research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

Crystal structure of a polymeric calcium levulinate dihydrate: catena-poly[[di­aqua­calcium]-bis­­(μ2-4-oxo­butano­ato)]

aDepartment of Chemistry, Prairie View A&M University, Prairie View, TX 77446, USA, bDepartment of Natural Sciences, New Mexico Highlands University, Las Vegas, NM 87701, USA, and cInstitute of Applied Physics, Academy of Sciences of Moldova, Academy Str. 5, MD2028, Chisinau, Moldova
*Correspondence e-mail: asamarasekara@pvamu.edu

Edited by G. Smith, Queensland University of Technology, Australia (Received 16 February 2015; accepted 2 April 2015; online 18 April 2015)

In the title calcium levulinate complex, [Ca(C5H7O3)2(H2O)2]n, the Ca2+ ion lies on a twofold rotation axis and is octa­coordinated by two aqua ligands and six O atoms from four symmetry-related carboxyl­ate ligands, giving a distorted square-anti­prismatic coordination stereochemistry [Ca—O bond-length range = 2.355 (1)–2.599 (1) Å]. The levulinate ligands act both in a bidentate carboxyl O,O′-chelate mode and in a bridging mode through one carboxyl O atom with an inversion-related Ca2+ atom, giving a Ca⋯Ca separation of 4.0326 (7) Å. A coordination polymeric chain structure is generated, extending along the c-axial direction. The coordinating water mol­ecules act as double donors and participate in intra-chain O—H⋯O hydrogen bonds with carboxyl O atoms, and in inter-chain O—H⋯O hydrogen bonds with carbonyl O atoms, thus forming an overall three-dimensional structure.

1. Chemical context

Levulinic acid (4-oxo­penta­noic acid) is a biomass-derived keto acid and is a potential precursor for renewable fuels as well as polymeric materials (Mukherjee et al., 2015[Mukherjee, A., Dumont, M.-J. & Raghavan, V. (2015). Biomass Bioenergy, 72, 143-183.]). A number of metal salts of levulinic acid have been prepared for a variety of applications and the calcium salt with formula Ca(C5H7O3)2·2H2O is the most widely studied levulinate, as it has been used for over 80 years as a calcium supplement (Proskouriakoff, 1933[Proskouriakoff, A. (1933). J. Am. Chem. Soc. 55, 2132-2134.]). The revived inter­est in calcium levulinate is due to a recent discovery that pyrolysis of this readily accessible renewable biomass-based calcium salt can be used to produce biofuels via a ketonic deca­rboxylation process with recycling of calcium as CaCO3 (Schwartz et al., 2010[Schwartz, T. J., van Heiningen, A. R. & Wheeler, M. C. (2010). Green Chem. 12, 1353-1356.]; Case et al., 2012[Case, P. A., van Heiningen, A. R. & Wheeler, M. C. (2012). Green Chem. 14, 85-89.]). In addition, we have recently shown that acid-catalyzed hydro­thermal degradation of cellulose and neutral­ization of the filtrate with calcium hydroxide can be used to prepare a mixture of calcium levulinate and calcium formate and the pyrolysis of this mixture at 623 K can be used to produce γ-valerolactone (Amarasekara et al., 2015[Amarasekara, A. S., Wiredu, B. & Edwards, D. N. (2015). Biomass Bioenergy, 72, 39-44.]). Recently, Bryce and co-workers published the solid-state 13C NMR spectrum of calcium levulinate in which they identified only one type of a levulinate anion (Widdifield et al., 2014[Widdifield, C. M., Moudrakovski, I. & Bryce, D. L. (2014). Phys. Chem. Chem. Phys. 16, 13340-13359.]). However, there are no reports on X-ray crystallographic studies on this well known calcium carboxyl­ate. Our inter­est in thermal properties and biofuel applications of calcium levulinate has led us to study the structure of this salt and in this communication we report the crystal structure of calcium levulinate dihydrate, [Ca(C5H7O3)2(H2O)2]n.

[Scheme 1]

2. Structural commentary

The calcium levulinate structure contains one Ca2+ cation, two levulinate anions and two water mol­ecules per formula unit, with the Ca2+ cation situated on a twofold rotation axis (Fig. 1[link]). The cation is octa­coordinated and exhibits a distorted square anti­prismatic stereochemistry with Ca—O bond lengths in the range of 2.355 (1)–2.599 (1) Å (Table 1[link]). The levulinate carboxyl O atoms (O1 and O2) coordinate to Ca2+ cations in two coordination modes, a bidentate O,O′-chelate mode and a bridging mode through O1i with an inversion-related Ca2+ centre, giving a Ca1⋯Ca1i or Ca1⋯Ca1v separation of 4.0326 (7) Å [for symmetry code (i) see Table 1[link]; symmetry code (v): −x + 1, −y, −z]. Furthermore, due to this type of coordination environment, the two levulinate anions are almost perpendicular to each other, with an O2—Ca1—O2iii angle = 75.78 (5)° [for code (iii), see Table 1[link]]. The extended one-dimensional coordination polymeric chain generated lies parallel to the c axis (Fig. 2[link]) and within each chain, the coordinating water mol­ecules form intra-chain O4—H4B⋯O2vcarbox­yl hydrogen-bonds (Table 2[link]).

Table 1
Selected bond lengths (Å)

Ca1—O1i 2.3546 (10) Ca1—O2iii 2.4820 (10)
Ca1—O1ii 2.3546 (10) Ca1—O2 2.4820 (11)
Ca1—O4iii 2.4367 (10) Ca1—O1 2.5989 (10)
Ca1—O4 2.4367 (10) Ca1—O1iii 2.5990 (10)
Symmetry codes: (i) -x+1, -y, -z+1; (ii) [x, -y, z-{\script{1\over 2}}]; (iii) [-x+1, y, -z+{\script{1\over 2}}].

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O4—H4A⋯O3iv 0.90 2.02 2.8568 (15) 155
O4—H4B⋯O2v 0.90 1.87 2.7519 (14) 168
Symmetry codes: (iv) [x-{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (v) -x+1, -y, -z.
[Figure 1]
Figure 1
A portion of the crystal structure of the title complex, displaying the atomic labeling. Displacement ellipsoids are drawn at the 50% probability level. Symmetry code (v): −x + 1, −y, −z; for other codes, see Table 1[link].
[Figure 2]
Figure 2
The one-dimensional coordination polymeric chain extending along the c axis.

3. Supra­molecular features

In the crystal, the polymer chains are linked via inter-chain hydrogen bonds between the second H atom of the coordinating water mol­ecule and the carbonyl O atom of an adjacent chain (O4—H4A⋯O3iv), giving an overall three-dimensional structure (Fig. 3[link]) [for symmetry code (iv), see Table 2[link]]. To achieve this hydrogen-bonding inter­action, the levulinate mol­ecule is twisted [torsion angle C1—C2—C3—C4 = 73.2 (2)°].

[Figure 3]
Figure 3
The three-dimensional hydrogen-bonded structure in the unit cell viewed along the c axis. Hydrogen-bonding inter­actions are shown as dashed lines.

4. Database survey

The Cu2+ levulinate structures represent examples of a very small number of metal levulinates in the crystallographic literature (Zubkowski et al., 1997[Zubkowski, J. D., Washington, D., Njoroge, N., Valente, E. J., Cannon, T., Parks, C. D., Berdahl, P. & Perry, D. L. (1997). Polyhedron, 16, 2341-2351.]). Only one of these involves the levulinate ligand alone: a polymeric structure formed through carboxyl O-linked tetra­carboxyl­ate-bridged dimers, in which the copper atoms have nearly square-pyramidal coordination geometry. In the same report are the structures of three additional Cu2+ complexes with levulinate as well as other ligands: pyridine, 2,2′-bi­pyridine and tri­phenyl­phosphine. The crystal structures of two polymorphic forms of the analogous calcium acetate monohydrate salt are also known (Klop et al., 1984[Klop, E. A., Schouten, A., van der Sluis, P. & Spek, A. L. (1984). Acta Cryst. C40, 51-53.]; Van der Sluis et al., 1987[Sluis, P. van der, Schouten, A. & Spek, A. L. (1987). Acta Cryst. C43, 1922-1924.]).

5. Synthesis and crystallization

Levulinic acid (1.160 g, 10.0 mmol) was added to a suspension of calcium hydroxide (0.370 g, 5.00 mmol) in 200 mL of deionized water in a beaker. The mixture was boiled with magnetic stirring on a hot plate to form a clear solution, then transferred to an evaporating dish and allowed to crystallize at room temperature. The product was collected under suction filtration, dried at 363 K for 24 h to give 1.455 g of calcium levulinate dihydrate as white needle-shaped crystals in 95% yield. Found: C, 39.02; H, 6.23; calculated for [Ca(C5H7O3)2(H2O)2]: C, 39.21; H, 5.92%. 1H NMR (DMSO-d6) δ 2.05 (3H, s), 2.19 (2H, t, J = 6.8 Hz), 2.54 (2H, t, J = 6.8 Hz). 13C NMR (DMSO-d6) δ 30.2, 31.5, 37.9, 179.6, 208.9. The single crystals for X-ray crystallographic analysis were grown by allowing a saturated solution of calcium levu­linate dihydrate in 20% methanol in water to stand at room temperature for five days.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3[link]. The C-bound H atoms were placed in calculated positions and allowed to ride on their carrier atoms: C—H = 0.93–0.97 Å with Uiso(H) = 1.5Ueq(C) for methyl H atoms and 1.2Ueq(C) for other H atoms. The water H atoms were found using a Fourier map and were also allowed to ride in the refinement, O—H = 0.90 Å and with Uiso(H) = 1.5Ueq(O).

Table 3
Experimental details

Crystal data
Chemical formula [Ca(C5H7O3)2(H2O)2]
Mr 306.32
Crystal system, space group Orthorhombic, Pbcn
Temperature (K) 100
a, b, c (Å) 17.644 (3), 9.9627 (19), 7.8160 (15)
V3) 1373.9 (5)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.49
Crystal size (mm) 0.94 × 0.11 × 0.08
 
Data collection
Diffractometer Bruker SMART APEXII CCD area detector
Absorption correction Multi-scan (SADABS; Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.656, 0.963
No. of measured, independent and observed [I > 2σ(I)] reflections 11806, 1664, 1571
Rint 0.020
(sin θ/λ)max−1) 0.660
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.083, 1.16
No. of reflections 1664
No. of parameters 88
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.53, −0.54
Computer programs: APEX2 and SAINT (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS97, SHELXL97 and SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Supporting information


Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

catena-Poly[[diaquacalcium]-bis(µ2-4-oxobutanoato)] top
Crystal data top
[Ca(C5H7O3)2(H2O)2]F(000) = 648
Mr = 306.32Dx = 1.481 Mg m3
Orthorhombic, PbcnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2abCell parameters from 8589 reflections
a = 17.644 (3) Åθ = 2.3–30.5°
b = 9.9627 (19) ŵ = 0.49 mm1
c = 7.8160 (15) ÅT = 100 K
V = 1373.9 (5) Å3Needle, colourless
Z = 40.94 × 0.11 × 0.08 mm
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
1664 independent reflections
Radiation source: fine-focus sealed tube1571 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.020
φ and ω scansθmax = 28.0°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
h = 2323
Tmin = 0.656, Tmax = 0.963k = 1313
11806 measured reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.030Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083H-atom parameters constrained
S = 1.16 w = 1/[σ2(Fo2) + (0.0384P)2 + 1.0525P]
where P = (Fo2 + 2Fc2)/3
1664 reflections(Δ/σ)max < 0.001
88 parametersΔρmax = 0.53 e Å3
0 restraintsΔρmin = 0.54 e Å3
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
xyzUiso*/Ueq
Ca10.50000.04993 (4)0.25000.00808 (12)
O40.40994 (5)0.20740 (10)0.12520 (12)0.0141 (2)
H4A0.36290.19290.16550.021*
H4B0.40860.19880.01070.021*
O20.58523 (5)0.14668 (10)0.21809 (12)0.0123 (2)
C40.71782 (8)0.37537 (14)0.25360 (16)0.0120 (3)
O10.55856 (5)0.10067 (9)0.48715 (12)0.0115 (2)
C10.58068 (7)0.18090 (13)0.37294 (16)0.0094 (2)
C20.59849 (8)0.32410 (14)0.42594 (18)0.0149 (3)
H2A0.55070.36820.46160.018*
H2B0.63240.32150.52690.018*
C30.63568 (8)0.40979 (13)0.28835 (19)0.0140 (3)
H3A0.63260.50520.32320.017*
H3B0.60660.39970.18070.017*
O30.74945 (6)0.28329 (10)0.32774 (13)0.0166 (2)
C50.75831 (8)0.46004 (14)0.12409 (18)0.0155 (3)
H5A0.81070.42870.11230.023*
H5B0.73250.45300.01350.023*
H5C0.75830.55390.16180.023*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ca10.00891 (19)0.00906 (19)0.00626 (18)0.0000.00041 (11)0.000
O40.0144 (5)0.0187 (5)0.0092 (4)0.0031 (4)0.0010 (3)0.0003 (4)
O20.0133 (4)0.0152 (5)0.0084 (4)0.0034 (4)0.0011 (3)0.0007 (4)
C40.0140 (6)0.0107 (6)0.0113 (6)0.0030 (5)0.0017 (4)0.0023 (5)
O10.0111 (4)0.0140 (5)0.0093 (4)0.0021 (3)0.0009 (3)0.0016 (4)
C10.0058 (5)0.0125 (6)0.0099 (6)0.0001 (4)0.0001 (4)0.0001 (5)
C20.0168 (6)0.0136 (6)0.0142 (6)0.0041 (5)0.0044 (5)0.0032 (5)
C30.0136 (6)0.0114 (6)0.0172 (6)0.0020 (5)0.0007 (5)0.0009 (5)
O30.0163 (5)0.0148 (5)0.0187 (5)0.0005 (4)0.0029 (4)0.0037 (4)
C50.0154 (6)0.0153 (6)0.0160 (6)0.0011 (5)0.0024 (5)0.0026 (5)
Geometric parameters (Å, º) top
Ca1—O1i2.3546 (10)C4—C31.5138 (19)
Ca1—O1ii2.3546 (10)O1—C11.2602 (16)
Ca1—O4iii2.4367 (10)O1—Ca1i2.3546 (10)
Ca1—O42.4367 (10)C1—C21.5185 (18)
Ca1—O2iii2.4820 (10)C2—C31.5218 (19)
Ca1—O22.4820 (11)C2—H2A0.9900
Ca1—O12.5989 (10)C2—H2B0.9900
Ca1—O1iii2.5990 (10)C3—H3A0.9900
O4—H4A0.8999C3—H3B0.9900
O4—H4B0.8994C5—H5A0.9800
O2—C11.2599 (16)C5—H5B0.9800
C4—O31.2203 (17)C5—H5C0.9800
C4—C51.4988 (18)
O1i—Ca1—O1ii155.21 (5)O2—Ca1—Ca1iv73.02 (2)
O1i—Ca1—O4iii78.38 (3)O1—Ca1—Ca1iv123.28 (3)
O1ii—Ca1—O4iii85.69 (3)O1iii—Ca1—Ca1iv33.53 (2)
O1i—Ca1—O485.69 (3)C1—Ca1—Ca1iv97.28 (3)
O1ii—Ca1—O478.39 (3)C1iii—Ca1—Ca1iv58.53 (3)
O4iii—Ca1—O499.84 (5)O1i—Ca1—Ca1i37.57 (2)
O1i—Ca1—O2iii79.39 (3)O1ii—Ca1—Ca1i153.97 (2)
O1ii—Ca1—O2iii121.53 (3)O4iii—Ca1—Ca1i76.76 (2)
O4iii—Ca1—O2iii149.65 (3)O4—Ca1—Ca1i123.15 (2)
O4—Ca1—O2iii98.81 (4)O2iii—Ca1—Ca1i73.02 (2)
O1i—Ca1—O2121.53 (3)O2—Ca1—Ca1i84.41 (2)
O1ii—Ca1—O279.39 (3)O1—Ca1—Ca1i33.53 (2)
O4iii—Ca1—O298.81 (4)O1iii—Ca1—Ca1i123.28 (3)
O4—Ca1—O2149.65 (3)C1—Ca1—Ca1i58.53 (3)
O2iii—Ca1—O275.78 (5)C1iii—Ca1—Ca1i97.28 (3)
O1i—Ca1—O171.10 (4)Ca1—O4—H4A111.0
O1ii—Ca1—O1124.87 (4)Ca1—O4—H4B110.8
O4iii—Ca1—O180.03 (3)H4A—O4—H4B108.0
O4—Ca1—O1156.41 (3)C1—O2—Ca194.50 (8)
O2iii—Ca1—O173.36 (3)O3—C4—C5121.72 (13)
O2—Ca1—O151.33 (3)O3—C4—C3121.53 (12)
O1i—Ca1—O1iii124.87 (4)C5—C4—C3116.75 (12)
O1ii—Ca1—O1iii71.10 (4)C1—O1—Ca1i152.89 (9)
O4iii—Ca1—O1iii156.41 (3)C1—O1—Ca189.09 (8)
O4—Ca1—O1iii80.03 (3)Ca1i—O1—Ca1108.90 (4)
O2iii—Ca1—O1iii51.33 (3)O2—C1—O1121.91 (12)
O2—Ca1—O1iii73.36 (3)O2—C1—C2120.21 (12)
O1—Ca1—O1iii109.48 (5)O1—C1—C2117.82 (11)
O1i—Ca1—C195.60 (4)O2—C1—Ca159.55 (7)
O1ii—Ca1—C1104.27 (4)O1—C1—Ca164.87 (7)
O4iii—Ca1—C193.35 (4)C2—C1—Ca1161.22 (9)
O4—Ca1—C1166.72 (4)C1—C2—C3115.05 (11)
O2iii—Ca1—C168.56 (4)C1—C2—H2A108.5
O2—Ca1—C125.95 (3)C3—C2—H2A108.5
O1—Ca1—C126.04 (3)C1—C2—H2B108.5
O1iii—Ca1—C188.47 (4)C3—C2—H2B108.5
O1i—Ca1—C1iii104.27 (4)H2A—C2—H2B107.5
O1ii—Ca1—C1iii95.60 (4)C4—C3—C2114.37 (11)
O4iii—Ca1—C1iii166.72 (4)C4—C3—H3A108.7
O4—Ca1—C1iii93.35 (4)C2—C3—H3A108.7
O2iii—Ca1—C1iii25.95 (3)C4—C3—H3B108.7
O2—Ca1—C1iii68.56 (4)C2—C3—H3B108.7
O1—Ca1—C1iii88.47 (4)H3A—C3—H3B107.6
O1iii—Ca1—C1iii26.04 (3)C4—C5—H5A109.5
C1—Ca1—C1iii73.51 (5)C4—C5—H5B109.5
O1i—Ca1—Ca1iv153.97 (2)H5A—C5—H5B109.5
O1ii—Ca1—Ca1iv37.57 (2)C4—C5—H5C109.5
O4iii—Ca1—Ca1iv123.15 (2)H5A—C5—H5C109.5
O4—Ca1—Ca1iv76.76 (2)H5B—C5—H5C109.5
O2iii—Ca1—Ca1iv84.41 (2)
O1i—Ca1—O2—C12.30 (9)O1i—Ca1—C1—O2178.03 (8)
O1ii—Ca1—O2—C1163.32 (8)O1ii—Ca1—C1—O216.92 (8)
O4iii—Ca1—O2—C179.43 (8)O4iii—Ca1—C1—O2103.32 (8)
O4—Ca1—O2—C1153.18 (8)O4—Ca1—C1—O283.05 (17)
O2iii—Ca1—O2—C170.07 (7)O2iii—Ca1—C1—O2101.76 (8)
O1—Ca1—O2—C19.82 (7)O1—Ca1—C1—O2162.35 (12)
O1iii—Ca1—O2—C1123.41 (8)O1iii—Ca1—C1—O253.14 (8)
C1iii—Ca1—O2—C196.30 (8)C1iii—Ca1—C1—O274.78 (8)
Ca1iv—Ca1—O2—C1158.49 (8)Ca1iv—Ca1—C1—O220.71 (8)
Ca1i—Ca1—O2—C13.79 (7)Ca1i—Ca1—C1—O2175.57 (9)
O1i—Ca1—O1—C1159.32 (9)O1i—Ca1—C1—O119.62 (9)
O1ii—Ca1—O1—C142.09 (8)O1ii—Ca1—C1—O1145.43 (7)
O4iii—Ca1—O1—C1119.65 (7)O4iii—Ca1—C1—O159.02 (7)
O4—Ca1—O1—C1148.55 (9)O4—Ca1—C1—O1114.60 (15)
O2iii—Ca1—O1—C175.10 (7)O2iii—Ca1—C1—O195.90 (7)
O2—Ca1—O1—C19.79 (7)O2—Ca1—C1—O1162.35 (12)
O1iii—Ca1—O1—C137.99 (6)O1iii—Ca1—C1—O1144.52 (6)
C1iii—Ca1—O1—C153.67 (9)C1iii—Ca1—C1—O1122.87 (9)
Ca1iv—Ca1—O1—C13.63 (8)Ca1iv—Ca1—C1—O1176.95 (7)
Ca1i—Ca1—O1—C1159.32 (9)Ca1i—Ca1—C1—O113.22 (6)
O1i—Ca1—O1—Ca1i0.0O1i—Ca1—C1—C283.2 (3)
O1ii—Ca1—O1—Ca1i158.59 (4)O1ii—Ca1—C1—C2111.8 (3)
O4iii—Ca1—O1—Ca1i81.03 (4)O4iii—Ca1—C1—C2161.8 (3)
O4—Ca1—O1—Ca1i10.77 (10)O4—Ca1—C1—C211.8 (4)
O2iii—Ca1—O1—Ca1i84.22 (4)O2iii—Ca1—C1—C26.9 (3)
O2—Ca1—O1—Ca1i169.10 (6)O2—Ca1—C1—C294.8 (3)
O1iii—Ca1—O1—Ca1i121.33 (4)O1—Ca1—C1—C2102.8 (3)
C1—Ca1—O1—Ca1i159.32 (9)O1iii—Ca1—C1—C241.7 (3)
C1iii—Ca1—O1—Ca1i105.65 (4)C1iii—Ca1—C1—C220.0 (3)
Ca1iv—Ca1—O1—Ca1i155.69 (2)Ca1iv—Ca1—C1—C274.1 (3)
Ca1—O2—C1—O118.87 (13)Ca1i—Ca1—C1—C289.6 (3)
Ca1—O2—C1—C2158.21 (10)O2—C1—C2—C311.36 (18)
Ca1i—O1—C1—O2150.77 (13)O1—C1—C2—C3171.45 (11)
Ca1—O1—C1—O217.93 (12)Ca1—C1—C2—C395.1 (3)
Ca1i—O1—C1—C226.4 (2)O3—C4—C3—C22.20 (18)
Ca1—O1—C1—C2159.21 (10)C5—C4—C3—C2177.69 (12)
Ca1i—O1—C1—Ca1132.83 (18)C1—C2—C3—C473.21 (15)
Symmetry codes: (i) x+1, y, z+1; (ii) x, y, z1/2; (iii) x+1, y, z+1/2; (iv) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H4A···O3v0.902.022.8568 (15)155
O4—H4B···O2iv0.901.872.7519 (14)168
Symmetry codes: (iv) x+1, y, z; (v) x1/2, y+1/2, z+1/2.
 

Acknowledgements

We acknowledge NSF grants DMR-0934212 (PREM), CBET-0929970, CBET-1336469, HRD-1036593 and USDA grant CBG-2010–38821-21569 for financial support.

References

First citationAmarasekara, A. S., Wiredu, B. & Edwards, D. N. (2015). Biomass Bioenergy, 72, 39–44.  CrossRef CAS Google Scholar
First citationBruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCase, P. A., van Heiningen, A. R. & Wheeler, M. C. (2012). Green Chem. 14, 85–89.  CrossRef CAS Google Scholar
First citationDolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationKlop, E. A., Schouten, A., van der Sluis, P. & Spek, A. L. (1984). Acta Cryst. C40, 51–53.  CSD CrossRef CAS IUCr Journals Google Scholar
First citationMukherjee, A., Dumont, M.-J. & Raghavan, V. (2015). Biomass Bioenergy, 72, 143–183.  CrossRef CAS Google Scholar
First citationProskouriakoff, A. (1933). J. Am. Chem. Soc. 55, 2132–2134.  CrossRef CAS Google Scholar
First citationSchwartz, T. J., van Heiningen, A. R. & Wheeler, M. C. (2010). Green Chem. 12, 1353–1356.  CrossRef CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSluis, P. van der, Schouten, A. & Spek, A. L. (1987). Acta Cryst. C43, 1922–1924.  CSD CrossRef IUCr Journals Google Scholar
First citationWiddifield, C. M., Moudrakovski, I. & Bryce, D. L. (2014). Phys. Chem. Chem. Phys. 16, 13340–13359.  Web of Science CrossRef CAS PubMed Google Scholar
First citationZubkowski, J. D., Washington, D., Njoroge, N., Valente, E. J., Cannon, T., Parks, C. D., Berdahl, P. & Perry, D. L. (1997). Polyhedron, 16, 2341–2351.  CSD CrossRef CAS Web of Science 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.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds