Download citation
Download citation
link to html
Single crystals of the mixed alkaline earth platinate, tristrontium magnesium platinum hexaoxide, Sr3MgPtO6, were grown from a KOH flux at 1273 K. The compound adopts the rhombohedral K4CdCl6 structure type, featuring chains of face-shared, distorted MgO6 trigonal prisms (Mg site symmetry 32) and PtO6 octahedra (Pt site symmetry \overline 3) surrounded by columns of Sr2+ ions (Sr site symmetry 2).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803005993/br6088sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803005993/br6088Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](Mg-O) = 0.004 Å
  • R factor = 0.024
  • wR factor = 0.049
  • Data-to-parameter ratio = 24.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
PLAT_731 Alert C Bond Calc 3.2080(5), Rep 3.2080(2) .... 2.50 su-Ratio PT -SR 1.555 15.554 PLAT_731 Alert C Bond Calc 3.2080(5), Rep 3.2080(2) .... 2.50 su-Ratio PT -SR 1.555 27.445 General Notes
ABSTM_02 When printed, the submitted absorption T values will be replaced by the scaled T values. Since the ratio of scaled T's is identical to the ratio of reported T values, the scaling does not imply a change to the absorption corrections used in the study. Ratio of Tmax expected/reported 0.563 Tmax scaled 0.135 Tmin scaled 0.041
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check

Comment top

The structure of Sr3MgPtO6 was determined in 1997 (Nùñez et al., 1997) by powder X-ray diffraction on a polycrystalline sample prepared by conventional sintering techniques, and was shown to adopt the K4CdCl6 structure type (Bergerhoff & Schmitz-Dumont, 1956). This structure type features two crystallographically and chemically distinct K+ positions and consists of chains along [001] of face-shared distorted KCl6 trigonal prisms and CdCl6 octahedra. The polyhedral chains are surrounded by spiral columns of K+ ions. To date, a large and compositionally diverse group of oxides adopting this structure type has been reported, typically as polycrystalline materials [reviewed in Stitzer et al. (2001)]. High-temperature flux growth from molten KOH has proven to be an effective oxide crystal growth medium. Single crystals of Sr3MgPtO6 were readily grown from molten KOH at 1273 K, using (NH4)2PtCl6 as the platinum source. Sr3MgPtO6 represents an Mg-substituted form of the K4CdCl6-type oxide Sr4PtO6 (Randall & Katz, 1959), with Mg ordered in the trigonal prism site (site-symmetry 32, Wyckoff symbol 6a) and Pt4+ in a rhombohedrally elongated octahedral site (site symmetry 3, Wyckoff symbol 6 b). Fig. 1 illustrates the local coordination of these metal centers. The Sr2+ ion resides in an irregular eight coordinate site (Wyckoff symbol 18 e) of site symmetry 2. Fig. 2 shows an off-[110] view of the polyhedral chains and Sr2+ columns. Bond lengths and angles from the present single-crystal determination of Sr3MgPtO6 are very close to those derived from powder data [Mg—O = 2.172 (16) Å, Pt—O = 2.011 (16) Å and Sr—O = 2.498 (17)–2.742 (17) Å]. Refinement of the site occupancies for Mg and Pt showed no significant deviation from unity occupancy, indicating a stoichiometric compound, and no Sr/Mg mixing on the trigonal prism site.

Experimental top

The (NH4)2PtCl6 precursor was prepared according to a published method (Kaufman, 1967). Subsequently, SrCO3 (Alfa, 99.95%), MgCO3 (Alfa, 99.8%), and (NH4)2PtCl6 (stoichiometric amounts, ca 1 g total reagent mass) and KOH (Fisher, reagent grade; approx. 10 times by mass the total reagent amount) were loaded into a covered alumina crucible. The mixture was heated at 1273 K for 2 h, cooled to 1023 K at a rate of 1 K h−1, at which point the furnace was shut off and allowed to cool to room temperature radiatively. The KOH matrix was dissolved with distilled water, leaving plentiful transparent brown crystals with a rhombohedral habit.

Refinement top

Systematic absences in the dataset confirmed a c-glide operation, indicating the space groups R3c and R3c. Preliminary powder X-ray diffraction showed the compound to be isostructural with K4CdCl6 (space group R3c); therefore, the expected centrosymmetric space group was chosen and confirmed by the solution. The largest difference peak/hole was located less than 0.8 Å from the Pt atom.

Computing details top

Data collection: SMART-NT (Bruker, 1999); cell refinement: SAINT-Plus-NT (Bruker, 1999); data reduction: SAINT-Plus-NT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 2001); software used to prepare material for publication: SHELXTL (Bruker, 1997).

Figures top
[Figure 1] Fig. 1. Fragment of the face-shared polyhedral chains in Sr3MgPtO6. Displacement ellipsoids are drawn at the 90% probability level.
[Figure 2] Fig. 2. Near-[110] polyhedral view of the unit cell of Sr3MgPtO6.
Tristrontium Magnesium Platinum Hexaoxide top
Crystal data top
Sr3MgPtO6Dx = 6.439 Mg m3
Mr = 578.26Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3cCell parameters from 1132 reflections
Hall symbol: -R 3 2"cθ = 4.2–36.3°
a = 9.6432 (4) ŵ = 50.13 mm1
c = 11.1112 (6) ÅT = 293 K
V = 894.82 (7) Å3Rhombohedron, brown
Z = 60.11 × 0.05 × 0.04 mm
F(000) = 1512
Data collection top
Bruker SMART APEX CCD
diffractometer
490 independent reflections
Radiation source: sealed tube431 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.037
ω scansθmax = 36.3°, θmin = 4.2°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 167
Tmin = 0.073, Tmax = 0.239k = 1116
2412 measured reflectionsl = 188
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)] = 0.024 w = 1/[σ2(Fo2) + (0.0227P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.049(Δ/σ)max < 0.001
S = 1.01Δρmax = 2.32 e Å3
490 reflectionsΔρmin = 3.12 e Å3
20 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00118 (8)
Crystal data top
Sr3MgPtO6Z = 6
Mr = 578.26Mo Kα radiation
Trigonal, R3cµ = 50.13 mm1
a = 9.6432 (4) ÅT = 293 K
c = 11.1112 (6) Å0.11 × 0.05 × 0.04 mm
V = 894.82 (7) Å3
Data collection top
Bruker SMART APEX CCD
diffractometer
490 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
431 reflections with I > 2σ(I)
Tmin = 0.073, Tmax = 0.239Rint = 0.037
2412 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02420 parameters
wR(F2) = 0.0490 restraints
S = 1.01Δρmax = 2.32 e Å3
490 reflectionsΔρmin = 3.12 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*/Ueq
Sr0.36540 (5)0.00000.25000.00375 (12)
Mg0.00000.00000.25000.0026 (6)
Pt0.00000.00000.00000.00164 (10)
O0.1736 (4)0.0221 (4)0.1151 (3)0.0059 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sr0.00374 (18)0.0039 (2)0.0036 (2)0.00197 (11)0.00030 (8)0.00060 (16)
Mg0.0030 (8)0.0030 (8)0.0017 (13)0.0015 (4)0.0000.000
Pt0.00186 (12)0.00186 (12)0.00122 (14)0.00093 (6)0.0000.000
O0.0062 (13)0.0078 (14)0.0043 (12)0.0039 (11)0.0030 (10)0.0002 (10)
Geometric parameters (Å, º) top
Sr—O2.472 (3)Mg—Ptxi2.7778 (2)
Sr—Oi2.472 (3)Mg—Srx3.5236 (5)
Sr—Oii2.637 (3)Mg—Srxiii3.5236 (5)
Sr—Oiii2.637 (3)Mg—Srxiv3.5865 (2)
Sr—Oiv2.663 (3)Pt—Oxv2.031 (3)
Sr—Ov2.663 (3)Pt—Oxvi2.031 (3)
Sr—Ovi2.731 (3)Pt—Oxiii2.031 (3)
Sr—Ovii2.731 (3)Pt—O2.031 (3)
Sr—Ptviii3.2080 (2)Pt—Oxvii2.031 (3)
Sr—Ptv3.2081 (2)Pt—Ox2.031 (3)
Sr—Mg3.5236 (5)Pt—Mgxv2.7778 (2)
Sr—Srix3.5865 (2)Pt—Srxviii3.2080 (2)
Mg—Ox2.177 (3)Pt—Srxiv3.2080 (2)
Mg—Oxi2.177 (3)Pt—Sriii3.2080 (2)
Mg—Oi2.177 (3)Pt—Srxix3.2080 (2)
Mg—Oxii2.177 (3)O—Sriii2.637 (3)
Mg—O2.177 (3)O—Srxx2.663 (3)
Mg—Oxiii2.177 (3)O—Srxiv2.731 (3)
Mg—Pt2.7778 (2)
O—Sr—Oi75.35 (14)Oxii—Mg—O146.71 (16)
O—Sr—Oii94.24 (9)Ox—Mg—Oxiii77.78 (12)
Oi—Sr—Oii76.37 (11)Oxi—Mg—Oxiii87.89 (15)
O—Sr—Oiii76.37 (11)Oi—Mg—Oxiii146.71 (16)
Oi—Sr—Oiii94.24 (9)Oxii—Mg—Oxiii128.62 (16)
Oii—Sr—Oiii168.27 (13)O—Mg—Oxiii77.78 (12)
O—Sr—Oiv131.68 (5)Oxv—Pt—Oxvi84.59 (13)
Oi—Sr—Oiv74.68 (12)Oxv—Pt—Oxiii95.41 (13)
Oii—Sr—Oiv114.14 (10)Oxvi—Pt—Oxiii180.0 (2)
Oiii—Sr—Oiv69.07 (12)Oxv—Pt—O180.0 (2)
O—Sr—Ov74.68 (12)Oxvi—Pt—O95.41 (13)
Oi—Sr—Ov131.68 (5)Oxiii—Pt—O84.59 (13)
Oii—Sr—Ov69.07 (12)Oxv—Pt—Oxvii84.59 (13)
Oiii—Sr—Ov114.14 (10)Oxvi—Pt—Oxvii84.59 (13)
Oiv—Sr—Ov150.67 (13)Oxiii—Pt—Oxvii95.41 (13)
O—Sr—Ovi122.00 (4)O—Pt—Oxvii95.41 (13)
Oi—Sr—Ovi140.32 (10)Oxv—Pt—Ox95.41 (13)
Oii—Sr—Ovi130.498 (19)Oxvi—Pt—Ox95.41 (13)
Oiii—Sr—Ovi61.20 (13)Oxiii—Pt—Ox84.59 (13)
Oiv—Sr—Ovi67.69 (11)O—Pt—Ox84.59 (13)
Ov—Sr—Ovi87.93 (9)Oxvii—Pt—Ox180.0 (2)
O—Sr—Ovii140.32 (10)Pt—O—Mg82.54 (11)
Oi—Sr—Ovii122.00 (4)Pt—O—Sr170.33 (16)
Oii—Sr—Ovii61.20 (13)Mg—O—Sr98.38 (11)
Oiii—Sr—Ovii130.498 (19)Pt—O—Sriii85.80 (10)
Oiv—Sr—Ovii87.93 (9)Mg—O—Sriii95.87 (11)
Ov—Sr—Ovii67.69 (11)Sr—O—Sriii103.63 (11)
Ovi—Sr—Ovii69.64 (13)Pt—O—Srxx85.08 (10)
Ox—Mg—Oxi146.71 (16)Mg—O—Srxx167.47 (14)
Ox—Mg—Oi128.62 (16)Sr—O—Srxx93.49 (10)
Oxi—Mg—Oi77.78 (12)Sriii—O—Srxx85.18 (9)
Ox—Mg—Oxii87.89 (15)Pt—O—Srxiv83.32 (10)
Oxi—Mg—Oxii77.78 (12)Mg—O—Srxiv93.22 (10)
Oi—Mg—Oxii77.78 (12)Sr—O—Srxiv87.02 (9)
Ox—Mg—O77.78 (12)Sriii—O—Srxiv164.79 (12)
Oxi—Mg—O128.62 (16)Srxx—O—Srxiv83.34 (9)
Oi—Mg—O87.89 (15)
Symmetry codes: (i) xy, y, z+1/2; (ii) x+y+1/3, y1/3, z+1/6; (iii) x+2/3, y+1/3, z+1/3; (iv) x+y+2/3, x+1/3, z+1/3; (v) y+1/3, x1/3, z+1/6; (vi) y+2/3, x+y+1/3, z+1/3; (vii) x+1/3, xy1/3, z+1/6; (viii) x+2/3, y+1/3, z+1/3; (ix) y+1/3, x+y+2/3, z+2/3; (x) x+y, x, z; (xi) y, x, z+1/2; (xii) x, x+y, z+1/2; (xiii) y, xy, z; (xiv) xy1/3, x2/3, z+1/3; (xv) x, y, z; (xvi) y, x+y, z; (xvii) xy, x, z; (xviii) x+y+1/3, x+2/3, z1/3; (xix) x2/3, y1/3, z1/3; (xx) y+1/3, xy1/3, z1/3.

Experimental details

Crystal data
Chemical formulaSr3MgPtO6
Mr578.26
Crystal system, space groupTrigonal, R3c
Temperature (K)293
a, c (Å)9.6432 (4), 11.1112 (6)
V3)894.82 (7)
Z6
Radiation typeMo Kα
µ (mm1)50.13
Crystal size (mm)0.11 × 0.05 × 0.04
Data collection
DiffractometerBruker SMART APEX CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1999)
Tmin, Tmax0.073, 0.239
No. of measured, independent and
observed [I > 2σ(I)] reflections
2412, 490, 431
Rint0.037
(sin θ/λ)max1)0.833
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.049, 1.01
No. of reflections490
No. of parameters20
Δρmax, Δρmin (e Å3)2.32, 3.12

Computer programs: SMART-NT (Bruker, 1999), SAINT-Plus-NT (Bruker, 1999), SAINT-Plus-NT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ATOMS (Dowty, 2001), SHELXTL (Bruker, 1997).

Selected bond lengths (Å) top
Sr—O2.472 (3)Mg—O2.177 (3)
Sr—Oi2.637 (3)Mg—Pt2.7778 (2)
Sr—Oii2.663 (3)Pt—O2.031 (3)
Sr—Oiii2.731 (3)
Symmetry codes: (i) x+y+1/3, y1/3, z+1/6; (ii) x+y+2/3, x+1/3, z+1/3; (iii) y+2/3, x+y+1/3, z+1/3.
 

Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds