Acta Cryst. (2007). E63, i175 [ doi:10.1107/S1600536807037099 ]
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.
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.
The maximum peak and deepest hole are located 1.40 Å and 1.23 Å, respectively, from Sr.
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).
![[Figure 1]](./mg2030fig1thm.gif)
| Fig. 1. Sr2Mg(BO3)2 viewed down the [010] direction. Displacement ellipsoids are drawn at the 80% probability level. |
| Sr2Mg(BO3)2 | F000 = 292 |
| Mr = 317.17 | Dx = 4.217 Mg m−3 |
| Monoclinic, C2/m | Mo Kα radiation λ = 0.71070 Å |
| Hall symbol: -C 2y | Cell parameters from 345 reflections |
| a = 9.046 (4) Å | θ = 3.8–29.8º |
| b = 5.1579 (18) Å | µ = 21.44 mm−1 |
| c = 6.103 (3) Å | T = 113 (2) K |
| β = 118.691 (12)º | Prism, colourless |
| V = 249.81 (19) Å3 | 0.34 × 0.22 × 0.20 mm |
| Z = 2 |
| Rigaku Saturn diffractometer | 329 independent reflections |
| Radiation source: rotating anode | 239 reflections with I > 2σ(I) |
| Monochromator: confocal | Rint = 0.124 |
| T = 113(2) K | θmax = 27.9º |
| ω scans | θmin = 3.8º |
| Absorption correction: numerical (NUMABS; Rigaku, 2005) | h = −11→11 |
| Tmin = 0.052, Tmax = 0.100 | k = −6→6 |
| 1180 measured reflections | l = −8→8 |
| 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)] = 0.065 | w = 1/[σ2(Fo2) + (0.0588P)2] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.153 | (Δ/σ)max < 0.001 |
| S = 1.14 | Δρmax = 1.93 e Å−3 |
| 329 reflections | Δρmin = −2.76 e Å−3 |
| 34 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| 6 restraints | Extinction coefficient: 0.015 (3) |
| Sr2Mg(BO3)2 | V = 249.81 (19) Å3 |
| Mr = 317.17 | Z = 2 |
| Monoclinic, C2/m | Mo Kα |
| a = 9.046 (4) Å | µ = 21.44 mm−1 |
| b = 5.1579 (18) Å | T = 113 (2) K |
| c = 6.103 (3) Å | 0.34 × 0.22 × 0.20 mm |
| β = 118.691 (12)º |
| Rigaku Saturn diffractometer | 329 independent reflections |
| Absorption correction: numerical (NUMABS; Rigaku, 2005) | 239 reflections with I > 2σ(I) |
| Tmin = 0.052, Tmax = 0.100 | Rint = 0.124 |
| 1180 measured reflections |
| R[F2 > 2σ(F2)] = 0.065 | 34 parameters |
| wR(F2) = 0.153 | 6 restraints |
| S = 1.14 | Δρmax = 1.93 e Å−3 |
| 329 reflections | Δρmin = −2.76 e Å−3 |
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 > 2sigma(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 | ||
| Sr1 | 0.2895 (2) | 0.0000 | 0.8170 (3) | 0.0101 (9) | |
| Mg1 | 0.5000 | 0.0000 | 0.5000 | 0.0100 (19) | |
| O1 | −0.0227 (11) | −0.2346 (16) | 0.2319 (14) | 0.013 (2) | |
| O2 | 0.2305 (15) | 0.0000 | 0.334 (2) | 0.014 (3) | |
| B1 | 0.065 (3) | 0.0000 | 0.262 (4) | 0.015 (5) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Sr1 | 0.0114 (11) | 0.0111 (13) | 0.0122 (11) | 0.000 | 0.0092 (8) | 0.000 |
| Mg1 | 0.008 (5) | 0.013 (5) | 0.014 (4) | 0.000 | 0.009 (4) | 0.000 |
| O1 | 0.017 (5) | 0.016 (5) | 0.016 (4) | 0.004 (4) | 0.015 (4) | 0.001 (4) |
| O2 | 0.012 (7) | 0.009 (8) | 0.025 (7) | 0.000 | 0.012 (6) | 0.000 |
| B1 | 0.015 (13) | 0.018 (14) | 0.014 (11) | 0.000 | 0.009 (10) | 0.000 |
| Sr1—O1i | 2.585 (8) | Mg1—Sr1x | 3.302 (2) |
| Sr1—O1ii | 2.585 (8) | Mg1—Sr1viii | 3.5196 (16) |
| Sr1—O1iii | 2.649 (8) | Mg1—Sr1xi | 3.5197 (16) |
| Sr1—O1iv | 2.649 (8) | Mg1—Sr1vii | 3.5197 (16) |
| Sr1—O1v | 2.654 (9) | Mg1—Sr1iv | 3.5197 (16) |
| Sr1—O1vi | 2.654 (8) | O1—B1 | 1.411 (14) |
| Sr1—O2vii | 2.716 (4) | O1—Mg1xii | 2.067 (8) |
| Sr1—O2iv | 2.716 (4) | O1—Sr1i | 2.585 (8) |
| Sr1—O2 | 2.730 (13) | O1—Sr1iv | 2.649 (8) |
| Sr1—B1 | 3.00 (2) | O1—Sr1xiii | 2.654 (8) |
| Sr1—B1i | 3.01 (2) | O2—B1 | 1.34 (2) |
| Sr1—B1vii | 3.036 (12) | O2—Sr1vii | 2.716 (4) |
| Mg1—O1iii | 2.067 (8) | O2—Sr1iv | 2.716 (4) |
| Mg1—O1viii | 2.067 (8) | B1—O1xiv | 1.411 (14) |
| Mg1—O1iv | 2.067 (8) | B1—Sr1i | 3.01 (2) |
| Mg1—O1ix | 2.067 (8) | B1—Sr1vii | 3.036 (12) |
| Mg1—O2x | 2.145 (12) | B1—Sr1iv | 3.036 (12) |
| Mg1—O2 | 2.145 (12) | ||
| O1i—Sr1—O1ii | 55.8 (4) | O1iii—Mg1—Sr1 | 53.3 (2) |
| O1i—Sr1—O1iii | 119.65 (7) | O1viii—Mg1—Sr1 | 126.7 (2) |
| O1ii—Sr1—O1iii | 168.1 (3) | O1iv—Mg1—Sr1 | 53.3 (2) |
| O1i—Sr1—O1iv | 168.1 (3) | O1ix—Mg1—Sr1 | 126.7 (2) |
| O1ii—Sr1—O1iv | 119.65 (7) | O2x—Mg1—Sr1 | 124.6 (4) |
| O1iii—Sr1—O1iv | 62.2 (4) | O2—Mg1—Sr1 | 55.4 (4) |
| O1i—Sr1—O1v | 90.2 (3) | Sr1x—Mg1—Sr1 | 180.0 |
| O1ii—Sr1—O1v | 119.07 (18) | O1iii—Mg1—Sr1viii | 46.7 (2) |
| O1iii—Sr1—O1v | 70.2 (3) | O1viii—Mg1—Sr1viii | 73.4 (2) |
| O1iv—Sr1—O1v | 101.2 (2) | O1iv—Mg1—Sr1viii | 106.6 (2) |
| O1i—Sr1—O1vi | 119.07 (18) | O1ix—Mg1—Sr1viii | 133.3 (2) |
| O1ii—Sr1—O1vi | 90.2 (3) | O2x—Mg1—Sr1viii | 50.46 (11) |
| O1iii—Sr1—O1vi | 101.2 (2) | O2—Mg1—Sr1viii | 129.54 (11) |
| O1iv—Sr1—O1vi | 70.2 (3) | Sr1x—Mg1—Sr1viii | 80.56 (5) |
| O1v—Sr1—O1vi | 62.1 (4) | Sr1—Mg1—Sr1viii | 99.44 (5) |
| O1i—Sr1—O2vii | 67.1 (3) | O1iii—Mg1—Sr1xi | 106.6 (2) |
| O1ii—Sr1—O2vii | 119.9 (3) | O1viii—Mg1—Sr1xi | 133.3 (2) |
| O1iii—Sr1—O2vii | 53.0 (3) | O1iv—Mg1—Sr1xi | 46.7 (2) |
| O1iv—Sr1—O2vii | 112.3 (3) | O1ix—Mg1—Sr1xi | 73.4 (2) |
| O1v—Sr1—O2vii | 75.1 (3) | O2x—Mg1—Sr1xi | 50.46 (11) |
| O1vi—Sr1—O2vii | 136.2 (3) | O2—Mg1—Sr1xi | 129.54 (11) |
| O1i—Sr1—O2iv | 119.9 (3) | Sr1x—Mg1—Sr1xi | 80.56 (5) |
| O1ii—Sr1—O2iv | 67.1 (3) | Sr1—Mg1—Sr1xi | 99.44 (5) |
| O1iii—Sr1—O2iv | 112.3 (3) | Sr1viii—Mg1—Sr1xi | 94.23 (5) |
| O1iv—Sr1—O2iv | 53.0 (3) | O1iii—Mg1—Sr1vii | 73.4 (2) |
| O1v—Sr1—O2iv | 136.2 (3) | O1viii—Mg1—Sr1vii | 46.7 (2) |
| O1vi—Sr1—O2iv | 75.1 (3) | O1iv—Mg1—Sr1vii | 133.3 (2) |
| O2vii—Sr1—O2iv | 143.5 (5) | O1ix—Mg1—Sr1vii | 106.6 (2) |
| O1i—Sr1—O2 | 100.8 (3) | O2x—Mg1—Sr1vii | 129.55 (11) |
| O1ii—Sr1—O2 | 100.8 (3) | O2—Mg1—Sr1vii | 50.46 (11) |
| O1iii—Sr1—O2 | 68.4 (3) | Sr1x—Mg1—Sr1vii | 99.44 (5) |
| O1iv—Sr1—O2 | 68.4 (3) | Sr1—Mg1—Sr1vii | 80.56 (5) |
| O1v—Sr1—O2 | 137.2 (3) | Sr1viii—Mg1—Sr1vii | 85.77 (5) |
| O1vi—Sr1—O2 | 137.2 (3) | Sr1xi—Mg1—Sr1vii | 180.0 |
| O2vii—Sr1—O2 | 71.7 (3) | O1iii—Mg1—Sr1iv | 133.3 (2) |
| O2iv—Sr1—O2 | 71.7 (3) | O1viii—Mg1—Sr1iv | 106.6 (2) |
| O1i—Sr1—B1 | 77.4 (4) | O1iv—Mg1—Sr1iv | 73.4 (2) |
| O1ii—Sr1—B1 | 77.4 (4) | O1ix—Mg1—Sr1iv | 46.7 (2) |
| O1iii—Sr1—B1 | 90.9 (4) | O2x—Mg1—Sr1iv | 129.54 (11) |
| O1iv—Sr1—B1 | 90.9 (4) | O2—Mg1—Sr1iv | 50.46 (11) |
| O1v—Sr1—B1 | 148.65 (19) | Sr1x—Mg1—Sr1iv | 99.44 (5) |
| O1vi—Sr1—B1 | 148.65 (19) | Sr1—Mg1—Sr1iv | 80.56 (5) |
| O2vii—Sr1—B1 | 73.6 (3) | Sr1viii—Mg1—Sr1iv | 180.0 |
| O2iv—Sr1—B1 | 73.6 (3) | Sr1xi—Mg1—Sr1iv | 85.77 (5) |
| O2—Sr1—B1 | 26.5 (5) | Sr1vii—Mg1—Sr1iv | 94.23 (5) |
| O1i—Sr1—B1i | 27.94 (19) | B1—O1—Mg1xii | 128.9 (10) |
| O1ii—Sr1—B1i | 27.94 (19) | B1—O1—Sr1i | 92.9 (9) |
| O1iii—Sr1—B1i | 145.9 (2) | Mg1xii—O1—Sr1i | 97.7 (3) |
| O1iv—Sr1—B1i | 145.9 (2) | B1—O1—Sr1iv | 91.6 (9) |
| O1v—Sr1—B1i | 107.4 (4) | Mg1xii—O1—Sr1iv | 88.0 (3) |
| O1vi—Sr1—B1i | 107.4 (4) | Sr1i—O1—Sr1iv | 168.1 (3) |
| O2vii—Sr1—B1i | 93.1 (3) | B1—O1—Sr1xiii | 129.1 (10) |
| O2iv—Sr1—B1i | 93.1 (3) | Mg1xii—O1—Sr1xiii | 100.9 (3) |
| O2—Sr1—B1i | 100.7 (5) | Sr1i—O1—Sr1xiii | 89.8 (3) |
| B1—Sr1—B1i | 74.2 (7) | Sr1iv—O1—Sr1xiii | 78.8 (2) |
| O1i—Sr1—B1vii | 92.0 (4) | B1—O2—Mg1 | 172.3 (13) |
| O1ii—Sr1—B1vii | 146.1 (4) | B1—O2—Sr1vii | 90.4 (4) |
| O1iii—Sr1—B1vii | 27.7 (4) | Mg1—O2—Sr1vii | 92.0 (3) |
| O1iv—Sr1—B1vii | 89.6 (4) | B1—O2—Sr1iv | 90.4 (4) |
| O1v—Sr1—B1vii | 65.6 (4) | Mg1—O2—Sr1iv | 92.0 (3) |
| O1vi—Sr1—B1vii | 117.6 (5) | Sr1vii—O2—Sr1iv | 143.5 (5) |
| O2vii—Sr1—B1vii | 26.2 (4) | B1—O2—Sr1 | 87.9 (11) |
| O2iv—Sr1—B1vii | 135.7 (4) | Mg1—O2—Sr1 | 84.4 (4) |
| O2—Sr1—B1vii | 72.7 (4) | Sr1vii—O2—Sr1 | 108.3 (3) |
| B1—Sr1—B1vii | 86.0 (5) | Sr1iv—O2—Sr1 | 108.3 (3) |
| B1i—Sr1—B1vii | 118.9 (4) | O2—B1—O1xiv | 120.9 (9) |
| O1iii—Mg1—O1viii | 97.0 (4) | O2—B1—O1 | 120.9 (9) |
| O1iii—Mg1—O1iv | 83.0 (4) | O1xiv—B1—O1 | 118.0 (17) |
| O1viii—Mg1—O1iv | 179.998 (1) | O2—B1—Sr1 | 65.6 (10) |
| O1iii—Mg1—O1ix | 180.0 | O1xiv—B1—Sr1 | 100.5 (9) |
| O1viii—Mg1—O1ix | 83.0 (4) | O1—B1—Sr1 | 100.5 (9) |
| O1iv—Mg1—O1ix | 97.0 (4) | O2—B1—Sr1i | 171.4 (14) |
| O1iii—Mg1—O2x | 88.2 (4) | O1xiv—B1—Sr1i | 59.1 (9) |
| O1viii—Mg1—O2x | 91.8 (4) | O1—B1—Sr1i | 59.1 (9) |
| O1iv—Mg1—O2x | 88.2 (4) | Sr1—B1—Sr1i | 105.8 (7) |
| O1ix—Mg1—O2x | 91.8 (4) | O2—B1—Sr1vii | 63.4 (5) |
| O1iii—Mg1—O2 | 91.8 (4) | O1xiv—B1—Sr1vii | 60.7 (6) |
| O1viii—Mg1—O2 | 88.2 (4) | O1—B1—Sr1vii | 165.3 (13) |
| O1iv—Mg1—O2 | 91.8 (4) | Sr1—B1—Sr1vii | 94.0 (5) |
| O1ix—Mg1—O2 | 88.2 (4) | Sr1i—B1—Sr1vii | 118.9 (4) |
| O2x—Mg1—O2 | 180.0 | O2—B1—Sr1iv | 63.4 (5) |
| O1iii—Mg1—Sr1x | 126.7 (2) | O1xiv—B1—Sr1iv | 165.3 (13) |
| O1viii—Mg1—Sr1x | 53.3 (2) | O1—B1—Sr1iv | 60.7 (6) |
| O1iv—Mg1—Sr1x | 126.7 (2) | Sr1—B1—Sr1iv | 94.0 (5) |
| O1ix—Mg1—Sr1x | 53.3 (2) | Sr1i—B1—Sr1iv | 118.9 (4) |
| O2x—Mg1—Sr1x | 55.4 (4) | Sr1vii—B1—Sr1iv | 116.3 (7) |
| O2—Mg1—Sr1x | 124.6 (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, −y−1/2, −z+1; (v) x+1/2, y+1/2, z+1; (vi) x+1/2, −y−1/2, z+1; (vii) −x+1/2, −y+1/2, −z+1; (viii) x+1/2, y+1/2, z; (ix) x+1/2, −y−1/2, z; (x) −x+1, −y, −z+1; (xi) x+1/2, y−1/2, z; (xii) x−1/2, y−1/2, z; (xiii) x−1/2, y−1/2, z−1; (xiv) x, −y, z. |
| Sr1—O1i | 2.585 (8) | Mg1—O1ii | 2.067 (8) |
| Sr1—O1ii | 2.649 (8) | Mg1—O2v | 2.145 (12) |
| Sr1—O1iii | 2.654 (9) | O1—B1 | 1.411 (14) |
| Sr1—O2iv | 2.716 (4) | O2—B1 | 1.34 (2) |
| Sr1—O2 | 2.730 (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. |
This work was supported by the National Natural Science Foundation of China (grant No. 50590402).
Akella, A. & Keszler, D. A. (1995). Main Group Met. Chem. 18, 35–41.
Brandenburg, K. (1999). DIAMOND. Release 2.1c. Crystal Impact GbR, Bonn, Germany.
Diaz, A. & Keszler, D. A. (1997). Chem. Mater. 9, 2071–2077.
Rigaku (2005). CrystalClear (Version 1.3.6) and NUMABS. Rigaku Corporation, Tokyo, Japan.
Rigaku/MSC (2004). CrystalStructure. Version 3.7.0. Rigaku/MSC, The Woodlands, Texas, USA.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.
Verstegen, J. M. P. J. (1974). J. Electrochem. Soc. 121, 1631–1633.
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.