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Growth, crystal structure and thermal properties of calcium bis(malate) dihydrate
Journal of Alloys and Compounds 433 (2007) 211–215
Growth, crystal structure and thermal properties of calcium bis(malate) dihydrate T. Jini a , K.V. Saban a , G. Varghese a , S. Naveen b , M.A. Sridhar b,∗ , J.S. Prasad b a
Department of Physics, St. Berchmans College, Changanassery 686 101, Kerala, India b Department of Studies in Physics, University of Mysore, Mysore 570 006, India Received 16 March 2006; accepted 6 June 2006 Available online 17 July 2006
Abstract A new coordination compound crystal of calcium with malic acid is prepared by gel aided solution growth. Single crystal X-ray diffraction studies revealed that the structural formula of the compound is Ca(C4 H4 O5 )2 ·2H2 O. It crystallizes in the monoclinic system with space group C2/c, ˚ b = 5.886(3) A, ˚ c = 13.046(6) A ˚ and β = 90.678(4)◦ . Data were collected by oscillation method Z = 4, with unit cell parameters a = 15.916(9) A, and full-matrix least squares refinement was applied to the model converging to final R indices R1 = 0.0416 and ωR2 = 0.1255. Compound forms a layer-type polymeric structure, stabilized by intermolecular hydrogen bonding. Ca2+ is eight-fold coordinated. Malate is coordinated to Ca2+ tridendate–bidendate through two carboxylates and monodendate through oxygen atom of the hydroxyl group. Thermal behavior investigated using TG and DTA studies is in conformity with the proposed structure. © 2006 Elsevier B.V. All rights reserved. Keywords: Crystal growth; Crystal structure; X-ray diffraction; Thermal analysis
1. Introduction
2. Experimental
Dicarboxylic acids and their metal complexes have been attracting immense interest due to their wide-ranging applications. In literature, we come across with the growth, properties and structural studies of various dicarboxylates such as oxalates [1–6], malonates [7–9], maleates [10–13], tartrates [14–16], etc. Because of its vital importance in food industry and in biochemistry, certain salts of malic acid with different metals like zinc, iron, nickel, sodium [17–18] have been grown and characterized by many methods. Recently, a few lanthanide malates also have been synthesized [19–21]. The crystal structures of calcium malates with different water of hydration are investigated [22–26] by some researchers. In this report, we present the growth of a novel single crystal-calcium bis(malate)dihydrate by gel aided solution technique and its structural analysis. The thermal decomposition pattern of the title compound also has been explored here.
Single crystals for the present investigations were developed by ionic diffusion in hydro-silica gel. The gelating medium was prepared by titrating aqueous solution of sodium meta silicate (Na2 SiO3 ·9H2 O) against malic acid [27]. Acidic strength and volume were adjusted to maintain the desired pH. The mixed solution was then introduced into standard Borosil test tube of length 20 cm and inner diameter 2 cm. These crystallization vessels were well sealed to eliminate surface contamination. Sufficient time was given to the gel to set in and then the supernatant calcium chloride solution was poured over it without tampering with the meniscus of the gel. Experiments were conducted at various gel densities and concentrations of inner and outer reactants. Well-developed crystals were separated from the gel medium after ensuring their maximum growth. Majority of the crystals prepared by this way were sufficiently good for crystallization studies. A good single crystal of the title compound with dimensions 0.3 mm × 0.27 mm × 0.25 mm was chosen for X-ray diffraction analysis. The measurements were made on a DIPLabo Imaging Plate Diffractometer with graphite monochromated Mo K␣ radiation. The crystal to detector distance was fixed at 120 mm with a detector area of 440 mm × 291 mm. Thirty-six frames of data were collected by the oscillation method with each frame being exposed for 300 s. Successive frames were scanned in steps of 5◦ min−1 with an oscillation range of 5◦ . Image processing and data reduction were done using Denzo [28]. The structure was solved and refined using maXus [29–31] program. The phase set with the highest combined figure of merit gave the positions of all non-hydrogen atoms. The full-matrix least squares refinement based on 1825
∗
Corresponding author. E-mail address: [email protected] (M.A. Sridhar).
0925-8388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2006.06.035
212
T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215
observed reflections and 98 parameters with anisotropic thermal parameters for non-hydrogen atoms and isotropic thermal parameters for hydrogen atoms converged the residual to R1 = 0.0416 and ωR2 = 0.1255. TG and DTA studies were carried out on the crystal, employing STA 1500 Simultaneous Thermal Analysis System (PL Thermal Sciences Division, UK). For conducting these thermal studies, sample was heated from ambient to 900 ◦ C in nitrogen atmosphere. The heating rate was 10 ◦ C min−1 .
3. Results and discussion 3.1. Crystal formation Comparing the results from a range of experiments, optimum parameters for obtaining better crystals are identified. It is observed that excellent crystals are formed in a gel of Table 1 Crystal data and structure refinement table Empirical formula Formula weight Temperature Wavelength Crystal system Space group Cell dimensions Volume Z Density calculated, Dc Absorption coefficient F0 0 0 Crystal size θ range for data collection Index ranges Reflections collected Independent reflections Refinement method Data/restraints/parameters Goodness-of-fit on F2 Final R indices [I > 2σ(I)] R indices (all data) Extinction coefficient Largest diffraction peak and hole Measurement Program system
C8 H12 CaO12 340.26 293(2) K ˚ 0.71073 A Monoclinic C2/c ˚ b = 5.8860(3) A, ˚ a = 15.9160(9) A, ˚ β = 90.678(4)◦ c = 13.0460(6) A, ˚3 1222.08(11) A 4 1.849 Mg/m3 0.582 mm−1 704 0.3 mm × 0.27 mm × 0.25 mm 3.12–32.49◦ −23 ≤ h ≤ 24; −7 ≤ k ≤ 8; −16 ≤ l ≤ 15 2968 1825[R (int) = 0.0161] Full-matrix least-squares on F2 1825/0/98 1.159 R1 = 0.0416, ωR2 = 0.1255 R1 = 0.0428, ωR2 = 0.1269 0.023(3) ˚ −3 0.758 and −0.764 A DIPLabo Kappa Denzo
Table 2 Atomic coordinates and equivalent thermal parameters of the non-hydrogen atoms Atom
x
y
z
Ueq
Ca(1) O(10) O(7) O(4) O(9) O(2) C(6) C(3) C(5) C(8) O(11)
0.5000 0.6097(8) 0.4226(7) 0.6451(7) 0.5166(8) 0.2824(7) 0.3727(9) 0.2901(8) 0.2864(9) 0.4202(9) 0.4229(7)
0.1391(6) −0.3443(2) 0.2311(2) 0.0166(2) −0.1710(2) 0.5185(2) 0.0514(2) 0.0239(2) 0.0411(3) 0.1734(2) 0.4619(2)
0.7500 0.9716(1) 0.5977(1) 0.7255(1) 0.8679(1) 0.7281(1) 0.5575(1) 0.7236(1) 0.6083(1) 1.0738(1) 0.8325(1)
0.0171(2) 0.0244(3) 0.0224(3) 0.0244(3) 0.0268(3) 0.0248(3) 0.0185(3) 0.0196(3) 0.022(3) 0.0187(3) 0.0219(3)
Table 3 ˚ Bond lengths (A) Atoms
Length
Ca(1) O(7)#1 Ca(1) O(9)#1 Ca(1) O(4)#1 Ca(1) O(11)#1 Ca(1) C(8)#2 O(10) C(8)#3 O(7) C(6) O(4) C(3)#1 O(9) C(8)#3 O(2) C(3)#4 C(6) C(5) C(6) C(8)#2 C(3) O(4)#1 C(3) O(2)#5 C(3) C(5) C(8) O(9)#3 C(8) O(10)#3 C(8) C(6)#6 C(8) Ca(1)#3
2.3875(1) 2.3999(1) 2.4445(1) 2.5108(1) 3.196(2) 1.257(2) 1.419(2) 1.219(2) 1.256(2) 1.322(2) 1.533(2) 1.536(2) 1.219(2) 1.322(2) 1.508(2) 1.256(2) 1.257(2) 1.536(2) 3.196(2)
Table 4 Bond angles (◦ ) Atoms
Angle
O(2)#5 C(3) C(5) C(3)#1 O(4) Ca(1) C(3) C(5) C(6) O(4) Ca(1) O(4)#1 O(4) Ca(1) C(8)#2 O(4) Ca(1) C(8)#3 O(4) Ca(1) O(11) O(4) Ca(1) O(11)#1 O(4)#1 Ca(1) O(11)#1 O(4)#1 Ca(1) C(8)#2 O(4)#1 Ca(1) O(11) O(4)#1 C(3) O(2)#5 O(4)#1 C(3) C(5) O(4)#1 Ca(1) C(8)#3 C(5) C(6) C(8)#2 C(6)#6 C(8) Ca(1)#3 C(6) O(7) Ca(1) O(7) Ca(1) O(7)#1 O(7) Ca(1) O(9)#1 O(7)#1 Ca(1) O(9)#1 O(7) Ca(1) O(9) O(7)#1 Ca(1) O(9) O(7) Ca(1) O(11) O(7)#1 Ca(1) O(11) O(7) Ca(1) O(4) O(7)#1 Ca(1) O(4) O(7) Ca(1) O(4)#1 O(7) Ca(1) O(11)#1 O(7)#1 Ca(1) O(11)#1 O(7)#1 Ca(1) O(4)#1 O(7) Ca(1) C(8)#2 O(7)#1 Ca(1) C(8)#2 O(7) Ca(1) C(8)#3 O(7)#1 Ca(1) C(8)#3 O(7) C(6) C(5) O(7) C(6) C(8)#2 C(8)#2 Ca(1) C(8)#3
116.89(1) 135.40(1) 114.14(1) 145.70(6) 96.04(4) 63.60(4) 138.26(4) 72.55(4) 138.26(4) 63.60(4) 72.55(4) 118.49(2) 124.62(1) 96.04(4) 110.27(1) 78.16(8) 114.81(9) 153.79(5) 65.61(4) 139.27(4) 139.27(4) 65.61(4) 86.30(4) 73.82(4) 115.92(4) 72.34(4) 72.34(4) 73.82(4) 86.30(4) 115.92(4) 48.30(4) 157.83(4) 157.83(4) 48.30(4) 111.72(1) 108.59(1) 109.75(5)
T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215 Table 4 (Continued ) Atoms
Angle
C(8)#3 O(9) Ca(1) O(9)#3 C(8) O(10)#3 O(9)#3 C(8) C(6)#6 O(9)#3 C(8) Ca(1)#3 O(9)#1 Ca(1) O(4)#1 O(9) Ca(1) O(4)#1 O(9)#1 Ca(1) O(9) O(9)#1 Ca(1) O(4) O(9) Ca(1) O(4) O(9)#1 Ca(1) O(11)#1 O(9) Ca(1) O(11)#1 O(9)#1 Ca(1) O(11) O(9) Ca(1) O(11) O(9)#1 Ca(1) C(8)#2 O(9) Ca(1) C(8)#2 O(9)#1 Ca(1) C(8)#3 O(9) Ca(1) C(8)#3 O(10)#3 C(8) C(6)#6 O(10)#3 C(8) Ca(1)#3 O(11)#1 Ca(1) O(11) O(11)#1 Ca(1) C(8)#2 O(11) Ca(1) C(8)#2 O(11)#1 Ca(1) C(8)#3 O(11) Ca(1) C(8)#3
118.53(9) 126.06(1) 117.63(1) 41.28(7) 76.27(4) 77.81(4) 80.98(7) 77.81(4) 76.27(4) 110.56(4) 143.13(4) 143.13(4) 110.56(4) 20.20(4) 93.63(4) 93.63(4) 20.19(4) 116.30(1) 160.68(1) 81.63(5) 108.63(4) 123.46(4) 123.46(4) 108.63(4)
Symmetry transformations used to generate equivalent atoms: #1 (−x + 1, y, −z + 3/2), #2 (x, −y, z −1/2), #3 (−x + 1, −y, −z + 2), #4 (−x + 1/2, y + 1/2, −z + 3/2), #5 (−x + 1/2, y −1/2, −z + 3/2), #6 (x, −y, z + 1/2).
density 1.06 g/cm3 at pH 3. Inner malic acid and outer calcium chloride concentrations were kept at 1 and 0.5 M, respectively for obtaining almost flawless crystals. At these values it took almost 1 week for the gel to set. Growth was initiated in 10 days. Colorless and prismatic crystals were appeared at the gel–solution interface. Maximum size of the crystals yielded was 8 mm × 4 mm × 2 mm. These crystals, which appeared to be transparent inside the gel, became translucent when exposed to atmosphere. 3.2. Crystal structure analysis Table 1 gives the details of the crystal and structure refinement data. The atomic coordinates and equivalent thermal parameters for all the non-hydrogen atoms are given in Table 2. The bond distances and angles are in good agreement with the standard values. Tables 3 and 4 give the selected bond lengths ˚ and bond angles. The average bond lengths (C C: 1.533(2) A,
213
˚ compare well with those in the other calcium C O: 1.2571(2) A) malates [22,23]. The structure exhibits intermolecular hydrogen bonds of the type O H· · ·O. The bond lengths and angles along with the symmetry codes are listed in Table 5. Fig. 1 represents the ORTEP [32,33] of the molecules with thermal ellipsoids at 50% probability. The packing of the molecules down b-axis (Fig. 2) shows layer-type polymeric structure, which is stabilized by intermolecular hydrogen bonds. The layers are formed by the chelate ring Ca O C O by monodentated coordination. In all the hydrogen bonds, the water oxygen (O(11)) along with O(7) act as donor atoms and the carboxylate groups or the other oxygens (O(2), O(10), O(9)) act as acceptor atom. The calcium atom is coordinated with two water molecules. These water molecules are involved in the extensive network of hydrogen bonds amongst themselves. It appears that, in addition to the oxygen bridge bonds involving the malate ligand, the hydrogen bonds are responsible for the stability of the structure. 3.3. Thermal properties Information regarding the stability and thermal decomposition of the grown crystal was collected with the aid of the TG and DTA curves. The thermogram recorded is shown in Fig. 3. A close analysis of the TG curve shows that the material is thermally stable up to 120 ◦ C. A stepped decomposition curve is obtained for the compound. Hydrated water molecules are liberated at the initial stage of decomposition, corresponding to a temperature range 120–180 ◦ C. The observed and calculated percent of weight loss during this dehydration process are 10.8 and 10.589, respectively. The anhydrous calcium bis(malate) [Ca(C4 H4 O5 )2 ] gets decomposed into Ca(C2 O4 )2 and elementary carbon in the temperature range 180–235 ◦ C along with the liberation of carbon monoxide and hydrogen molecule. The forthcoming stage of decomposition that gets completed at 440 ◦ C results in the formation of calcium oxalate. In the above transition carbon monoxide was evolved. Further heating up to 490 ◦ C results in the conversion of oxalate group to carbonate along with the elimination of carbon monoxide. In the final stage of decomposition, this calcium carbonate is reduced to calcium oxide at 690 ◦ C. No further decomposition was observed up to 900 ◦ C. It is noted that all the transformations are associated with some mass loss. It suggests that there is no structural change independent of mass change in the compound. In Table 5, various thermal decomposition stages and corresponding mass losses are listed. It is evident from the data that the observed percent of mass loss in each stage is in conformity with the calculated one.
Table 5 The decomposition process of Ca(C4 H4 O5 )2 ·2H2 O Stage
Decomposition temperature (◦ C)
Product after decomposition
Molecules evolved
Observed mass loss (%)
Calculated mass loss (%)
I II III IV V
120–180 180–235 250–440 440–490 500–690
Ca(C4 H4 O5 )2 Ca(C2 O4 )2 + 2C Ca(C2 O4 ) CaCO3 CaO
2H2 O 2CO + 4H2 4CO CO CO2
10.8 18.9 33 8.8 12.9
10.589 18.834 32.929 8.232 12.934
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Fig. 1. ORTEP of the molecule at 50% probability.
Peaks in the DTA curve stand as additional support to the TG results. The broader endotherm near 180 ◦ C corresponds to the dehydration process. The exothermic peak observed around 490 ◦ C indicates the transformation of calcium oxalate into calcium carbonate with the liberation of carbon dioxide .The endothermic peak near 700 ◦ C shows the decomposition of calcium carbonate into calcium oxide.
Fig. 3. TG–DTA curve for calcium bis(malate) dihydrate.
4. Conclusions Diffusion of supernatant calcium chloride ions into the silica gel impregnated with malic acid results in the formation of calcium malate crystals. Single crystal studies revealed that the compound is Ca(C4 H4 O5 )2 ·2H2 O. It crystallizes in the monoclinic system with space group C2/c. Thermal behavior suggests that the material is stable up to 120 ◦ C. Passing through various intermediate stages, it ultimately gets reduced to calcium oxide at 690 ◦ C. Acknowledgements The authors are grateful to DST, Government of India for providing the financial assistance under the project SP/I2/FOO/93 and Central Electrochemical Research Institute(CECRI), Karaikudi for providing the TG-DTA facilities. One of the authors GV is grateful to the UGC for a minor research project. References Fig. 2. Packing of the molecules down b-axis.
[1] H. Shing-Hua, T.C.W. Mak, Z. Kristallogr. 190 (1990) 305.
T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215 [2] H. Shing-Hua, G.D. Zhon, T.C.W. Mak, J. Cryst. Spect. Res. 21 (2) (1991) 127. [3] E.K. Girija, S.C. Latha, S.N. Kalkura, C. Subrahmanian, P. Ramasamy, Mater. Chem. Phys. 52 (1998) 253. [4] S.M. Dharmaprakash, P. Mohanrao, Cryst. Res. Technol. 23 (3) (1988) K143. [5] W. Ollendorf, F. Weigel, Inorg. Nucl. Chem. Lett. 5 (1969) 263. [6] E. Hanson, D. Tropllet, S. Romero, A. Mosset, J.C. Trombe, C.R. Acad. Sci. Paris 325 (1997) 663. [7] M.H. Molina, P.A.L. Luis, T. Lopez, C.R. Oerez, F. Lloret, M. Julve, Cryst. Eng. Commun. 31 (2003) 1. [8] B.H. Doreswamy, M. Mahendra, M.A. Sridhar, J. Sasidharaprasad, P.A. Varughese, K.V. Saban, G. Varghese, J. Mol. Struct. 659 (2003) 81. [9] P.A. Varughese, K.V. Saban, J. George, I. Paul, G. Varghese, J. Mater. Sci. 39 (2004) 6325. [10] G. Oczko, J. Legendzienicz, M.S. Wickeleder, G. Meyer, J. Alloys Compd. 341 (2002) 255. [11] C. Bromant, M.S. Wickeleder, G. Meyer, Z. Anorg. Allg. Chem. 627 (2001) 768. [12] M.P. Gupta, K. Banerjee, Z. Kristallogr. 162 (1983) 277. [13] B. Hsu, E.O. Schlemper, Acta Crystallogr. B 34 (1978) 980. [14] P.N. Kotru, K.K. Raina, M.L. Koul, J. Mater. Sci. 21 (1986) 3933. [15] P.N. Kotru, N.K. Gupta, K.K. Raina, Kristallogr. Technik 21 (1986) 15. [16] P.N. Kotru, N.K. Gupta, K.K. Raina, J. Mater. Sci. 21 (1986) 90. [17] L. Patron, O. Carp, I. Mindru, G. Marinescu, E. Segal, J. Therm. Anal. Cal. 72 (2003) 281. [18] G. Arunmozhi, E.D. Gomes, M. Belsley, A. Criado, S.P. Garrido, F. Proenca, Ferroelectrics 295 (2003) 47.
215
[19] I.V. Shabanova, V.T. Panyushkin, V.Y. Frolov, V.I. Zelenov, T.P. Storozhenko, Russ. J. Electrochem. 40 (4) (2004) 474. [20] I.V. Sukhno, M.B. Gavrilyuk, V.Y. Buz’ko, V.T. Panyushkin, Russ. J. Coord. Chem. 30 (7) (2004) 520. [21] I.V. Sukhno, V.Yu. Buz’ko, V.T. Panyushkin, M.B. Gavrilyuk, Russ. J. Coord. Chem. 30 (8) (2004) 591. [22] C.A. Br¨anden, B.O. S¨oderberg, Acta Chem. Scand. 20 (1966) 730. [23] A.T.H. Lenstra, W.V. Havere, Acta Crystallogr. B 36 (1980) 156. [24] R. Wartchow, Z. Kristallogr. 211 (1996) 329. [25] F. Iwig, O. Hecht, Ann. Chem. Pharm. 233 (1886) 166. [26] A. Devatine, J.P. Canselier, N. Gabas, J. Jaud, J. Coord. Chem. 33 (2) (2003) 85. [27] H.K. Henisch, Crystal Growth in Gels, Pennsylvania University Press, Pittsburg, 1970. [28] Z. Otwinowski, W. Minor, C.M. Carter Jr., R.M. Sweet, Methods in Enzymology, vol. 276, Academic Press, New York, 1997, p. 307. [29] S. Mackay, C.J. Gilmore, C. Edwards, N. Stewart, K. Shankland, maXus Computer Program for the Solution and Refinement of Crystal Structures Bruker: Nonius, Japan and The University of Glasgow, The Netherlands, MacScience, 1999. [30] G.M. Sheldrick, SHELXS-97, Program for Crystal Structure Solution, University of G¨ottingen, Germany, 1997. [31] G.M. Sheldrick, SHELXL-97, Program for the Refinement of Crystal Structures, University of G¨ottingen, Germany, 1997. [32] A.L. Spek, Acta. Crystallogr. A 46 (1990) C 34. [33] A.L. Spek, PLATON, A Multipurpose Crystallographic Tool, University of Utretcht, The Netherlands, 1998.
Growth, crystal structure and thermal properties of calcium bis(malate) dihydrate T. Jini a , K.V. Saban a , G. Varghese a , S. Naveen b , M.A. Sridhar b,∗ , J.S. Prasad b a
Department of Physics, St. Berchmans College, Changanassery 686 101, Kerala, India b Department of Studies in Physics, University of Mysore, Mysore 570 006, India Received 16 March 2006; accepted 6 June 2006 Available online 17 July 2006
Abstract A new coordination compound crystal of calcium with malic acid is prepared by gel aided solution growth. Single crystal X-ray diffraction studies revealed that the structural formula of the compound is Ca(C4 H4 O5 )2 ·2H2 O. It crystallizes in the monoclinic system with space group C2/c, ˚ b = 5.886(3) A, ˚ c = 13.046(6) A ˚ and β = 90.678(4)◦ . Data were collected by oscillation method Z = 4, with unit cell parameters a = 15.916(9) A, and full-matrix least squares refinement was applied to the model converging to final R indices R1 = 0.0416 and ωR2 = 0.1255. Compound forms a layer-type polymeric structure, stabilized by intermolecular hydrogen bonding. Ca2+ is eight-fold coordinated. Malate is coordinated to Ca2+ tridendate–bidendate through two carboxylates and monodendate through oxygen atom of the hydroxyl group. Thermal behavior investigated using TG and DTA studies is in conformity with the proposed structure. © 2006 Elsevier B.V. All rights reserved. Keywords: Crystal growth; Crystal structure; X-ray diffraction; Thermal analysis
1. Introduction
2. Experimental
Dicarboxylic acids and their metal complexes have been attracting immense interest due to their wide-ranging applications. In literature, we come across with the growth, properties and structural studies of various dicarboxylates such as oxalates [1–6], malonates [7–9], maleates [10–13], tartrates [14–16], etc. Because of its vital importance in food industry and in biochemistry, certain salts of malic acid with different metals like zinc, iron, nickel, sodium [17–18] have been grown and characterized by many methods. Recently, a few lanthanide malates also have been synthesized [19–21]. The crystal structures of calcium malates with different water of hydration are investigated [22–26] by some researchers. In this report, we present the growth of a novel single crystal-calcium bis(malate)dihydrate by gel aided solution technique and its structural analysis. The thermal decomposition pattern of the title compound also has been explored here.
Single crystals for the present investigations were developed by ionic diffusion in hydro-silica gel. The gelating medium was prepared by titrating aqueous solution of sodium meta silicate (Na2 SiO3 ·9H2 O) against malic acid [27]. Acidic strength and volume were adjusted to maintain the desired pH. The mixed solution was then introduced into standard Borosil test tube of length 20 cm and inner diameter 2 cm. These crystallization vessels were well sealed to eliminate surface contamination. Sufficient time was given to the gel to set in and then the supernatant calcium chloride solution was poured over it without tampering with the meniscus of the gel. Experiments were conducted at various gel densities and concentrations of inner and outer reactants. Well-developed crystals were separated from the gel medium after ensuring their maximum growth. Majority of the crystals prepared by this way were sufficiently good for crystallization studies. A good single crystal of the title compound with dimensions 0.3 mm × 0.27 mm × 0.25 mm was chosen for X-ray diffraction analysis. The measurements were made on a DIPLabo Imaging Plate Diffractometer with graphite monochromated Mo K␣ radiation. The crystal to detector distance was fixed at 120 mm with a detector area of 440 mm × 291 mm. Thirty-six frames of data were collected by the oscillation method with each frame being exposed for 300 s. Successive frames were scanned in steps of 5◦ min−1 with an oscillation range of 5◦ . Image processing and data reduction were done using Denzo [28]. The structure was solved and refined using maXus [29–31] program. The phase set with the highest combined figure of merit gave the positions of all non-hydrogen atoms. The full-matrix least squares refinement based on 1825
∗
Corresponding author. E-mail address: [email protected] (M.A. Sridhar).
0925-8388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2006.06.035
212
T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215
observed reflections and 98 parameters with anisotropic thermal parameters for non-hydrogen atoms and isotropic thermal parameters for hydrogen atoms converged the residual to R1 = 0.0416 and ωR2 = 0.1255. TG and DTA studies were carried out on the crystal, employing STA 1500 Simultaneous Thermal Analysis System (PL Thermal Sciences Division, UK). For conducting these thermal studies, sample was heated from ambient to 900 ◦ C in nitrogen atmosphere. The heating rate was 10 ◦ C min−1 .
3. Results and discussion 3.1. Crystal formation Comparing the results from a range of experiments, optimum parameters for obtaining better crystals are identified. It is observed that excellent crystals are formed in a gel of Table 1 Crystal data and structure refinement table Empirical formula Formula weight Temperature Wavelength Crystal system Space group Cell dimensions Volume Z Density calculated, Dc Absorption coefficient F0 0 0 Crystal size θ range for data collection Index ranges Reflections collected Independent reflections Refinement method Data/restraints/parameters Goodness-of-fit on F2 Final R indices [I > 2σ(I)] R indices (all data) Extinction coefficient Largest diffraction peak and hole Measurement Program system
C8 H12 CaO12 340.26 293(2) K ˚ 0.71073 A Monoclinic C2/c ˚ b = 5.8860(3) A, ˚ a = 15.9160(9) A, ˚ β = 90.678(4)◦ c = 13.0460(6) A, ˚3 1222.08(11) A 4 1.849 Mg/m3 0.582 mm−1 704 0.3 mm × 0.27 mm × 0.25 mm 3.12–32.49◦ −23 ≤ h ≤ 24; −7 ≤ k ≤ 8; −16 ≤ l ≤ 15 2968 1825[R (int) = 0.0161] Full-matrix least-squares on F2 1825/0/98 1.159 R1 = 0.0416, ωR2 = 0.1255 R1 = 0.0428, ωR2 = 0.1269 0.023(3) ˚ −3 0.758 and −0.764 A DIPLabo Kappa Denzo
Table 2 Atomic coordinates and equivalent thermal parameters of the non-hydrogen atoms Atom
x
y
z
Ueq
Ca(1) O(10) O(7) O(4) O(9) O(2) C(6) C(3) C(5) C(8) O(11)
0.5000 0.6097(8) 0.4226(7) 0.6451(7) 0.5166(8) 0.2824(7) 0.3727(9) 0.2901(8) 0.2864(9) 0.4202(9) 0.4229(7)
0.1391(6) −0.3443(2) 0.2311(2) 0.0166(2) −0.1710(2) 0.5185(2) 0.0514(2) 0.0239(2) 0.0411(3) 0.1734(2) 0.4619(2)
0.7500 0.9716(1) 0.5977(1) 0.7255(1) 0.8679(1) 0.7281(1) 0.5575(1) 0.7236(1) 0.6083(1) 1.0738(1) 0.8325(1)
0.0171(2) 0.0244(3) 0.0224(3) 0.0244(3) 0.0268(3) 0.0248(3) 0.0185(3) 0.0196(3) 0.022(3) 0.0187(3) 0.0219(3)
Table 3 ˚ Bond lengths (A) Atoms
Length
Ca(1) O(7)#1 Ca(1) O(9)#1 Ca(1) O(4)#1 Ca(1) O(11)#1 Ca(1) C(8)#2 O(10) C(8)#3 O(7) C(6) O(4) C(3)#1 O(9) C(8)#3 O(2) C(3)#4 C(6) C(5) C(6) C(8)#2 C(3) O(4)#1 C(3) O(2)#5 C(3) C(5) C(8) O(9)#3 C(8) O(10)#3 C(8) C(6)#6 C(8) Ca(1)#3
2.3875(1) 2.3999(1) 2.4445(1) 2.5108(1) 3.196(2) 1.257(2) 1.419(2) 1.219(2) 1.256(2) 1.322(2) 1.533(2) 1.536(2) 1.219(2) 1.322(2) 1.508(2) 1.256(2) 1.257(2) 1.536(2) 3.196(2)
Table 4 Bond angles (◦ ) Atoms
Angle
O(2)#5 C(3) C(5) C(3)#1 O(4) Ca(1) C(3) C(5) C(6) O(4) Ca(1) O(4)#1 O(4) Ca(1) C(8)#2 O(4) Ca(1) C(8)#3 O(4) Ca(1) O(11) O(4) Ca(1) O(11)#1 O(4)#1 Ca(1) O(11)#1 O(4)#1 Ca(1) C(8)#2 O(4)#1 Ca(1) O(11) O(4)#1 C(3) O(2)#5 O(4)#1 C(3) C(5) O(4)#1 Ca(1) C(8)#3 C(5) C(6) C(8)#2 C(6)#6 C(8) Ca(1)#3 C(6) O(7) Ca(1) O(7) Ca(1) O(7)#1 O(7) Ca(1) O(9)#1 O(7)#1 Ca(1) O(9)#1 O(7) Ca(1) O(9) O(7)#1 Ca(1) O(9) O(7) Ca(1) O(11) O(7)#1 Ca(1) O(11) O(7) Ca(1) O(4) O(7)#1 Ca(1) O(4) O(7) Ca(1) O(4)#1 O(7) Ca(1) O(11)#1 O(7)#1 Ca(1) O(11)#1 O(7)#1 Ca(1) O(4)#1 O(7) Ca(1) C(8)#2 O(7)#1 Ca(1) C(8)#2 O(7) Ca(1) C(8)#3 O(7)#1 Ca(1) C(8)#3 O(7) C(6) C(5) O(7) C(6) C(8)#2 C(8)#2 Ca(1) C(8)#3
116.89(1) 135.40(1) 114.14(1) 145.70(6) 96.04(4) 63.60(4) 138.26(4) 72.55(4) 138.26(4) 63.60(4) 72.55(4) 118.49(2) 124.62(1) 96.04(4) 110.27(1) 78.16(8) 114.81(9) 153.79(5) 65.61(4) 139.27(4) 139.27(4) 65.61(4) 86.30(4) 73.82(4) 115.92(4) 72.34(4) 72.34(4) 73.82(4) 86.30(4) 115.92(4) 48.30(4) 157.83(4) 157.83(4) 48.30(4) 111.72(1) 108.59(1) 109.75(5)
T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215 Table 4 (Continued ) Atoms
Angle
C(8)#3 O(9) Ca(1) O(9)#3 C(8) O(10)#3 O(9)#3 C(8) C(6)#6 O(9)#3 C(8) Ca(1)#3 O(9)#1 Ca(1) O(4)#1 O(9) Ca(1) O(4)#1 O(9)#1 Ca(1) O(9) O(9)#1 Ca(1) O(4) O(9) Ca(1) O(4) O(9)#1 Ca(1) O(11)#1 O(9) Ca(1) O(11)#1 O(9)#1 Ca(1) O(11) O(9) Ca(1) O(11) O(9)#1 Ca(1) C(8)#2 O(9) Ca(1) C(8)#2 O(9)#1 Ca(1) C(8)#3 O(9) Ca(1) C(8)#3 O(10)#3 C(8) C(6)#6 O(10)#3 C(8) Ca(1)#3 O(11)#1 Ca(1) O(11) O(11)#1 Ca(1) C(8)#2 O(11) Ca(1) C(8)#2 O(11)#1 Ca(1) C(8)#3 O(11) Ca(1) C(8)#3
118.53(9) 126.06(1) 117.63(1) 41.28(7) 76.27(4) 77.81(4) 80.98(7) 77.81(4) 76.27(4) 110.56(4) 143.13(4) 143.13(4) 110.56(4) 20.20(4) 93.63(4) 93.63(4) 20.19(4) 116.30(1) 160.68(1) 81.63(5) 108.63(4) 123.46(4) 123.46(4) 108.63(4)
Symmetry transformations used to generate equivalent atoms: #1 (−x + 1, y, −z + 3/2), #2 (x, −y, z −1/2), #3 (−x + 1, −y, −z + 2), #4 (−x + 1/2, y + 1/2, −z + 3/2), #5 (−x + 1/2, y −1/2, −z + 3/2), #6 (x, −y, z + 1/2).
density 1.06 g/cm3 at pH 3. Inner malic acid and outer calcium chloride concentrations were kept at 1 and 0.5 M, respectively for obtaining almost flawless crystals. At these values it took almost 1 week for the gel to set. Growth was initiated in 10 days. Colorless and prismatic crystals were appeared at the gel–solution interface. Maximum size of the crystals yielded was 8 mm × 4 mm × 2 mm. These crystals, which appeared to be transparent inside the gel, became translucent when exposed to atmosphere. 3.2. Crystal structure analysis Table 1 gives the details of the crystal and structure refinement data. The atomic coordinates and equivalent thermal parameters for all the non-hydrogen atoms are given in Table 2. The bond distances and angles are in good agreement with the standard values. Tables 3 and 4 give the selected bond lengths ˚ and bond angles. The average bond lengths (C C: 1.533(2) A,
213
˚ compare well with those in the other calcium C O: 1.2571(2) A) malates [22,23]. The structure exhibits intermolecular hydrogen bonds of the type O H· · ·O. The bond lengths and angles along with the symmetry codes are listed in Table 5. Fig. 1 represents the ORTEP [32,33] of the molecules with thermal ellipsoids at 50% probability. The packing of the molecules down b-axis (Fig. 2) shows layer-type polymeric structure, which is stabilized by intermolecular hydrogen bonds. The layers are formed by the chelate ring Ca O C O by monodentated coordination. In all the hydrogen bonds, the water oxygen (O(11)) along with O(7) act as donor atoms and the carboxylate groups or the other oxygens (O(2), O(10), O(9)) act as acceptor atom. The calcium atom is coordinated with two water molecules. These water molecules are involved in the extensive network of hydrogen bonds amongst themselves. It appears that, in addition to the oxygen bridge bonds involving the malate ligand, the hydrogen bonds are responsible for the stability of the structure. 3.3. Thermal properties Information regarding the stability and thermal decomposition of the grown crystal was collected with the aid of the TG and DTA curves. The thermogram recorded is shown in Fig. 3. A close analysis of the TG curve shows that the material is thermally stable up to 120 ◦ C. A stepped decomposition curve is obtained for the compound. Hydrated water molecules are liberated at the initial stage of decomposition, corresponding to a temperature range 120–180 ◦ C. The observed and calculated percent of weight loss during this dehydration process are 10.8 and 10.589, respectively. The anhydrous calcium bis(malate) [Ca(C4 H4 O5 )2 ] gets decomposed into Ca(C2 O4 )2 and elementary carbon in the temperature range 180–235 ◦ C along with the liberation of carbon monoxide and hydrogen molecule. The forthcoming stage of decomposition that gets completed at 440 ◦ C results in the formation of calcium oxalate. In the above transition carbon monoxide was evolved. Further heating up to 490 ◦ C results in the conversion of oxalate group to carbonate along with the elimination of carbon monoxide. In the final stage of decomposition, this calcium carbonate is reduced to calcium oxide at 690 ◦ C. No further decomposition was observed up to 900 ◦ C. It is noted that all the transformations are associated with some mass loss. It suggests that there is no structural change independent of mass change in the compound. In Table 5, various thermal decomposition stages and corresponding mass losses are listed. It is evident from the data that the observed percent of mass loss in each stage is in conformity with the calculated one.
Table 5 The decomposition process of Ca(C4 H4 O5 )2 ·2H2 O Stage
Decomposition temperature (◦ C)
Product after decomposition
Molecules evolved
Observed mass loss (%)
Calculated mass loss (%)
I II III IV V
120–180 180–235 250–440 440–490 500–690
Ca(C4 H4 O5 )2 Ca(C2 O4 )2 + 2C Ca(C2 O4 ) CaCO3 CaO
2H2 O 2CO + 4H2 4CO CO CO2
10.8 18.9 33 8.8 12.9
10.589 18.834 32.929 8.232 12.934
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T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215
Fig. 1. ORTEP of the molecule at 50% probability.
Peaks in the DTA curve stand as additional support to the TG results. The broader endotherm near 180 ◦ C corresponds to the dehydration process. The exothermic peak observed around 490 ◦ C indicates the transformation of calcium oxalate into calcium carbonate with the liberation of carbon dioxide .The endothermic peak near 700 ◦ C shows the decomposition of calcium carbonate into calcium oxide.
Fig. 3. TG–DTA curve for calcium bis(malate) dihydrate.
4. Conclusions Diffusion of supernatant calcium chloride ions into the silica gel impregnated with malic acid results in the formation of calcium malate crystals. Single crystal studies revealed that the compound is Ca(C4 H4 O5 )2 ·2H2 O. It crystallizes in the monoclinic system with space group C2/c. Thermal behavior suggests that the material is stable up to 120 ◦ C. Passing through various intermediate stages, it ultimately gets reduced to calcium oxide at 690 ◦ C. Acknowledgements The authors are grateful to DST, Government of India for providing the financial assistance under the project SP/I2/FOO/93 and Central Electrochemical Research Institute(CECRI), Karaikudi for providing the TG-DTA facilities. One of the authors GV is grateful to the UGC for a minor research project. References Fig. 2. Packing of the molecules down b-axis.
[1] H. Shing-Hua, T.C.W. Mak, Z. Kristallogr. 190 (1990) 305.
T. Jini et al. / Journal of Alloys and Compounds 433 (2007) 211–215 [2] H. Shing-Hua, G.D. Zhon, T.C.W. Mak, J. Cryst. Spect. Res. 21 (2) (1991) 127. [3] E.K. Girija, S.C. Latha, S.N. Kalkura, C. Subrahmanian, P. Ramasamy, Mater. Chem. Phys. 52 (1998) 253. [4] S.M. Dharmaprakash, P. Mohanrao, Cryst. Res. Technol. 23 (3) (1988) K143. [5] W. Ollendorf, F. Weigel, Inorg. Nucl. Chem. Lett. 5 (1969) 263. [6] E. Hanson, D. Tropllet, S. Romero, A. Mosset, J.C. Trombe, C.R. Acad. Sci. Paris 325 (1997) 663. [7] M.H. Molina, P.A.L. Luis, T. Lopez, C.R. Oerez, F. Lloret, M. Julve, Cryst. Eng. Commun. 31 (2003) 1. [8] B.H. Doreswamy, M. Mahendra, M.A. Sridhar, J. Sasidharaprasad, P.A. Varughese, K.V. Saban, G. Varghese, J. Mol. Struct. 659 (2003) 81. [9] P.A. Varughese, K.V. Saban, J. George, I. Paul, G. Varghese, J. Mater. Sci. 39 (2004) 6325. [10] G. Oczko, J. Legendzienicz, M.S. Wickeleder, G. Meyer, J. Alloys Compd. 341 (2002) 255. [11] C. Bromant, M.S. Wickeleder, G. Meyer, Z. Anorg. Allg. Chem. 627 (2001) 768. [12] M.P. Gupta, K. Banerjee, Z. Kristallogr. 162 (1983) 277. [13] B. Hsu, E.O. Schlemper, Acta Crystallogr. B 34 (1978) 980. [14] P.N. Kotru, K.K. Raina, M.L. Koul, J. Mater. Sci. 21 (1986) 3933. [15] P.N. Kotru, N.K. Gupta, K.K. Raina, Kristallogr. Technik 21 (1986) 15. [16] P.N. Kotru, N.K. Gupta, K.K. Raina, J. Mater. Sci. 21 (1986) 90. [17] L. Patron, O. Carp, I. Mindru, G. Marinescu, E. Segal, J. Therm. Anal. Cal. 72 (2003) 281. [18] G. Arunmozhi, E.D. Gomes, M. Belsley, A. Criado, S.P. Garrido, F. Proenca, Ferroelectrics 295 (2003) 47.
215
[19] I.V. Shabanova, V.T. Panyushkin, V.Y. Frolov, V.I. Zelenov, T.P. Storozhenko, Russ. J. Electrochem. 40 (4) (2004) 474. [20] I.V. Sukhno, M.B. Gavrilyuk, V.Y. Buz’ko, V.T. Panyushkin, Russ. J. Coord. Chem. 30 (7) (2004) 520. [21] I.V. Sukhno, V.Yu. Buz’ko, V.T. Panyushkin, M.B. Gavrilyuk, Russ. J. Coord. Chem. 30 (8) (2004) 591. [22] C.A. Br¨anden, B.O. S¨oderberg, Acta Chem. Scand. 20 (1966) 730. [23] A.T.H. Lenstra, W.V. Havere, Acta Crystallogr. B 36 (1980) 156. [24] R. Wartchow, Z. Kristallogr. 211 (1996) 329. [25] F. Iwig, O. Hecht, Ann. Chem. Pharm. 233 (1886) 166. [26] A. Devatine, J.P. Canselier, N. Gabas, J. Jaud, J. Coord. Chem. 33 (2) (2003) 85. [27] H.K. Henisch, Crystal Growth in Gels, Pennsylvania University Press, Pittsburg, 1970. [28] Z. Otwinowski, W. Minor, C.M. Carter Jr., R.M. Sweet, Methods in Enzymology, vol. 276, Academic Press, New York, 1997, p. 307. [29] S. Mackay, C.J. Gilmore, C. Edwards, N. Stewart, K. Shankland, maXus Computer Program for the Solution and Refinement of Crystal Structures Bruker: Nonius, Japan and The University of Glasgow, The Netherlands, MacScience, 1999. [30] G.M. Sheldrick, SHELXS-97, Program for Crystal Structure Solution, University of G¨ottingen, Germany, 1997. [31] G.M. Sheldrick, SHELXL-97, Program for the Refinement of Crystal Structures, University of G¨ottingen, Germany, 1997. [32] A.L. Spek, Acta. Crystallogr. A 46 (1990) C 34. [33] A.L. Spek, PLATON, A Multipurpose Crystallographic Tool, University of Utretcht, The Netherlands, 1998.