
O3	0.2747 (3)	0.1149 (3)	−0.09162 (18)	0.0300 (4)
O4	0.4538 (3)	0.3523 (3)	−0.15702 (18)	0.0300 (4)
O5	0.2952 (3)	0.0518 (3)	0.31332 (18)	0.0260 (4)
O6	0.1257 (3)	−0.0737 (2)	0.17968 (19)	0.0324 (4)
O7	−0.0943 (3)	0.2466 (2)	0.11071 (17)	0.0210 (3)
O8	0.6828 (3)	−0.1961 (3)	0.41525 (19)	0.0334 (4)
H2	0.7285	−0.0927	0.3885	0.050*
H1	0.6486	−0.2004	0.5051	0.050*
H1A	−0.191 (6)	0.237 (5)	0.173 (4)	0.049 (11)*

	U11	U22	U33	U12	U13	U23
Zn1	0.0297 (2)	0.0247 (2)	0.01762 (18)	−0.01201 (16)	−0.00723 (15)	−0.00034 (15)
Zn2	0.02577 (16)	0.02446 (16)	0.01887 (15)	−0.00433 (11)	0.00168 (10)	−0.00202 (11)
C1	0.0259 (12)	0.0329 (13)	0.0189 (10)	−0.0080 (10)	0.0010 (9)	−0.0016 (10)
C2	0.0240 (11)	0.0246 (12)	0.0160 (10)	−0.0050 (9)	0.0003 (8)	−0.0023 (9)
C3	0.0198 (10)	0.0219 (11)	0.0130 (9)	−0.0066 (9)	−0.0025 (8)	−0.0018 (8)
C4	0.0256 (12)	0.0246 (12)	0.0168 (10)	−0.0103 (9)	0.0010 (9)	−0.0011 (9)
C5	0.0185 (11)	0.0260 (12)	0.0182 (10)	−0.0029 (9)	−0.0011 (8)	−0.0014 (9)
C6	0.0210 (11)	0.0242 (11)	0.0140 (9)	−0.0064 (9)	−0.0011 (8)	−0.0010 (9)
O1	0.0598 (15)	0.119 (2)	0.0318 (11)	−0.0641 (17)	0.0145 (10)	−0.0292 (14)
O2	0.0445 (11)	0.0434 (11)	0.0162 (8)	−0.0231 (9)	0.0056 (7)	−0.0072 (8)
O3	0.0324 (10)	0.0317 (10)	0.0256 (9)	−0.0144 (8)	0.0045 (7)	−0.0106 (8)
O4	0.0338 (10)	0.0315 (10)	0.0215 (8)	−0.0144 (8)	0.0094 (7)	−0.0056 (7)
O5	0.0269 (9)	0.0278 (9)	0.0254 (8)	−0.0009 (7)	−0.0118 (7)	−0.0031 (7)
O6	0.0510 (12)	0.0192 (9)	0.0351 (10)	−0.0106 (8)	−0.0243 (9)	0.0041 (7)
O7	0.0204 (8)	0.0277 (9)	0.0157 (7)	−0.0045 (7)	−0.0047 (6)	−0.0013 (6)
O8	0.0377 (11)	0.0377 (11)	0.0253 (9)	−0.0043 (8)	−0.0086 (8)	−0.0020 (8)

Zn1—O3	2.0707 (18)	C3—O7	1.449 (3)
Zn1—O3i	2.0707 (18)	C3—C4	1.529 (3)
Zn1—O6i	2.0768 (18)	C3—C6	1.535 (3)
Zn1—O6	2.0768 (18)	C4—C5	1.515 (3)
Zn1—O7i	2.1029 (18)	C4—H4A	0.9700
Zn1—O7	2.1029 (18)	C4—H4B	0.9700
Zn2—O2ii	1.9475 (19)	C5—O3	1.252 (3)
Zn2—O4iii	1.9528 (18)	C5—O4	1.264 (3)
Zn2—O5	1.9992 (19)	C6—O6	1.252 (3)
Zn2—O8	2.0141 (19)	C6—O5	1.261 (3)
C1—O1	1.245 (3)	O2—Zn2ii	1.9475 (19)
C1—O2	1.254 (3)	O4—Zn2iii	1.9528 (18)
C1—C2	1.516 (3)	O7—H1A	0.78 (4)
C2—C3	1.526 (3)	O8—H2	0.8500
C2—H2A	0.9700	O8—H1	0.8500
C2—H2B	0.9700
O3—Zn1—O3i	180.00 (9)	O7—C3—C2	109.47 (18)
O3—Zn1—O6i	91.13 (8)	O7—C3—C4	107.60 (17)
O3i—Zn1—O6i	88.87 (8)	C2—C3—C4	110.10 (18)
O3—Zn1—O6	88.87 (8)	O7—C3—C6	108.42 (17)
O3i—Zn1—O6	91.13 (8)	C2—C3—C6	110.98 (18)
O6i—Zn1—O6	180.00 (11)	C4—C3—C6	110.19 (19)
O3—Zn1—O7i	94.73 (7)	C5—C4—C3	116.49 (18)
O3i—Zn1—O7i	85.27 (7)	C5—C4—H4A	108.2
O6i—Zn1—O7i	78.62 (7)	C3—C4—H4A	108.2
O6—Zn1—O7i	101.38 (7)	C5—C4—H4B	108.2
O3—Zn1—O7	85.27 (7)	C3—C4—H4B	108.2
O3i—Zn1—O7	94.73 (7)	H4A—C4—H4B	107.3
O6i—Zn1—O7	101.38 (7)	O3—C5—O4	122.0 (2)
O6—Zn1—O7	78.62 (7)	O3—C5—C4	122.6 (2)
O7i—Zn1—O7	180.00 (8)	O4—C5—C4	115.4 (2)
O2ii—Zn2—O4iii	109.95 (8)	O6—C6—O5	122.3 (2)
O2ii—Zn2—O5	108.17 (9)	O6—C6—C3	119.8 (2)
O4iii—Zn2—O5	119.97 (8)	O5—C6—C3	117.8 (2)
O2ii—Zn2—O8	108.62 (8)	C1—O2—Zn2ii	116.04 (16)
O4iii—Zn2—O8	106.38 (8)	C5—O3—Zn1	128.61 (16)
O5—Zn2—O8	103.11 (8)	C5—O4—Zn2iii	111.81 (15)
O1—C1—O2	122.6 (2)	C6—O5—Zn2	108.96 (16)
O1—C1—C2	118.9 (2)	C6—O6—Zn1	111.25 (16)
O2—C1—C2	118.5 (2)	C3—O7—Zn1	106.24 (13)
C1—C2—C3	112.11 (19)	C3—O7—H1A	103 (3)
C1—C2—H2A	109.2	Zn1—O7—H1A	111 (3)
C3—C2—H2A	109.2	Zn2—O8—H2	109.3
C1—C2—H2B	109.2	Zn2—O8—H1	111.9
C3—C2—H2B	109.2	H2—O8—H1	107.6
H2A—C2—H2B	107.9

Table 1

Selected bond lengths (Å)

Zn1—O3	2.0707 (18)
Zn1—O6	2.0768 (18)
Zn1—O7	2.1029 (18)
Zn2—O2i	1.9475 (19)
Zn2—O4ii	1.9528 (18)
Zn2—O5	1.9992 (19)
Zn2—O8	2.0141 (19)

Symmetry codes: (i) ; (ii) .