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In the title compound, [Ca(C6H5O4)2(C6H6O4)2]·4H2O, which is a kojic acid-Ca2+ complex, the Ca atom is on a twofold axis and is octacoordinated by O atoms from four pyrone ligand mol­ecules. The hydroxyl and ketone O atoms of each ligand form a five-membered chelate ring with the Ca atom. The crystal structure is stabilized by partial stacking and O-H...O hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102013537/ob1075sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270102013537/ob1075Isup2.hkl
Contains datablock I

CCDC reference: 195604

Comment top

Kojic acid [5-hydroxy-2-hydroxymethyl-4-pyrone, (I)] is a metabolic product of several species of the genus Aspergillus. It has been reported that kojic acid is an efficient inhibitor of mashroom tyrosinase and other polyphenol oxidases (Chen et al., 1991), which consequently suppresses biosynthesis of melanin in melanocytes. Kojic acid is also widely known to be an iron chelator (McBryde & Atkinson, 1961; Mitani et al., 2001) and a radical scavenger (Niwa & Akamatsu, 1991). Metal complexes containing kojic acid has been studied in solution (Barret et al., 2001; Malhotra et al., 2001; Buglyo et al., 2000; Yuen et al., 1997; Katoh et al., 1992), however, with regard to the crystal structures of kojic acid–metal chelate complexes, only the methyltin(IV) (Lockhart & Davidson, 1987) and dioxomolybdenum(VI) (Lord et al., 1999) complexes have been reported. To clarify the chelating mode of kojic acid to the alkaline earth metal, we have analyzed the crystal structure of the kojic acid–Ca2+ complex, (II), and present its structure here.

In (II), the Ca atom lies on a twofold axis and is octacoordinated by the O atoms of four ligand molecules, in which two of four hydroxyl groups are ionized (Fig. 1 and Table 1). The hydroxyl and ketone O atoms of each ligand form a five-membered chelate ring with the Ca atom. Until now, the crystal structures of only two kojic acid–metal complexes, viz. the Me2Sn4+ and MoO26+ complexes, have been analyzed. Although the number of ligand molecules is different in the Ca2+ complex, the five-membered ring between each ligand and the metal are similar.

In (II), the ketone C O bond lengths are somewhat longer [O1—C1 1.255 (4) Å and O5—C7 1.261 (4) Å] than that in kojic acid [1.244 (1) Å; Lokaj et al., 1991], but they are similar to those in other complexes [Me2Sn4+ 1.254 (7)–1.267 (7) Å and MoO26+ 1.272 (3) and 1.278 (3) Å].

The Ca—Oketone bond lengths in (II) are slightly longer [Ca1—O1 2.483 (2) Å and Ca1—O5 2.494 (2) Å] than the Ca—OOH distances [Ca1—O2 2.462 (2) Å and Ca1—O6 2.462 (2) Å]. In the [Me2Sn]4+ and [MoO2]6+ complexes, the M—Oketone bond lengths are markedly longer than the M—OOH distances [Sn—Oketone 2.365 (4)–2.435 (4) Å and Sn—OOH(deprotonated) 2.106 (4)–2.145 (4) Å; Mo—Oketone O 2.236 (2) and 2.286 (2) Å, and Mo—OOH(deprotonated) 1.981 (2) and 1.994 (2) Å], which indicates a distinction between Lewis acid–base and ionic bonding for the two types of O atoms. In the case of (II), the complex molecules are connected by strong hydrogen bonding [O2—H26···O6, with O2···O6 = 2.462 (4) Å; Table 2], and consequently atom H26 is shared by two hydroxylate anions. Therefore, the Ca—OOH distances reflect the co-existence of deprotonated O atoms and hydroxyl groups.

The crystal structure of (II) is stabilized by partial stacking between the ligand molecules of neighboring compounds [O3···C2i 3.176 (5) Å and C2···O3i 3.176 (5) Å; symmetry code: (i) 1 - x, -y, 1 - z] and hydrogen bonds between chelate complexes and water molecules (Table 2). In the ligand molecules, the hydroxymethyl groups are disordered over two positions (C6—O4A and C6—O4B). This may be due to comparatively loose packing, in which four water molecules are cocrystallized per Ca2+ complex molecule.

Experimental top

Yellow pillar-shaped crystals of (II) were obtained by slow evaporation from an 80% ethanol–water solution of kojic acid and calcium nitrate tetrahydrate in a 4:1 molar ratio at room temperature.

Refinement top

The H atoms of the ligand molecules, except for H26 and those of the disorderd methyl group, were placed in calculated positions and refined as riding atoms. H26, H4A, H4B and the water H atoms were located from difference Fourier maps and were fixed, except of H26. The long O2—H26 bond [1.24 (2) Å] is due to the strong O2—H26···O6 hydrogen bond. Three H atoms bonded to O10 was located as the disordered atoms that exist as H10A—O10—H10B and H10A—O10—H10C.

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1992); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 2000); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: TEXSAN.

Figures top
[Figure 1] Fig. 1. ORTEPII (Johnson, 1976) drawing of the title compound with the atomic numbering scheme. Ellipsoids for non-H atoms correspond to 50% probability. The occupation factors of O4A and O4B are 60 and 40%, respectively.
(I) top
Crystal data top
[Ca(C6H5O4)2(C6H6O4)2]·4H2OF(000) = 1416.0
Mr = 678.56Dx = 1.550 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.7107 Å
Hall symbol: -C 2ycCell parameters from 24 reflections
a = 22.020 (4) Åθ = 10.1–12.5°
b = 6.223 (4) ŵ = 0.31 mm1
c = 21.225 (3) ÅT = 296 K
β = 91.61 (1)°Pillar, yellow
V = 2907 (2) Å30.20 × 0.10 × 0.10 mm
Z = 4
Data collection top
Rigaku AFC-5R
diffractometer
Rint = 0.062
ω–2θ scansθmax = 27.5°
Absorption correction: ψ scan
(North et al., 1968)
h = 028
Tmin = 0.942, Tmax = 0.970k = 08
3773 measured reflectionsl = 2727
3332 independent reflections3 standard reflections every 150 reflections
1748 reflections with I > 2σ(I) intensity decay: 4.3%
Refinement top
Refinement on F2H atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.048 w = 1/[σ2(Fo2) + (0.0563P)2 + 3.2041P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.152(Δ/σ)max = 0.001
S = 1.00Δρmax = 0.30 e Å3
3332 reflectionsΔρmin = 0.52 e Å3
217 parameters
Crystal data top
[Ca(C6H5O4)2(C6H6O4)2]·4H2OV = 2907 (2) Å3
Mr = 678.56Z = 4
Monoclinic, C2/cMo Kα radiation
a = 22.020 (4) ŵ = 0.31 mm1
b = 6.223 (4) ÅT = 296 K
c = 21.225 (3) Å0.20 × 0.10 × 0.10 mm
β = 91.61 (1)°
Data collection top
Rigaku AFC-5R
diffractometer
1748 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.062
Tmin = 0.942, Tmax = 0.9703 standard reflections every 150 reflections
3773 measured reflections intensity decay: 4.3%
3332 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.048217 parameters
wR(F2) = 0.152H atoms treated by a mixture of independent and constrained refinement
S = 1.00Δρmax = 0.30 e Å3
3332 reflectionsΔρmin = 0.52 e Å3
Special details top

Refinement. Refinement using reflections with F2 > 0.0 σ(F2). The weighted R-factor (wR), goodness of fit (S) and R-factor (gt) are based on F, with F set to zero for negative F. The threshold expression of F2 > 2.0 σ(F2) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ca10.50000.1509 (2)0.75000.0244 (2)
O10.4529 (1)0.1946 (4)0.6431 (1)0.0374 (6)
O20.5058 (1)0.1697 (4)0.6825 (1)0.0323 (5)
O30.4501 (1)0.3188 (4)0.5263 (1)0.0468 (7)
O4A0.3552 (2)0.0074 (8)0.4293 (2)0.057 (1)0.60
O4B0.3240 (4)0.232 (1)0.4573 (4)0.075 (3)0.40
O50.3886 (1)0.1163 (4)0.7655 (1)0.0351 (6)
O60.4506 (1)0.4781 (4)0.7889 (1)0.0334 (6)
O70.3015 (1)0.6194 (4)0.8432 (1)0.0378 (6)
O80.1671 (1)0.3252 (4)0.8119 (1)0.0450 (7)
O90.1512 (1)0.0474 (5)0.8753 (2)0.069 (1)
O100.2338 (2)0.0468 (8)0.4745 (2)0.109 (2)
C10.4511 (1)0.0360 (5)0.6066 (2)0.0277 (7)
C20.4206 (2)0.0359 (6)0.5462 (2)0.0357 (8)
C30.4202 (2)0.1393 (7)0.5094 (2)0.0397 (9)
C40.4793 (2)0.3278 (6)0.5832 (2)0.0421 (9)
C50.4802 (1)0.1634 (5)0.6248 (2)0.0264 (7)
C60.3865 (2)0.1658 (8)0.4481 (2)0.060 (1)
C70.3599 (2)0.2720 (5)0.7883 (2)0.0272 (7)
C80.2971 (2)0.2699 (6)0.8016 (2)0.0326 (8)
C90.2706 (2)0.4402 (6)0.8288 (2)0.0310 (8)
C100.3615 (2)0.6325 (6)0.8299 (2)0.0364 (8)
C110.3916 (1)0.4706 (5)0.8033 (2)0.0250 (7)
C120.2064 (2)0.4566 (7)0.8484 (2)0.0435 (10)
H20.40080.15960.53220.0428*
H40.49980.45360.59420.0506*
H4A0.35770.13960.43680.0862*0.60
H4B0.30510.40790.45710.1128*0.40
H6A0.41550.20500.41620.0718*0.60
H6B0.35840.28540.45180.0718*0.60
H6C0.38610.03140.42570.0718*0.40
H6D0.40790.27120.42270.0718*0.40
H80.27390.14940.79140.0392*
H8M0.15320.39420.78190.0675*
H9A0.16040.04560.84210.0824*
H9B0.11530.12800.87200.0824*
H100.38240.75850.83970.0437*
H10A0.21780.04520.43700.1306*
H10B0.27540.05270.45680.1306*0.60
H10C0.25140.08890.46540.1306*0.40
H12A0.20400.41550.89230.0522*
H12B0.19310.60470.84460.0522*
H260.531 (1)0.345 (3)0.692 (2)0.0388*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ca10.0234 (5)0.0203 (5)0.0293 (5)0.00000.0034 (4)0.0000
O10.053 (2)0.025 (1)0.034 (1)0.010 (1)0.011 (1)0.003 (1)
O20.039 (1)0.025 (1)0.032 (1)0.009 (1)0.009 (1)0.001 (1)
O30.070 (2)0.036 (2)0.034 (1)0.007 (1)0.009 (1)0.009 (1)
O4A0.079 (4)0.047 (3)0.045 (3)0.003 (3)0.019 (3)0.012 (2)
O4B0.079 (6)0.072 (6)0.073 (6)0.014 (5)0.032 (5)0.000 (5)
O50.027 (1)0.025 (1)0.053 (2)0.001 (1)0.001 (1)0.010 (1)
O60.027 (1)0.025 (1)0.049 (2)0.0076 (10)0.004 (1)0.008 (1)
O70.031 (1)0.030 (1)0.053 (2)0.001 (1)0.009 (1)0.011 (1)
O80.031 (1)0.039 (2)0.065 (2)0.005 (1)0.009 (1)0.018 (1)
O90.056 (2)0.044 (2)0.105 (3)0.014 (2)0.022 (2)0.026 (2)
O100.096 (3)0.138 (4)0.092 (3)0.013 (3)0.019 (2)0.018 (3)
C10.026 (2)0.027 (2)0.030 (2)0.001 (1)0.000 (1)0.002 (1)
C20.038 (2)0.035 (2)0.033 (2)0.007 (2)0.004 (2)0.003 (2)
C30.045 (2)0.043 (2)0.030 (2)0.001 (2)0.001 (2)0.002 (2)
C40.060 (2)0.030 (2)0.036 (2)0.011 (2)0.009 (2)0.003 (2)
C50.027 (2)0.024 (2)0.028 (2)0.000 (1)0.001 (1)0.001 (1)
C60.075 (3)0.066 (3)0.037 (2)0.004 (3)0.014 (2)0.002 (2)
C70.029 (2)0.025 (2)0.028 (2)0.001 (1)0.004 (1)0.002 (1)
C80.026 (2)0.029 (2)0.042 (2)0.006 (1)0.002 (1)0.003 (2)
C90.027 (2)0.031 (2)0.036 (2)0.001 (1)0.002 (1)0.001 (2)
C100.032 (2)0.027 (2)0.051 (2)0.006 (2)0.006 (2)0.008 (2)
C110.022 (2)0.022 (2)0.031 (2)0.002 (1)0.001 (1)0.002 (1)
C120.029 (2)0.040 (2)0.062 (3)0.002 (2)0.008 (2)0.001 (2)
Geometric parameters (Å, º) top
CA1—O12.483 (2)O10—H10B1.000
CA1—O22.462 (2)O10—H10C0.951
CA1—O52.494 (2)C1—C21.431 (5)
CA1—O62.462 (2)C1—C51.443 (5)
O1—C11.255 (4)C2—C31.342 (5)
O2—C51.335 (4)C2—H20.930
O2—H261.24 (2)C3—C61.487 (6)
O3—C31.341 (5)C4—C51.351 (5)
O3—C41.353 (4)C4—H40.930
O4A—C61.335 (7)C6—H6A0.975 (5)
O4A—H4A0.840 (5)C6—H6B0.972 (5)
O4B—C61.46 (1)C6—H6C0.962 (5)
O4B—H4B1.170 (9)C6—H6D0.978 (5)
O5—C71.261 (4)C7—C81.418 (5)
O6—C111.342 (4)C7—C111.451 (4)
O6—H26i1.24 (2)C8—C91.347 (5)
O7—C91.337 (4)C8—H80.930
O7—C101.362 (4)C9—C121.490 (5)
O8—C121.406 (5)C10—C111.339 (5)
O8—H8M0.820C10—H100.930
O9—H9A0.937C12—H12A0.970
O9—H9B0.937C12—H12B0.970
O10—H10A0.861
O1···O9ii2.818 (4)O5···O8vii2.715 (4)
O1···C4iii3.291 (4)O5···C12vii3.305 (5)
O2···C10iv3.188 (4)O5···C10v3.367 (4)
O2···C11iv3.188 (4)O8···C10vii3.285 (5)
O2···O6v3.396 (3)O8···C1ii3.427 (4)
O3···O3vi3.360 (6)O8···C11vii3.513 (4)
O3···O9vii3.411 (4)O8···C7ii3.540 (4)
O3···C4vi3.585 (5)O8···C5ii3.547 (4)
O4A···C10viii3.084 (6)O9···O10xi2.744 (5)
O4A···O7viii3.163 (5)O9···C4ii3.324 (5)
O4A···C8ix3.431 (6)O9···C12v3.371 (5)
O4A···C7ix3.465 (6)O9···C1vii3.464 (4)
O4B···O10x2.77 (1)O9···C2vii3.486 (5)
O4B···C9ix3.211 (9)O10···O10xii2.835 (10)
O4B···C8ix3.349 (9)C6···C7ix3.490 (5)
O4B···O7ix3.441 (9)
O1—CA1—O1xiii167.4 (1)C2—C1—C5115.6 (3)
O1—CA1—O265.41 (7)C1—C2—C3121.2 (3)
O1—CA1—O2xiii126.41 (8)C1—C2—H2119.4
O1—CA1—O575.14 (8)C3—C2—H2119.4
O1—CA1—O5xiii105.99 (8)O3—C3—C2121.7 (3)
O1—CA1—O692.21 (8)O3—C3—C6111.8 (3)
O1—CA1—O6xiii77.31 (8)C2—C3—C6126.5 (4)
O1xiii—CA1—O2126.41 (8)O3—C4—C5123.3 (3)
O1xiii—CA1—O2xiii65.41 (7)O3—C4—H4118.3
O1xiii—CA1—O5105.99 (8)C5—C4—H4118.3
O1xiii—CA1—O5xiii75.14 (8)O2—C5—C1116.3 (3)
O1xiii—CA1—O677.31 (8)O2—C5—C4125.1 (3)
O1xiii—CA1—O6xiii92.21 (8)C1—C5—C4118.6 (3)
O2—CA1—O2xiii71.7 (1)O4A—C6—C3114.4 (4)
O2—CA1—O594.26 (8)O4A—C6—H6A109.7 (5)
O2—CA1—O5xiii77.63 (8)O4A—C6—H6B108.5 (5)
O2—CA1—O6153.62 (7)O4B—C6—C3111.4 (5)
O2—CA1—O6xiii116.40 (8)O4B—C6—H6C108.5 (6)
O2xiii—CA1—O577.63 (8)O4B—C6—H6D110.7 (5)
O2xiii—CA1—O5xiii94.26 (8)C3—C6—H6A108.4 (4)
O2xiii—CA1—O6116.40 (8)C3—C6—H6B108.5 (4)
O2xiii—CA1—O6xiii153.62 (7)C3—C6—H6C109.4 (4)
O5—CA1—O5xiii170.1 (1)C3—C6—H6D108.7 (4)
O5—CA1—O665.25 (7)H6A—C6—H6B107.1 (5)
O5—CA1—O6xiii124.16 (8)H6C—C6—H6D108.0 (4)
O5xiii—CA1—O6124.16 (8)O5—C7—C8124.8 (3)
O5xiii—CA1—O6xiii65.25 (7)O5—C7—C11119.6 (3)
O6—CA1—O6xiii68.4 (1)C8—C7—C11115.5 (3)
CA1—O1—C1118.9 (2)C7—C8—C9120.9 (3)
CA1—O2—C5118.9 (2)C7—C8—H8119.6
CA1—O2—H26130.1 (19)C9—C8—H8119.6
C5—O2—H26110.9 (16)O7—C9—C8122.1 (3)
C3—O3—C4119.4 (3)O7—C9—C12111.1 (3)
C6—O4A—H4A134.7 (5)C8—C9—C12126.8 (3)
C6—O4B—H4B127.1 (8)O7—C10—C11122.5 (3)
CA1—O5—C7119.4 (2)O7—C10—H10118.7
CA1—O6—C11119.2 (2)C11—C10—H10118.7
CA1—O6—H26i134.7O6—C11—C7116.3 (3)
C11—O6—H26i105.3O6—C11—C10124.3 (3)
C9—O7—C10119.5 (3)C7—C11—C10119.4 (3)
C12—O8—H8M109.5O8—C12—C9112.4 (3)
H9A—O9—H9B118.26O8—C12—H12A109.1
H10A—O10—H10B90.5 (4)O8—C12—H12B109.1
H10A—O10—H10C87.7 (4)C9—C12—H12A109.1
O1—C1—C2124.0 (3)C9—C12—H12B109.1
O1—C1—C5120.4 (3)H12A—C12—H12B107.9
CA1—O1—C1—C2174.3 (2)O3—C4—C5—C13.1 (5)
CA1—O1—C1—C54.9 (4)O4A—C6—C3—C21.2 (7)
CA1—O1xiii—C1xiii—C2xiii174.3 (2)O4B—C6—C3—C284.5 (6)
CA1—O1xiii—C1xiii—C5xiii4.9 (4)O5—CA1—O1—C198.4 (2)
CA1—O2—C5—C10.4 (4)O5—CA1—O1xiii—C1xiii71.4 (2)
CA1—O2—C5—C4179.1 (3)O5—CA1—O2—C569.7 (2)
CA1—O2xiii—C5xiii—C1xiii0.4 (4)O5—CA1—O2xiii—C5xiii116.1 (2)
CA1—O2xiii—C5xiii—C4xiii179.1 (3)O5—CA1—O6—C115.1 (2)
CA1—O5—C7—C8177.6 (3)O5—CA1—O6xiii—C11xiii171.4 (2)
CA1—O5—C7—C111.8 (4)O5—C7—C8—C9176.7 (3)
CA1—O5xiii—C7xiii—C8xiii177.6 (3)O5—C7—C11—O62.9 (4)
CA1—O5xiii—C7xiii—C11xiii1.8 (4)O5—C7—C11—C10177.2 (3)
CA1—O6—C11—C76.3 (4)O6—CA1—O1—C1162.0 (2)
CA1—O6—C11—C10173.9 (3)O6—CA1—O1xiii—C1xiii130.7 (2)
CA1—O6xiii—C11xiii—C7xiii6.3 (4)O6—CA1—O2—C532.3 (3)
CA1—O6xiii—C11xiii—C10xiii173.9 (3)O6—CA1—O2xiii—C5xiii62.0 (2)
O1—CA1—O1xiii—C1xiii164.8 (2)O6—CA1—O5—C73.5 (2)
O1—CA1—O2—C51.8 (2)O6—CA1—O5xiii—C7xiii40.1 (3)
O1—CA1—O2xiii—C5xiii176.9 (2)O6—CA1—O6xiii—C11xiii153.0 (3)
O1—CA1—O5—C7103.1 (2)O6—C11—C7—C8177.6 (3)
O1—CA1—O5xiii—C7xiii63.9 (2)O6—C11—C10—O7179.3 (3)
O1—CA1—O6—C1177.6 (2)O7—C9—C8—C71.5 (5)
O1—CA1—O6xiii—C11xiii109.4 (2)O7—C9—C12—O8153.9 (3)
O1—C1—C2—C3179.8 (3)O7—C10—C11—C70.6 (5)
O1—C1—C5—O23.0 (5)O8—C12—C9—C827.8 (5)
O1—C1—C5—C4177.4 (3)C1—C2—C3—C6175.1 (4)
O2—CA1—O1—C13.5 (2)C2—C1—C5—C43.3 (5)
O2—CA1—O1xiii—C1xiii36.5 (3)C2—C3—O3—C43.2 (5)
O2—CA1—O2xiii—C5xiii145.2 (3)C3—O3—C4—C50.2 (5)
O2—CA1—O5—C7166.3 (2)C3—C2—C1—C50.6 (5)
O2—CA1—O5xiii—C7xiii123.5 (2)C4—O3—C3—C6174.9 (3)
O2—CA1—O6—C1146.8 (3)C7—C8—C9—C12176.7 (3)
O2—CA1—O6xiii—C11xiii55.5 (2)C8—C7—C11—C102.2 (5)
O2—C5—C1—C2176.2 (3)C8—C9—O7—C100.3 (5)
O2—C5—C4—O3176.4 (3)C9—O7—C10—C110.8 (5)
O3—C3—C2—C12.7 (6)C9—C8—C7—C112.7 (5)
O3—C3—C6—O4A179.2 (4)C10—O7—C9—C12178.7 (3)
O3—C3—C6—O4B93.5 (6)C10—O7—C9—C12178.7 (3)
Symmetry codes: (i) x+1, y+1, z+3/2; (ii) x+1/2, y+1/2, z+3/2; (iii) x, y+1, z; (iv) x+1, y1, z+3/2; (v) x, y1, z; (vi) x+1, y1, z+1; (vii) x+1/2, y1/2, z+3/2; (viii) x, y+1, z1/2; (ix) x, y, z1/2; (x) x+1/2, y1/2, z+1; (xi) x, y, z+1/2; (xii) x+1/2, y+1/2, z+1; (xiii) x+1, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O8—H8M···O5ii0.821.932.715 (3)160
O9—H9A···O80.941.862.708 (4)149
O9—H9B···O1vii0.941.892.818 (4)173
O10—H10A···O9ix0.861.942.744 (5)155
O10—H10B···O4A1.001.892.874 (7)169
O10—H10C···O4B0.951.842.670 (10)144
O2—H26···O6iv1.24 (2)1.24 (2)2.462 (4)168 (3)
Symmetry codes: (ii) x+1/2, y+1/2, z+3/2; (iv) x+1, y1, z+3/2; (vii) x+1/2, y1/2, z+3/2; (ix) x, y, z1/2.

Experimental details

Crystal data
Chemical formula[Ca(C6H5O4)2(C6H6O4)2]·4H2O
Mr678.56
Crystal system, space groupMonoclinic, C2/c
Temperature (K)296
a, b, c (Å)22.020 (4), 6.223 (4), 21.225 (3)
β (°) 91.61 (1)
V3)2907 (2)
Z4
Radiation typeMo Kα
µ (mm1)0.31
Crystal size (mm)0.20 × 0.10 × 0.10
Data collection
DiffractometerRigaku AFC-5R
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.942, 0.970
No. of measured, independent and
observed [I > 2σ(I)] reflections
3773, 3332, 1748
Rint0.062
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.048, 0.152, 1.00
No. of reflections3332
No. of parameters217
No. of restraints?
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.30, 0.52

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1992), MSC/AFC Diffractometer Control Software, TEXSAN (Molecular Structure Corporation, 2000), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), TEXSAN.

Selected geometric parameters (Å, º) top
CA1—O12.483 (2)CA1—O52.494 (2)
CA1—O22.462 (2)CA1—O62.462 (2)
O1—CA1—O1i167.4 (1)O2—CA1—O6153.62 (7)
O1—CA1—O265.41 (7)O2—CA1—O6i116.40 (8)
O1—CA1—O2i126.41 (8)O5—CA1—O5i170.1 (1)
O1—CA1—O575.14 (8)O5—CA1—O665.25 (7)
O1—CA1—O5i105.99 (8)O5—CA1—O6i124.16 (8)
O1—CA1—O692.21 (8)O6—CA1—O6i68.4 (1)
O1—CA1—O6i77.31 (8)CA1—O1—C1118.9 (2)
O2—CA1—O2i71.7 (1)CA1—O2—C5118.9 (2)
O2—CA1—O594.26 (8)CA1—O5—C7119.4 (2)
O2—CA1—O5i77.63 (8)CA1—O6—C11119.2 (2)
Symmetry code: (i) x+1, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O8—H8M···O5ii0.821.932.715 (3)160
O9—H9A···O80.941.862.708 (4)149
O9—H9B···O1iii0.941.892.818 (4)173
O10—H10A···O9iv0.861.942.744 (5)155
O10—H10B···O4A1.001.892.874 (7)169
O10—H10C···O4B0.951.842.670 (10)144
O2—H26···O6v1.24 (2)1.24 (2)2.462 (4)168 (3)
Symmetry codes: (ii) x+1/2, y+1/2, z+3/2; (iii) x+1/2, y1/2, z+3/2; (iv) x, y, z1/2; (v) x+1, y1, z+3/2.
 

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