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In addition to associating into cyclic hydrogen-bonded dimers [O...O = 2.663 (1) and 2.914 (1) Å], each hydrogen peroxide mol­ecule in the title structure, K3[Al(C2O4)3]·1.75H2O2·0.25H2O, hydrogen bonds to a neighbouring oxalate ligand [O...O = 2.700 (1) and 2.730 (1) Å] and coordinates to two K+ ions [K...O = 2.6620 (9)–2.8380 (7) Å].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103006905/gg1158sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103006905/gg1158Isup2.hkl
Contains datablock I

CCDC reference: 190972

Comment top

Several oxyacid salts form perhydrates on recrystallization from aqueous hydrogen peroxide. These include the commercially important bleaches, Na2CO3·1.5H2O2 (sodium percarbonate) (Adams & Pritchard, 1977; Carrondo et al., 1977; Adams et al., 1979) and Na9(SO4)4Cl·2H2O2 (Adams et al., 1978, 1981; Adams & Pritchard 1978).

As the hydrogen peroxide molecules are disordered in the above compounds, accurate geometries for H2O2 solvate molecules are usually obtained from other perhydrates, notably the alkali metal oxalate monoperhydrates (Table 3). Even in these structures the hydrogen peroxide geometry is variable, particularly the torsion angle, which adapts to the local environment. The title structure, (I), is the first example of an oxalate perhydrate containing a higher valency main group metal and consists of a racemic mixture of Λ- and Δ-trisoxalatoaluminium anions interspersed with potassium cations and hydrogen peroxide solvate molecules (Fig. 1). Hydrogen bonds link the two crystallographically independent hydrogen peroxide molecules into novel cyclic dimers, which use their two remaining H atoms to associate into chains with the trans O atoms (O10 and O11) of an oxalate ligand (Fig. 2). Each hydrogen peroxide molecule also uses one of its O atoms to coordinate to two K+ ions at K···O distances ranging from 2.6620 (9) to 2.8380 (7) Å (selected data are given in Tables 1 and 2). This arrangement leads to H—O—O—H torsion angles of 119 (1) and 124 (1)°, which correspond to low-energy conformations (Hunt et al., 1965).

In 25% of their sites, hydrogen peroxide atoms O15 and O16 have been replaced by a single water O atom, O15B. Both hydrogen peroxide and water molecules share the same H atoms and, although the water geometry is somewhat distorted, [O—H = 1.15 (2) and 1.34 (2) Å, and H—O—H = 117 (1)°[, it clearly shows that a water molecule could replace hydrogen peroxide in the hydrogen-bonding scheme. Also, with distances of 2.799 (3) and 2.881 (3) Å, the water K···O distances make a satisfactory substitute for the corresponding distances to hydrogen peroxide.

The non-solvate part of the structure is isostructural with the analogous trihydrate K3[Al(C2O4)3]·3H2O, which itself forms an isostructural series with the Cr (Taylor, 1978), Fe and V trihydrates (Gillard et al., 1969). Two water molecules are located in peroxide sites O13 and O15, thereby maintaining the four K···O bridging bonds, which range from 2.683 (6) to 2.958 (8) Å in the trihydrate. This leaves sufficient space for an additional water molecule, which coordinates to K3 at a distance of 2.995 (7) Å. Although disorder prevents the H atoms being located in the trihydrate it is possible to deduce a hydrogen-bonding scheme from short non-bonded O···O contacts (range 2.753–2.785 Å). These indicate that the two hydrogen bonds to the oxalate ligand are maintained and that the only other hydrogen bond is between the additional water molecule coordinated to K3 and the one replacing O13. The complicated relationship between the title compound and its trihydrate contrasts with the more straightforward situation in the alkali metal oxalate monoperhydrates K2(C2O4)·H2O2 and Rb2(C2O4)·H2O2. These are isostructural with their monohydrates; however, in their case, a C2-symmetric site can accomodate either a hydrogen peroxide or water solvate molecule (Pedersen, 1967).

Experimental top

K3[Al(C2O4)3]·3H2O was prepared by reacting aluminium turnings (1 g) with KOH (6 g) in water (50 ml), heating and adding oxalic acid crystals (14 g). The solution was then filtered and cooled to room temperature before ethanol (50 ml) was added and the solution cooled to 273 K to induce crystallization. Crystals of (I) were prepared by dissolving the above hydrate in a 30% w/w aqueous H2O2 solution and then evaporating to dryness at room temperature.

Refinement top

Although atom H14 appeared in a chemically reasonable position in the ΔF map, its displacement parameter expanded on least-squares refinement and the atom moved away from O14 to encompass diffuse electron density on the nearby oxalate O atom to which it is hydrogen bonded. This problem has been resolved by fixing the vibrational amplitude of H14 to the average value of the other three H atoms, whilst leaving its positional parameters to refine freely. The 25% occupancy water H atoms attached to O15B are assumed to coincide with the hydrogen peroxide atoms H15 and H16, although it is envisaged that their actual site will be slightly shifted so that hydrogen bonding is maintained and the water geometry is more typical.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The unit cell of (I), viewed down the a axis.
[Figure 2] Fig. 2. View of (I), showing the atomic labelling scheme (50% probability displacement ellipsoids). Only the boundary ellipse has been drawn for the 25% occupancy water molecule, O15B. The hydrogen peroxide environment in highlighted with primes (') and double primes ('') denoting symmetry codes (x − 1, 1/2 − y, z + 1/2) and (x, 1/2 − y, 1/2 + z), respectively.
(I) top
Crystal data top
K3[Al(C2O4)3]·1.75H2O2·0.25H2OF(000) = 944
Mr = 472.37Dx = 2.157 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 7200 reflections
a = 7.6194 (2) Åθ = 1.0–27.5°
b = 19.3531 (6) ŵ = 1.09 mm1
c = 10.3668 (4) ÅT = 150 K
β = 107.905 (1)°Needle, colourless
V = 1454.64 (8) Å30.15 × 0.15 × 0.07 mm
Z = 4
Data collection top
Nonius KappaCCD
diffractometer
2390 reflections with I > 2σ(I)
CCD rotation images scansRint = 0.041
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
θmax = 27.4°, θmin = 2.3°
Tmin = 0.849, Tmax = 0.926h = 89
7571 measured reflectionsk = 1925
3256 independent reflectionsl = 1113
Refinement top
Refinement on F2All H-atom parameters refined
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0101P)2 + 2.2968P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.044(Δ/σ)max = 0.004
wR(F2) = 0.088Δρmax = 0.41 e Å3
S = 1.09Δρmin = 0.49 e Å3
3256 reflectionsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
256 parametersExtinction coefficient: 0.00282 (13)
0 restraints
Crystal data top
K3[Al(C2O4)3]·1.75H2O2·0.25H2OV = 1454.64 (8) Å3
Mr = 472.37Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.6194 (2) ŵ = 1.09 mm1
b = 19.3531 (6) ÅT = 150 K
c = 10.3668 (4) Å0.15 × 0.15 × 0.07 mm
β = 107.905 (1)°
Data collection top
Nonius KappaCCD
diffractometer
3256 independent reflections
Absorption correction: multi-scan
(SORTAV; Blessing, 1995)
2390 reflections with I > 2σ(I)
Tmin = 0.849, Tmax = 0.926Rint = 0.041
7571 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0440 restraints
wR(F2) = 0.088All H-atom parameters refined
S = 1.09Δρmax = 0.41 e Å3
3256 reflectionsΔρmin = 0.49 e Å3
256 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Al10.73663 (3)0.125511 (12)0.24646 (3)0.01052 (7)
O10.65979 (7)0.05626 (3)0.35144 (6)0.01291 (17)
O20.96179 (8)0.12106 (3)0.38650 (6)0.01402 (17)
O30.73862 (8)0.02030 (3)0.56849 (6)0.01669 (17)
O41.08945 (8)0.07691 (3)0.59343 (6)0.01663 (18)
O50.83894 (7)0.07002 (3)0.13610 (6)0.01264 (16)
O60.51379 (8)0.11318 (3)0.10628 (6)0.01291 (16)
O70.76446 (8)0.02863 (3)0.07688 (6)0.01748 (18)
O80.40017 (8)0.06610 (3)0.09988 (6)0.01512 (17)
O90.61644 (8)0.18862 (3)0.32935 (6)0.01519 (17)
O100.81517 (8)0.20708 (3)0.17655 (6)0.01383 (17)
O110.55418 (9)0.30056 (3)0.33991 (6)0.02243 (19)
O120.79302 (8)0.32290 (3)0.18277 (6)0.02043 (19)
C10.77096 (11)0.05032 (4)0.47340 (9)0.0129 (2)
C20.96004 (11)0.08538 (4)0.49098 (8)0.0111 (2)
C30.72641 (11)0.05710 (4)0.01723 (9)0.0118 (2)
C40.52694 (11)0.08033 (4)0.00203 (9)0.0121 (2)
C50.63163 (12)0.25224 (4)0.30184 (9)0.0171 (3)
C60.75738 (12)0.26462 (4)0.21299 (9)0.0155 (3)
K10.03065 (3)0.421043 (10)0.33064 (2)0.01857 (6)
K20.47354 (3)0.087936 (10)0.664027 (19)0.01665 (5)
K30.26057 (3)0.413367 (10)0.75571 (2)0.01981 (5)
O130.29851 (9)0.18436 (3)0.45847 (7)0.0303 (2)
O140.39967 (10)0.24534 (3)0.51832 (7)0.0299 (2)
O150.13748 (11)0.33121 (4)0.54081 (9)0.0231 (3)0.75 (1)
O15B0.0760 (4)0.32244 (16)0.5359 (3)0.0332 (7)*0.25 (1)
O160.01000 (11)0.27276 (4)0.49843 (9)0.0241 (3)0.75 (1)
H130.185 (2)0.2040 (8)0.4638 (16)0.107 (6)*
H140.461 (2)0.2650 (8)0.4328 (15)0.095*
H150.2218 (18)0.3026 (7)0.5439 (14)0.079 (5)*
H160.041 (2)0.2771 (8)0.5636 (16)0.103 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Al10.01066 (10)0.00961 (11)0.01151 (11)0.00029 (9)0.00372 (8)0.00061 (10)
O10.0099 (3)0.0133 (3)0.0149 (3)0.0018 (2)0.0029 (2)0.0006 (2)
O20.0147 (3)0.0147 (3)0.0122 (3)0.0034 (2)0.0034 (2)0.0021 (2)
O30.0216 (3)0.0156 (3)0.0166 (3)0.0013 (2)0.0115 (2)0.0046 (3)
O40.0130 (3)0.0202 (3)0.0165 (3)0.0031 (2)0.0042 (2)0.0010 (3)
O50.0112 (3)0.0131 (3)0.0134 (3)0.0000 (2)0.0035 (2)0.0001 (2)
O60.0138 (3)0.0132 (3)0.0127 (3)0.0016 (2)0.0055 (2)0.0002 (2)
O70.0210 (3)0.0152 (3)0.0187 (3)0.0013 (2)0.0098 (2)0.0031 (3)
O80.0134 (3)0.0165 (3)0.0143 (3)0.0035 (2)0.0026 (2)0.0007 (3)
O90.0200 (3)0.0118 (3)0.0159 (3)0.0017 (2)0.0086 (2)0.0002 (2)
O100.0158 (3)0.0119 (3)0.0147 (3)0.0005 (2)0.0061 (2)0.0008 (2)
O110.0334 (3)0.0143 (3)0.0227 (3)0.0061 (3)0.0131 (3)0.0004 (3)
O120.0254 (3)0.0106 (3)0.0256 (3)0.0020 (2)0.0083 (3)0.0016 (3)
C10.0124 (4)0.0094 (4)0.0167 (4)0.0030 (3)0.0042 (3)0.0026 (3)
C20.0140 (4)0.0107 (4)0.0100 (4)0.0025 (3)0.0058 (3)0.0032 (3)
C30.0166 (4)0.0053 (4)0.0145 (4)0.0022 (3)0.0064 (3)0.0003 (3)
C40.0138 (4)0.0086 (4)0.0137 (4)0.0013 (3)0.0041 (3)0.0042 (3)
C50.0173 (4)0.0173 (4)0.0153 (4)0.0002 (3)0.0029 (3)0.0009 (4)
C60.0146 (4)0.0155 (4)0.0119 (4)0.0005 (3)0.0025 (3)0.0013 (4)
K10.01445 (8)0.02389 (10)0.01852 (9)0.00209 (7)0.00676 (7)0.00365 (8)
K20.01584 (8)0.01809 (9)0.01681 (9)0.00127 (7)0.00616 (7)0.00223 (8)
K30.02105 (9)0.01956 (9)0.01971 (9)0.00034 (8)0.00755 (7)0.00167 (9)
O130.0323 (3)0.0225 (3)0.0373 (4)0.0102 (3)0.0126 (3)0.0044 (3)
O140.0360 (4)0.0256 (3)0.0286 (3)0.0058 (3)0.0107 (3)0.0070 (3)
O150.0222 (4)0.0145 (4)0.0332 (5)0.0035 (3)0.0095 (3)0.0065 (4)
O160.0182 (4)0.0295 (5)0.0252 (4)0.0112 (4)0.0078 (3)0.0098 (4)
Geometric parameters (Å, º) top
Al1—O11.9274 (7)C5—C61.5383 (14)
Al1—O21.8780 (5)C5—K2i3.4643 (9)
Al1—O51.9022 (7)C6—K2i3.5217 (9)
Al1—O61.8801 (5)K1—O4ix2.6319 (7)
Al1—O91.8849 (7)K1—O7x2.6790 (7)
Al1—O101.9084 (7)K1—O8xi2.6946 (6)
Al1—K3i3.7345 (4)K1—O152.7096 (9)
O1—K2ii2.9572 (6)K1—O12xii2.7440 (6)
O1—K3i2.9541 (6)K1—O15B2.799 (3)
O1—C11.2926 (9)K1—O5xiii3.0344 (6)
O2—K3iii3.0599 (7)K1—O3ix3.1475 (6)
O2—C21.2881 (11)K1—O7xiii3.2922 (6)
O3—K22.8290 (7)K1—C3xiii3.3244 (8)
O3—K3iv2.7564 (6)K1—O163.3844 (9)
O3—K1v3.1475 (6)K1—C2ix3.3969 (9)
O3—K2ii3.2274 (6)K2—O8xiv2.7061 (7)
O3—C11.2326 (11)K2—O11xi2.7695 (6)
O4—K1v2.6319 (7)K2—O4xii2.7980 (6)
O4—K2vi2.7980 (6)K2—O132.8380 (7)
O4—C21.2179 (9)K2—O12xi2.9411 (7)
O5—C31.2910 (9)K2—O1ii2.9573 (6)
O5—K1vii3.0344 (6)K2—O7xiv3.1280 (6)
O5—K3iii3.0842 (6)K2—O3ii3.2274 (6)
O6—C41.2840 (11)K2—C1ii3.3208 (8)
O6—K3i2.8677 (7)K2—O143.3698 (7)
O7—C31.2302 (11)K2—C4xiv3.4043 (9)
O7—K1iii2.6790 (7)K3—O152.6620 (9)
O7—K3vii2.8691 (6)K3—O3xv2.7564 (6)
O7—K2viii3.1280 (6)K3—O13xi2.7759 (7)
O7—K1vii3.2922 (6)K3—O6xi2.8677 (7)
O8—C41.2237 (9)K3—O7xiii2.8691 (6)
O8—K1i2.6946 (6)K3—O15B2.881 (3)
O8—K2viii2.7061 (7)K3—O1xi2.9541 (6)
O9—C51.2770 (10)K3—O2x3.0599 (7)
O9—K3i3.2493 (6)K3—O5x3.0842 (6)
O10—C61.2957 (11)K3—O9xi3.2493 (6)
O11—C51.2336 (11)K3—Al1xi3.7345 (4)
O11—K2i2.7695 (6)K3—K1xvi3.8436 (3)
O12—C61.2233 (11)K3—H153.018 (14)
O12—K1vi2.7440 (6)O13—O141.4415 (9)
O12—K2i2.9411 (7)O13—K3i2.7759 (7)
C1—C21.5517 (12)O13—H130.963 (17)
C1—K2ii3.3208 (8)O14—H141.183 (17)
C1—K23.5106 (10)O15—O161.4675 (12)
C2—K1v3.3969 (9)O15—H150.842 (14)
C3—C41.5459 (12)O16—H160.881 (18)
C3—K1vii3.3244 (8)O15B—H151.154 (15)
C3—K1iii3.4715 (10)O15B—H161.344 (17)
C4—K2viii3.4042 (9)
O2—Al1—O6170.07 (3)O3ix—K1—C2ix43.411 (19)
O2—Al1—O997.68 (3)O7xiii—K1—C2ix135.490 (19)
O6—Al1—O989.13 (3)C3xiii—K1—C2ix114.10 (2)
O2—Al1—O589.61 (3)O16—K1—C2ix118.96 (2)
O6—Al1—O584.44 (3)O8xiv—K2—O11xi65.916 (19)
O9—Al1—O5170.55 (3)O8xiv—K2—O4xii74.595 (18)
O2—Al1—O1090.74 (3)O11xi—K2—O4xii103.54 (2)
O6—Al1—O1097.21 (3)O8xiv—K2—O3127.779 (18)
O9—Al1—O1083.69 (3)O11xi—K2—O3123.588 (19)
O5—Al1—O1090.25 (3)O4xii—K2—O3132.457 (18)
O2—Al1—O184.00 (3)O8xiv—K2—O13126.99 (2)
O6—Al1—O189.38 (3)O11xi—K2—O1386.556 (19)
O9—Al1—O185.33 (3)O4xii—K2—O1368.99 (2)
O5—Al1—O1101.47 (3)O3—K2—O13105.23 (2)
O10—Al1—O1167.09 (3)O8xiv—K2—O12xi115.392 (18)
O2—Al1—K3i129.39 (2)O11xi—K2—O12xi59.19 (2)
O6—Al1—K3i48.76 (2)O4xii—K2—O12xi147.130 (18)
O9—Al1—K3i60.460 (19)O3—K2—O12xi68.230 (18)
O5—Al1—K3i118.853 (19)O13—K2—O12xi81.497 (19)
O10—Al1—K3i126.64 (2)O8xiv—K2—O1ii74.848 (18)
O1—Al1—K3i51.637 (17)O11xi—K2—O1ii140.71 (2)
C1—O1—Al1113.12 (5)O4xii—K2—O1ii66.397 (17)
C1—O1—K3i130.07 (6)O3—K2—O1ii79.324 (18)
Al1—O1—K3i97.59 (2)O13—K2—O1ii120.364 (17)
C1—O1—K2ii94.59 (5)O12xi—K2—O1ii145.165 (18)
Al1—O1—K2ii141.67 (3)O8xiv—K2—O7xiv56.973 (17)
K3i—O1—K2ii82.443 (15)O11xi—K2—O7xiv76.429 (17)
C2—O2—Al1115.56 (5)O4xii—K2—O7xiv127.208 (19)
C2—O2—K3iii117.22 (5)O3—K2—O7xiv74.758 (17)
Al1—O2—K3iii107.14 (3)O13—K2—O7xiv158.651 (18)
C1—O3—K3iv157.26 (6)O12xi—K2—O7xiv78.752 (17)
C1—O3—K2113.69 (5)O1ii—K2—O7xiv80.864 (15)
K3iv—O3—K288.43 (2)O8xiv—K2—O3ii112.263 (18)
C1—O3—K1v104.98 (5)O11xi—K2—O3ii162.996 (18)
K3iv—O3—K1v80.945 (15)O4xii—K2—O3ii60.771 (17)
K2—O3—K1v85.536 (17)O3—K2—O3ii71.687 (18)
C1—O3—K2ii83.45 (5)O13—K2—O3ii81.612 (17)
K3iv—O3—K2ii84.565 (16)O12xi—K2—O3ii130.128 (19)
K2—O3—K2ii108.313 (18)O1ii—K2—O3ii42.453 (16)
K1v—O3—K2ii159.68 (2)O7xiv—K2—O3ii117.592 (16)
C2—O4—K1v119.21 (6)O8xiv—K2—C1ii91.01 (2)
C2—O4—K2vi135.98 (6)O11xi—K2—C1ii153.12 (2)
K1v—O4—K2vi102.667 (18)O4xii—K2—C1ii54.73 (2)
C3—O5—Al1114.13 (5)O3—K2—C1ii81.01 (2)
C3—O5—K1vii91.30 (4)O13—K2—C1ii97.79 (2)
Al1—O5—K1vii130.43 (3)O12xi—K2—C1ii147.65 (2)
C3—O5—K3iii135.07 (6)O1ii—K2—C1ii22.830 (17)
Al1—O5—K3iii105.55 (2)O7xiv—K2—C1ii103.222 (18)
K1vii—O5—K3iii77.828 (14)O3ii—K2—C1ii21.64 (2)
C4—O6—Al1115.33 (5)O8xiv—K2—O14119.61 (2)
C4—O6—K3i127.27 (5)O11xi—K2—O1464.113 (18)
Al1—O6—K3i101.71 (3)O4xii—K2—O1486.248 (18)
C3—O7—K1iii120.66 (5)O3—K2—O14107.47 (2)
C3—O7—K3vii151.12 (6)O13—K2—O1425.022 (17)
K1iii—O7—K3vii87.63 (2)O12xi—K2—O1461.315 (17)
C3—O7—K2viii103.83 (5)O1ii—K2—O14145.237 (16)
K1iii—O7—K2viii88.504 (18)O7xiv—K2—O14133.886 (16)
K3vii—O7—K2viii80.889 (15)O3ii—K2—O14106.003 (16)
C3—O7—K1vii80.76 (4)C1ii—K2—O14122.800 (18)
K1iii—O7—K1vii106.065 (18)O8xiv—K2—C4xiv19.061 (18)
K3vii—O7—K1vii86.031 (16)O11xi—K2—C4xiv54.823 (19)
K2viii—O7—K1vii160.02 (2)O4xii—K2—C4xiv92.89 (2)
C4—O8—K1i133.83 (6)O3—K2—C4xiv117.908 (19)
C4—O8—K2viii114.71 (6)O13—K2—C4xiv132.94 (2)
K1i—O8—K2viii103.486 (18)O12xi—K2—C4xiv97.053 (19)
C5—O9—Al1115.65 (6)O1ii—K2—C4xiv86.867 (19)
C5—O9—K3i131.27 (5)O7xiv—K2—C4xiv43.229 (19)
Al1—O9—K3i89.23 (2)O3ii—K2—C4xiv127.926 (19)
C6—O10—Al1115.20 (6)C1ii—K2—C4xiv106.29 (2)
C5—O11—K2i114.28 (6)O14—K2—C4xiv116.815 (19)
C6—O12—K1vi130.96 (5)O15—K3—O3xv158.50 (2)
C6—O12—K2i108.27 (6)O15—K3—O13xi98.90 (2)
K1vi—O12—K2i91.222 (19)O3xv—K3—O13xi91.85 (2)
O3—C1—O1126.31 (8)O15—K3—O6xi64.11 (2)
O3—C1—C2121.25 (7)O3xv—K3—O6xi128.795 (19)
O1—C1—C2112.43 (8)O13xi—K3—O6xi110.87 (2)
O3—C1—K2ii74.91 (4)O15—K3—O7xiii89.27 (2)
O1—C1—K2ii62.58 (4)O3xv—K3—O7xiii80.192 (19)
C2—C1—K2ii141.34 (6)O13xi—K3—O7xiii171.80 (2)
O3—C1—K247.56 (4)O6xi—K3—O7xiii73.282 (18)
O1—C1—K2100.94 (5)O15—K3—O15B9.00 (7)
C2—C1—K2125.44 (5)O3xv—K3—O15B152.01 (6)
K2ii—C1—K291.98 (2)O13xi—K3—O15B95.44 (6)
O4—C2—O2126.20 (8)O6xi—K3—O15B73.09 (7)
O4—C2—C1121.14 (8)O7xiii—K3—O15B92.55 (6)
O2—C2—C1112.64 (6)O15—K3—O1xi117.48 (2)
O2—C2—K1v148.43 (5)O3xv—K3—O1xi80.545 (18)
C1—C2—K1v87.20 (5)O13xi—K3—O1xi91.401 (19)
O7—C3—O5126.48 (8)O6xi—K3—O1xi54.749 (16)
O7—C3—C4120.90 (7)O7xiii—K3—O1xi85.377 (17)
O5—C3—C4112.62 (8)O15B—K3—O1xi126.10 (7)
O7—C3—K1vii77.81 (4)O15—K3—O2x97.01 (2)
O5—C3—K1vii65.86 (4)O3xv—K3—O2x73.815 (18)
C4—C3—K1vii131.70 (5)O13xi—K3—O2x55.566 (19)
O5—C3—K1iii98.45 (5)O6xi—K3—O2x156.365 (17)
C4—C3—K1iii135.38 (5)O7xiii—K3—O2x123.017 (18)
K1vii—C3—K1iii89.49 (2)O15B—K3—O2x88.21 (7)
O8—C4—O6126.36 (8)O1xi—K3—O2x136.385 (17)
O8—C4—C3120.86 (8)O15—K3—O5x70.75 (2)
O6—C4—C3112.76 (6)O3xv—K3—O5x88.731 (17)
O8—C4—K2viii46.23 (5)O13xi—K3—O5x103.21 (2)
O6—C4—K2viii146.04 (5)O6xi—K3—O5x126.308 (17)
C3—C4—K2viii85.42 (5)O7xiii—K3—O5x78.758 (17)
O11—C5—O9125.05 (9)O15B—K3—O5x63.30 (6)
O11—C5—C6121.38 (8)O1xi—K3—O5x162.177 (17)
O9—C5—C6113.57 (8)O2x—K3—O5x51.387 (16)
O11—C5—K2i46.78 (5)O15—K3—O9xi83.55 (2)
O9—C5—K2i155.37 (6)O3xv—K3—O9xi117.948 (16)
C6—C5—K2i79.37 (5)O13xi—K3—O9xi61.52 (2)
O12—C6—O10126.56 (9)O6xi—K3—O9xi50.706 (16)
O12—C6—C5121.68 (8)O7xiii—K3—O9xi120.598 (19)
O10—C6—C5111.76 (7)O15B—K3—O9xi89.09 (6)
O12—C6—K2i52.47 (5)O1xi—K3—O9xi48.948 (15)
O10—C6—K2i154.55 (5)O2x—K3—O9xi116.385 (17)
C5—C6—K2i75.20 (5)O5x—K3—O9xi148.063 (16)
O4ix—K1—O7x133.947 (18)O15—K3—Al1xi87.32 (2)
O4ix—K1—O8xi77.547 (19)O3xv—K3—Al1xi111.315 (14)
O7x—K1—O8xi135.605 (19)O13xi—K3—Al1xi90.363 (17)
O4ix—K1—O15131.73 (3)O6xi—K3—Al1xi29.536 (11)
O7x—K1—O1591.08 (2)O7xiii—K3—Al1xi90.699 (15)
O8xi—K1—O1579.24 (2)O15B—K3—Al1xi95.65 (7)
O4ix—K1—O12xii76.18 (2)O1xi—K3—Al1xi30.770 (12)
O7x—K1—O12xii90.54 (2)O2x—K3—Al1xi145.928 (12)
O8xi—K1—O12xii131.99 (2)O5x—K3—Al1xi155.586 (14)
O15—K1—O12xii89.35 (2)O9xi—K3—Al1xi30.310 (12)
O4ix—K1—O15B134.73 (7)O15—K3—K1xvi105.871 (18)
O7x—K1—O15B84.60 (7)O3xv—K3—K1xvi53.967 (12)
O8xi—K1—O15B89.15 (6)O13xi—K3—K1xvi131.505 (18)
O15—K1—O15B9.96 (6)O6xi—K3—K1xvi117.364 (13)
O12xii—K1—O15B81.88 (6)O7xiii—K3—K1xvi44.139 (14)
O4ix—K1—O5xiii87.019 (19)O15B—K3—K1xvi102.62 (6)
O7x—K1—O5xiii82.611 (18)O1xi—K3—K1xvi111.927 (13)
O8xi—K1—O5xiii66.618 (17)O2x—K3—K1xvi80.205 (12)
O15—K1—O5xiii120.75 (2)O5x—K3—K1xvi50.509 (11)
O12xii—K1—O5xiii149.088 (17)O9xi—K3—K1xvi160.302 (13)
O15B—K1—O5xiii127.00 (6)Al1xi—K3—K1xvi131.128 (8)
O4ix—K1—O3ix57.729 (18)O15—K3—H1515.5 (2)
O7x—K1—O3ix76.459 (18)O3xv—K3—H15173.9 (2)
O8xi—K1—O3ix126.921 (19)O13xi—K3—H1591.8 (3)
O15—K1—O3ix152.07 (2)O6xi—K3—H1553.9 (3)
O12xii—K1—O3ix66.259 (17)O7xiii—K3—H1596.3 (3)
O15B—K1—O3ix142.31 (6)O15B—K3—H1522.4 (3)
O5xiii—K1—O3ix82.838 (15)O1xi—K3—H15104.3 (3)
O4ix—K1—O7xiii122.588 (19)O2x—K3—H15104.4 (3)
O7x—K1—O7xiii73.935 (18)O5x—K3—H1585.7 (3)
O8xi—K1—O7xiii61.764 (18)O9xi—K3—H1568.1 (2)
O15—K1—O7xiii80.14 (2)Al1xi—K3—H1573.6 (3)
O12xii—K1—O7xiii160.93 (2)K1xvi—K3—H15120.2 (2)
O15B—K1—O7xiii85.62 (6)O14—O13—K3i143.24 (6)
O5xiii—K1—O7xiii41.439 (15)O14—O13—K298.60 (4)
O3ix—K1—O7xiii118.831 (16)K3i—O13—K292.07 (2)
O4ix—K1—C3xiii101.62 (2)O14—O13—H1391.4 (9)
O7x—K1—C3xiii85.10 (2)K3i—O13—H13115.2 (9)
O8xi—K1—C3xiii54.30 (2)K2—O13—H13116.0 (10)
O15—K1—C3xiii98.10 (2)O13—O14—K256.38 (3)
O12xii—K1—C3xiii171.428 (19)O13—O14—H14102.8 (7)
O15B—K1—C3xiii105.00 (6)K2—O14—H14125.2 (7)
O5xiii—K1—C3xiii22.844 (17)O16—O15—K3137.85 (7)
O3ix—K1—C3xiii105.467 (18)O16—O15—K1104.26 (5)
O7xiii—K1—C3xiii21.42 (2)K3—O15—K1103.37 (3)
O4ix—K1—O16122.76 (2)O16—O15—H1586.0 (9)
O7x—K1—O1687.96 (2)K3—O15—H15107.1 (9)
O8xi—K1—O1698.670 (19)K1—O15—H15119.3 (10)
O15—K1—O1624.85 (2)O16—O15B—K1113.07 (19)
O12xii—K1—O1664.737 (19)O16—O15B—K3150.8 (2)
O15B—K1—O1617.38 (6)K1—O15B—K395.80 (9)
O5xiii—K1—O16144.349 (19)O16—O15B—H1593.4 (7)
O3ix—K1—O16128.122 (18)K1—O15B—H15100.0 (8)
O7xiii—K1—O16102.922 (18)K3—O15B—H1585.5 (7)
C3xiii—K1—O16122.33 (2)K1—O15B—H16132.3 (6)
O4ix—K1—C2ix18.236 (18)K3—O15B—H16115.1 (7)
O7x—K1—C2ix119.224 (19)H15—O15B—H16117.0 (10)
O8xi—K1—C2ix95.74 (2)O15B—O16—K149.55 (16)
O15—K1—C2ix136.28 (2)O15—O16—K150.89 (4)
O12xii—K1—C2ix61.87 (2)O15B—O16—H1684.7 (10)
O15B—K1—C2ix134.92 (7)O15—O16—H1696.0 (10)
O5xiii—K1—C2ix95.424 (19)K1—O16—H16114.5 (10)
Symmetry codes: (i) x, y+1/2, z1/2; (ii) x+1, y, z+1; (iii) x+1, y+1/2, z1/2; (iv) x+1, y1/2, z+3/2; (v) x+1, y+1/2, z+1/2; (vi) x+1, y, z; (vii) x+1, y1/2, z+1/2; (viii) x, y, z1; (ix) x1, y+1/2, z1/2; (x) x1, y+1/2, z+1/2; (xi) x, y+1/2, z+1/2; (xii) x1, y, z; (xiii) x+1, y+1/2, z+1/2; (xiv) x, y, z+1; (xv) x+1, y+1/2, z+3/2; (xvi) x, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O13—H13···O160.963 (17)1.992 (17)2.9139 (12)159.5 (14)
O14—H14···O111.183 (17)1.527 (17)2.6996 (11)169.9 (12)
O15—H15···O140.842 (14)1.832 (15)2.6633 (11)169.4 (14)
O16—H16···O10x0.881 (18)1.858 (18)2.7297 (12)169.6 (14)
Symmetry code: (x) x1, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaK3[Al(C2O4)3]·1.75H2O2·0.25H2O
Mr472.37
Crystal system, space groupMonoclinic, P21/c
Temperature (K)150
a, b, c (Å)7.6194 (2), 19.3531 (6), 10.3668 (4)
β (°) 107.905 (1)
V3)1454.64 (8)
Z4
Radiation typeMo Kα
µ (mm1)1.09
Crystal size (mm)0.15 × 0.15 × 0.07
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionMulti-scan
(SORTAV; Blessing, 1995)
Tmin, Tmax0.849, 0.926
No. of measured, independent and
observed [I > 2σ(I)] reflections
7571, 3256, 2390
Rint0.041
(sin θ/λ)max1)0.647
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.088, 1.09
No. of reflections3256
No. of parameters256
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.41, 0.49

Computer programs: COLLECT (Nonius, 1998), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
Al1—O11.9274 (7)Al1—O61.8801 (5)
Al1—O21.8780 (5)Al1—O91.8849 (7)
Al1—O51.9022 (7)Al1—O101.9084 (7)
O2—Al1—O6170.07 (3)O9—Al1—O1083.69 (3)
O6—Al1—O584.44 (3)O2—Al1—O184.00 (3)
O9—Al1—O5170.55 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O13—H13···O160.963 (17)1.992 (17)2.9139 (12)159.5 (14)
O14—H14···O111.183 (17)1.527 (17)2.6996 (11)169.9 (12)
O15—H15···O140.842 (14)1.832 (15)2.6633 (11)169.4 (14)
O16—H16···O10i0.881 (18)1.858 (18)2.7297 (12)169.6 (14)
Symmetry code: (i) x1, y+1/2, z+1/2.
Comparison of the hydrogen peroxide bond lengths (Å) and angles (°) in the alkali metal oxalates, M2C2O4·H2O2, with those in the title compound. The hydrogen peroxide is bisected by an inversion point in the Li an Na salts and by a twofold rotation axis in the K, Rb and NH4 compounds. top
Cation(s)O—HO—OO—O—HH—O—O—H
Li+a0.83 (10)1.439 (15)104 (5)180
Na+b0.89 (5)1.466 (9)97 (3)180
Na+c*1.0094 (9)1.4670 (10)99.95 (8)180
K+d*1.0117 (5)1.4578 (6)100.69 (3)101.6 (4)
Rb+e*0.99 (1)1.509 (7)100.8 (5)-100 (1)
Rb+f*0.972 (7)1.487 (4)101.8 (4)104.5 (5)
NH4+g0.83 (2)1.452 (2)99 (1)121 (3)
Al3+/K+h0.96 (2), 1.18 (2)i1.4415 (9)91 (1),101 (1)119 (1)
Al3+/K+h (disorder)0.84 (1), 0.88 (2)1.4675 (12)96 (1), 86 (1)j124 (1)
Notes: (a) Pedersen (1969); (b) Pedersen & Pedersen (1964); (c) Pedersen & Kvick (1989); (d) Pedersen & Kvick (1990); (e) Adams et al. (1980a); (f) Adams et al. (1980b); (g) Pedersen, (1972); (h) this work; (i) the H atom had a fixed vibrational amplitude; (j) Probably influenced by the close proximity of partial water O15B; (*) Neutrons used.
 

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