Diguanidinium bis-(μ-2-hydroxy-propane-1,2,3-tricarboxyl-ato)bis-[diaqua-zincate(II)] dihydrate.

The asymmetric unit of the title compound, (CH(6)N(3))(2)[Zn(2)(C(6)H(5)O(7))(2)(H(2)O)(2)]·2H(2)O, contains one-half of a centrosymmetric dizinc(II) complex anion, one guanidinium cation and one water mol-ecule. Each Zn(II) ion is hexa-coordinated by two citrate anions, one in a bidentate fashion and the second monodentate, and two water mol-ecules in a distorted octa-hedral geometry. Intra-molecular O-H⋯O hydrogen bonds add further stability to the mol-ecular structure. In the crystal structure, mol-ecules are linked into a three-dimensional framework by inter-molecular N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds.

Related literature

For general background to guanidine and citric acid, see: Raczyńska et al. (2003 ▶); Yamada et al. (2009 ▶); Sigman et al. (1993 ▶); Schuck (1934 ▶); Sherman et al. (1936 ▶). For applications of citric acid in industry and materials science, see: Blair et al. (1991 ▶); Jiang et al. (2007 ▶). For related guanidinium structures, see: Al-Dajani et al. (2009 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

(CH6N3)2[Zn2(C6H5O7)2(H2O)2]·2H2O

M = 737.21

Monoclinic,

a = 28.9405 (4) Å

b = 8.5708 (1) Å

c = 11.3395 (2) Å

β = 95.249 (1)°

V = 2800.89 (7) Å3

Z = 4

Mo Kα radiation

μ = 1.81 mm−1

T = 296 K

0.32 × 0.30 × 0.18 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T min = 0.593, T max = 0.734

32332 measured reflections

7693 independent reflections

5495 reflections with I > 2σ(I)

R int = 0.026

Refinement

R[F 2 > 2σ(F 2)] = 0.031

wR(F 2) = 0.084

S = 1.05

7693 reflections

190 parameters

H-atom parameters constrained

Δρmax = 0.45 e Å−3

Δρmin = −0.29 e Å−3

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809054439/sj2710sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809054439/sj2710Isup2.hkl

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

(CH6N3)2[Zn2(C6H5O7)2(H2O)2]·2H2O	F(000) = 1520
Mr = 737.21	Dx = 1.748 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 9983 reflections
a = 28.9405 (4) Å	θ = 2.5–34.8°
b = 8.5708 (1) Å	µ = 1.81 mm−1
c = 11.3395 (2) Å	T = 296 K
β = 95.249 (1)°	Block, colourless
V = 2800.89 (7) Å3	0.32 × 0.30 × 0.18 mm
Z = 4

Bruker SMART APEXII CCD area-detector diffractometer	7693 independent reflections
Radiation source: fine-focus sealed tube	5495 reflections with I > 2σ(I)
graphite	Rint = 0.026
φ and ω scans	θmax = 38.3°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −48→50
Tmin = 0.593, Tmax = 0.734	k = −14→12
32332 measured reflections	l = −19→16

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)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.084	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.0404P)2 + 0.5068P] where P = (Fo2 + 2Fc2)/3
7693 reflections	(Δ/σ)max = 0.002
190 parameters	Δρmax = 0.45 e Å−3
0 restraints	Δρmin = −0.29 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.

	x	y	z	Uiso*/Ueq
Zn1	0.322092 (4)	0.394890 (14)	0.631912 (11)	0.02481 (4)
O1	0.33231 (4)	0.37163 (9)	0.45220 (8)	0.03439 (19)
O2	0.36716 (3)	0.20991 (10)	0.33603 (8)	0.03573 (18)
O3	0.31089 (3)	0.15045 (9)	0.60117 (7)	0.02494 (14)
H1O3	0.2815	0.1428	0.5651	0.037*
O4	0.39328 (3)	0.33281 (11)	0.66307 (9)	0.03675 (19)
O5	0.44700 (3)	0.16069 (13)	0.72462 (10)	0.0474 (2)
O6	0.24882 (3)	0.07623 (10)	0.42434 (9)	0.0365 (2)
O7	0.25557 (3)	−0.16794 (10)	0.36365 (10)	0.0427 (2)
C1	0.34724 (4)	0.23880 (12)	0.42612 (9)	0.02427 (18)
C2	0.34175 (3)	0.10406 (10)	0.51507 (9)	0.02214 (16)
C3	0.38848 (4)	0.06848 (13)	0.58412 (10)	0.0288 (2)
H3A	0.3844	−0.0221	0.6334	0.035*
H3B	0.4101	0.0393	0.5275	0.035*
C4	0.41101 (4)	0.19654 (14)	0.66293 (10)	0.0295 (2)
C5	0.32367 (4)	−0.04392 (12)	0.44989 (10)	0.0273 (2)
H5A	0.3410	−0.0586	0.3814	0.033*
H5B	0.3302	−0.1325	0.5020	0.033*
C6	0.27248 (4)	−0.04513 (12)	0.40863 (10)	0.02705 (19)
C7	0.45073 (5)	0.64963 (16)	0.50364 (12)	0.0382 (3)
N1	0.45132 (5)	0.61025 (16)	0.61676 (12)	0.0511 (3)
H1N1	0.4644	0.6641	0.6751	0.061*
H2N1	0.4393	0.5187	0.6424	0.061*
N2	0.47821 (5)	0.76043 (17)	0.47097 (13)	0.0552 (3)
H1N2	0.4783	0.7888	0.3966	0.066*
H2N2	0.5000	0.7945	0.5235	0.066*
N3	0.42259 (5)	0.57429 (17)	0.42351 (13)	0.0547 (3)
H1N3	0.4208	0.6209	0.3559	0.066*
H2N3	0.4020	0.5135	0.4454	0.066*
O1W	0.46013 (4)	0.85648 (15)	0.82510 (11)	0.0525 (3)
H1W1	0.4335	0.8373	0.8306	0.079*
H2W1	0.4593	0.9470	0.8020	0.079*
O2W	0.31354 (4)	0.38177 (10)	0.80498 (8)	0.0388 (2)
H1W2	0.3163	0.4610	0.8492	0.058*
H2W2	0.2975	0.3236	0.8321	0.058*
O3W	0.33513 (3)	0.63182 (9)	0.63707 (8)	0.03042 (16)
H1W3	0.3494	0.6661	0.7004	0.046*
H2W3	0.3106	0.6561	0.6328	0.046*

	U11	U22	U33	U12	U13	U23
Zn1	0.02665 (6)	0.02218 (6)	0.02509 (7)	0.00090 (4)	−0.00047 (4)	−0.00195 (4)
O1	0.0534 (5)	0.0230 (3)	0.0269 (4)	0.0080 (3)	0.0047 (4)	0.0038 (3)
O2	0.0384 (4)	0.0412 (4)	0.0285 (4)	0.0094 (4)	0.0079 (3)	0.0043 (3)
O3	0.0251 (3)	0.0245 (3)	0.0252 (3)	−0.0002 (3)	0.0025 (3)	−0.0024 (3)
O4	0.0276 (4)	0.0324 (4)	0.0490 (5)	−0.0006 (3)	−0.0035 (3)	−0.0064 (4)
O5	0.0344 (5)	0.0509 (6)	0.0527 (6)	0.0026 (4)	−0.0192 (4)	−0.0009 (5)
O6	0.0275 (4)	0.0277 (4)	0.0521 (5)	0.0073 (3)	−0.0089 (4)	−0.0145 (4)
O7	0.0306 (4)	0.0291 (4)	0.0666 (7)	0.0027 (3)	−0.0057 (4)	−0.0205 (4)
C1	0.0243 (4)	0.0252 (4)	0.0226 (4)	0.0018 (3)	−0.0016 (3)	0.0015 (3)
C2	0.0221 (4)	0.0207 (4)	0.0231 (4)	0.0036 (3)	−0.0010 (3)	−0.0007 (3)
C3	0.0259 (5)	0.0282 (4)	0.0307 (5)	0.0052 (4)	−0.0055 (4)	0.0016 (4)
C4	0.0226 (4)	0.0355 (5)	0.0298 (5)	−0.0006 (4)	−0.0011 (4)	0.0022 (4)
C5	0.0246 (4)	0.0220 (4)	0.0345 (5)	0.0042 (3)	−0.0010 (4)	−0.0040 (4)
C6	0.0262 (4)	0.0242 (4)	0.0302 (5)	0.0032 (4)	−0.0005 (4)	−0.0051 (4)
C7	0.0341 (6)	0.0395 (6)	0.0399 (7)	−0.0022 (5)	−0.0028 (5)	0.0025 (5)
N1	0.0547 (8)	0.0579 (8)	0.0388 (7)	−0.0176 (6)	−0.0058 (6)	0.0040 (5)
N2	0.0531 (7)	0.0576 (8)	0.0534 (8)	−0.0190 (6)	−0.0043 (6)	0.0139 (6)
N3	0.0586 (8)	0.0594 (8)	0.0436 (7)	−0.0202 (7)	−0.0091 (6)	0.0033 (6)
O1W	0.0347 (5)	0.0645 (7)	0.0585 (7)	0.0026 (5)	0.0055 (5)	0.0105 (6)
O2W	0.0571 (6)	0.0320 (4)	0.0284 (4)	−0.0179 (4)	0.0093 (4)	−0.0048 (3)
O3W	0.0321 (4)	0.0257 (3)	0.0332 (4)	−0.0030 (3)	0.0009 (3)	−0.0003 (3)

Zn1—O2W	2.0036 (9)	C3—H3B	0.9700
Zn1—O3W	2.0653 (8)	C5—C6	1.5123 (15)
Zn1—O1	2.0953 (9)	C5—H5A	0.9700
Zn1—O6i	2.1071 (9)	C5—H5B	0.9700
Zn1—O4	2.1259 (9)	C7—N2	1.3135 (18)
Zn1—O3	2.1436 (8)	C7—N1	1.3250 (19)
O1—C1	1.2624 (12)	C7—N3	1.3305 (18)
O2—C1	1.2430 (13)	N1—H1N1	0.8653
O3—C2	1.4382 (12)	N1—H2N1	0.9161
O3—H1O3	0.9125	N2—H1N2	0.8782
O4—C4	1.2757 (15)	N2—H2N2	0.8767
O5—C4	1.2389 (14)	N3—H1N3	0.8616
O6—C6	1.2669 (12)	N3—H2N3	0.8455
O6—Zn1i	2.1071 (9)	O1W—H1W1	0.7969
O7—C6	1.2498 (13)	O1W—H2W1	0.8189
C1—C2	1.5510 (14)	O2W—H1W2	0.8432
C2—C3	1.5302 (14)	O2W—H2W2	0.7641
C2—C5	1.5355 (14)	O3W—H1W3	0.8481
C3—C4	1.5237 (16)	O3W—H2W3	0.7377
C3—H3A	0.9700
O2W—Zn1—O3W	93.79 (3)	C2—C3—H3B	107.8
O2W—Zn1—O1	171.26 (3)	H3A—C3—H3B	107.2
O3W—Zn1—O1	94.55 (3)	O5—C4—O4	122.94 (11)
O2W—Zn1—O6i	95.68 (4)	O5—C4—C3	116.42 (11)
O3W—Zn1—O6i	93.63 (3)	O4—C4—C3	120.64 (9)
O1—Zn1—O6i	86.38 (4)	C6—C5—C2	115.82 (8)
O2W—Zn1—O4	91.59 (4)	C6—C5—H5A	108.3
O3W—Zn1—O4	94.00 (4)	C2—C5—H5A	108.3
O1—Zn1—O4	85.24 (4)	C6—C5—H5B	108.3
O6i—Zn1—O4	169.08 (3)	C2—C5—H5B	108.3
O2W—Zn1—O3	94.25 (3)	H5A—C5—H5B	107.4
O3W—Zn1—O3	171.92 (3)	O7—C6—O6	123.51 (10)
O1—Zn1—O3	77.38 (3)	O7—C6—C5	117.91 (9)
O6i—Zn1—O3	86.39 (3)	O6—C6—C5	118.54 (9)
O4—Zn1—O3	84.96 (3)	N2—C7—N1	120.18 (13)
C1—O1—Zn1	113.29 (7)	N2—C7—N3	120.45 (14)
C2—O3—Zn1	106.65 (6)	N1—C7—N3	119.36 (13)
C2—O3—H1O3	106.7	C7—N1—H1N1	124.8
Zn1—O3—H1O3	105.3	C7—N1—H2N1	123.6
C4—O4—Zn1	127.79 (7)	H1N1—N1—H2N1	111.5
C6—O6—Zn1i	125.31 (7)	C7—N2—H1N2	121.7
O2—C1—O1	124.51 (10)	C7—N2—H2N2	117.8
O2—C1—C2	117.97 (9)	H1N2—N2—H2N2	119.7
O1—C1—C2	117.48 (9)	C7—N3—H1N3	111.4
O3—C2—C3	106.41 (8)	C7—N3—H2N3	120.1
O3—C2—C5	110.47 (8)	H1N3—N3—H2N3	124.1
C3—C2—C5	109.15 (8)	H1W1—O1W—H2W1	102.7
O3—C2—C1	110.03 (7)	Zn1—O2W—H1W2	121.5
C3—C2—C1	110.05 (9)	Zn1—O2W—H2W2	124.3
C5—C2—C1	110.64 (9)	H1W2—O2W—H2W2	108.4
C4—C3—C2	117.86 (9)	Zn1—O3W—H1W3	116.0
C4—C3—H3A	107.8	Zn1—O3W—H2W3	95.9
C2—C3—H3A	107.8	H1W3—O3W—H2W3	110.5
C4—C3—H3B	107.8
O3W—Zn1—O1—C1	150.43 (8)	O1—C1—C2—O3	12.55 (13)
O6i—Zn1—O1—C1	−116.20 (9)	O2—C1—C2—C3	73.57 (12)
O4—Zn1—O1—C1	56.79 (8)	O1—C1—C2—C3	−104.39 (11)
O3—Zn1—O1—C1	−29.10 (8)	O2—C1—C2—C5	−47.13 (12)
O2W—Zn1—O3—C2	−143.52 (7)	O1—C1—C2—C5	134.91 (10)
O1—Zn1—O3—C2	33.95 (6)	O3—C2—C3—C4	−56.32 (12)
O6i—Zn1—O3—C2	121.05 (6)	C5—C2—C3—C4	−175.54 (10)
O4—Zn1—O3—C2	−52.29 (6)	C1—C2—C3—C4	62.86 (12)
O2W—Zn1—O4—C4	91.34 (10)	Zn1—O4—C4—O5	−150.02 (10)
O3W—Zn1—O4—C4	−174.75 (10)	Zn1—O4—C4—C3	30.55 (16)
O1—Zn1—O4—C4	−80.50 (10)	C2—C3—C4—O5	174.68 (11)
O6i—Zn1—O4—C4	−40.5 (3)	C2—C3—C4—O4	−5.86 (17)
O3—Zn1—O4—C4	−2.78 (10)	O3—C2—C5—C6	45.40 (12)
Zn1—O1—C1—O2	−160.08 (9)	C3—C2—C5—C6	162.07 (10)
Zn1—O1—C1—C2	17.74 (12)	C1—C2—C5—C6	−76.69 (12)
Zn1—O3—C2—C3	84.83 (8)	Zn1i—O6—C6—O7	−4.75 (18)
Zn1—O3—C2—C5	−156.82 (6)	Zn1i—O6—C6—C5	177.29 (8)
Zn1—O3—C2—C1	−34.36 (9)	C2—C5—C6—O7	−174.40 (11)
O2—C1—C2—O3	−169.49 (9)	C2—C5—C6—O6	3.68 (16)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1O3···O6	0.91	1.87	2.6445 (13)	142
N1—H1N1···O1W	0.86	2.38	3.1607 (19)	150
N1—H2N1···O4	0.92	2.10	2.9855 (17)	161
N2—H1N2···O5ii	0.88	2.12	2.9351 (18)	154
N2—H2N2···O1Wiii	0.88	2.05	2.9077 (19)	166
N3—H1N3···O4ii	0.86	2.29	3.1011 (18)	156
N3—H1N3···O5ii	0.86	2.55	3.3221 (18)	150
N3—H2N3···O1	0.85	2.36	3.1788 (18)	162
O1W—H1W1···O2iv	0.80	1.97	2.7640 (15)	177
O1W—H2W1···O5v	0.82	2.05	2.8568 (17)	170
O2W—H1W2···O1iv	0.84	1.88	2.7172 (12)	171
O2W—H2W2···O7vi	0.76	1.86	2.6116 (13)	167
O3W—H1W3···O2iv	0.85	1.90	2.7215 (12)	163
O3W—H2W3···O7i	0.74	1.92	2.6424 (12)	166
C5—H5B···O3Wvii	0.97	2.53	3.4943 (13)	172

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1O3⋯O6	0.91	1.87	2.6445 (13)	142
N1—H1N1⋯O1W	0.86	2.38	3.1607 (19)	150
N1—H2N1⋯O4	0.92	2.10	2.9855 (17)	161
N2—H1N2⋯O5i	0.88	2.12	2.9351 (18)	154
N2—H2N2⋯O1Wii	0.88	2.05	2.9077 (19)	166
N3—H1N3⋯O4i	0.86	2.29	3.1011 (18)	156
N3—H1N3⋯O5i	0.86	2.55	3.3221 (18)	150
N3—H2N3⋯O1	0.85	2.36	3.1788 (18)	162
O1W—H1W1⋯O2iii	0.80	1.97	2.7640 (15)	177
O1W—H2W1⋯O5iv	0.82	2.05	2.8568 (17)	170
O2W—H1W2⋯O1iii	0.84	1.88	2.7172 (12)	171
O2W—H2W2⋯O7v	0.76	1.86	2.6116 (13)	167
O3W—H1W3⋯O2iii	0.85	1.90	2.7215 (12)	163
O3W—H2W3⋯O7vi	0.74	1.92	2.6424 (12)	166
C5—H5B⋯O3Wvii	0.97	2.53	3.4943 (13)	172

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .