The iron phosphate K₃Fe₅(PO₄)₆

The crystal structure of tripotassium pentairon hexaphosphate has been determined by single-crystal X-ray diffraction. The structure contains one Fe atom on a center of symmetry, one K, two Fe and two P atoms on twofold axes, and one Fe, two P and one K atom in general positions. The K₃Fe₅(PO₄)₆ structure consists of a complex three-dimensional framework of corner-sharing between iron polyhedra, and corner- and edge-sharing between PO₄ tetrahedra and iron polyhedra (FeO₅ and FeO₆). This linkage between iron and phosphorus forms intersecting channels containing the K atoms.

S1. Comment

Iron phosphates generate considerable interest not only for their magnetic properties, due to the great number of possible different cation arrangements, but also for their potential practical applications, including corrosion inhibition (Meisel et al., 1983), passivation of metal surfaces (Attali et al.,1980) and heterogeneous catalysis (Moffat, 1978). These materials offer a considerable number of complex and versatile network structures due to the ability of iron to be in both the +2 and +3 oxidation states, and to adopt various coordination environments. In the monophosphates, iron(III) coordinates, in most cases, to six O atoms and rarely with five O atoms (Belkhiria et al., 1998; Pintard-Screpel et al., 1978; Andrew-Allen et al., 1988). It is four-coordinated in a few cases, such as in FePO₄ (Ng & Calvo, 1975). Moreover, it can exhibit two different coordination modes in the same structure, such as in K₃Fe₂(PO₄)₃ (Pintard-Screpel et al., 1983) and Cs₇Fe₇(PO₄)₈O₂ (Andrew-Allen et al., 1988), in which iron(III) adopts five- and six-coordination. The potassium iron phosphate K₃Fe₅(PO₄)₆ reported in this paper, falls into the latter category of compounds.

Fig. 1 illustrates the complete crystal structure of K₃Fe₅(PO₄)₆ projected along the [100] direction. There are four crystallographically distinct Fe atoms in this structure. Fe1 is located on a center of symmetry, Fe2 and Fe3 lie on twofold axes and Fe4 is located in a general position. The Fe atoms are both five- and six-coordinated. Atoms P1, P2 and K2 lie on twofold axes, while atoms P3, P4 and K1 are in general positions. The K₃Fe₅(PO₄)₆ structure consists of a three-dimensional complex framework constructed of iron polyhedra connected to each other by corner-linkage or by phosphate tetrahedra via corner- and edge-sharing. The structure can be easily described as the association of two building blocks. The first gathers Fe1, Fe2 and Fe3 octahedra, P1, P2 and P3 tetrahedra and K atoms. It consists of iron–phosphate layers, in the ac plane, with the interlayer space filled with K⁺ cations, as illustrated in the perspective view parallel to the [100] direction shown in Fig. 1. There are two iron–phosphate layers within the repeat distance b; each layer lies on a medium plane perpendicular to the b axis at y = 1/4 and y = 3/4. The layers are formed by corner-sharing FeO₆ octahedra, which are further connected by phosphate tetrahedra through corner- and edge-sharing. The mode of association involved by the iron octahedra and the phosphorus tetrahedra in layers is pointed in Fig. 2. Each Fe1O₆ octahedron shares a first corner with, at once, one Fe2O₆ octahedron and one P1O₄ tetrahedron, a second corner with, at once, one Fe3O₆ octahedron and one P2O₄ tetrahedron, and finally, a third corner with a P3O₄ tetrahedron. The P1O₄ and P2O₄ tetrahedra share one edge, respectively, with Fe2O₆ and Fe3O₆ octahedra, and corners of the common edge with two different Fe1O₆ octahedra. The remaining corners are coordinated to two Fe3O₆ octahedra for P1O₄, and two Fe2O₆ octahedra for P2O₄. P3O₄ coordinates to Fe atoms (Fe1, Fe2 and Fe3) through three O atoms. The distortion observed in the Fe2O₆ and Fe3O₆ octahedra, and in the P1O₄ and P2O₄ tetrahedra is a result of the edge-sharing between these polyhedra, since the existence of the common edge induces a strong repulsion between the positive charges carried by the Fe and P atoms, and consequently atoms Fe2, Fe3, P1 and P2 are forced to shift to off-centred positions of their respective polyhedra and the lengths of the common edges are shorter than the other O···O distances in order to screen efficiently this repulsion effect. It is of interest to remark that atoms O31, O32 and O34 all bond to P and only one Fe, whereas atoms O11, O12, O21 and O22 bond to P and two Fe atoms. Thus, the Fe—O bonds are weaker when the O atom bonds to two Fe atoms, as one would expect. The sharing of edges also affects the geometry, but it may only be possible because the Fe—O bonds are already longer. Fig. 3 shows the atomic displacement ellipsoids in layers.

The structural arrangement adopted by the first building block is similar to that observed in the K₃Fe₃(PO₄)₄·H₂O structure (Lii, 1995), which is made up of layers involving corner-linkage between FeO₆ octahedra, and corner- and edge-sharing between FeO₆ octahedra and PO₄ tetrahedra. The layers are linked by seven- or six-oxygen coordinated K⁺ cations and hydrogen bonding.

The second building block formed by Fe4 and P4O₄ tetrahedra is found in the interlayer space between the first building blocks, which has a result of destroying the layered arrangement. Atom Fe4 is pentacoordinated and shares its corners with one P3O₄ and four different P4O₄ tetrahedra. Fe4O₅ polyhedra are connected to each other and to the other iron octahedra by phosphate tetrahedra via corner-sharing. The average Fe4—O distances is 1.941 Å, a value close to that observed in K₃Fe₂(PO₄)₃ for pentacoordinated iron (1.935 Å; Pintard-Screpel et al., 1983). Each P4O₄ tetrahedron shares its four corners with four different Fe4O₅ polyhedra.

The three-dimensional structural arrangement formed by the P, Fe and O atoms contains interstitial spaces forming intersecting channels in which the K atoms are located. K1 has an environment formed by eight O atoms, with K—O distances ranging from 2.587 (2) to 3.213 (2) Å, while K2 is six-coordinated, with K—O distances between 2.883 (2) and 3.025 (2) Å. The coordination number of each K⁺ cation was determined on the basis of the maximum cation–anion distance; L_max = 3.35 Å for K—O according to Donnay & Allman (1970).

S2. Experimental

Crystals of K₃Fe₅(PO₄)₆ were prepared by the flux method from K₂CO₃, (NH₄)₂HPO₄, MoO₃ and Fe(NO₃)₃·9H₂O. The starting materials (equimolar ratio) were placed in a platinum crucible (in air) and heated at 1073 K for 1 h. The mixture was cooled to 773 K at a rate of 10 K h^-1. Finally, parallelepipedic brown crystals of K₃Fe₅(PO₄)₆ were obtained after washing with boiling water.

Computing details

Data collection: CAD-4 EXPRESS (Enraf Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 1994); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A projection of the structural network of K3Fe5(PO4)6 along the [100] direction.
	Fig. 2. The association mode of iron and phosphorus polyhedra in layers.
	Fig. 3. The connectivity of atoms in layers, showing 50% probability displacement ellipsolids.

(I)

Crystal data

K3Fe5(PO4)6	F(000) = 1876
Mr = 966.37	Dx = 3.006 Mg m^−3 Dm = 3.05 (5) Mg m^−3 Dm measured by pycnometry
Monoclinic, C2/c	Ag Kα radiation, λ = 0.56087 Å
Hall symbol: -C 2yc	Cell parameters from 25 reflections
a = 6.460 (4) Å	θ = 7–12°
b = 30.997 (7) Å	µ = 2.30 mm^−1
c = 10.665 (2) Å	T = 293 K
β = 90.22 (4)°	Parallelepiped, brown
V = 2135.6 (15) Å^3	0.30 × 0.20 × 0.16 mm
Z = 4

Data collection

Enraf-Nonius CAD-4 diffractometer	3354 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.030
Graphite monochromator	θmax = 25.0°, θmin = 2.5°
ω/2θ scans	h = −9→9
Absorption correction: analytical (Katayama, 1986)	k = −46→9
Tmin = 0.630, Tmax = 0.710	l = −16→16
7763 measured reflections	2 standard reflections every 120 min
3823 independent reflections	intensity decay: 2%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.019	w = 1/[σ^2(Fo^2) + (0.0214P)^2 + 4.5065P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.051	(Δ/σ)max = 0.001
S = 1.08	Δρmax = 0.76 e Å^−3
3823 reflections	Δρmin = −0.79 e Å^−3
177 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00198 (13)

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
Fe1	0.2500	0.2500	0.5000	0.00582 (6)
Fe2	0.0000	0.189384 (10)	0.2500	0.00677 (6)
Fe3	0.0000	0.193115 (10)	0.7500	0.00679 (6)
Fe4	0.24698 (3)	0.049909 (7)	0.57712 (2)	0.00737 (5)
P1	0.0000	0.278396 (17)	0.2500	0.00575 (9)
O11	0.18853 (17)	0.30583 (4)	0.22474 (11)	0.00946 (19)
O12	0.03724 (17)	0.24513 (3)	0.35948 (10)	0.00758 (18)
P2	0.0000	0.281775 (17)	0.7500	0.00594 (9)
O21	0.03802 (17)	0.24838 (4)	0.64090 (10)	0.00749 (18)
O22	0.18915 (17)	0.30916 (4)	0.77764 (11)	0.00936 (19)
P3	0.14632 (6)	0.148952 (12)	0.50261 (3)	0.00607 (7)
O31	0.01426 (18)	0.14707 (4)	0.38235 (11)	0.0108 (2)
O32	0.00308 (18)	0.15329 (4)	0.61488 (11)	0.0116 (2)
O33	0.27196 (18)	0.10763 (4)	0.51169 (12)	0.0123 (2)
O34	0.29346 (17)	0.18761 (3)	0.49822 (10)	0.00887 (19)
P4	0.24699 (6)	0.030414 (12)	0.87738 (4)	0.00673 (7)
O41	0.22854 (19)	0.02291 (4)	0.73522 (11)	0.0145 (2)
O42	0.44496 (18)	0.05457 (4)	0.91038 (13)	0.0164 (2)
O43	0.06373 (19)	0.05619 (4)	0.92864 (13)	0.0161 (2)
O44	0.2465 (2)	−0.01530 (4)	0.93308 (12)	0.0180 (2)
K1	0.64766 (6)	0.138114 (15)	0.51135 (4)	0.02211 (9)
K2	0.0000	0.93923 (3)	0.7500	0.0477 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.00612 (12)	0.00613 (12)	0.00521 (11)	−0.00042 (9)	−0.00027 (9)	0.00017 (9)
Fe2	0.00683 (12)	0.00698 (12)	0.00649 (12)	0.000	−0.00057 (9)	0.000
Fe3	0.00667 (12)	0.00730 (13)	0.00640 (12)	0.000	0.00049 (9)	0.000
Fe4	0.00765 (9)	0.00694 (9)	0.00752 (9)	−0.00004 (7)	−0.00081 (7)	0.00029 (7)
P1	0.00450 (19)	0.0065 (2)	0.0062 (2)	0.000	−0.00064 (15)	0.000
O11	0.0062 (4)	0.0103 (5)	0.0118 (5)	−0.0018 (4)	−0.0004 (3)	0.0020 (4)
O12	0.0081 (4)	0.0083 (4)	0.0063 (4)	−0.0002 (3)	−0.0018 (3)	0.0008 (3)
P2	0.0047 (2)	0.0066 (2)	0.0065 (2)	0.000	0.00025 (16)	0.000
O21	0.0079 (4)	0.0080 (4)	0.0066 (4)	−0.0005 (3)	0.0014 (3)	−0.0005 (3)
O22	0.0066 (4)	0.0108 (5)	0.0107 (5)	−0.0020 (4)	0.0002 (3)	−0.0017 (4)
P3	0.00581 (14)	0.00597 (14)	0.00643 (14)	0.00054 (11)	−0.00024 (11)	0.00031 (11)
O31	0.0124 (5)	0.0117 (5)	0.0083 (4)	−0.0026 (4)	−0.0032 (4)	0.0021 (4)
O32	0.0103 (5)	0.0150 (5)	0.0096 (5)	−0.0029 (4)	0.0034 (4)	−0.0044 (4)
O33	0.0077 (4)	0.0069 (5)	0.0223 (6)	0.0009 (4)	0.0013 (4)	0.0033 (4)
O34	0.0095 (4)	0.0068 (4)	0.0103 (5)	−0.0013 (3)	−0.0005 (4)	0.0004 (4)
P4	0.00469 (14)	0.00813 (15)	0.00736 (15)	−0.00038 (12)	−0.00054 (11)	0.00131 (12)
O41	0.0144 (5)	0.0210 (6)	0.0081 (5)	−0.0007 (4)	−0.0011 (4)	0.0035 (4)
O42	0.0067 (5)	0.0192 (6)	0.0233 (6)	−0.0026 (4)	−0.0015 (4)	−0.0058 (5)
O43	0.0073 (5)	0.0184 (6)	0.0226 (6)	0.0016 (4)	0.0001 (4)	−0.0061 (5)
O44	0.0285 (7)	0.0120 (5)	0.0137 (5)	0.0005 (5)	0.0002 (5)	0.0050 (4)
K1	0.00890 (15)	0.0259 (2)	0.0315 (2)	−0.00305 (13)	−0.00095 (14)	0.00066 (16)
K2	0.0578 (5)	0.0224 (3)	0.0628 (6)	0.000	−0.0302 (5)	0.000

Geometric parameters (Å, º)

Fe1—O34^i	1.9544 (12)	P3—O33	1.5193 (12)
Fe1—O34	1.9544 (12)	P3—O32	1.5220 (13)
Fe1—O12^i	2.0351 (14)	P3—O34	1.5302 (12)
Fe1—O12	2.0351 (14)	P3—O31	1.5387 (13)
Fe1—O21	2.0376 (14)	P3—K1^iv	3.241 (2)
Fe1—O21^i	2.0376 (14)	P3—K1	3.257 (2)
Fe2—O31	1.9289 (12)	O31—K1^iv	2.757 (2)
Fe2—O31^ii	1.9289 (12)	O31—K2^vi	3.0257 (15)
Fe2—O22^iii	2.0312 (16)	O32—K1^iv	2.5870 (19)
Fe2—O22^i	2.0312 (16)	O33—K1	2.6045 (18)
Fe2—O12^ii	2.0987 (12)	O34—K1	2.7579 (17)
Fe2—O12	2.0988 (12)	P4—O42	1.5220 (14)
Fe2—P1	2.7591 (9)	P4—O43	1.5310 (14)
Fe2—K1^iv	3.9400 (15)	P4—O44	1.5366 (13)
Fe2—K1^v	3.9400 (15)	P4—O41	1.5380 (13)
Fe2—K2^vi	3.9865 (12)	P4—K2^xi	3.5163 (11)
Fe3—O32	1.8977 (12)	P4—K1^ix	3.6070 (9)
Fe3—O32^vii	1.8977 (12)	O41—K2^xi	2.9890 (16)
Fe3—O11^viii	2.0293 (16)	O42—Fe4^ix	1.9992 (17)
Fe3—O11^i	2.0293 (17)	O42—K1^ix	2.7867 (15)
Fe3—O21^vii	2.0859 (12)	O43—Fe4^vii	2.0173 (17)
Fe3—O21	2.0859 (12)	O43—K1^ix	3.2132 (16)
Fe3—P2	2.7482 (9)	O44—Fe4^xii	1.8736 (13)
Fe3—K1^iv	3.8107 (15)	O44—K2^xi	2.8830 (18)
Fe3—K1^ix	3.8107 (15)	K1—O32^xiii	2.5870 (19)
Fe4—O44^x	1.8736 (13)	K1—O33	2.6045 (18)
Fe4—O41	1.8867 (12)	K1—O31^xiii	2.757 (2)
Fe4—O33	1.9273 (12)	K1—O34	2.7579 (17)
Fe4—O42^ix	1.9992 (17)	K1—O42^ix	2.7867 (15)
Fe4—O43^vii	2.0173 (17)	K1—O11^xiv	2.8746 (13)
Fe4—K1	3.8316 (13)	K1—O22^xv	2.9934 (13)
Fe4—K2^vi	3.8454 (13)	K1—O43^ix	3.2132 (16)
P1—O11	1.5105 (13)	K1—P3^xiii	3.241 (2)
P1—O11^ii	1.5105 (13)	K1—P4^ix	3.6070 (9)
P1—O12	1.5756 (11)	K1—P1^i	3.7556 (9)
P1—O12^ii	1.5756 (11)	K2—O44^xvi	2.8830 (18)
P1—K1^i	3.7556 (9)	K2—O44^xvii	2.8830 (18)
P1—K1^iii	3.7556 (9)	K2—O41^xvi	2.9890 (16)
O11—Fe3^i	2.0293 (16)	K2—O41^xvii	2.9890 (16)
O11—K1^iii	2.8746 (13)	K2—O31^vi	3.0257 (15)
P2—O22^vii	1.5158 (13)	K2—O31^xviii	3.0257 (15)
P2—O22	1.5158 (13)	K2—P4^xvi	3.5163 (11)
P2—O21	1.5772 (11)	K2—P4^xvii	3.5163 (11)
P2—O21^vii	1.5772 (12)	K2—Fe4^xviii	3.8454 (13)
P2—K1^viii	3.8503 (9)	K2—Fe4^vi	3.8454 (13)
P2—K1^i	3.8503 (9)	K2—Fe2^vi	3.9865 (13)
O22—Fe2^i	2.0312 (16)	K2—K1^xix	4.3296 (15)
O22—K1^viii	2.9934 (13)
O34^i—Fe1—O34	180.0	O22^vii—P2—O22	111.89 (10)
O34^i—Fe1—O12^i	90.92 (5)	O22^vii—P2—O21	110.59 (6)
O34—Fe1—O12^i	89.08 (5)	O22—P2—O21	112.54 (7)
O34^i—Fe1—O12	89.08 (5)	O22^vii—P2—O21^vii	112.54 (7)
O34—Fe1—O12	90.92 (5)	O22—P2—O21^vii	110.59 (6)
O12^i—Fe1—O12	180.0	O21—P2—O21^vii	97.97 (9)
O34^i—Fe1—O21	85.42 (5)	O33—P3—O32	110.52 (7)
O34—Fe1—O21	94.58 (5)	O33—P3—O34	109.29 (7)
O12^i—Fe1—O21	84.99 (6)	O32—P3—O34	109.54 (7)
O12—Fe1—O21	95.01 (6)	O33—P3—O31	108.39 (7)
O34^i—Fe1—O21^i	94.58 (5)	O32—P3—O31	108.80 (8)
O34—Fe1—O21^i	85.42 (5)	O34—P3—O31	110.28 (7)
O12^i—Fe1—O21^i	95.01 (6)	O42—P4—O43	108.11 (8)
O12—Fe1—O21^i	84.99 (6)	O42—P4—O44	111.53 (8)
O21—Fe1—O21^i	180.0	O43—P4—O44	109.92 (8)
O31—Fe2—O31^ii	94.31 (7)	O42—P4—O41	111.36 (8)
O31—Fe2—O22^iii	87.33 (6)	O43—P4—O41	111.95 (8)
O31^ii—Fe2—O22^iii	94.41 (6)	O44—P4—O41	103.96 (7)
O31—Fe2—O22^i	94.41 (6)	O32^xiii—K1—O33	152.98 (5)
O31^ii—Fe2—O22^i	87.33 (6)	O32^xiii—K1—O31^xiii	55.39 (5)
O22^iii—Fe2—O22^i	177.45 (6)	O33—K1—O31^xiii	147.07 (5)
O31—Fe2—O12^ii	166.43 (5)	O32^xiii—K1—O34	130.94 (5)
O31^ii—Fe2—O12^ii	98.49 (5)	O33—K1—O34	55.18 (5)
O22^iii—Fe2—O12^ii	87.20 (5)	O31^xiii—K1—O34	129.25 (5)
O22^i—Fe2—O12^ii	90.70 (5)	O32^xiii—K1—O42^ix	103.44 (4)
O31—Fe2—O12	98.49 (5)	O33—K1—O42^ix	57.40 (4)
O31^ii—Fe2—O12	166.43 (5)	O31^xiii—K1—O42^ix	115.39 (4)
O22^iii—Fe2—O12	90.70 (5)	O34—K1—O42^ix	110.68 (5)
O22^i—Fe2—O12	87.20 (5)	O32^xiii—K1—O11^xiv	58.23 (4)
O12^ii—Fe2—O12	69.17 (6)	O33—K1—O11^xiv	107.51 (5)
O32—Fe3—O32^vii	98.84 (8)	O31^xiii—K1—O11^xiv	104.93 (4)
O32—Fe3—O11^viii	85.58 (6)	O34—K1—O11^xiv	77.15 (5)
O32^vii—Fe3—O11^viii	95.63 (6)	O42^ix—K1—O11^xiv	110.10 (4)
O32—Fe3—O11^i	95.63 (6)	O32^xiii—K1—O22^xv	100.02 (5)
O32^vii—Fe3—O11^i	85.58 (6)	O33—K1—O22^xv	106.60 (5)
O11^viii—Fe3—O11^i	178.15 (7)	O31^xiii—K1—O22^xv	56.62 (4)
O32—Fe3—O21^vii	163.62 (5)	O34—K1—O22^xv	74.39 (5)
O32^vii—Fe3—O21^vii	96.26 (5)	O42^ix—K1—O22^xv	140.97 (4)
O11^viii—Fe3—O21^vii	86.68 (5)	O11^xiv—K1—O22^xv	108.72 (4)
O11^i—Fe3—O21^vii	91.81 (5)	O32^xiii—K1—O43^ix	62.96 (4)
O32—Fe3—O21	96.26 (5)	O33—K1—O43^ix	104.65 (5)
O32^vii—Fe3—O21	163.62 (5)	O31^xiii—K1—O43^ix	71.34 (4)
O11^viii—Fe3—O21	91.81 (5)	O34—K1—O43^ix	158.49 (4)
O11^i—Fe3—O21	86.68 (5)	O42^ix—K1—O43^ix	48.01 (4)
O21^vii—Fe3—O21	69.57 (6)	O11^xiv—K1—O43^ix	105.57 (4)
O44^x—Fe4—O41	118.61 (6)	O22^xv—K1—O43^ix	122.93 (4)
O44^x—Fe4—O33	103.56 (6)	O44^xvi—K2—O44^xvii	121.47 (6)
O41—Fe4—O33	137.82 (6)	O44^xvi—K2—O41^xvi	48.68 (4)
O44^x—Fe4—O42^ix	95.42 (7)	O44^xvii—K2—O41^xvi	79.15 (5)
O41—Fe4—O42^ix	92.22 (6)	O44^xvi—K2—O41^xvii	79.15 (5)
O33—Fe4—O42^ix	82.67 (5)	O44^xvii—K2—O41^xvii	48.68 (4)
O44^x—Fe4—O43^vii	91.83 (7)	O41^xvi—K2—O41^xvii	59.59 (6)
O41—Fe4—O43^vii	90.22 (7)	O44^xvi—K2—O31^vi	139.81 (4)
O33—Fe4—O43^vii	89.08 (5)	O44^xvii—K2—O31^vi	95.77 (4)
O42^ix—Fe4—O43^vii	170.10 (6)	O41^xvi—K2—O31^vi	139.18 (4)
O11—P1—O11^ii	111.48 (10)	O41^xvii—K2—O31^vi	141.04 (4)
O11—P1—O12	112.32 (7)	O44^xvi—K2—O31^xviii	95.77 (4)
O11^ii—P1—O12	110.93 (7)	O44^xvii—K2—O31^xviii	139.81 (4)
O11—P1—O12^ii	110.93 (7)	O41^xvi—K2—O31^xviii	141.04 (4)
O11^ii—P1—O12^ii	112.32 (7)	O41^xvii—K2—O31^xviii	139.18 (4)
O12—P1—O12^ii	98.24 (9)	O31^vi—K2—O31^xviii	55.73 (5)

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