KMg(0.09)Fe(1.91)(PO(4))(2).

KMg(0.09)Fe(1.91)(PO(4))(2), potassium [iron(II)/magnesium] iron(III) bis(orthophosphate), is a solid solution derived from compounds with general formula KM(II)Fe(PO(4))(2) (M(II) = Fe, Cu), in which the Mg atoms substitute Fe atoms only in the octa-hedrally surrounded sites. The framework of the structure is built up from [FeO(5)] trigonal bipyramids and [MO(6)] (M = (Fe, Mg) octa-hedra sharing corners and edges and connected by two types of bridging PO(4) tetra-hedra. The K(+) cations are nine-coordinated and are situated in channels running along [101].

Related literature

For the structure of KFe2(PO4)2, see: Yakubovich et al. (1986 ▶) and for the structure of KCuFe(PO4)2, see: Badri et al. (2011 ▶). For calculations of bond-valence sums, see: Brown & Altermatt (1985 ▶).

Experimental

Crystal data

KMg0.09Fe1.91(PO4)2

M = 337.97

Monoclinic,

a = 7.8444 (3) Å

b = 10.0033 (3) Å

c = 9.0371 (4) Å

β = 114.838 (5)°

V = 643.54 (4) Å3

Z = 4

Mo Kα radiation

μ = 5.48 mm−1

T = 293 K

0.12 × 0.02 × 0.02 mm

Data collection

Oxford Diffraction XCalibur-3 CCD diffractometer

Absorption correction: multi-scan (Blessing, 1995 ▶) T min = 0.857, T max = 0.903

10004 measured reflections

2230 independent reflections

2155 reflections with I > 2σ(I)

R int = 0.034

Refinement

R[F 2 > 2σ(F 2)] = 0.042

wR(F 2) = 0.117

S = 1.19

2230 reflections

120 parameters

Δρmax = 2.08 e Å−3

Δρmin = −1.01 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 ▶); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999 ▶) and enCIFer (Allen et al., 2004 ▶)’.

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812023975/wm2629sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812023975/wm2629Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

KMg0.09Fe1.91(PO4)2	F(000) = 654.4
Mr = 337.97	Dx = 3.488 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 10004 reflections
a = 7.8444 (3) Å	θ = 2.9–32°
b = 10.0033 (3) Å	µ = 5.48 mm−1
c = 9.0371 (4) Å	T = 293 K
β = 114.838 (5)°	Needle, light pink
V = 643.54 (4) Å3	0.12 × 0.02 × 0.02 mm
Z = 4

Oxford Diffraction XCalibur-3 CCD diffractometer	2230 independent reflections
Radiation source: fine-focus sealed tube	2155 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
φ and ω scans	θmax = 32°, θmin = 2.9°
Absorption correction: multi-scan (Blessing, 1995)	h = −10→11
Tmin = 0.857, Tmax = 0.903	k = −14→14
10004 measured reflections	l = −13→13

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042	w = 1/[σ2(Fo2) + (0.0371P)2 + 6.6825P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.117	(Δ/σ)max < 0.001
S = 1.19	Δρmax = 2.08 e Å−3
2230 reflections	Δρmin = −1.01 e Å−3
120 parameters	Extinction correction: SHELXL
0 restraints	Extinction coefficient: 0.0145 (14)

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.

	x	y	z	Uiso*/Ueq	Occ. (<1)
K1	0.42060 (18)	−0.13394 (13)	0.07587 (14)	0.0267 (3)
Fe1	0.37733 (7)	0.11765 (5)	−0.55702 (6)	0.00590 (15)
Fe2	0.01350 (8)	0.12386 (5)	−0.25744 (7)	0.0065 (2)	0.912 (8)
Mg2	0.01350 (8)	0.12386 (5)	−0.25744 (7)	0.0065 (2)	0.088 (8)
P1	0.12822 (14)	0.16101 (10)	−0.86090 (12)	0.0088 (2)
P2	0.26703 (14)	−0.09247 (10)	−0.35182 (12)	0.0085 (2)
O11	0.4483 (4)	0.2619 (3)	−0.3964 (4)	0.0127 (5)
O12	0.2987 (4)	0.2495 (3)	−0.7494 (4)	0.0112 (5)
O13	0.1465 (4)	0.0404 (3)	−0.7444 (4)	0.0120 (5)
O14	0.1437 (5)	0.1137 (3)	−0.0138 (4)	0.0138 (6)
O21	0.0945 (4)	−0.1311 (3)	−0.5040 (4)	0.0133 (5)
O22	0.3516 (4)	−0.2128 (3)	−0.2422 (4)	0.0126 (5)
O23	0.2247 (4)	0.0124 (3)	−0.2489 (4)	0.0125 (5)
O24	0.4195 (4)	−0.0311 (3)	−0.4003 (4)	0.0131 (5)

	U11	U22	U33	U12	U13	U23
K1	0.0313 (6)	0.0285 (6)	0.0181 (5)	−0.0129 (4)	0.0080 (4)	−0.0006 (4)
Fe1	0.0070 (2)	0.0052 (2)	0.0045 (2)	−0.00011 (16)	0.00150 (18)	0.00047 (16)
Fe2	0.0080 (3)	0.0057 (3)	0.0054 (3)	−0.00005 (17)	0.0023 (2)	−0.00025 (17)
Mg2	0.0080 (3)	0.0057 (3)	0.0054 (3)	−0.00005 (17)	0.0023 (2)	−0.00025 (17)
P1	0.0103 (4)	0.0086 (4)	0.0068 (4)	−0.0005 (3)	0.0030 (3)	0.0000 (3)
P2	0.0100 (4)	0.0082 (4)	0.0074 (4)	0.0006 (3)	0.0036 (3)	0.0001 (3)
O11	0.0136 (12)	0.0126 (13)	0.0120 (12)	−0.0031 (10)	0.0054 (10)	−0.0031 (10)
O12	0.0127 (12)	0.0110 (12)	0.0077 (11)	−0.0028 (10)	0.0020 (10)	0.0005 (9)
O13	0.0128 (12)	0.0104 (12)	0.0095 (12)	−0.0022 (10)	0.0015 (10)	0.0019 (10)
O14	0.0176 (14)	0.0159 (14)	0.0076 (12)	−0.0002 (11)	0.0050 (11)	−0.0024 (10)
O21	0.0151 (13)	0.0150 (13)	0.0073 (12)	0.0000 (10)	0.0024 (10)	−0.0011 (10)
O22	0.0157 (13)	0.0117 (13)	0.0113 (12)	0.0041 (10)	0.0066 (11)	0.0026 (10)
O23	0.0134 (12)	0.0120 (13)	0.0114 (12)	0.0022 (10)	0.0045 (10)	−0.0022 (10)
O24	0.0134 (12)	0.0123 (13)	0.0164 (13)	0.0033 (10)	0.0089 (11)	0.0049 (11)

K1—O22	2.806 (3)	Fe2—O22v	1.947 (3)
K1—O23i	2.830 (3)	Fe2—O21vi	1.959 (3)
K1—O11ii	2.854 (3)	Fe2—O23	1.971 (3)
K1—O11i	2.930 (3)	Fe2—O14	2.003 (3)
K1—O21iii	2.955 (3)	Fe2—O13vi	2.072 (3)
K1—O12ii	3.007 (3)	Fe2—O12vii	2.133 (3)
K1—O23	3.054 (3)	P1—O14viii	1.513 (3)
K1—O24i	3.131 (3)	P1—O11ix	1.520 (3)
K1—O14	3.167 (3)	P1—O12	1.567 (3)
Fe1—O11	1.955 (3)	P1—O13	1.567 (3)
Fe1—O24	1.984 (3)	P2—O21	1.520 (3)
Fe1—O24iv	1.989 (3)	P2—O22	1.523 (3)
Fe1—O13	2.041 (3)	P2—O23	1.528 (3)
Fe1—O12	2.060 (3)	P2—O24	1.562 (3)
O22—K1—O23i	114.12 (10)	O23—Fe2—O13vi	93.03 (13)
O22—K1—O11ii	66.54 (9)	O14—Fe2—O13vi	88.97 (12)
O23i—K1—O11ii	175.96 (10)	O22v—Fe2—O12vii	86.54 (12)
O22—K1—O11i	136.60 (10)	O21vi—Fe2—O12vii	91.89 (12)
O23i—K1—O11i	77.66 (9)	O23—Fe2—O12vii	175.72 (12)
O11ii—K1—O11i	104.68 (8)	O14—Fe2—O12vii	92.19 (12)
O22—K1—O21iii	55.69 (9)	O13vi—Fe2—O12vii	88.90 (12)
O23i—K1—O21iii	91.67 (9)	O14viii—P1—O11ix	112.93 (18)
O11ii—K1—O21iii	91.87 (9)	O14viii—P1—O12	112.93 (17)
O11i—K1—O21iii	83.54 (9)	O11ix—P1—O12	108.38 (18)
O22—K1—O12ii	121.25 (9)	O14viii—P1—O13	110.67 (18)
O23i—K1—O12ii	121.56 (9)	O11ix—P1—O13	110.31 (17)
O11ii—K1—O12ii	59.29 (8)	O12—P1—O13	100.98 (16)
O11i—K1—O12ii	49.85 (8)	O21—P2—O22	111.52 (18)
O21iii—K1—O12ii	104.06 (9)	O21—P2—O23	112.74 (18)
O22—K1—O23	49.28 (9)	O22—P2—O23	107.06 (17)
O23i—K1—O23	107.82 (8)	O21—P2—O24	110.00 (18)
O11ii—K1—O23	69.39 (9)	O22—P2—O24	108.52 (17)
O11i—K1—O23	170.19 (9)	O23—P2—O24	106.79 (18)
O21iii—K1—O23	104.12 (9)	P1x—O11—Fe1	118.74 (18)
O12ii—K1—O23	121.31 (9)	P1x—O11—K1v	124.41 (17)
O22—K1—O24i	159.49 (9)	Fe1—O11—K1v	86.74 (11)
O23i—K1—O24i	48.85 (8)	P1x—O11—K1i	95.94 (14)
O11ii—K1—O24i	129.51 (9)	Fe1—O11—K1i	106.47 (13)
O11i—K1—O24i	57.90 (9)	K1v—O11—K1i	124.91 (11)
O21iii—K1—O24i	127.13 (9)	P1—O12—Fe1	93.03 (14)
O12ii—K1—O24i	78.93 (8)	P1—O12—Fe2xi	141.86 (18)
O23—K1—O24i	119.28 (9)	Fe1—O12—Fe2xi	116.63 (14)
O22—K1—O14	98.12 (9)	P1—O12—K1v	91.93 (13)
O23i—K1—O14	102.39 (9)	Fe1—O12—K1v	80.92 (10)
O11ii—K1—O14	73.59 (9)	Fe2xi—O12—K1v	114.88 (12)
O11i—K1—O14	120.87 (9)	P1—O13—Fe1	93.73 (14)
O21iii—K1—O14	153.74 (9)	P1—O13—Fe2vi	136.95 (18)
O12ii—K1—O14	87.46 (9)	Fe1—O13—Fe2vi	128.51 (15)
O23—K1—O14	50.59 (8)	P1xii—O14—Fe2	142.0 (2)
O24i—K1—O14	77.83 (8)	P1xii—O14—K1	108.69 (16)
O11—Fe1—O24	96.53 (13)	Fe2—O14—K1	107.41 (12)
O11—Fe1—O24iv	117.65 (13)	P2—O21—K1xiii	107.95 (16)
O24—Fe1—O24iv	84.56 (13)	Fe2vi—O21—K1xiii	105.53 (13)
O11—Fe1—O13	140.54 (13)	P2—O22—Fe2ii	138.67 (19)
O24—Fe1—O13	97.59 (13)	P2—O22—K1	106.73 (15)
O24iv—Fe1—O13	100.27 (13)	Fe2ii—O22—K1	111.49 (13)
O11—Fe1—O12	92.56 (13)	P2—O23—Fe2	139.32 (19)
O24—Fe1—O12	169.72 (13)	P2—O23—K1i	102.50 (14)
O24iv—Fe1—O12	95.47 (12)	Fe2—O23—K1i	113.17 (13)
O13—Fe1—O12	72.26 (12)	P2—O23—K1	96.07 (14)
O22v—Fe2—O21vi	87.21 (13)	Fe2—O23—K1	112.59 (13)
O22v—Fe2—O23	91.51 (13)	K1i—O23—K1	72.18 (8)
O21vi—Fe2—O23	91.82 (13)	P2—O24—Fe1	125.27 (18)
O22v—Fe2—O14	91.01 (13)	P2—O24—Fe1iv	130.84 (19)
O21vi—Fe2—O14	175.44 (13)	Fe1—O24—Fe1iv	95.44 (13)
O23—Fe2—O14	84.03 (13)	P2—O24—K1i	89.85 (13)
O22v—Fe2—O13vi	175.43 (13)	Fe1—O24—K1i	98.85 (12)
O21vi—Fe2—O13vi	93.14 (13)	Fe1iv—O24—K1i	111.87 (13)

Table 1

Selected bond lengths (Å)

Fe1—O11	1.955 (3)
Fe1—O24	1.984 (3)
Fe1—O24i	1.989 (3)
Fe1—O13	2.041 (3)
Fe1—O12	2.060 (3)
(Fe,Mg)2—O22ii	1.947 (3)
(Fe,Mg)2—O21iii	1.959 (3)
(Fe,Mg)2—O23	1.971 (3)
(Fe,Mg)2—O14	2.003 (3)
(Fe,Mg)2—O13iii	2.072 (3)
(Fe,Mg)2—O12iv	2.133 (3)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .