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The title compound, KMg(HP2O7)·2H2O, is isotypic with other members of the series KM(HP2O7)·2H2O, where M = Mn, Co and Zn. The structure consists of a three-dimensional framework of [MgHP2O7]- layers parallel to (100) linked by K+ cations and hydrogen-bonding inter­actions. The metal ions and water O atoms lie on mirror planes, as does the bridging O atom of the eclipsed (HP2O7)3- anion. The acid H atom of the diphosphate anion is split into two half-occupied positions around a center of inversion.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805036731/wm6097sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536805036731/wm6097Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](g-O) = 0.002 Å
  • R factor = 0.033
  • wR factor = 0.089
  • Data-to-parameter ratio = 17.6

checkCIF/PLATON results

No syntax errors found



Alert level B PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low ....... 0.94
Alert level C REFLT03_ALERT_3_C Reflection count < 95% complete From the CIF: _diffrn_reflns_theta_max 31.89 From the CIF: _diffrn_reflns_theta_full 31.89 From the CIF: _reflns_number_total 1353 TEST2: Reflns within _diffrn_reflns_theta_max Count of symmetry unique reflns 1434 Completeness (_total/calc) 94.35% PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature . 293 K
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2004); cell refinement: CrysAlis RED (Oxford Diffraction, 2004); data reduction: CrysAlis RED; 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) and PLATON (Spek, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999).

potassium magnesium hydrogendiphosphate dihydrate top
Crystal data top
KMg(HP2O7)(H2O)2F(000) = 552
Mr = 274.39Dx = 2.329 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 3218 reflections
a = 15.5203 (13) Åθ = 3.1–31.8°
b = 7.7786 (6) ŵ = 1.19 mm1
c = 6.4822 (5) ÅT = 293 K
V = 782.57 (11) Å3Prism, colourless
Z = 40.15 × 0.12 × 0.10 mm
Data collection top
Oxford XCALIBUR-2 CCD
diffractometer
1173 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
ω scansθmax = 31.9°, θmin = 3.4°
Absorption correction: numerical
(CrysAlis RED; Oxford Diffraction, 2004)
h = 1822
Tmin = 0.754, Tmax = 0.825k = 1111
6826 measured reflectionsl = 99
1353 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.089H atoms treated by a mixture of independent and constrained refinement
S = 1.05 w = 1/[σ2(Fo2) + (0.0498P)2]
where P = (Fo2 + 2Fc2)/3
1353 reflections(Δ/σ)max = 0.001
77 parametersΔρmax = 0.46 e Å3
3 restraintsΔρmin = 0.54 e Å3
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.

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
P10.86405 (2)0.06195 (5)0.36157 (6)0.01036 (12)
O40.77213 (7)0.06553 (14)0.43220 (18)0.0151 (2)
O10.88901 (10)0.25000.2744 (2)0.0143 (3)
O5W0.89127 (12)0.25000.8112 (3)0.0198 (3)
H5W0.8945 (18)0.344 (3)0.708 (3)0.045 (5)*
O6W0.71889 (11)0.25000.3220 (3)0.0183 (3)
H6W0.7365 (16)0.147 (3)0.391 (3)0.045 (5)*
O20.92483 (7)0.03029 (16)0.54646 (17)0.0168 (3)
H20.977 (2)0.016 (7)0.516 (10)0.045 (5)*0.50
O30.88318 (7)0.05737 (14)0.18544 (17)0.0156 (2)
K10.96413 (3)0.25000.12003 (8)0.02210 (15)
Mg10.69513 (5)0.25000.56069 (11)0.01128 (17)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
P10.0097 (2)0.00918 (19)0.01219 (19)0.00038 (12)0.00041 (12)0.00174 (12)
O40.0102 (5)0.0129 (5)0.0221 (6)0.0003 (4)0.0041 (4)0.0029 (4)
O10.0175 (7)0.0105 (7)0.0149 (7)0.0000.0051 (6)0.000
O5W0.0257 (9)0.0179 (8)0.0160 (8)0.0000.0046 (7)0.000
O6W0.0209 (8)0.0138 (7)0.0204 (8)0.0000.0027 (6)0.000
O20.0146 (5)0.0222 (6)0.0136 (5)0.0035 (4)0.0031 (4)0.0008 (4)
O30.0146 (5)0.0149 (5)0.0173 (5)0.0007 (4)0.0005 (4)0.0074 (4)
K10.0179 (3)0.0295 (3)0.0188 (3)0.0000.00018 (18)0.000
Mg10.0101 (3)0.0105 (3)0.0132 (3)0.0000.0008 (3)0.000
Geometric parameters (Å, º) top
P1—O41.4986 (11)O3—K1vi2.8356 (12)
P1—O31.5010 (11)O3—K13.3490 (12)
P1—O21.5450 (11)K1—O2vii2.8225 (12)
P1—O11.6153 (8)K1—O2viii2.8225 (12)
P1—K13.7813 (6)K1—O3ix2.8356 (12)
O4—Mg12.0447 (12)K1—O3vi2.8356 (12)
O1—P1i1.6153 (8)K1—O6Wiv2.8652 (19)
O1—K12.8099 (16)K1—O5Wiii3.0074 (19)
O5W—Mg1ii2.1010 (19)K1—O3i3.3490 (12)
O5W—K1iii3.0074 (19)K1—Mg1x3.6057 (9)
O5W—H5W0.989 (16)K1—P1i3.7813 (6)
O6W—Mg1iv2.1566 (18)Mg1—O4i2.0447 (12)
O6W—K1ii2.8652 (19)Mg1—O3ii2.0920 (12)
O6W—H6W0.959 (16)Mg1—O3xi2.0920 (12)
O2—K1v2.8225 (12)Mg1—O5Wiv2.1010 (19)
O2—H20.91 (2)Mg1—O6Wii2.1566 (18)
O3—Mg1iv2.0920 (12)Mg1—K1xii3.6057 (9)
O4—P1—O3115.61 (7)O3ix—K1—O6Wiv143.99 (3)
O4—P1—O2110.32 (7)O3vi—K1—O6Wiv143.99 (3)
O3—P1—O2111.76 (7)O1—K1—O5Wiii72.78 (5)
O4—P1—O1108.57 (7)O2vii—K1—O5Wiii132.16 (3)
O3—P1—O1104.26 (7)O2viii—K1—O5Wiii132.16 (3)
O2—P1—O1105.62 (8)O3ix—K1—O5Wiii58.39 (3)
P1—O4—Mg1133.94 (7)O3vi—K1—O5Wiii58.39 (3)
P1—O1—P1i129.80 (10)O6Wiv—K1—O5Wiii145.80 (5)
P1—O1—K1114.70 (5)O1—K1—O3i46.08 (2)
P1i—O1—K1114.70 (5)O2vii—K1—O3i143.52 (4)
Mg1ii—O5W—K1iii87.93 (6)O2viii—K1—O3i86.53 (3)
Mg1ii—O5W—H5W123.4 (15)O3ix—K1—O3i91.41 (3)
K1iii—O5W—H5W114.2 (16)O3vi—K1—O3i141.19 (2)
Mg1iv—O6W—K1ii135.76 (8)O6Wiv—K1—O3i72.88 (3)
Mg1iv—O6W—H6W100.9 (15)O5Wiii—K1—O3i83.47 (3)
K1ii—O6W—H6W102.8 (15)O1—K1—O346.08 (2)
P1—O2—K1v129.02 (7)O2vii—K1—O386.53 (3)
P1—O2—H2116 (4)O2viii—K1—O3143.52 (4)
K1v—O2—H2102 (4)O3ix—K1—O3141.19 (2)
P1—O3—Mg1iv128.46 (7)O3vi—K1—O391.41 (3)
P1—O3—K1vi127.29 (6)O6Wiv—K1—O372.88 (3)
Mg1iv—O3—K1vi92.82 (4)O5Wiii—K1—O383.47 (3)
P1—O3—K194.73 (5)O3i—K1—O391.11 (4)
Mg1iv—O3—K1120.05 (5)O4i—Mg1—O489.14 (7)
K1vi—O3—K188.59 (3)O4i—Mg1—O3ii178.54 (6)
O1—K1—O2vii127.39 (4)O4—Mg1—O3ii89.68 (4)
O1—K1—O2viii127.39 (4)O4i—Mg1—O3xi89.68 (4)
O2vii—K1—O2viii74.53 (5)O4—Mg1—O3xi178.54 (6)
O1—K1—O3ix118.87 (4)O3ii—Mg1—O3xi91.49 (7)
O2vii—K1—O3ix112.71 (4)O4i—Mg1—O5Wiv93.41 (5)
O2viii—K1—O3ix75.29 (3)O4—Mg1—O5Wiv93.41 (5)
O1—K1—O3vi118.87 (4)O3ii—Mg1—O5Wiv85.80 (5)
O2vii—K1—O3vi75.29 (3)O3xi—Mg1—O5Wiv85.80 (5)
O2viii—K1—O3vi112.71 (4)O4i—Mg1—O6Wii87.61 (5)
O3ix—K1—O3vi63.80 (5)O4—Mg1—O6Wii87.61 (5)
O1—K1—O6Wiv73.02 (5)O3ii—Mg1—O6Wii93.20 (5)
O2vii—K1—O6Wiv71.66 (4)O3xi—Mg1—O6Wii93.20 (5)
O2viii—K1—O6Wiv71.66 (4)O5Wiv—Mg1—O6Wii178.57 (8)
Symmetry codes: (i) x, y+1/2, z; (ii) x+3/2, y, z+1/2; (iii) x+2, y, z+1; (iv) x+3/2, y, z1/2; (v) x, y, z+1; (vi) x+2, y, z; (vii) x, y, z1; (viii) x, y+1/2, z1; (ix) x+2, y+1/2, z; (x) x+1/2, y, z+1/2; (xi) x+3/2, y+1/2, z+1/2; (xii) x1/2, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O6W—H6W···O40.96 (2)1.76 (2)2.6864 (13)161 (2)
O5W—H5W···O2xiii0.99 (2)1.85 (2)2.8231 (13)166 (2)
O2—H2···O2iii0.91 (2)1.57 (2)2.455 (2)161 (4)
Symmetry codes: (iii) x+2, y, z+1; (xiii) x, y1/2, z.
 

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