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The title compound contains layers built up from isolated BO3 triangles and MgO6 octa­hedra, inter­leaved with SrO9 polyhedra to form a three-dimensional framework. The Sr atom is nine-coordinate in a distorted tricapped trigonal prismatic geometry. Sr, B and one O atom have m point symmetry and Mg 2/m point symmetry.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807037099/mg2030sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807037099/mg2030Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 113 K
  • Mean [sigma](O-B) = 0.024 Å
  • R factor = 0.065
  • wR factor = 0.153
  • Data-to-parameter ratio = 9.7

checkCIF/PLATON results

No syntax errors found



Alert level C RINTA01_ALERT_3_C The value of Rint is greater than 0.10 Rint given 0.123 PLAT020_ALERT_3_C The value of Rint is greater than 0.10 ......... 0.12 PLAT088_ALERT_3_C Poor Data / Parameter Ratio .................... 9.68 PLAT213_ALERT_2_C Atom O1 has ADP max/min Ratio ............. 3.20 oblat
Alert level G PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 6
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 4 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

Sr2Mg(BO3)2 has been examined as a luminescent host material (Verstegen, 1974; Diaz & Keszler, 1997). Although Diaz & Keszler (1997) alluded to its structure determination and provided cell parameters (a = 9.035 Å, b = 5.146 Å, c = 6.099 Å, β = 118.59°), a full structure report had not appeared to date, to our knowledge. The structure determined here confirms that it is isostructural to Ba2Mg(BO3)2, which has been previously described in detail (Akella & Keszler, 1995). Briefly, MgO6 octahedra and BO3 triangles are connected to form calcite-like layers which are alternately stacked with double layers of Sr atoms (Fig. 1). Each Sr atom is nine-coordinate, in a distorted tricapped trigonal prismatic geometry.

Related literature top

For related literature, see: Akella & Keszler (1995); Diaz & Keszler (1997); Verstegen (1974).

Experimental top

A mixture of 0.3 mol SrCO3, 0.6 mol MgO, 0.6 mol, H3BO3, 0.1 mol SrF2, and 0.7 mol LiF was heated until molten. A Pt thread was dipped into the melt, and the temperature was decreased from 1173 K to 1123 K at 5 K/day, during which time crystals grew on the Pt thread. Upon cooling to room temperature at 20 K/h, block-shaped colourless crystals with dimensions up to 25×15×13 mm3 were obtained. The crystal used for the data collection was a fragment of the larger crystal.

Refinement top

The maximum peak and deepest hole are located 1.40 Å and 1.23 Å, respectively, from Sr.

Structure description top

Sr2Mg(BO3)2 has been examined as a luminescent host material (Verstegen, 1974; Diaz & Keszler, 1997). Although Diaz & Keszler (1997) alluded to its structure determination and provided cell parameters (a = 9.035 Å, b = 5.146 Å, c = 6.099 Å, β = 118.59°), a full structure report had not appeared to date, to our knowledge. The structure determined here confirms that it is isostructural to Ba2Mg(BO3)2, which has been previously described in detail (Akella & Keszler, 1995). Briefly, MgO6 octahedra and BO3 triangles are connected to form calcite-like layers which are alternately stacked with double layers of Sr atoms (Fig. 1). Each Sr atom is nine-coordinate, in a distorted tricapped trigonal prismatic geometry.

For related literature, see: Akella & Keszler (1995); Diaz & Keszler (1997); Verstegen (1974).

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2004).

Figures top
[Figure 1] Fig. 1. Sr2Mg(BO3)2 viewed down the [010] direction. Displacement ellipsoids are drawn at the 80% probability level.
Distrontium magnesium diborate top
Crystal data top
Sr2Mg(BO3)2F(000) = 292
Mr = 317.17Dx = 4.217 Mg m3
Monoclinic, C2/mMo Kα radiation, λ = 0.71070 Å
Hall symbol: -C 2yCell parameters from 345 reflections
a = 9.046 (4) Åθ = 3.8–29.8°
b = 5.1579 (18) ŵ = 21.44 mm1
c = 6.103 (3) ÅT = 113 K
β = 118.691 (12)°Prism, colourless
V = 249.81 (19) Å30.34 × 0.22 × 0.20 mm
Z = 2
Data collection top
Rigaku Saturn
diffractometer
329 independent reflections
Radiation source: rotating anode239 reflections with I > 2σ(I)
Confocal monochromatorRint = 0.124
Detector resolution: 7.31 pixels mm-1θmax = 27.9°, θmin = 3.8°
ω scansh = 1111
Absorption correction: numerical
(NUMABS; Rigaku, 2005)
k = 66
Tmin = 0.052, Tmax = 0.100l = 88
1180 measured 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)] = 0.065 w = 1/[σ2(Fo2) + (0.0588P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.153(Δ/σ)max < 0.001
S = 1.14Δρmax = 1.93 e Å3
329 reflectionsΔρmin = 2.76 e Å3
34 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
6 restraintsExtinction coefficient: 0.015 (3)
Crystal data top
Sr2Mg(BO3)2V = 249.81 (19) Å3
Mr = 317.17Z = 2
Monoclinic, C2/mMo Kα radiation
a = 9.046 (4) ŵ = 21.44 mm1
b = 5.1579 (18) ÅT = 113 K
c = 6.103 (3) Å0.34 × 0.22 × 0.20 mm
β = 118.691 (12)°
Data collection top
Rigaku Saturn
diffractometer
329 independent reflections
Absorption correction: numerical
(NUMABS; Rigaku, 2005)
239 reflections with I > 2σ(I)
Tmin = 0.052, Tmax = 0.100Rint = 0.124
1180 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.06534 parameters
wR(F2) = 0.1536 restraints
S = 1.14Δρmax = 1.93 e Å3
329 reflectionsΔρmin = 2.76 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
Sr10.2895 (2)0.00000.8170 (3)0.0101 (9)
Mg10.50000.00000.50000.0100 (19)
O10.0227 (11)0.2346 (16)0.2319 (14)0.013 (2)
O20.2305 (15)0.00000.334 (2)0.014 (3)
B10.065 (3)0.00000.262 (4)0.015 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sr10.0114 (11)0.0111 (13)0.0122 (11)0.0000.0092 (8)0.000
Mg10.008 (5)0.013 (5)0.014 (4)0.0000.009 (4)0.000
O10.017 (5)0.016 (5)0.016 (4)0.004 (4)0.015 (4)0.001 (4)
O20.012 (7)0.009 (8)0.025 (7)0.0000.012 (6)0.000
B10.015 (13)0.018 (14)0.014 (11)0.0000.009 (10)0.000
Geometric parameters (Å, º) top
Sr1—O1i2.585 (8)Mg1—Sr1x3.302 (2)
Sr1—O1ii2.585 (8)Mg1—Sr1viii3.5196 (16)
Sr1—O1iii2.649 (8)Mg1—Sr1xi3.5197 (16)
Sr1—O1iv2.649 (8)Mg1—Sr1vii3.5197 (16)
Sr1—O1v2.654 (9)Mg1—Sr1iv3.5197 (16)
Sr1—O1vi2.654 (8)O1—B11.411 (14)
Sr1—O2vii2.716 (4)O1—Mg1xii2.067 (8)
Sr1—O2iv2.716 (4)O1—Sr1i2.585 (8)
Sr1—O22.730 (13)O1—Sr1iv2.649 (8)
Sr1—B13.00 (2)O1—Sr1xiii2.654 (8)
Sr1—B1i3.01 (2)O2—B11.34 (2)
Sr1—B1vii3.036 (12)O2—Sr1vii2.716 (4)
Mg1—O1iii2.067 (8)O2—Sr1iv2.716 (4)
Mg1—O1viii2.067 (8)B1—O1xiv1.411 (14)
Mg1—O1iv2.067 (8)B1—Sr1i3.01 (2)
Mg1—O1ix2.067 (8)B1—Sr1vii3.036 (12)
Mg1—O2x2.145 (12)B1—Sr1iv3.036 (12)
Mg1—O22.145 (12)
O1i—Sr1—O1ii55.8 (4)O1iii—Mg1—Sr153.3 (2)
O1i—Sr1—O1iii119.65 (7)O1viii—Mg1—Sr1126.7 (2)
O1ii—Sr1—O1iii168.1 (3)O1iv—Mg1—Sr153.3 (2)
O1i—Sr1—O1iv168.1 (3)O1ix—Mg1—Sr1126.7 (2)
O1ii—Sr1—O1iv119.65 (7)O2x—Mg1—Sr1124.6 (4)
O1iii—Sr1—O1iv62.2 (4)O2—Mg1—Sr155.4 (4)
O1i—Sr1—O1v90.2 (3)Sr1x—Mg1—Sr1180.0
O1ii—Sr1—O1v119.07 (18)O1iii—Mg1—Sr1viii46.7 (2)
O1iii—Sr1—O1v70.2 (3)O1viii—Mg1—Sr1viii73.4 (2)
O1iv—Sr1—O1v101.2 (2)O1iv—Mg1—Sr1viii106.6 (2)
O1i—Sr1—O1vi119.07 (18)O1ix—Mg1—Sr1viii133.3 (2)
O1ii—Sr1—O1vi90.2 (3)O2x—Mg1—Sr1viii50.46 (11)
O1iii—Sr1—O1vi101.2 (2)O2—Mg1—Sr1viii129.54 (11)
O1iv—Sr1—O1vi70.2 (3)Sr1x—Mg1—Sr1viii80.56 (5)
O1v—Sr1—O1vi62.1 (4)Sr1—Mg1—Sr1viii99.44 (5)
O1i—Sr1—O2vii67.1 (3)O1iii—Mg1—Sr1xi106.6 (2)
O1ii—Sr1—O2vii119.9 (3)O1viii—Mg1—Sr1xi133.3 (2)
O1iii—Sr1—O2vii53.0 (3)O1iv—Mg1—Sr1xi46.7 (2)
O1iv—Sr1—O2vii112.3 (3)O1ix—Mg1—Sr1xi73.4 (2)
O1v—Sr1—O2vii75.1 (3)O2x—Mg1—Sr1xi50.46 (11)
O1vi—Sr1—O2vii136.2 (3)O2—Mg1—Sr1xi129.54 (11)
O1i—Sr1—O2iv119.9 (3)Sr1x—Mg1—Sr1xi80.56 (5)
O1ii—Sr1—O2iv67.1 (3)Sr1—Mg1—Sr1xi99.44 (5)
O1iii—Sr1—O2iv112.3 (3)Sr1viii—Mg1—Sr1xi94.23 (5)
O1iv—Sr1—O2iv53.0 (3)O1iii—Mg1—Sr1vii73.4 (2)
O1v—Sr1—O2iv136.2 (3)O1viii—Mg1—Sr1vii46.7 (2)
O1vi—Sr1—O2iv75.1 (3)O1iv—Mg1—Sr1vii133.3 (2)
O2vii—Sr1—O2iv143.5 (5)O1ix—Mg1—Sr1vii106.6 (2)
O1i—Sr1—O2100.8 (3)O2x—Mg1—Sr1vii129.55 (11)
O1ii—Sr1—O2100.8 (3)O2—Mg1—Sr1vii50.46 (11)
O1iii—Sr1—O268.4 (3)Sr1x—Mg1—Sr1vii99.44 (5)
O1iv—Sr1—O268.4 (3)Sr1—Mg1—Sr1vii80.56 (5)
O1v—Sr1—O2137.2 (3)Sr1viii—Mg1—Sr1vii85.77 (5)
O1vi—Sr1—O2137.2 (3)Sr1xi—Mg1—Sr1vii180.0
O2vii—Sr1—O271.7 (3)O1iii—Mg1—Sr1iv133.3 (2)
O2iv—Sr1—O271.7 (3)O1viii—Mg1—Sr1iv106.6 (2)
O1i—Sr1—B177.4 (4)O1iv—Mg1—Sr1iv73.4 (2)
O1ii—Sr1—B177.4 (4)O1ix—Mg1—Sr1iv46.7 (2)
O1iii—Sr1—B190.9 (4)O2x—Mg1—Sr1iv129.54 (11)
O1iv—Sr1—B190.9 (4)O2—Mg1—Sr1iv50.46 (11)
O1v—Sr1—B1148.65 (19)Sr1x—Mg1—Sr1iv99.44 (5)
O1vi—Sr1—B1148.65 (19)Sr1—Mg1—Sr1iv80.56 (5)
O2vii—Sr1—B173.6 (3)Sr1viii—Mg1—Sr1iv180.0
O2iv—Sr1—B173.6 (3)Sr1xi—Mg1—Sr1iv85.77 (5)
O2—Sr1—B126.5 (5)Sr1vii—Mg1—Sr1iv94.23 (5)
O1i—Sr1—B1i27.94 (19)B1—O1—Mg1xii128.9 (10)
O1ii—Sr1—B1i27.94 (19)B1—O1—Sr1i92.9 (9)
O1iii—Sr1—B1i145.9 (2)Mg1xii—O1—Sr1i97.7 (3)
O1iv—Sr1—B1i145.9 (2)B1—O1—Sr1iv91.6 (9)
O1v—Sr1—B1i107.4 (4)Mg1xii—O1—Sr1iv88.0 (3)
O1vi—Sr1—B1i107.4 (4)Sr1i—O1—Sr1iv168.1 (3)
O2vii—Sr1—B1i93.1 (3)B1—O1—Sr1xiii129.1 (10)
O2iv—Sr1—B1i93.1 (3)Mg1xii—O1—Sr1xiii100.9 (3)
O2—Sr1—B1i100.7 (5)Sr1i—O1—Sr1xiii89.8 (3)
B1—Sr1—B1i74.2 (7)Sr1iv—O1—Sr1xiii78.8 (2)
O1i—Sr1—B1vii92.0 (4)B1—O2—Mg1172.3 (13)
O1ii—Sr1—B1vii146.1 (4)B1—O2—Sr1vii90.4 (4)
O1iii—Sr1—B1vii27.7 (4)Mg1—O2—Sr1vii92.0 (3)
O1iv—Sr1—B1vii89.6 (4)B1—O2—Sr1iv90.4 (4)
O1v—Sr1—B1vii65.6 (4)Mg1—O2—Sr1iv92.0 (3)
O1vi—Sr1—B1vii117.6 (5)Sr1vii—O2—Sr1iv143.5 (5)
O2vii—Sr1—B1vii26.2 (4)B1—O2—Sr187.9 (11)
O2iv—Sr1—B1vii135.7 (4)Mg1—O2—Sr184.4 (4)
O2—Sr1—B1vii72.7 (4)Sr1vii—O2—Sr1108.3 (3)
B1—Sr1—B1vii86.0 (5)Sr1iv—O2—Sr1108.3 (3)
B1i—Sr1—B1vii118.9 (4)O2—B1—O1xiv120.9 (9)
O1iii—Mg1—O1viii97.0 (4)O2—B1—O1120.9 (9)
O1iii—Mg1—O1iv83.0 (4)O1xiv—B1—O1118.0 (17)
O1viii—Mg1—O1iv179.998 (1)O2—B1—Sr165.6 (10)
O1iii—Mg1—O1ix180.0O1xiv—B1—Sr1100.5 (9)
O1viii—Mg1—O1ix83.0 (4)O1—B1—Sr1100.5 (9)
O1iv—Mg1—O1ix97.0 (4)O2—B1—Sr1i171.4 (14)
O1iii—Mg1—O2x88.2 (4)O1xiv—B1—Sr1i59.1 (9)
O1viii—Mg1—O2x91.8 (4)O1—B1—Sr1i59.1 (9)
O1iv—Mg1—O2x88.2 (4)Sr1—B1—Sr1i105.8 (7)
O1ix—Mg1—O2x91.8 (4)O2—B1—Sr1vii63.4 (5)
O1iii—Mg1—O291.8 (4)O1xiv—B1—Sr1vii60.7 (6)
O1viii—Mg1—O288.2 (4)O1—B1—Sr1vii165.3 (13)
O1iv—Mg1—O291.8 (4)Sr1—B1—Sr1vii94.0 (5)
O1ix—Mg1—O288.2 (4)Sr1i—B1—Sr1vii118.9 (4)
O2x—Mg1—O2180.0O2—B1—Sr1iv63.4 (5)
O1iii—Mg1—Sr1x126.7 (2)O1xiv—B1—Sr1iv165.3 (13)
O1viii—Mg1—Sr1x53.3 (2)O1—B1—Sr1iv60.7 (6)
O1iv—Mg1—Sr1x126.7 (2)Sr1—B1—Sr1iv94.0 (5)
O1ix—Mg1—Sr1x53.3 (2)Sr1i—B1—Sr1iv118.9 (4)
O2x—Mg1—Sr1x55.4 (4)Sr1vii—B1—Sr1iv116.3 (7)
O2—Mg1—Sr1x124.6 (4)
Symmetry codes: (i) x, y, z+1; (ii) x, y, z+1; (iii) x+1/2, y+1/2, z+1; (iv) x+1/2, y1/2, z+1; (v) x+1/2, y+1/2, z+1; (vi) x+1/2, y1/2, z+1; (vii) x+1/2, y+1/2, z+1; (viii) x+1/2, y+1/2, z; (ix) x+1/2, y1/2, z; (x) x+1, y, z+1; (xi) x+1/2, y1/2, z; (xii) x1/2, y1/2, z; (xiii) x1/2, y1/2, z1; (xiv) x, y, z.

Experimental details

Crystal data
Chemical formulaSr2Mg(BO3)2
Mr317.17
Crystal system, space groupMonoclinic, C2/m
Temperature (K)113
a, b, c (Å)9.046 (4), 5.1579 (18), 6.103 (3)
β (°) 118.691 (12)
V3)249.81 (19)
Z2
Radiation typeMo Kα
µ (mm1)21.44
Crystal size (mm)0.34 × 0.22 × 0.20
Data collection
DiffractometerRigaku Saturn
Absorption correctionNumerical
(NUMABS; Rigaku, 2005)
Tmin, Tmax0.052, 0.100
No. of measured, independent and
observed [I > 2σ(I)] reflections
1180, 329, 239
Rint0.124
(sin θ/λ)max1)0.657
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.065, 0.153, 1.14
No. of reflections329
No. of parameters34
No. of restraints6
Δρmax, Δρmin (e Å3)1.93, 2.76

Computer programs: CrystalClear (Rigaku, 2005), CrystalClear, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1999), CrystalStructure (Rigaku/MSC, 2004).

Selected bond lengths (Å) top
Sr1—O1i2.585 (8)Mg1—O1ii2.067 (8)
Sr1—O1ii2.649 (8)Mg1—O2v2.145 (12)
Sr1—O1iii2.654 (9)O1—B11.411 (14)
Sr1—O2iv2.716 (4)O2—B11.34 (2)
Sr1—O22.730 (13)
Symmetry codes: (i) x, y, z+1; (ii) x+1/2, y+1/2, z+1; (iii) x+1/2, y+1/2, z+1; (iv) x+1/2, y+1/2, z+1; (v) x+1, y, z+1.
 

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