We have been able, via a new synthetic route, to obtain a complete crystal structure of the title compound, tetraaquabarium hydroxide iodide, [Ba(OH)I(H2O)4], for which the heavy atoms only were characterized by Kellersohn, Beckenkamp & Lutz [Z. Naturforsch. Teil B (1991), 46, 1279-1286]. In the present results, the H-atom positions could be located using X-ray data collection at low temperature. A three-dimensional network is built up via hydrogen bonds. It was also observed that the title compound undergoes hydrolysis and might therefore be regarded as an intermediate in the formation of sol-gels, starting from BaI2 and leading to [Ba(OH)2(H2O)x].
Supporting information
The synthesis of compound (I) was carried out under an inert atmosphere (nitrogen) and all solvents were dried and distilled prior to use. tBuLi was purchased from Fluka and partially hydrolysed to yield (tBuLi)(LiOH). [BaI2(H2O)2.5] (0.443 g; 1 mmol) was placed in a Schlenk tube and dried at 773 K under vacuum. Tetrahydrofuran (12.5 ml) was added and the slightly yellow solution was stirred to dissolve all solids. LiOH (0.01 g; 0.41 mmol) was placed in a second Schlenk tube, evacuated and flushed with nitrogen before being added to the first solution. The resulting slightly yellow solution was heated to reflux and stirred for 20 min. After cooling down to room temperature, a 1.1 M hexane solution of (tBuLi)(LiOH) (0.5 ml; 0.5 mmol) was added dropwise until the solution became colourless. A white precipitate formed on addition of each drop but redissolved immediately. Distilled and degassed water (0.03 ml; 2 mmol) was added to yield a milky white solution. This was stirred for 2 h before being filtered under nitrogen on a G4 frit and cooled to 243 K. Crystals of compound (I) crystallized in the form of light-yellow rods in a yield of 32%.
Data collection: STADI4 (Stoe & Cie, 1996a); cell refinement: STADI4; data reduction: X-RED (Stoe & Cie, 1996b); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SCHAKAL88 (Keller, 1988).
Tetraaquabarium hydroxide iodide
top
Crystal data top
Ba(OH)I(H2O)4 | Z = 2 |
Mr = 353.31 | F(000) = 316 |
Triclinic, P1 | Dx = 3.012 Mg m−3 |
a = 6.2757 (13) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 8.026 (2) Å | Cell parameters from 60 reflections |
c = 8.090 (2) Å | θ = 2.5–12.5° |
α = 90.37 (3)° | µ = 9.01 mm−1 |
β = 107.03 (3)° | T = 203 K |
γ = 90.86 (3)° | Rod, light yellow |
V = 389.56 (14) Å3 | 0.70 × 0.23 × 0.20 mm |
Data collection top
Stoe Stadi-4 diffractometer | 1655 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.028 |
Graphite monochromator | θmax = 27.0°, θmin = 2.5° |
ω/2θ scans | h = −8→8 |
Absorption correction: ψ-scan ? | k = −10→10 |
Tmin = 0.120, Tmax = 0.210 | l = −10→10 |
3392 measured reflections | 1 standard reflections every 120 min |
1697 independent reflections | intensity decay: 1.9% |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.016 | All H-atom parameters refined |
wR(F2) = 0.039 | Calculated w = 1/[s2(Fo2) + ( 0.0132P)2 + 0.2331P] where P = (Fo2 + 2Fc2)/3 |
S = 1.16 | (Δ/σ)max = 0.002 |
1697 reflections | Δρmax = 0.85 e Å−3 |
101 parameters | Δρmin = −0.85 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2l3/sin(2q)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0101 (5) |
Crystal data top
Ba(OH)I(H2O)4 | γ = 90.86 (3)° |
Mr = 353.31 | V = 389.56 (14) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.2757 (13) Å | Mo Kα radiation |
b = 8.026 (2) Å | µ = 9.01 mm−1 |
c = 8.090 (2) Å | T = 203 K |
α = 90.37 (3)° | 0.70 × 0.23 × 0.20 mm |
β = 107.03 (3)° | |
Data collection top
Stoe Stadi-4 diffractometer | 1655 reflections with I > 2σ(I) |
Absorption correction: ψ-scan ? | Rint = 0.028 |
Tmin = 0.120, Tmax = 0.210 | 1 standard reflections every 120 min |
3392 measured reflections | intensity decay: 1.9% |
1697 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.016 | 0 restraints |
wR(F2) = 0.039 | All H-atom parameters refined |
S = 1.16 | Δρmax = 0.85 e Å−3 |
1697 reflections | Δρmin = −0.85 e Å−3 |
101 parameters | |
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 on F2 for ALL reflections except for 0 with very negative F2 or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating _R_factor_obs 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 | |
Ba1 | 0.32579 (2) | 0.46527 (2) | 0.220416 (16) | 0.01981 (8) | |
I1 | 0.33266 (3) | 0.00528 (2) | 0.21475 (2) | 0.02986 (8) | |
O1 | 0.0099 (3) | 0.3215 (3) | 0.3475 (2) | 0.0253 (4) | |
H1 | 0.033 (9) | 0.230 (7) | 0.336 (7) | 0.084 (18)* | |
O2 | 0.0588 (4) | 0.3352 (3) | −0.0982 (3) | 0.0235 (4) | |
H21 | 0.119 (7) | 0.344 (5) | −0.164 (5) | 0.048 (12)* | |
H22 | 0.025 (7) | 0.249 (6) | −0.083 (6) | 0.049 (13)* | |
O3 | 0.7104 (4) | 0.6799 (3) | 0.3350 (3) | 0.0266 (4) | |
H31 | 0.791 (7) | 0.682 (5) | 0.425 (5) | 0.043 (11)* | |
H32 | 0.664 (7) | 0.767 (6) | 0.328 (6) | 0.059 (15)* | |
O4 | 0.6840 (3) | 0.3397 (2) | 0.4915 (2) | 0.0219 (4) | |
H41 | 0.664 (6) | 0.253 (5) | 0.510 (4) | 0.028 (10)* | |
H42 | 0.806 (6) | 0.320 (5) | 0.440 (4) | 0.038 (9)* | |
O5 | 0.6542 (3) | 0.3453 (3) | 0.0720 (2) | 0.0230 (4) | |
H51 | 0.629 (6) | 0.262 (5) | 0.046 (5) | 0.030 (10)* | |
H52 | 0.789 (6) | 0.341 (5) | 0.164 (5) | 0.045 (10)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ba1 | 0.01712 (11) | 0.02769 (11) | 0.01511 (9) | 0.00058 (7) | 0.00547 (6) | −0.00024 (6) |
I1 | 0.03501 (13) | 0.02009 (11) | 0.03310 (11) | 0.00150 (8) | 0.00779 (8) | 0.00002 (8) |
O1 | 0.0273 (10) | 0.0250 (10) | 0.0268 (9) | 0.0023 (9) | 0.0129 (7) | −0.0003 (8) |
O2 | 0.0278 (10) | 0.0220 (10) | 0.0221 (9) | −0.0009 (8) | 0.0094 (7) | −0.0004 (8) |
O3 | 0.0263 (10) | 0.0269 (10) | 0.0259 (9) | 0.0019 (9) | 0.0067 (8) | 0.0021 (8) |
O4 | 0.0251 (10) | 0.0208 (9) | 0.0226 (8) | 0.0011 (8) | 0.0112 (7) | 0.0013 (7) |
O5 | 0.0259 (10) | 0.0203 (9) | 0.0238 (9) | 0.0017 (8) | 0.0089 (7) | −0.0013 (8) |
Geometric parameters (Å, º) top
Ba1—O1 | 2.731 (2) | O1—H1 | 0.76 (6) |
Ba1—O4i | 2.815 (2) | O2—Ba1ii | 2.848 (2) |
Ba1—O2 | 2.815 (2) | O2—H21 | 0.74 (4) |
Ba1—O4 | 2.844 (2) | O2—H22 | 0.74 (5) |
Ba1—O2ii | 2.848 (2) | O3—H31 | 0.75 (4) |
Ba1—O5 | 2.848 (2) | O3—H32 | 0.76 (5) |
Ba1—O5iii | 2.853 (2) | O4—Ba1i | 2.815 (2) |
Ba1—O3 | 2.863 (2) | O4—H41 | 0.73 (4) |
Ba1—I1 | 3.6928 (8) | O4—H42 | 0.99 (4) |
Ba1—Ba1i | 4.4378 (14) | O5—Ba1iii | 2.853 (2) |
Ba1—Ba1ii | 4.6156 (18) | O5—H51 | 0.70 (4) |
Ba1—Ba1iii | 4.7296 (11) | O5—H52 | 0.95 (4) |
Ba1—H1 | 2.96 (5) | | |
| | | |
O1—Ba1—O4i | 73.87 (6) | O5—Ba1—Ba1ii | 108.00 (4) |
O1—Ba1—O2 | 83.94 (7) | O5iii—Ba1—Ba1ii | 61.88 (5) |
O4i—Ba1—O2 | 143.39 (6) | O3—Ba1—Ba1ii | 129.82 (5) |
O1—Ba1—O4 | 93.02 (6) | I1—Ba1—Ba1ii | 98.07 (4) |
O4i—Ba1—O4 | 76.71 (7) | Ba1i—Ba1—Ba1ii | 146.348 (18) |
O2—Ba1—O4 | 134.25 (6) | O1—Ba1—Ba1iii | 151.48 (5) |
O1—Ba1—O2ii | 74.64 (6) | O4i—Ba1—Ba1iii | 133.43 (5) |
O4i—Ba1—O2ii | 75.37 (6) | O2—Ba1—Ba1iii | 68.49 (5) |
O2—Ba1—O2ii | 70.81 (7) | O4—Ba1—Ba1iii | 100.90 (4) |
O4—Ba1—O2ii | 151.65 (6) | O2ii—Ba1—Ba1iii | 101.73 (5) |
O1—Ba1—O5 | 135.23 (6) | O5—Ba1—Ba1iii | 33.98 (4) |
O4i—Ba1—O5 | 137.21 (6) | O5iii—Ba1—Ba1iii | 33.91 (4) |
O2—Ba1—O5 | 78.50 (6) | O3—Ba1—Ba1iii | 69.16 (5) |
O4—Ba1—O5 | 71.98 (6) | I1—Ba1—Ba1iii | 95.55 (3) |
O2ii—Ba1—O5 | 134.27 (6) | Ba1i—Ba1—Ba1iii | 123.866 (17) |
O1—Ba1—O5iii | 138.41 (6) | Ba1ii—Ba1—Ba1iii | 84.363 (19) |
O4i—Ba1—O5iii | 114.03 (6) | O1—Ba1—H1 | 14.7 (11) |
O2—Ba1—O5iii | 65.86 (7) | O4i—Ba1—H1 | 85.4 (11) |
O4—Ba1—O5iii | 128.48 (6) | O2—Ba1—H1 | 78.8 (10) |
O2ii—Ba1—O5iii | 68.92 (7) | O4—Ba1—H1 | 86.9 (10) |
O5—Ba1—O5iii | 67.88 (7) | O2ii—Ba1—H1 | 86.1 (10) |
O1—Ba1—O3 | 139.21 (6) | O5—Ba1—H1 | 120.6 (11) |
O4i—Ba1—O3 | 68.24 (7) | O5iii—Ba1—H1 | 141.6 (10) |
O2—Ba1—O3 | 136.43 (7) | O3—Ba1—H1 | 144.2 (10) |
O4—Ba1—O3 | 64.36 (6) | I1—Ba1—H1 | 51.9 (11) |
O2ii—Ba1—O3 | 108.77 (6) | Ba1i—Ba1—H1 | 85.1 (10) |
O5—Ba1—O3 | 72.20 (7) | Ba1ii—Ba1—H1 | 80.8 (10) |
O5iii—Ba1—O3 | 73.46 (7) | Ba1iii—Ba1—H1 | 141.2 (11) |
O1—Ba1—I1 | 66.61 (5) | Ba1—O1—H1 | 100 (4) |
O4i—Ba1—I1 | 124.35 (4) | Ba1—O2—Ba1ii | 109.19 (7) |
O2—Ba1—I1 | 68.82 (5) | Ba1—O2—H21 | 109 (3) |
O4—Ba1—I1 | 68.22 (5) | Ba1ii—O2—H21 | 105 (3) |
O2ii—Ba1—I1 | 125.79 (5) | Ba1—O2—H22 | 107 (3) |
O5—Ba1—I1 | 68.66 (5) | Ba1ii—O2—H22 | 110 (3) |
O5iii—Ba1—I1 | 121.58 (5) | H21—O2—H22 | 116 (5) |
O3—Ba1—I1 | 125.38 (5) | Ba1—O3—H31 | 126 (3) |
O1—Ba1—Ba1i | 81.81 (5) | Ba1—O3—H32 | 105 (3) |
O4i—Ba1—Ba1i | 38.59 (4) | H31—O3—H32 | 102 (4) |
O2—Ba1—Ba1i | 163.02 (5) | Ba1i—O4—Ba1 | 103.29 (7) |
O4—Ba1—Ba1i | 38.12 (4) | Ba1i—O4—H41 | 108 (3) |
O2ii—Ba1—Ba1i | 113.81 (5) | Ba1—O4—H41 | 111 (3) |
O5—Ba1—Ba1i | 105.50 (5) | Ba1i—O4—H42 | 130 (2) |
O5iii—Ba1—Ba1i | 131.08 (5) | Ba1—O4—H42 | 105.8 (19) |
O3—Ba1—Ba1i | 59.18 (5) | H41—O4—H42 | 97 (4) |
I1—Ba1—Ba1i | 96.90 (3) | Ba1—O5—Ba1iii | 112.12 (7) |
O1—Ba1—Ba1ii | 76.83 (4) | Ba1—O5—H51 | 109 (3) |
O4i—Ba1—Ba1ii | 109.49 (5) | Ba1iii—O5—H51 | 109 (3) |
O2—Ba1—Ba1ii | 35.64 (4) | Ba1—O5—H52 | 106 (2) |
O4—Ba1—Ba1ii | 165.59 (4) | Ba1iii—O5—H52 | 116 (2) |
O2ii—Ba1—Ba1ii | 35.17 (4) | H51—O5—H52 | 105 (4) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y+1, −z; (iii) −x+1, −y+1, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···I1 | 0.76 (6) | 2.99 (6) | 3.618 (2) | 142 (5) |
O2—H21···O3iii | 0.74 (4) | 1.99 (5) | 2.722 (3) | 169 (5) |
O2—H22···I1iv | 0.74 (5) | 2.96 (5) | 3.577 (3) | 142 (4) |
O2—H22···I1 | 0.74 (5) | 3.28 (4) | 3.748 (2) | 124 (4) |
O3—H31···O1i | 0.75 (4) | 1.90 (4) | 2.653 (3) | 178 (4) |
O3—H32···I1v | 0.76 (5) | 2.80 (4) | 3.501 (2) | 155 (4) |
O4—H41···I1vi | 0.73 (4) | 3.05 (4) | 3.681 (2) | 147 (3) |
O4—H41···I1 | 0.73 (4) | 3.30 (4) | 3.733 (2) | 122 (3) |
O4—H42···O1vii | 0.99 (4) | 1.66 (4) | 2.639 (3) | 171 (3) |
O5—H51···I1 | 0.70 (4) | 3.31 (4) | 3.754 (2) | 124 (4) |
O5—H51···I1viii | 0.70 (4) | 3.06 (4) | 3.652 (2) | 144 (4) |
O5—H52···O1vii | 0.95 (4) | 1.72 (4) | 2.663 (3) | 172 (3) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (iii) −x+1, −y+1, −z; (iv) −x, −y, −z; (v) x, y+1, z; (vi) −x+1, −y, −z+1; (vii) x+1, y, z; (viii) −x+1, −y, −z. |
Experimental details
Crystal data |
Chemical formula | Ba(OH)I(H2O)4 |
Mr | 353.31 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 203 |
a, b, c (Å) | 6.2757 (13), 8.026 (2), 8.090 (2) |
α, β, γ (°) | 90.37 (3), 107.03 (3), 90.86 (3) |
V (Å3) | 389.56 (14) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 9.01 |
Crystal size (mm) | 0.70 × 0.23 × 0.20 |
|
Data collection |
Diffractometer | Stoe Stadi-4 diffractometer |
Absorption correction | ψ-scan |
Tmin, Tmax | 0.120, 0.210 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3392, 1697, 1655 |
Rint | 0.028 |
(sin θ/λ)max (Å−1) | 0.639 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.016, 0.039, 1.16 |
No. of reflections | 1697 |
No. of parameters | 101 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.85, −0.85 |
Selected geometric parameters (Å, º) topBa1—O1 | 2.731 (2) | Ba1—O5 | 2.848 (2) |
Ba1—O4i | 2.815 (2) | Ba1—O5iii | 2.853 (2) |
Ba1—O2 | 2.815 (2) | Ba1—O3 | 2.863 (2) |
Ba1—O4 | 2.844 (2) | Ba1—I1 | 3.6928 (8) |
Ba1—O2ii | 2.848 (2) | | |
| | | |
O1—Ba1—I1 | 66.61 (5) | O5—Ba1—I1 | 68.66 (5) |
O4i—Ba1—I1 | 124.35 (4) | O5iii—Ba1—I1 | 121.58 (5) |
O2—Ba1—I1 | 68.82 (5) | O3—Ba1—I1 | 125.38 (5) |
O4—Ba1—I1 | 68.22 (5) | Ba1—O1—H1 | 100 (4) |
O2ii—Ba1—I1 | 125.79 (5) | | |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y+1, −z; (iii) −x+1, −y+1, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···I1 | 0.76 (6) | 2.99 (6) | 3.618 (2) | 142 (5) |
O2—H21···O3iii | 0.74 (4) | 1.99 (5) | 2.722 (3) | 169 (5) |
O2—H22···I1iv | 0.74 (5) | 2.96 (5) | 3.577 (3) | 142 (4) |
O2—H22···I1 | 0.74 (5) | 3.28 (4) | 3.748 (2) | 124 (4) |
O3—H31···O1i | 0.75 (4) | 1.90 (4) | 2.653 (3) | 178 (4) |
O3—H32···I1v | 0.76 (5) | 2.80 (4) | 3.501 (2) | 155 (4) |
O4—H41···I1vi | 0.73 (4) | 3.05 (4) | 3.681 (2) | 147 (3) |
O4—H41···I1 | 0.73 (4) | 3.30 (4) | 3.733 (2) | 122 (3) |
O4—H42···O1vii | 0.99 (4) | 1.66 (4) | 2.639 (3) | 171 (3) |
O5—H51···I1 | 0.70 (4) | 3.31 (4) | 3.754 (2) | 124 (4) |
O5—H51···I1viii | 0.70 (4) | 3.06 (4) | 3.652 (2) | 144 (4) |
O5—H52···O1vii | 0.95 (4) | 1.72 (4) | 2.663 (3) | 172 (3) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (iii) −x+1, −y+1, −z; (iv) −x, −y, −z; (v) x, y+1, z; (vi) −x+1, −y, −z+1; (vii) x+1, y, z; (viii) −x+1, −y, −z. |
The title compound, (I), was obtained in the form of light yellow crystals from partial basic hydrolysis of the complex [BaI2(thf)5] (thf is tetrahydrofuran; Fromm, 1997) in the presence of tBuLi and LiOH. This is in contrast with the synthesis reported by Kellersohn et al. (1991). The structure was solved by direct methods in the space group P1 and refined anisotropically for all heavy atoms using the SHELXL97 (Sheldrick, 1997) package, to a higher precision and with smaller standard deviations for distances and angles and a lower overall R-index than for the structure reported by Kellersohn et al. (1991). By using low-temperature techniques, our measurements allowed the location and refinement of all H atoms in the Fourier map (Fig. 1).
The Ba—O distances in [Ba(OH)I(H2O)4] in the present work differ by about 0.01 Å, twice the standard deviation, from the values given by Kellersohn et al. (1991). The Ba1—I bond length, however, is significantly shorter (0.03 Å) than in the structure reported by Kellersohn et al. (1991). This bond is parallel to the b axis, for which we observe a longer thermal contraction (0.034 Å) than for the other two axes (0.028 Å for the c axis and 0.003 Å for the a axis), when compared with the room-temperature structure of (I) by Kellersohn et al. (1991).
Since the H atoms could be located in the Fourier map, we were able to confirm the hydrogen-bonding scheme proposed by Kellersohn et al. (1991), based on the schemes found for [Sr(OH)Cl(H2O)4] and [Sr(OH)Br(H2O)4] (Fig. 1). H—I hydrogen-bond lengths, which range from 2.80 to 3.31 Å, are similar to those found in [trans-(py)4Mg(OH2)2]I22py (py is pyridine?; Kepert et al., 1996), [Mg(HOMe)6]I22tmeda, [(tmeda)SrI2(HOMe)3]1/2tmeda (tmeda is ?; Waters & White, 1996) and Li[Ca7(µ3-OH)8I6(thf)12]2I (Fromm, 1999). A coordination sphere for Ba similar to that in (I) is observed in [Ba2(OH)2(H2O)10][Se4], described by Green et al. (1995), where a single-capped distorted square prism, formed only by O donors, is reported. The Ba—O(H2Obridge) distances in compound (I) are of the same order of magnitude as in comparable hydrate complexes such as [BaCl2(H2O)2] (Padmanabhan et al., 1978).
Compound (I) is interesting because it represents the mid-point in the hydrolysis of BaI2 to Ba(OH)2. The structure of Ba(OH)2 being unknown to our knowledge, compound (I) is a precursor to hydrated barium hydroxide Ba(OH)2(H2O)x, since it yields, on addition of excess tBuLi/LiOH, a white gel of this composition. Further investigations for the use of BaI2-derived polymers and clusters as precursors for sol-gels and their intermediates are underway.