The title compound, calcium oxide-dialuminium trioxide-calcium dibromide-calcium dichloride hydrate (3/1/0.5/0.5/10), also formulated as Ca
2Al(OH)
6Br
0.478Cl
0.522·2H
2O (dicalcium aluminium hydroxide hemibromide hemichloride dihydrate), is a double-layered hydroxide which belongs to the solid solution Ca
2Al(OH)
6Br
xCl
1-x·2H
2O, where
x can vary from 0 to 1. Chloride and bromide anions of the negatively charged interlayer [Br
0.5Cl
0.5·2H
2O]
- share statistically the same crystallographic site. Al
3+ and Ca
2+ cations are coordinated by six and seven O atoms, respectively. All water molecules are bonded to Ca
2+ cations and assume the seventh coordination position. Anions in the interlayer are surrounded by ten H atoms. Br
- and Cl
- are therefore connected to the main layer by ten hydrogen bonds, six of 2.74 (2) Å and four of 2.52 (5) Å, where the donors are hydroxyl groups and water molecules, respectively. Like the chloride equivalent, the title compound is a 6
R polytype with trigonal space group
Rc and lattice parameters
a = 5.7537 (4) Å and
c = 48.108 (4) Å.
Supporting information
Single crystals of the title compound were prepared by hydrothermal synthesis.
The starting powders Ca(OH)2, Al(OH)3, CaCl2·6H2O and
CaBr2·2H2O (molar proportion 2/1/0.5/0.5) are mixed with water (ratio
solid/water = 1/2) and loaded in a silver capsule (length: 100 mm, diameter: 5 mm, thickness: 0.1 mm) sealed under Argon atmosphere. The experiment was
performed during sixty days at 393 K and 2 kbar (1 bar = 10 5Pa).
Chlorine and bromine atoms were located on the same site. The sum of their
occupancy factor is fixed at the unity. H atoms of hydroxyl group and water
molecules were located from a difference Fourier map. The O—H distance is
restrained to 0.95 Å, with a fixed individual isotropic displacement
parameter Uiso = 1.2Ueq(O). The O atom (Ow) of the water
molecule was located on a special site 12(c), whereas its H atom occupy
then general site 36(f), with an occupancy factor of 2/3.
Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO and SCALEPACK; program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 1995); software used to prepare material for publication: WINWORD (Version 5.0).
Crystal data top
AlBr0.478Ca2Cl0.522H10O8 | Dx = 2.182 Mg m−3 |
Mr = 302.01 | Mo Kα radiation, λ = 0.71073 Å |
Trigonal, R3c | Cell parameters from 25 reflections |
Hall symbol: -R 3 2"c | θ = 25–50° |
a = 5.7537 (4) Å | µ = 3.58 mm−1 |
c = 48.108 (4) Å | T = 293 K |
V = 1379.21 (18) Å3 | Plate, colorless |
Z = 6 | 0.20 × 0.15 × 0.04 mm |
F(000) = 916 | |
Data collection top
Nonius B.V. Diffractometer | 516 independent reflections |
Radiation source: fine-focus sealed tube | 390 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
CCD scans | θmax = 31.4°, θmin = 2.5° |
Absorption correction: empirical (using intensity measurements) fitted by spherical harmonic functions (SORTAV; Blessing, 1995) | h = −8→8 |
Tmin = 0.48, Tmax = 0.86 | k = −8→8 |
8579 measured reflections | l = 0→70 |
Refinement top
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)] = 0.038 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.090 | H-atom parameters constrained |
S = 1.05 | Weighting scheme based on measured s.u.'s w = 1/[σ2(Fo2) + (0.0151P)2 + 6.119P] where P = (Fo2 + 2Fc2)/3 |
516 reflections | (Δ/σ)max < 0.001 |
29 parameters | Δρmax = 0.55 e Å−3 |
3 restraints | Δρmin = −0.76 e Å−3 |
Crystal data top
AlBr0.478Ca2Cl0.522H10O8 | Z = 6 |
Mr = 302.01 | Mo Kα radiation |
Trigonal, R3c | µ = 3.58 mm−1 |
a = 5.7537 (4) Å | T = 293 K |
c = 48.108 (4) Å | 0.20 × 0.15 × 0.04 mm |
V = 1379.21 (18) Å3 | |
Data collection top
Nonius B.V. Diffractometer | 516 independent reflections |
Absorption correction: empirical (using intensity measurements) fitted by spherical harmonic functions (SORTAV; Blessing, 1995) | 390 reflections with I > 2σ(I) |
Tmin = 0.48, Tmax = 0.86 | Rint = 0.035 |
8579 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 3 restraints |
wR(F2) = 0.090 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.55 e Å−3 |
516 reflections | Δρmin = −0.76 e Å−3 |
29 parameters | |
Special details top
Experimental. The cristal to detector distance was of 40.0 (1) mm. 320 frames were recorded by
oscillation method with an exposure time of 60 secondes per frame. |
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 | x | y | z | Uiso*/Ueq | Occ. (<1) |
Al | 0.0000 | 0.0000 | 0.0000 | 0.0136 (3) | |
Ca | 0.3333 | 0.6667 | 0.012218 (19) | 0.0161 (2) | |
Br | 0.6667 | 0.3333 | 0.0833 | 0.048 (3) | 0.478 (8) |
Cl | 0.6667 | 0.3333 | 0.0833 | 0.061 (8) | 0.522 (8) |
O | 0.3067 (3) | 0.2507 (3) | 0.02080 (4) | 0.0165 (4) | |
H | 0.329 (6) | 0.206 (6) | 0.0386 (4) | 0.021* | |
OW | 0.3333 | 0.6667 | 0.0640 (11) | 0.0539 (12) | |
HW | 0.438 (12) | 0.597 (7) | 0.0713 (13) | 0.066* | 0.6667 |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Al | 0.0075 (4) | 0.0075 (4) | 0.0257 (9) | 0.0038 (2) | 0.000 | 0.000 |
Ca | 0.0095 (2) | 0.0095 (2) | 0.0294 (5) | 0.00477 (12) | 0.000 | 0.000 |
Br | 0.054 (3) | 0.054 (3) | 0.035 (4) | 0.0271 (13) | 0.000 | 0.000 |
Cl | 0.085 (10) | 0.085 (10) | 0.011 (5) | 0.043 (5) | 0.000 | 0.000 |
O | 0.0116 (7) | 0.0126 (8) | 0.0245 (9) | 0.0054 (6) | −0.0020 (6) | 0.001 |
OW | 0.0605 (19) | 0.0605 (19) | 0.041 (2) | 0.0303 (9) | 0.000 | 0.000 |
Geometric parameters (Å, º) top
Al—O | 1.9105 (16) | Ca—Oxi | 2.3568 (18) |
Al—Oi | 1.9105 (16) | Ca—O | 2.3568 (18) |
Al—Oii | 1.9105 (16) | Ca—Oxii | 2.4608 (18) |
Al—Oiii | 1.9105 (16) | Ca—Oiv | 2.4608 (18) |
Al—Oiv | 1.9105 (16) | Ca—Oviii | 2.4608 (18) |
Al—Ov | 1.9105 (16) | Ca—OW | 2.492 (5) |
Al—Cavi | 3.3735 (3) | Ca—Alxiii | 3.3735 (3) |
Al—Cavii | 3.3735 (3) | Ca—Alxiv | 3.3735 (3) |
Al—Caiii | 3.3735 (3) | Ca—Cavi | 3.5238 (6) |
Al—Ca | 3.3735 (3) | Ca—Caxv | 3.5238 (6) |
Al—Caviii | 3.3735 (3) | O—Caviii | 2.4607 (18) |
Al—Caix | 3.3735 (3) | O—H | 0.923 (18) |
Ca—Ox | 2.3568 (18) | OW—HW | 0.94 (2) |
| | | |
O—Al—Oi | 95.08 (7) | Oxi—Ca—Oxii | 86.01 (6) |
O—Al—Oii | 95.08 (7) | O—Ca—Oxii | 146.73 (5) |
Oi—Al—Oii | 95.08 (7) | Ox—Ca—Oiv | 86.01 (6) |
O—Al—Oiii | 180.0 | Oxi—Ca—Oiv | 146.73 (5) |
Oi—Al—Oiii | 84.92 (7) | O—Ca—Oiv | 64.71 (8) |
Oii—Al—Oiii | 84.92 (7) | Oxii—Ca—Oiv | 82.82 (7) |
O—Al—Oiv | 84.92 (7) | Ox—Ca—Oviii | 146.73 (5) |
Oi—Al—Oiv | 84.92 (7) | Oxi—Ca—Oviii | 64.71 (8) |
Oii—Al—Oiv | 180.0 | O—Ca—Oviii | 86.01 (6) |
Oiii—Al—Oiv | 95.08 (7) | Oxii—Ca—Oviii | 82.82 (7) |
O—Al—Ov | 84.92 (7) | Oiv—Ca—Oviii | 82.82 (7) |
Oi—Al—Ov | 180.0 | Ox—Ca—OW | 79.91 (5) |
Oii—Al—Ov | 84.92 (7) | Oxi—Ca—OW | 79.91 (5) |
Oiii—Al—Ov | 95.08 (7) | O—Ca—OW | 79.91 (5) |
Oiv—Al—Ov | 95.08 (7) | Oxii—Ca—OW | 130.20 (4) |
O—Al—Cavi | 103.59 (5) | Oiv—Ca—OW | 130.20 (4) |
Oi—Al—Cavi | 45.87 (5) | Oviii—Ca—OW | 130.20 (4) |
Oii—Al—Cavi | 137.32 (5) | Ox—Ca—Alxiii | 33.34 (4) |
Oiii—Al—Cavi | 76.41 (5) | Oxi—Ca—Alxiii | 94.94 (4) |
Oiv—Al—Cavi | 42.68 (5) | O—Ca—Alxiii | 147.24 (4) |
Ov—Al—Cavi | 134.13 (5) | Oxii—Ca—Alxiii | 33.87 (4) |
O—Al—Cavii | 76.41 (5) | Oiv—Ca—Alxiii | 93.00 (4) |
Oi—Al—Cavii | 134.13 (5) | Oviii—Ca—Alxiii | 116.14 (5) |
Oii—Al—Cavii | 42.68 (5) | OW—Ca—Alxiii | 100.034 (15) |
Oiii—Al—Cavii | 103.59 (5) | Ox—Ca—Al | 94.94 (4) |
Oiv—Al—Cavii | 137.32 (5) | Oxi—Ca—Al | 147.24 (4) |
Ov—Al—Cavii | 45.87 (5) | O—Ca—Al | 33.34 (4) |
Cavi—Al—Cavii | 180.0 | Oxii—Ca—Al | 116.14 (5) |
O—Al—Caiii | 137.32 (5) | Oiv—Ca—Al | 33.87 (4) |
Oi—Al—Caiii | 103.59 (5) | Oviii—Ca—Al | 93.00 (4) |
Oii—Al—Caiii | 45.87 (5) | OW—Ca—Al | 100.034 (15) |
Oiii—Al—Caiii | 42.68 (5) | Alxiii—Ca—Al | 117.030 (9) |
Oiv—Al—Caiii | 134.13 (5) | Ox—Ca—Alxiv | 147.24 (4) |
Ov—Al—Caiii | 76.41 (5) | Oxi—Ca—Alxiv | 33.34 (4) |
Cavi—Al—Caiii | 117.030 (9) | O—Ca—Alxiv | 94.94 (4) |
Cavii—Al—Caiii | 62.970 (9) | Oxii—Ca—Alxiv | 93.00 (4) |
O—Al—Ca | 42.68 (5) | Oiv—Ca—Alxiv | 116.14 (5) |
Oi—Al—Ca | 76.41 (5) | Oviii—Ca—Alxiv | 33.87 (4) |
Oii—Al—Ca | 134.13 (5) | OW—Ca—Alxiv | 100.034 (15) |
Oiii—Al—Ca | 137.32 (5) | Alxiii—Ca—Alxiv | 117.030 (9) |
Oiv—Al—Ca | 45.87 (5) | Al—Ca—Alxiv | 117.030 (9) |
Ov—Al—Ca | 103.59 (5) | Ox—Ca—Cavi | 44.16 (4) |
Cavi—Al—Ca | 62.970 (9) | Oxi—Ca—Cavi | 152.56 (4) |
Cavii—Al—Ca | 117.030 (9) | O—Ca—Cavi | 90.30 (4) |
Caiii—Al—Ca | 180.0 | Oxii—Ca—Cavi | 68.09 (4) |
O—Al—Caviii | 45.87 (5) | Oiv—Ca—Cavi | 41.85 (4) |
Oi—Al—Caviii | 137.32 (5) | Oviii—Ca—Cavi | 118.16 (6) |
Oii—Al—Caviii | 103.59 (5) | OW—Ca—Cavi | 109.49 (3) |
Oiii—Al—Caviii | 134.13 (5) | Alxiii—Ca—Cavi | 58.515 (4) |
Oiv—Al—Caviii | 76.41 (5) | Al—Ca—Cavi | 58.515 (4) |
Ov—Al—Caviii | 42.68 (5) | Alxiv—Ca—Cavi | 150.48 (4) |
Cavi—Al—Caviii | 117.030 (9) | Ox—Ca—Caxv | 90.30 (4) |
Cavii—Al—Caviii | 62.970 (9) | Oxi—Ca—Caxv | 44.16 (4) |
Caiii—Al—Caviii | 117.030 (9) | O—Ca—Caxv | 152.56 (4) |
Ca—Al—Caviii | 62.970 (9) | Oxii—Ca—Caxv | 41.85 (4) |
O—Al—Caix | 134.13 (5) | Oiv—Ca—Caxv | 118.16 (6) |
Oi—Al—Caix | 42.68 (5) | Oviii—Ca—Caxv | 68.09 (4) |
Oii—Al—Caix | 76.41 (5) | OW—Ca—Caxv | 109.49 (3) |
Oiii—Al—Caix | 45.87 (5) | Alxiii—Ca—Caxv | 58.515 (4) |
Oiv—Al—Caix | 103.59 (5) | Al—Ca—Caxv | 150.48 (4) |
Ov—Al—Caix | 137.32 (5) | Alxiv—Ca—Caxv | 58.515 (4) |
Cavi—Al—Caix | 62.970 (9) | Cavi—Ca—Caxv | 109.45 (3) |
Cavii—Al—Caix | 117.030 (9) | Al—O—Ca | 103.98 (8) |
Caiii—Al—Caix | 62.970 (9) | Al—O—Caviii | 100.26 (8) |
Ca—Al—Caix | 117.030 (9) | Ca—O—Caviii | 93.99 (6) |
Caviii—Al—Caix | 180.0 | Al—O—H | 118.7 (19) |
Ox—Ca—Oxi | 117.00 (3) | Ca—O—H | 120.0 (19) |
Ox—Ca—O | 117.00 (3) | Caviii—O—H | 115.6 (19) |
Oxi—Ca—O | 117.00 (3) | Ca—OW—HW | 112 (4) |
Ox—Ca—Oxii | 64.71 (8) | | |
Symmetry codes: (i) −y, x−y, z; (ii) −x+y, −x, z; (iii) −x, −y, −z; (iv) x−y, x, −z; (v) y, −x+y, −z; (vi) −x, −y+1, −z; (vii) x, y−1, z; (viii) −x+1, −y+1, −z; (ix) x−1, y−1, z; (x) −x+y, −x+1, z; (xi) −y+1, x−y+1, z; (xii) y, −x+y+1, −z; (xiii) x, y+1, z; (xiv) x+1, y+1, z; (xv) −x+1, −y+2, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O—H···Br | 0.92 (2) | 2.74 (2) | 3.547 (3) | 146 (5) |
OW—HW···Br | 0.94 (2) | 2.52 (5) | 3.449 (3) | 167 (9) |
Experimental details
Crystal data |
Chemical formula | AlBr0.478Ca2Cl0.522H10O8 |
Mr | 302.01 |
Crystal system, space group | Trigonal, R3c |
Temperature (K) | 293 |
a, c (Å) | 5.7537 (4), 48.108 (4) |
V (Å3) | 1379.21 (18) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 3.58 |
Crystal size (mm) | 0.20 × 0.15 × 0.04 |
|
Data collection |
Diffractometer | Nonius B.V. Diffractometer |
Absorption correction | Empirical (using intensity measurements) fitted by spherical harmonic functions (SORTAV; Blessing, 1995) |
Tmin, Tmax | 0.48, 0.86 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8579, 516, 390 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.733 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.090, 1.05 |
No. of reflections | 516 |
No. of parameters | 29 |
No. of restraints | 3 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.55, −0.76 |
Selected bond lengths (Å) topAl—O | 1.9105 (16) | Ca—O | 2.3568 (18) |
Al—Oi | 1.9105 (16) | Ca—Oviii | 2.4608 (18) |
Al—Oii | 1.9105 (16) | Ca—Oiv | 2.4608 (18) |
Al—Oiii | 1.9105 (16) | Ca—Oix | 2.4608 (18) |
Al—Oiv | 1.9105 (16) | Ca—OW | 2.492 (5) |
Al—Ov | 1.9105 (16) | O—H | 0.923 (18) |
Ca—Ovi | 2.3568 (18) | OW—HW | 0.94 (2) |
Ca—Ovii | 2.3568 (18) | | |
Symmetry codes: (i) −y, x−y, z; (ii) −x+y, −x, z; (iii) −x, −y, −z; (iv) x−y, x, −z; (v) y, −x+y, −z; (vi) −x+y, −x+1, z; (vii) −y+1, x−y+1, z; (viii) y, −x+y+1, −z; (ix) −x+1, −y+1, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O—H···Br | 0.92 (2) | 2.74 (2) | 3.547 (3) | 146 (5) |
OW—HW···Br | 0.94 (2) | 2.52 (5) | 3.449 (3) | 167 (9) |
The title compound was studied in the course of our investigations on the phases called AFm, which are hydrated compounds formed in cimentitious pastes. Their structures are layered and constituted by positively charged main layers [Ca2Al(OH)6]+ and negatively charged interlayers [X–, nH2O]-, where X is one monovalent or half of a divalent anion and where n depends on the humidity. The chlorinated compound or Friedel's salt is of monoclinic symmetry (space group C2/c) at room temperature. It undergoes a structural transition at 308 K and becomes rhombohedral with space group R -3c and lattice parameters a = 5.724 Å and c = 46.689 Å (Renaudin et al., 1999). The c parameter corresponds to six inter-layers which are spaced at 7.78 Å (6R polytype). This transition is presumably related to the size of the inserted halide [r = 1.81 Å, 1.96 Å, 2.20 Å for Cl-, Br- and I-, respectively (Shannon, 1976)]. Indeed, the AFm-Br transforms at 223 K while AFm-I does not present structural change above 77 K. The structures of AFm-Br (Rapin, Mohamed Noor et al., 1999) and AFm-I (Rapin, Walcarius et al., 1999) have been determined by single-crystal diffraction experiments at room temperature. They are isostructural with space group R -3 and their c parameters correspond to three interlayers spacing (3R polytypes). In order to check the size effect of halide on the transition, the solid solution [Ca2Al(OH)6][BrxCl1 - x,2H2O] was studied. The transition temperature decreases linearly from 308 to 223 K when x increases from 0 to 1. In particular, the phase corresponding to x = 0.5 changes at 263 K. The single crystals of this phase are not twinned at room temperature, contrary to those of the pure chlorinated phase. The structure of the rhombohedral phase thus could be determined on single-crystal at room temperature. Anions Cl- and Br- share in a statistical disorder the same crystallographic site. The increase of the inter layer spacing from 7.78 (1) Å to 8.02 (1) Å going from x = 0 to x = 1/2, corresponds to the increase of the anionic radii tabulated by Shannon (1976) when Cl- is replaced by the larger halide Br-. The structure is represented in figure 1. The main layers of composition [Ca2Al(OH)6]- are brucite-like layers with an octahedral environment for Al3+ and a coordination up to seven for the Ca2+ cations. The seventh coordination is occupied by water molecules. In the inter layers spacing of composition (Br0.5, Cl0.5. 2H2O), the chloride and bromide anions are surrounded by ten hydrogen atoms, of which six belong to hydroxyl group and four to water molecules (see Fig. 2). Br- and Cl- anions are therefore connected to the main layer by ten hydrogen bonds, six of 2.74 (2) Å and four of 2.52 (5) Å, where the donors are hydroxyl groups and water molecules, respectively.