Mg-rich wolfeite, (Fe^II,Mg)₂(PO₄)(OH): structure refinement and Raman spectroscopic data

Mg-rich wolfeite [diiron(II) hydro­xide phosphate], (Fe^II,Mg)₂(PO₄)(OH), from the Big Fish River area, Yukon Territory, Canada, is isotypic with its Mn^II-dominant analogue triploidite. The framework structure contains edge- and corner-sharing, distorted MO₄(OH) and MO₄(OH)₂ (M = Fe^II or Fe^II,Mg) polyhedra linked by fairly regular PO₄ tetrahedra. All atoms are on general positions. Four of the eight independent Fe sites contain between 9 and 25% Mg substituting for Fe. Two of these four sites show distorted trigonal-bipyramidal coordination, whereas the remaining two sites show distorted octahedral coordination. The average (Fe^II,Mg)—O bond length decreases with increasing Mg content. Average P—O distances range between 1.538 and 1.543 Å. The hydrogen bonds are all strongly bent and weak, with O...O distances > 2.73 Å, an observation confirmed by single-crystal Raman spectroscopic data which show five bands due to O—H stretching vibrations between 3478 and 3557 cm⁻¹.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](P-O) = 0.001 Å
• R factor = 0.022
• wR factor = 0.065
• Data-to-parameter ratio = 17.3

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT420_ALERT_2_B D-H Without Acceptor       O18    -   H2                ?
PLAT420_ALERT_2_B D-H Without Acceptor       O20    -   H4                ?

Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ..          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ..........       0.06 Ratio
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing).          ?
PLAT301_ALERT_3_C Main Residue  Disorder .......................      11.00 Perc.

   0 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Wolfeite, (Fe^II,Mn^II)₂(PO₄)(OH) (Mandarino, 1999), is a rare iron phosphate mineral which occurs as a metasomatic alteration phase in pegmatites, and also rarely in hydrothermal veins, phosphatic nodules in shales, and amphibolite-facies metamorphosed iron formations (Anthony et al., 2000; Masau et al., 2000; Stalder & Rozendaal, 2002, and references therein). Wolfeite is a member of a large family of compounds with the general formula M^II₂(XO₄)Z, where M = Fe, Mn, Mg, ···; X = P, As, ···; and Z = F, OH, O, Cl etc. According to the crystal-chemical classification of Strunz & Nickel (2001), wolfeite belongs to the triploidite group of minerals, whose other members are triploidite [(Mn^II,Fe^II)₂(PO₄)(OH); Waldrop, 1970], wagnerite [Mg₂(PO₄)F; Coda et al., 1967], stanekite [(Mn,Fe^II,Mg)Fe^III(PO₄)O; Keller et al., 1997] and sarkinite [Mn^II₂(AsO₄)(OH); Dal Negro et al., 1974]. Various synthetic compounds are also isotypic with triploidite [e.g. β-Mg₂(PO₄)(OH) (Raade & Rømming, 1986) and Zn₂(PO₄)(F,OH) (Taasti et al., 2002)]. All triploidite-type compounds crystallize with space group P2₁/a and have similar unit-cell parameters. The common structure type is closely related to that of triplite, (Mn^II,Fe^II)₂(PO₄)F (space group I2/a; Waldrop, 1969; alternative setting in C2/c for synthetic triplite by Rea & Kostiner, 1972).

The crystal structure of wolfeite has not been studied yet, although X-ray powder diffraction data and unit-cell parameters have been provided by Frondel (1949), Antenucci et al. (1989), and Masau et al. (2000). The present article reports the results of a single-crystal structure refinement and of single-crystal Raman spectroscopic studies of a Mg-rich wolfeite sample from the Big Fish River area, Yukon Territory, Canada (Robertson, 1982; Robinson et al., 1992). The article supplements an earlier study of the crystal structure and IR spectra of a Mg-rich satterlyite, (Fe,Mg)₁₂(PO₃OH)(PO₄)₅(OH,O)₆, from the same locality (Kolitsch et al., 2002).

At the Big Fish River area, the mineral is a common constituent of epigenetic phosphatic nodules and forms divergent, columnar aggregates of crude, glassy, light brown to clove-brown crystals up to several centimetres in length. Crystallization occurred at temperatures of about 453 to 473 K according to fluid inclusion studies (Robinson et al., 1992). Previous electron microprobe analyses of wolfeite from this locality yielded an average formula close to (Fe_1.65Mg_0.20Mn_0.15)₂(PO₄) (OH_0.95F_0.05) (Robinson et al., 1992). The presently studied sample is from the collection of the author, and its appearance closely fits the published descriptions (Robinson et al., 1992). The chemical composition of the sample has been characterized by semiquantitative SEM–EDS data which revealed major Fe and P, minor Mg and only very small amounts of Mn (ratio Fe:Mn ca 13:1), and insignificant compositional inhomogeneities. The EDS-based chemical composition is in good agreement with the formula subsequently derived from the structure refinement.

Mg-rich wolfeite is confirmed to be isotypic with triploidite (Mn^II,Fe^II)₂(PO₄)(OH); space group P2₁/a; Waldrop, (1970). It has a complex framework structure based on edge- and corner-sharing, distorted MO₄(OH) and MO₄(OH)₂ polyhedra (M = Fe^II,Mg), corner-linked to PO₄ tetrahedra (Figs. 1,2). For detailed descriptions of the connectivity, the reader is referred to the previous reports on the isotypic members of the triploidite group (see above). The present paper restricts itself to the Mg distribution and the hydrogen bonding in Mg-rich wolfeite. To facilitate comparisons, the atomic coordinates and the labeling used by Waldrop (1970) for triploidite were adopted for Mg-rich wolfeite, except for the H atoms which had not been located during the earlier study of triploidite. The crystal structure of Mg-rich wolfeite contains eight non-equivalent Fe sites, four P sites, twenty O sites, and four H sites (belonging to OH groups). All atoms are on general positions. The Fe sites Fe1, Fe4, Fe6, and Fe8 are all five-coordinated (with distorted trigonal-bipyramidal geometry), whereas the remaining Fe sites show distorted octahedral coordinations (with OH groups in cis configuration). Site occupany refinements demonstrated that the considerable Mg present in the structure strictly prefers the following four out of the eight Fe sites: Fe5, Fe6, Fe7, and Fe8. The refined Fe:Mg ratios on these sites range between approximately 0.76:0.24 (Fe6) and 0.90:0.10 (Fe5) (Table 1). Thus, the Mg substitutes for Fe on two five-coordinated and two six-coordinated sites, and therefore exhibits no preference for a certain coordination environment. A view of the polyhedral arrangement along [001] (Fig. 1) shows that the Mg-bearing polyhedra Fe7O₄(OH)₂ and Fe8O₄(OH) (shown in blue) are connected into indulating chains running parallel to [100] by alternately sharing corners and edges. The other two Mg-bearing polyhedra, Fe5O₄(OH)₂ and Fe6O₄(OH), are connected via a shared corner on a level below the undulating chain (Fig. 2); the Fe5—Fe6 vector also runs approximately parallel to [100]. The two polyhedra most rich in Mg, Fe6O₄(OH) and Fe7O₄(OH)₂, are not connected to each other. Seemingly, the structure thereby avoids misfit-induced strain in the structure.

Average Fe—O distances for the five-coordinated sites are 2.103 (Fe1), 2.109 (Fe4), 2.062 (Fe6), and 2.077 Å (Fe8). The six-coordinated sites show average Fe—O distances of 2.188 (Fe2), 2.180 (Fe3), 2.152 (Fe5), and 2.139 Å (Fe7). All Mg-containing sites have shorter average distances than their Mg-free counterparts. This is consistent with the fact that the commonly observed average ^[6]Fe^II—O distance, 2.138 Å, is distinctly larger than the corresponding value for Mg, 2.085 Å (Baur, 1981). Because Fe is generally considered an actively distorting cation which prefers distorted octahedra if present, it also comes as no surprise that the six-coordinated Fe sites containing no Mg (Fe2 and Fe3) exhibit a higher bond-length distortion than both their Mg-containing counterparts (Fe5 and Fe7). Hydrothermal syntheses would be necessary to determine how much Mg can substitute for Fe^II in synthetic wolfeite under specified p-T conditions. The unit-cell volume of the presently studied Mg-rich wolfeite, 1493.9 (5) ų, is distinctly smaller than previously reported cell volumes for wolfeites very poor in Mg [1521.74 ų (Antenucci et al., 1989) and 1523.0 (5) ų (Masau et al., 2000)]. The cell edge most strongly affected by the Mg incorporation is the a edge whose length decreases by nearly 3% by comparison to the literature data (Antenucci et al., 1989; Masau et al., 2000). This is convincingly explained by the arrangement along [100] of the Mg-containing polyhedra (cf. Figs. 1 and 2).

The four non-equivalent PO₄ tetrahedra all show fairly regular geometries (Table 1). Average P—O distances are 1.543 (P1), 1.538 (P2), 1.540 (P3), and 1.542 Å (P4). The hydrogen bonding scheme in Mg-rich wolfeite is somewhat unusual. The hydrogen bonds are all weak, with O···O distances between 2.73 and c. 3.1 Å. Each OH group is bonded to three cations (Fe or Mg), i.e. its bond-valence requirements are basically satisfied, and formally one might not expect the H atoms to form any hydrogen bond at all. However, the framework topology allows a larger number of weak hydrogen bonds, and in fact three of the four OH groups are involved in bifurcated, possibly even trifurcated hydrogen bonds which are strongly bent (Table 2). Only the bond donated by the O20—H4 group has a single acceptor atom, O7. None of the four (freely refined) H sites shows any unusual displacement parameters, and O—H distances are within a very narrow range between 0.78 and 0.80 Å (Table 2). In isotypic synthetic β-Mg₂(PO₄)(OH) (Raade & Rømming, 1986), the hydrogen bonds are also weak and strongly bent (O—H—O angles range between 116 and 144°, similar to the situation in Mg-rich wolfeite). The hydrogen bonding scheme in triploidite is unknown because positions of H atoms could not be located during the structure determination by Waldorf (1970).

A further, spectroscopic characterization of the hydrogen bonds was obtained by laser Raman spectroscopy. Spectra of a single- crystal fragment were recorded in the range from 4000 to 100 cm⁻¹ with a Renishaw M1000 MicroRaman Imaging System using a laser wavelength of 633 nm and excitation through a Leica DMLM optical microscope (spectral resolution ±2 cm⁻¹, minimum lateral resolution ca 2 µm, unpolarized laser light, 180° backscatter mode, random sample orientation). Two representative spectra, given in Fig. 3, were recorded from different, but unspecified cleavage planes. The spectra show four sharp bands (and one shoulder) due to O—H stretching vibrations at 3557 (shoulder), 3544, 3518, 3497 (only seen in one spectrum due to orientation effects), and 3478 cm⁻¹. Using the correlation of O—H stretching frequencies and O···O hydrogen bond lengths in minerals by Libowitzky (1999), the observed O—H stretching frequencies in Mg-rich wolfeite would correspond to approximate O···O bond lengths ranging between 2.8 and 3.0 Å, in good agreement with the results of the structure refinement. In the powder infrared spectrum of isotypic synthetic β-Mg₂(PO₄)(OH), only two sharp bands at 3595 and 3580 cm⁻¹ were observed (Raade & Rømming, 1986), thus indicating weaker hydrogen bonding than in Mg-rich wolfeite.

S2. Experimental

Natural sample (see Comment).

S3. Refinement

H atoms were freely refined. The Fe:Mg ratios of the four Mg-containing sites, Fe5, Fe6, Fe7 and Fe8, were freely refined, assuming full occupancy of each site. All atomic displacement ellipsoids were regular.

Computing details

Data collection: COLLECT (Nonius, 2002); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Shape Software, 1999).

Figures

	Fig. 1. View along [001] of the complex framework structure of Mg-rich wolfeite from the Big Fish River area, Yukon Territory, Canada. Edge- and corner-sharing, distorted MO4(OH) (M = Fe^II,Mg) trigonal bipyramids (striped) and MO4(OH)2 octahedra (unmarked) are corner-linked to PO4 tetrahedra (yellow, marked with crosses). All Mg-containing polyhedra are shown in blue. The unit cell is outlined.
	Fig. 2. The complex crystal structure of Mg-rich wolfeite projected along [010]. For key see Fig. 1.
	Fig. 3. Two single-crystal laser-Raman spectra of Mg-rich wolfeite from the Big Fish River area, Yukon Territory, Canada, in the OH stretching region. See text for details and band positions.

diiron(II) hydroxide phosphate

Crystal data

Fe1.84Mg0.16(PO4)(OH)	F(000) = 1692
Mr = 218.63	Dx = 3.888 Mg m^−3
Monoclinic, P21/a	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yab	Cell parameters from 5647 reflections
a = 12.274 (2) Å	θ = 2.0–32.6°
b = 13.169 (3) Å	µ = 7.52 mm^−1
c = 9.754 (2) Å	T = 293 K
β = 108.64 (3)°	Fragment, yellow
V = 1493.9 (6) Å^3	0.18 × 0.18 × 0.13 mm
Z = 16

Data collection

Nonius KappaCCD diffractometer	5432 independent reflections
Radiation source: fine-focus sealed tube	4267 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.014
ψ and ω scans	θmax = 32.6°, θmin = 2.2°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski & Minor, 1997)	h = −18→18
Tmin = 0.294, Tmax = 0.376	k = −19→19
10662 measured reflections	l = −14→14

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	All H-atom parameters refined
wR(F^2) = 0.065	w = 1/[σ^2(Fo^2) + (0.034P)^2 + 0.36P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max = 0.003
5432 reflections	Δρmax = 0.55 e Å^−3
314 parameters	Δρmin = −0.67 e Å^−3
4 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00357 (15)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Fe1	0.18625 (2)	0.479059 (19)	0.19287 (3)	0.00980 (6)
Fe2	0.19712 (2)	0.996441 (18)	0.21294 (3)	0.01034 (6)
Fe3	0.30503 (2)	0.752291 (19)	0.29253 (3)	0.00998 (6)
Fe4	0.31941 (2)	0.269768 (19)	0.30463 (3)	0.00970 (6)
Fe5	0.09673 (2)	0.070820 (19)	0.46928 (3)	0.00829 (8)	0.9027 (17)
Mg5	0.09673 (2)	0.070820 (19)	0.46928 (3)	0.00829 (8)	0.0973 (18)
Fe6	0.08530 (2)	0.57376 (2)	0.45154 (3)	0.00886 (8)	0.7596 (17)
Mg6	0.08530 (2)	0.57376 (2)	0.45154 (3)	0.00886 (8)	0.2404 (17)
Fe7	0.39431 (2)	0.67498 (2)	0.03060 (3)	0.00814 (8)	0.8138 (18)
Mg7	0.39431 (2)	0.67498 (2)	0.03060 (3)	0.00814 (8)	0.1862 (18)
Fe8	0.42084 (2)	0.178485 (19)	0.03902 (3)	0.00827 (8)	0.8806 (18)
Mg8	0.42084 (2)	0.178485 (19)	0.03902 (3)	0.00827 (8)	0.1194 (18)
P1	0.07895 (3)	0.82096 (3)	0.38003 (4)	0.00565 (8)
P2	0.07554 (3)	0.32667 (3)	0.38279 (4)	0.00547 (8)
P3	0.42320 (3)	0.42224 (3)	0.11305 (4)	0.00546 (8)
P4	0.42369 (3)	0.92805 (3)	0.11974 (4)	0.00582 (8)
O1	0.04746 (10)	0.41493 (9)	0.46857 (12)	0.0105 (2)
O2	0.06154 (10)	0.90756 (9)	0.47864 (12)	0.0095 (2)
O3	0.43160 (10)	0.84078 (9)	0.01678 (12)	0.0097 (2)
O4	0.45635 (10)	0.33768 (8)	0.02509 (12)	0.0094 (2)
O5	0.02635 (10)	0.04737 (9)	0.24273 (12)	0.0107 (2)
O6	0.04291 (10)	0.55442 (9)	0.23235 (12)	0.0110 (2)
O7	0.46682 (9)	0.70250 (9)	0.25868 (12)	0.0098 (2)
O8	0.46690 (10)	0.20262 (9)	0.25864 (12)	0.0113 (2)
O9	0.17393 (9)	0.84775 (9)	0.31437 (12)	0.0094 (2)
O10	0.17245 (9)	0.36054 (9)	0.32331 (12)	0.0095 (2)
O11	0.32337 (9)	0.38398 (8)	0.16515 (12)	0.0092 (2)
O12	0.33522 (9)	0.90386 (9)	0.19588 (12)	0.0094 (2)
O13	0.11856 (10)	0.72748 (9)	0.48034 (12)	0.0094 (2)
O14	0.11776 (10)	0.23476 (9)	0.48261 (12)	0.0093 (2)
O15	0.38512 (10)	0.02300 (9)	0.02283 (12)	0.0095 (2)
O16	0.37799 (10)	0.51398 (9)	0.01303 (13)	0.0096 (2)
O17	0.25351 (10)	0.03131 (9)	0.43671 (12)	0.0102 (2)
O18	0.20613 (10)	0.16268 (9)	0.19383 (13)	0.0113 (2)
O19	0.24283 (9)	0.71893 (9)	0.06783 (12)	0.0095 (2)
O20	0.30215 (10)	0.58247 (9)	0.30905 (12)	0.0112 (2)
H1	0.264 (2)	−0.026 (2)	0.459 (3)	0.044 (8)*
H2	0.155 (2)	0.172 (2)	0.224 (3)	0.061 (10)*
H3	0.236 (2)	0.776 (2)	0.044 (3)	0.037 (7)*
H4	0.353 (2)	0.5759 (18)	0.276 (3)	0.038 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.00932 (11)	0.00976 (12)	0.01031 (12)	0.00155 (8)	0.00313 (9)	0.00193 (8)
Fe2	0.01194 (12)	0.01006 (12)	0.00902 (11)	0.00231 (8)	0.00332 (9)	−0.00030 (8)
Fe3	0.01030 (11)	0.01092 (12)	0.00870 (12)	0.00261 (8)	0.00302 (9)	−0.00027 (8)
Fe4	0.01000 (11)	0.00933 (12)	0.00988 (12)	0.00135 (8)	0.00332 (9)	0.00222 (8)
Fe5	0.00825 (12)	0.00839 (13)	0.00808 (13)	0.00027 (8)	0.00240 (9)	−0.00064 (8)
Mg5	0.00825 (12)	0.00839 (13)	0.00808 (13)	0.00027 (8)	0.00240 (9)	−0.00064 (8)
Fe6	0.00867 (13)	0.00781 (14)	0.01029 (14)	−0.00013 (9)	0.00328 (10)	−0.00088 (10)
Mg6	0.00867 (13)	0.00781 (14)	0.01029 (14)	−0.00013 (9)	0.00328 (10)	−0.00088 (10)
Fe7	0.00801 (13)	0.00822 (13)	0.00862 (14)	0.00041 (9)	0.00326 (10)	−0.00066 (9)
Mg7	0.00801 (13)	0.00822 (13)	0.00862 (14)	0.00041 (9)	0.00326 (10)	−0.00066 (9)
Fe8	0.00724 (12)	0.00756 (13)	0.00944 (13)	−0.00005 (8)	0.00186 (9)	−0.00043 (9)
Mg8	0.00724 (12)	0.00756 (13)	0.00944 (13)	−0.00005 (8)	0.00186 (9)	−0.00043 (9)
P1	0.00545 (17)	0.00578 (18)	0.00571 (17)	−0.00009 (13)	0.00176 (14)	0.00009 (14)
P2	0.00580 (17)	0.00500 (18)	0.00588 (17)	−0.00005 (13)	0.00223 (14)	0.00013 (13)
P3	0.00535 (16)	0.00528 (18)	0.00568 (17)	0.00005 (13)	0.00167 (14)	0.00015 (14)
P4	0.00575 (17)	0.00600 (19)	0.00584 (17)	−0.00029 (13)	0.00204 (14)	0.00004 (14)
O1	0.0128 (5)	0.0079 (5)	0.0132 (6)	−0.0012 (4)	0.0076 (5)	−0.0028 (4)
O2	0.0112 (5)	0.0089 (5)	0.0097 (5)	−0.0009 (4)	0.0049 (4)	−0.0034 (4)
O3	0.0107 (5)	0.0096 (5)	0.0103 (5)	−0.0011 (4)	0.0054 (4)	−0.0037 (4)
O4	0.0102 (5)	0.0080 (5)	0.0111 (5)	−0.0011 (4)	0.0049 (4)	−0.0023 (4)
O5	0.0082 (5)	0.0139 (6)	0.0087 (5)	0.0021 (4)	0.0008 (4)	0.0012 (4)
O6	0.0081 (5)	0.0158 (6)	0.0076 (5)	0.0037 (4)	0.0005 (4)	−0.0011 (4)
O7	0.0073 (5)	0.0130 (6)	0.0082 (5)	0.0017 (4)	0.0012 (4)	0.0003 (4)
O8	0.0101 (5)	0.0147 (6)	0.0073 (5)	0.0035 (4)	0.0001 (4)	−0.0003 (4)
O9	0.0081 (5)	0.0098 (5)	0.0117 (5)	0.0004 (4)	0.0053 (4)	0.0012 (4)
O10	0.0089 (5)	0.0097 (5)	0.0124 (5)	0.0012 (4)	0.0068 (4)	0.0026 (4)
O11	0.0077 (5)	0.0094 (5)	0.0117 (5)	0.0011 (4)	0.0051 (4)	0.0024 (4)
O12	0.0100 (5)	0.0089 (5)	0.0116 (5)	0.0010 (4)	0.0067 (4)	0.0012 (4)
O13	0.0107 (5)	0.0076 (5)	0.0091 (5)	0.0002 (4)	0.0021 (4)	0.0022 (4)
O14	0.0105 (5)	0.0074 (5)	0.0094 (5)	0.0010 (4)	0.0023 (4)	0.0028 (4)
O15	0.0110 (5)	0.0081 (5)	0.0093 (5)	0.0007 (4)	0.0031 (4)	0.0020 (4)
O16	0.0101 (5)	0.0076 (5)	0.0107 (5)	0.0009 (4)	0.0028 (4)	0.0033 (4)
O17	0.0087 (5)	0.0089 (5)	0.0117 (6)	0.0007 (4)	0.0014 (4)	0.0003 (4)
O18	0.0130 (6)	0.0098 (5)	0.0110 (5)	−0.0023 (4)	0.0038 (5)	−0.0025 (4)
O19	0.0076 (5)	0.0089 (5)	0.0109 (5)	0.0000 (4)	0.0013 (4)	−0.0002 (4)
O20	0.0129 (5)	0.0110 (6)	0.0106 (5)	−0.0014 (4)	0.0053 (5)	−0.0014 (4)

Geometric parameters (Å, º)

Fe1—O20	2.0326 (13)	Fe6—O1	2.1604 (13)
Fe1—O10	2.0546 (12)	Fe7—O4^vii	2.0782 (12)
Fe1—O15^i	2.0858 (13)	Fe7—O19	2.0869 (12)
Fe1—O6	2.1591 (12)	Fe7—O16	2.1314 (13)
Fe1—O11	2.1827 (11)	Fe7—O7	2.1464 (13)
Fe2—O16^i	2.1124 (13)	Fe7—O18^i	2.1478 (14)
Fe2—O17^ii	2.1185 (13)	Fe7—O3	2.2437 (13)
Fe2—O12	2.1372 (11)	Fe8—O19^viii	2.0167 (13)
Fe2—O18^ii	2.2029 (13)	Fe8—O8	2.0580 (12)
Fe2—O9	2.2526 (12)	Fe8—O3^vii	2.0666 (11)
Fe2—O5^ii	2.3059 (12)	Fe8—O15	2.0893 (13)
Fe3—O14^iii	2.1054 (13)	Fe8—O4	2.1543 (12)
Fe3—O9	2.1058 (11)	P1—O7^ix	1.5327 (13)
Fe3—O19	2.1237 (13)	P1—O9	1.5397 (12)
Fe3—O7	2.2139 (12)	P1—O2	1.5501 (12)
Fe3—O20	2.2433 (13)	P1—O13	1.5508 (12)
Fe3—O12	2.2877 (12)	P2—O1	1.5343 (12)
Fe4—O18	2.0320 (13)	P2—O14	1.5359 (12)
Fe4—O11	2.0391 (12)	P2—O8^x	1.5366 (13)
Fe4—O13^iv	2.0660 (13)	P2—O10	1.5464 (11)
Fe4—O8	2.1862 (12)	P3—O5^xi	1.5295 (13)
Fe4—O10	2.2195 (11)	P3—O4	1.5379 (12)
Fe5—O17	2.1131 (12)	P3—O16	1.5405 (12)
Fe5—O5	2.1223 (13)	P3—O11	1.5529 (11)
Fe5—O20^iv	2.1269 (14)	P4—O12	1.5322 (11)
Fe5—O14	2.1733 (13)	P4—O6^xii	1.5407 (13)
Fe5—O2^v	2.1781 (12)	P4—O15^ii	1.5476 (12)
Fe5—O2^vi	2.2006 (13)	P4—O3	1.5496 (12)
Fe6—O17^iii	2.0090 (13)	O17—H1	0.79 (3)
Fe6—O1^v	2.0240 (12)	O18—H2	0.79 (3)
Fe6—O6	2.0482 (12)	O19—H3	0.78 (3)
Fe6—O13	2.0665 (13)	O20—H4	0.80 (2)
O20—Fe1—O10	110.19 (5)	O17^iii—Fe6—O13	94.67 (5)
O20—Fe1—O15^i	111.71 (5)	O1^v—Fe6—O13	91.37 (5)
O10—Fe1—O15^i	138.09 (5)	O6—Fe6—O13	103.70 (5)
O20—Fe1—O6	93.30 (5)	O17^iii—Fe6—O1	83.54 (5)
O10—Fe1—O6	90.32 (5)	O1^v—Fe6—O1	79.77 (5)
O15^i—Fe1—O6	87.07 (5)	O6—Fe6—O1	88.33 (5)
O20—Fe1—O11	91.34 (5)	O13—Fe6—O1	167.41 (4)
O10—Fe1—O11	81.98 (5)	O4^vii—Fe7—O19	167.68 (5)
O15^i—Fe1—O11	97.25 (5)	O4^vii—Fe7—O16	88.12 (4)
O6—Fe1—O11	172.01 (4)	O19—Fe7—O16	102.93 (4)
O16^i—Fe2—O17^ii	160.25 (5)	O4^vii—Fe7—O7	100.16 (5)
O16^i—Fe2—O12	94.22 (5)	O19—Fe7—O7	82.54 (5)
O17^ii—Fe2—O12	101.40 (5)	O16—Fe7—O7	104.39 (5)
O16^i—Fe2—O18^ii	79.63 (4)	O4^vii—Fe7—O18^i	89.68 (5)
O17^ii—Fe2—O18^ii	82.13 (5)	O19—Fe7—O18^i	86.86 (5)
O12—Fe2—O18^ii	119.85 (5)	O16—Fe7—O18^i	80.47 (4)
O16^i—Fe2—O9	118.63 (4)	O7—Fe7—O18^i	169.08 (4)
O17^ii—Fe2—O9	77.37 (5)	O4^vii—Fe7—O3	81.29 (4)
O12—Fe2—O9	75.70 (4)	O19—Fe7—O3	87.18 (4)
O18^ii—Fe2—O9	156.61 (4)	O16—Fe7—O3	168.21 (4)
O16^i—Fe2—O5^ii	89.34 (5)	O7—Fe7—O3	82.70 (4)
O17^ii—Fe2—O5^ii	79.51 (5)	O18^i—Fe7—O3	94.23 (4)
O12—Fe2—O5^ii	162.04 (4)	O19^viii—Fe8—O8	113.20 (5)
O18^ii—Fe2—O5^ii	78.10 (4)	O19^viii—Fe8—O3^vii	135.10 (5)
O9—Fe2—O5^ii	87.13 (4)	O8—Fe8—O3^vii	108.71 (5)
O14^iii—Fe3—O9	93.68 (5)	O19^viii—Fe8—O15	93.98 (5)
O14^iii—Fe3—O19	161.09 (5)	O8—Fe8—O15	102.19 (5)
O9—Fe3—O19	101.17 (5)	O3^vii—Fe8—O15	92.30 (5)
O14^iii—Fe3—O7	89.79 (5)	O19^viii—Fe8—O4	84.18 (5)
O9—Fe3—O7	160.52 (5)	O8—Fe8—O4	85.50 (5)
O19—Fe3—O7	80.13 (5)	O3^vii—Fe8—O4	83.73 (4)
O14^iii—Fe3—O20	80.10 (4)	O15—Fe8—O4	172.17 (4)
O9—Fe3—O20	123.90 (5)	O7^ix—P1—O9	109.72 (6)
O19—Fe3—O20	81.90 (4)	O7^ix—P1—O2	111.08 (7)
O7—Fe3—O20	75.58 (4)	O9—P1—O2	111.24 (7)
O14^iii—Fe3—O12	116.53 (4)	O7^ix—P1—O13	110.50 (7)
O9—Fe3—O12	75.55 (4)	O9—P1—O13	108.53 (6)
O19—Fe3—O12	78.89 (4)	O2—P1—O13	105.67 (7)
O7—Fe3—O12	85.75 (4)	O1—P2—O14	109.90 (7)
O20—Fe3—O12	155.20 (4)	O1—P2—O8^x	109.29 (7)
O18—Fe4—O11	108.38 (5)	O14—P2—O8^x	109.50 (7)
O18—Fe4—O13^iv	108.68 (5)	O1—P2—O10	108.65 (7)
O11—Fe4—O13^iv	142.80 (5)	O14—P2—O10	108.72 (6)
O18—Fe4—O8	94.64 (5)	O8^x—P2—O10	110.77 (7)
O11—Fe4—O8	87.91 (5)	O5^xi—P3—O4	110.74 (7)
O13^iv—Fe4—O8	92.21 (5)	O5^xi—P3—O16	110.73 (7)
O18—Fe4—O10	88.94 (5)	O4—P3—O16	108.70 (7)
O11—Fe4—O10	81.42 (5)	O5^xi—P3—O11	110.20 (6)
O13^iv—Fe4—O10	96.16 (5)	O4—P3—O11	108.95 (7)
O8—Fe4—O10	169.33 (4)	O16—P3—O11	107.43 (6)
O17—Fe5—O5	83.96 (5)	O12—P4—O6^xii	110.15 (6)
O17—Fe5—O20^iv	84.67 (5)	O12—P4—O15^ii	109.77 (6)
O5—Fe5—O20^iv	168.53 (4)	O6^xii—P4—O15^ii	110.48 (7)
O17—Fe5—O14	99.04 (4)	O12—P4—O3	111.15 (7)
O5—Fe5—O14	102.00 (5)	O6^xii—P4—O3	109.34 (7)
O20^iv—Fe5—O14	81.25 (4)	O15^ii—P4—O3	105.88 (7)
O17—Fe5—O2^v	171.98 (5)	Fe6^iv—O17—H1	93.8 (18)
O5—Fe5—O2^v	99.51 (5)	Fe5—O17—H1	106.0 (19)
O20^iv—Fe5—O2^v	91.58 (5)	Fe2^vi—O17—H1	92.9 (19)
O14—Fe5—O2^v	87.36 (4)	Fe4—O18—H2	101 (2)
O17—Fe5—O2^vi	88.05 (4)	Fe7^viii—O18—H2	96 (2)
O5—Fe5—O2^vi	83.17 (4)	Fe2^vi—O18—H2	94 (2)
O20^iv—Fe5—O2^vi	94.98 (5)	Fe8^i—O19—H3	96.3 (18)
O14—Fe5—O2^vi	171.58 (4)	Fe7—O19—H3	103.0 (19)
O2^v—Fe5—O2^vi	85.21 (4)	Fe3—O19—H3	94.5 (19)
O17^iii—Fe6—O1^v	125.87 (5)	Fe1—O20—H4	101.9 (18)
O17^iii—Fe6—O6	114.16 (5)	Fe5^iii—O20—H4	96.9 (18)
O1^v—Fe6—O6	116.35 (5)	Fe3—O20—H4	92.7 (18)

Symmetry codes: (i) −x+1/2, y+1/2, −z; (ii) x, y+1, z; (iii) −x+1/2, y+1/2, −z+1; (iv) −x+1/2, y−1/2, −z+1; (v) −x, −y+1, −z+1; (vi) x, y−1, z; (vii) −x+1, −y+1, −z; (viii) −x+1/2, y−1/2, −z; (ix) x−1/2, −y+3/2, z; (x) x−1/2, −y+1/2, z; (xi) x+1/2, −y+1/2, z; (xii) x+1/2, −y+3/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O17—H1···O9^vi	0.79 (3)	2.23 (3)	2.7343 (17)	122 (2)
O17—H1···O1^iv	0.79 (3)	2.32 (3)	2.7798 (17)	118 (2)
O17—H1···O10^iv	0.79 (3)	2.50 (3)	3.1627 (18)	142 (2)
O18—H2···O5	0.79 (3)	2.33 (3)	2.8418 (17)	124 (3)
O18—H2···O4^x	0.79 (3)	2.58 (3)	2.9803 (19)	113 (2)
O19—H3···O12	0.78 (3)	2.32 (3)	2.8057 (17)	122 (2)
O19—H3···O4^i	0.78 (3)	2.39 (2)	2.7978 (17)	114 (2)
O19—H3···O11^i	0.78 (3)	2.40 (3)	3.0609 (17)	143 (2)
O20—H4···O7	0.80 (2)	2.21 (2)	2.7313 (17)	123 (2)

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