Bis(melaminium) tartrate dihydrate

Su, H.; Lv, Y.-K.; Feng, Y.-L.

doi:10.1107/S1600536809011143

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 4| April 2009| Page o933

doi:10.1107/S1600536809011143

Open

access

Bis(melaminium) tartrate dihydrate

Hong Su,^a Yao-Kang Lv ^a and Yun-Long Feng ^a ^*

^aZhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004, People's Republic of China
^*Correspondence e-mail: sky37@zjnu.cn

(Received 8 March 2009; accepted 26 March 2009; online 31 March 2009)

In the title compound, 2C₃H₇N₆⁺·C₄H₄O₆²⁻·2H₂O, in which the complete anion is generated by crystallographic twofold symmetry, there are O—H⋯O, N—H⋯O and N—H⋯N hydrogen-bonding interactions between neighbouring moieties, forming layers parallel to the bc plane. In addition, π–π contacts [centroid–centroid distance = 3.6541 (9) Å] between the six-membered rings of the melamine cations are observed.

Related literature

For general background, see: Row (1999 ); Krische & Lehn (2000 ); Sherrington & Taskinen (2001 ); Marchewka et al. (2003 ); Thushari et al. (2005 ). For related structures, see: Udaya Lakshmi et al. (2006 ).

Experimental

Crystal data

2C₃H₇N₆⁺·C₄H₄O₆²⁻·2H₂O
M_r = 436.38
Monoclinic, C 2/c
a = 7.6963 (9) Å
b = 21.955 (3) Å
c = 10.7405 (12) Å
β = 98.179 (6)°
V = 1796.4 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.14 mm⁻¹
T = 296 K
0.26 × 0.22 × 0.12 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: multiscan (SADABS; Sheldrick, 1996 ) T_min = 0.963, T_max = 0.980
13436 measured reflections
2047 independent reflections
1712 reflections with I > 2σ(I)
R_int = 0.027

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.108
S = 1.00
2047 reflections
166 parameters
15 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2ⁱ	0.870 (11)	1.802 (12)	2.6680 (14)	173.2 (16)
N1—H1NA⋯O1	0.884 (13)	2.271 (14)	3.0466 (19)	146.3 (16)
N1—H1NB⋯N4ⁱⁱ	0.879 (13)	2.151 (13)	3.0287 (19)	177.3 (17)
N2—H2NA⋯O3	0.889 (15)	2.093 (15)	2.8333 (16)	140.2 (14)
N2—H2NA⋯O1	0.889 (15)	2.190 (15)	2.9497 (18)	143.2 (14)
N3—H3NA⋯O1Wⁱⁱⁱ	0.872 (14)	2.261 (19)	2.8609 (18)	125.9 (15)
N3—H3NA⋯O3	0.872 (14)	2.573 (16)	3.2241 (18)	132.2 (16)
N3—H3NB⋯N6^iv	0.900 (14)	2.133 (14)	3.0313 (19)	176.2 (18)
N5—H5NA⋯O1W^v	0.901 (13)	1.940 (14)	2.8148 (16)	163.2 (15)
N5—H5NB⋯O2^vi	0.895 (13)	2.153 (15)	2.9581 (16)	149.4 (15)
O1W—H1WA⋯O1	0.858 (14)	1.852 (14)	2.6861 (16)	163.8 (17)
O1W—H1WB⋯O2^vii	0.804 (13)	2.297 (15)	2.9738 (17)	142.3 (17)
Symmetry codes: (i) $[x, -y, z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[-x+1, y, -z+{\script{1\over 2}}]$ ; (iv) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (v) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]$ ; (vi) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (vii) -x+1, -y, -z.

Data collection: APEX2 (Bruker, 2006 ); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809011143/at2740sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809011143/at2740Isup2.hkl

checkCIF report

Comment top

Melamine and its organic and inorganic counterparts can develop supramolecular assemblies via multiple hydrogen bonds (Row, 1999; Krische & Lehn, 2000; Sherrington & Taskinen, 2001; Marchewka et al., 2003), while tartaric acid is a small organic molecule [C₄H₄O₆] with a bewildering array of ligation possibilities (Thushari et al., 2005). Herein we report the synthesis and crystal structure of the title compound (I).

In (I) (Fig. 1), the melaminium cations form infinite floors via N—H···N hydrogen bonds and the D-tartrate anions link pair with waters via O—H···O form floors lying between two floors of melaminium. Furthermore, the N—H···O hydrogen bonds connected the neighboring cations floors and anions floors is together into a three-dimensional network. We found that the architecture of compound (I) is similar to bis (melaminium) L– tartrate 2.5-hydrate (Udaya Lakshmi et al., 2006) but not the same, which indicate that using different stereo-chemical configurations can give different three-dimensional arrangements. In addition, π–π contacts [centroid-centroid distance 3.6541 (9) Å] between the six-membered rings of the melamine moieties are observed.

Related literature top

For related literature, see: Krische & Lehn (2000); Udaya Lakshmi et al. (2006); Marchewka et al. (2003); Row (1999); Sherrington & Taskinen (2001); Thushari et al. (2005).

Experimental top

Compound (I) is formed by hydrothermal reaction of D-tartaric acid (1.5 mmol) and Melamine (1 mmol) in 15 ml water for 2 days at 533 K.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. View of the molecule of (I), showing the atom-numbering scheme. Displacement ellipsoids plotted at 30% probability level. [The atoms labelled with 'A' are related to the center of inversion].
	Fig. 2. Packing diagram for compound (I). The O—H···O and O—H···N interactions are depicted by dashed lines.

Bis(melaminium) tartrate dihydrate top

Crystal data top

2C₃H₇N₆⁺·C₄H₄O₆²⁻·2H₂O	F(000) = 920
M_r = 436.38	D_x = 1.621 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 4811 reflections
a = 7.6963 (9) Å	θ = 1.9–27.5°
b = 21.955 (3) Å	µ = 0.14 mm⁻¹
c = 10.7405 (12) Å	T = 296 K
β = 98.179 (6)°	Block, colourless
V = 1796.4 (4) Å³	0.26 × 0.22 × 0.12 mm
Z = 4

Data collection top

Bruker APEXII area-detector diffractometer	2047 independent reflections
Radiation source: fine-focus sealed tube	1712 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.027
ω scans	θ_max = 27.5°, θ_min = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→10
T_min = 0.963, T_max = 0.980	k = −27→28
13436 measured reflections	l = −13→13

Refinement top

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ²(F_o²) + (0.059P)² + 0.9299P] where P = (F_o² + 2F_c²)/3
2047 reflections	(Δ/σ)_max < 0.001
166 parameters	Δρ_max = 0.25 e Å⁻³
15 restraints	Δρ_min = −0.24 e Å⁻³

Crystal data top

2C₃H₇N₆⁺·C₄H₄O₆²⁻·2H₂O	V = 1796.4 (4) Å³
M_r = 436.38	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 7.6963 (9) Å	µ = 0.14 mm⁻¹
b = 21.955 (3) Å	T = 296 K
c = 10.7405 (12) Å	0.26 × 0.22 × 0.12 mm
β = 98.179 (6)°

Data collection top

Bruker APEXII area-detector diffractometer	2047 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1712 reflections with I > 2σ(I)
T_min = 0.963, T_max = 0.980	R_int = 0.027
13436 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	15 restraints
wR(F²) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	Δρ_max = 0.25 e Å⁻³
2047 reflections	Δρ_min = −0.24 e Å⁻³
166 parameters

Special details top

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
O1	0.25143 (17)	0.05132 (5)	0.11300 (12)	0.0603 (3)
O2	0.17077 (17)	−0.04576 (5)	0.08785 (10)	0.0535 (3)
O3	0.15841 (13)	0.05730 (4)	0.33946 (9)	0.0394 (3)
H3	0.158 (2)	0.0508 (7)	0.4193 (11)	0.047*
N1	0.06055 (18)	0.17081 (6)	0.04393 (13)	0.0470 (3)
H1NA	0.074 (2)	0.1308 (6)	0.0459 (17)	0.056*
H1NB	−0.004 (2)	0.1902 (7)	−0.0177 (15)	0.056*
N2	0.23582 (16)	0.17105 (6)	0.23551 (12)	0.0428 (3)
H2NA	0.233 (2)	0.1306 (7)	0.2342 (16)	0.051*
N3	0.4140 (2)	0.17049 (7)	0.42646 (15)	0.0558 (4)
H3NA	0.407 (2)	0.1308 (7)	0.4247 (18)	0.067*
H3NB	0.477 (2)	0.1917 (8)	0.4890 (16)	0.067*
N4	0.32789 (15)	0.26210 (5)	0.33724 (11)	0.0373 (3)
N5	0.22621 (18)	0.35022 (5)	0.24256 (11)	0.0451 (3)
H5NA	0.157 (2)	0.3702 (8)	0.1812 (13)	0.054*
H5NB	0.282 (2)	0.3704 (8)	0.3088 (13)	0.054*
N6	0.13898 (15)	0.26268 (5)	0.13787 (10)	0.0353 (3)
C1	0.18246 (18)	0.00368 (6)	0.14673 (13)	0.0392 (3)
C2	0.09995 (16)	0.00520 (5)	0.26757 (11)	0.0308 (3)
H2A	0.1329	−0.0309	0.3157	0.037*
C3	0.23110 (16)	0.29059 (6)	0.23929 (11)	0.0338 (3)
C4	0.14503 (16)	0.20248 (6)	0.13831 (13)	0.0352 (3)
C5	0.32593 (17)	0.20212 (6)	0.33379 (13)	0.0386 (3)
O1W	0.45183 (14)	0.06665 (5)	−0.06993 (11)	0.0465 (3)
H1WA	0.391 (2)	0.0544 (8)	−0.0137 (16)	0.056*
H1WB	0.535 (2)	0.0446 (8)	−0.0730 (17)	0.056*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0750 (8)	0.0567 (7)	0.0575 (7)	0.0020 (6)	0.0378 (6)	0.0128 (6)
O2	0.0879 (8)	0.0446 (6)	0.0312 (5)	0.0254 (5)	0.0197 (5)	0.0046 (4)
O3	0.0533 (6)	0.0362 (5)	0.0272 (5)	−0.0122 (4)	0.0010 (4)	0.0008 (4)
N1	0.0582 (8)	0.0324 (6)	0.0480 (8)	−0.0069 (5)	−0.0006 (6)	−0.0048 (5)
N2	0.0496 (7)	0.0278 (6)	0.0494 (7)	0.0002 (5)	0.0013 (5)	0.0020 (5)
N3	0.0641 (8)	0.0382 (7)	0.0591 (9)	0.0069 (6)	−0.0120 (7)	0.0110 (6)
N4	0.0433 (6)	0.0337 (6)	0.0333 (6)	0.0020 (4)	0.0003 (5)	0.0027 (4)
N5	0.0658 (8)	0.0288 (6)	0.0358 (7)	−0.0001 (5)	−0.0097 (6)	0.0001 (5)
N6	0.0434 (6)	0.0308 (6)	0.0310 (6)	−0.0022 (4)	0.0033 (5)	0.0001 (4)
C1	0.0454 (7)	0.0420 (8)	0.0320 (7)	0.0151 (6)	0.0118 (5)	0.0100 (5)
C2	0.0422 (7)	0.0264 (6)	0.0236 (6)	0.0017 (5)	0.0046 (5)	0.0031 (4)
C3	0.0395 (6)	0.0329 (7)	0.0291 (6)	−0.0004 (5)	0.0048 (5)	0.0012 (5)
C4	0.0366 (6)	0.0328 (7)	0.0372 (7)	−0.0028 (5)	0.0086 (5)	−0.0003 (5)
C5	0.0383 (6)	0.0359 (7)	0.0412 (7)	0.0022 (5)	0.0044 (5)	0.0051 (6)
O1W	0.0443 (6)	0.0467 (6)	0.0496 (6)	0.0051 (4)	0.0102 (5)	0.0143 (5)

Geometric parameters (Å, º) top

O1—C1	1.2497 (18)	N4—C5	1.3174 (18)
O2—C1	1.2530 (18)	N4—C3	1.3527 (16)
O3—C2	1.4170 (15)	N5—C3	1.3104 (18)
O3—H3	0.870 (11)	N5—H5NA	0.901 (13)
N1—C4	1.3215 (18)	N5—H5NB	0.895 (13)
N1—H1NA	0.884 (13)	N6—C4	1.3224 (18)
N1—H1NB	0.879 (13)	N6—C3	1.3583 (16)
N2—C4	1.3590 (18)	C1—C2	1.5242 (18)
N2—C5	1.3610 (18)	C2—C2ⁱ	1.531 (2)
N2—H2NA	0.889 (15)	C2—H2A	0.9600
N3—C5	1.3193 (18)	O1W—H1WA	0.858 (14)
N3—H3NA	0.872 (14)	O1W—H1WB	0.804 (13)
N3—H3NB	0.900 (14)

C2—O3—H3	111.1 (11)	O2—C1—C2	116.11 (12)
C4—N1—H1NA	117.6 (12)	O3—C2—C1	110.08 (10)
C4—N1—H1NB	119.1 (12)	O3—C2—C2ⁱ	111.37 (8)
H1NA—N1—H1NB	123.3 (16)	C1—C2—C2ⁱ	108.42 (12)
C4—N2—C5	119.39 (13)	O3—C2—H2A	109.5
C4—N2—H2NA	119.1 (11)	C1—C2—H2A	109.3
C5—N2—H2NA	121.5 (11)	C2ⁱ—C2—H2A	108.2
C5—N3—H3NA	119.1 (13)	N5—C3—N4	117.12 (12)
C5—N3—H3NB	117.1 (12)	N5—C3—N6	117.29 (12)
H3NA—N3—H3NB	123.8 (17)	N4—C3—N6	125.59 (13)
C5—N4—C3	115.95 (12)	N1—C4—N6	120.66 (13)
C3—N5—H5NA	118.9 (11)	N1—C4—N2	117.72 (13)
C3—N5—H5NB	120.3 (11)	N6—C4—N2	121.62 (12)
H5NA—N5—H5NB	120.5 (15)	N4—C5—N3	120.17 (13)
C4—N6—C3	115.71 (11)	N4—C5—N2	121.69 (12)
O1—C1—O2	125.57 (13)	N3—C5—N2	118.14 (14)
O1—C1—C2	118.30 (13)	H1WA—O1W—H1WB	110.6 (16)

O1—C1—C2—O3	−15.91 (17)	C3—N6—C4—N1	−179.76 (12)
O2—C1—C2—O3	165.79 (11)	C3—N6—C4—N2	0.99 (18)
O1—C1—C2—C2ⁱ	106.14 (12)	C5—N2—C4—N1	179.33 (13)
O2—C1—C2—C2ⁱ	−72.17 (12)	C5—N2—C4—N6	−1.4 (2)
C5—N4—C3—N5	177.80 (13)	C3—N4—C5—N3	−178.79 (13)
C5—N4—C3—N6	−2.34 (19)	C3—N4—C5—N2	1.85 (19)
C4—N6—C3—N5	−179.21 (12)	C4—N2—C5—N4	−0.1 (2)
C4—N6—C3—N4	0.93 (18)	C4—N2—C5—N3	−179.50 (13)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2ⁱⁱ	0.87 (1)	1.80 (1)	2.6680 (14)	173 (2)
N1—H1NA···O1	0.88 (1)	2.27 (1)	3.0466 (19)	146 (2)
N1—H1NB···N4ⁱⁱⁱ	0.88 (1)	2.15 (1)	3.0287 (19)	177 (2)
N2—H2NA···O3	0.89 (2)	2.09 (2)	2.8333 (16)	140 (1)
N2—H2NA···O1	0.89 (2)	2.19 (2)	2.9497 (18)	143 (1)
N3—H3NA···O1W^iv	0.87 (1)	2.26 (2)	2.8609 (18)	126 (2)
N3—H3NA···O3	0.87 (1)	2.57 (2)	3.2241 (18)	132 (2)
N3—H3NB···N6^v	0.90 (1)	2.13 (1)	3.0313 (19)	176 (2)
N5—H5NA···O1W^vi	0.90 (1)	1.94 (1)	2.8148 (16)	163 (2)
N5—H5NB···O2^vii	0.90 (1)	2.15 (2)	2.9581 (16)	149 (2)
O1W—H1WA···O1	0.86 (1)	1.85 (1)	2.6861 (16)	164 (2)
O1W—H1WB···O2^viii	0.80 (1)	2.30 (2)	2.9738 (17)	142 (2)

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

Experimental details

Crystal data
Chemical formula	2C₃H₇N₆⁺·C₄H₄O₆²⁻·2H₂O
M_r	436.38
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	296
a, b, c (Å)	7.6963 (9), 21.955 (3), 10.7405 (12)
β (°)	98.179 (6)
V (Å³)	1796.4 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.14
Crystal size (mm)	0.26 × 0.22 × 0.12

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.963, 0.980
No. of measured, independent and observed [I > 2σ(I)] reflections	13436, 2047, 1712
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.108, 1.00
No. of reflections	2047
No. of parameters	166
No. of restraints	15
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.25, −0.24

Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2ⁱ	0.870 (11)	1.802 (12)	2.6680 (14)	173.2 (16)
N1—H1NA···O1	0.884 (13)	2.271 (14)	3.0466 (19)	146.3 (16)
N1—H1NB···N4ⁱⁱ	0.879 (13)	2.151 (13)	3.0287 (19)	177.3 (17)
N2—H2NA···O3	0.889 (15)	2.093 (15)	2.8333 (16)	140.2 (14)
N2—H2NA···O1	0.889 (15)	2.190 (15)	2.9497 (18)	143.2 (14)
N3—H3NA···O1Wⁱⁱⁱ	0.872 (14)	2.261 (19)	2.8609 (18)	125.9 (15)
N3—H3NA···O3	0.872 (14)	2.573 (16)	3.2241 (18)	132.2 (16)
N3—H3NB···N6^iv	0.900 (14)	2.133 (14)	3.0313 (19)	176.2 (18)
N5—H5NA···O1W^v	0.901 (13)	1.940 (14)	2.8148 (16)	163.2 (15)
N5—H5NB···O2^vi	0.895 (13)	2.153 (15)	2.9581 (16)	149.4 (15)
O1W—H1WA···O1	0.858 (14)	1.852 (14)	2.6861 (16)	163.8 (17)
O1W—H1WB···O2^vii	0.804 (13)	2.297 (15)	2.9738 (17)	142.3 (17)

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

References

Bruker (2006). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Krische, M. J. & Lehn, J. M. (2000). Struct. Bond. 96, 3–29. CrossRef CAS Google Scholar
Marchewka, M. K., Janczak, J., Debrus, S., Baran, J. & Ratajczak, H. (2003). Solid State Sci. 5, 643–652. Web of Science CSD CrossRef CAS Google Scholar
Row, T. N. G. (1999). Coord. Chem. Rev. 183, 81–100. CAS Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sherrington, D. C. & Taskinen, K. A. (2001). Chem. Soc. Rev. 30, 83–91. Web of Science CrossRef CAS Google Scholar
Thushari, S., Cha, J. A. K., Sung, H. H.-Y., Chui, S. S.-Y., Leung, A. L.-F., Yen, Y. F. & Williams, I. D. (2005). Chem. Commun. pp. 5515–5517. Web of Science CSD CrossRef Google Scholar
Udaya Lakshmi, K., Thamotharan, S., Ramamurthi, K. & Varghese, B. (2006). Acta Cryst. E62, o455–o457. Web of Science CSD CrossRef IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 4| April 2009| Page o933

doi:10.1107/S1600536809011143

Open

access