Crystal structure of NH₄[La(SO₄)₂(H₂O)]

The structure of (NH₄)[La(SO₄)₂(H₂O)] comprises LaO₉ polyhedra and SO₄ tetra­hedra, which are linked by common edges and vertices, forming a three-dimensional network with the hydrogen-bonded NH₄ ⁺ ions in the cavities.

Abstract

The principal building units in the crystal structure of ammonium aqua­bis(sulfato)­lanthanate(III) are slightly distorted SO₄ tetra­hedra, LaO₉ polyhedra in the form of distorted tricapped trigonal prisms, and NH₄ ⁺ ions. The La³⁺ cation is coordinated by eight O atoms from six different sulfate tetra­hedra, two of which are bidentate coordinating and four monodentate, as well as one O atom from a water mol­ecule; each sulfate anion bridges three La³⁺ cations. These bridging modes result in the formation of a three-dimensional anionic [La(SO₄)₂(H₂O)]⁻ framework that is stabilized by O—H⋯O hydrogen-bonding inter­actions. The disordered ammonium cations are situated in the cavities of this framework and are hydrogen-bonded to six surrounding O atoms.

Chemical context  

Three-dimensional framework materials are characterized by their structural diversity. They are of continuing inter­est as a result of their technologically important properties and potential applications in catalysis, ion-exchange, adsorption, inter­calation, and radioactive waste remediation (Szostak, 1989 ▸; Cheetham et al., 1999 ▸; Rosi et al., 2003 ▸; Ok et al., 2007 ▸). Many materials showing such functional features contain structurally versatile cations, in particular heavier metal cations with large coordination spheres. Among many other cations, lanthanide cations have been used widely, since they exhibit high coordination numbers and can show a large topological diversity in the resulting framework structures (Bataille & Louër, 2002 ▸; Wickleder, 2002 ▸; Yuan et al., 2005 ▸). One of the most promising synthetic methods for the preparation of compounds with framework structures is the hydro­thermal (or solvothermal) reaction technique (Feng et al., 1997 ▸; Natarajan et al., 2000 ▸) in which mineralizers such as acids or bases are introduced to increase the solubility and reactivity of the reagents (Laudise, 1959 ▸; Laudise & Ballman, 1958 ▸). Moreover, organic or inorganic templates are used to direct the topologies of the framework structures and the concomitant physical and chemical properties of the products (Szostak, 1989 ▸; Breck, 1974 ▸; Barrer, 1982 ▸). Thus, we have tried to utilize the hydro­thermal technique to react a lanthanide cation (La³⁺) with sulfuric acid in the presence of NH₄OH and 3-amino­benzoic acid as a template to prepare higher dimensional framework materials. However, in the present case the organic template was not incorporated in the resultant crystal structure of the title compound, NH₄[La(SO₄)₂(H₂O)], which represents a new hydrate form. Other members in the system NH₄ ⁺/La³⁺/SO₄ ²⁻/(H₂O) are two forms of anhydrous (NH₄)[La(SO₄)₂] (Sarukhanyan et al., 1984a ▸; Bénard-Rocherullé et al., 2001 ▸), (NH₄)₅[La(SO₄)₄] (Niinisto et al., 1980 ▸) and (NH₄)[La(SO₄)₂(H₂O)₄] (Keppert et al., 1999 ▸).

Sulfates with an A ⁺:Ln ³⁺ (A ⁺ = alkaline ions, Ln ³⁺ = lanthanide ions) ratio of 1:1 are one of the best investigated groups among hydrous ternary sulfates. They crystallize either as monohydrates (Blackburn & Gerkin, 1995 ▸; Barnes, 1995 ▸; Iskhakova et al., 1985a ▸) or tetra­hydrates (Eriksson et al., 1974 ▸), and in few cases also as dihydrates (Kaucic et al., 1985 ▸; Iskhakova & Trunov, 1985 ▸). The tetra­hydrates are mainly found for the bigger monovalent ions Cs⁺, NH₄ ⁺, and Rb⁺. For the smaller A ⁺ ions such as Na⁺, the monohydrate becomes dominant.

Structural commentary  

The structure of the title compound comprises LaO₉ polyhedra and SO₄ tetra­hedra as the principal building units (Fig. 1 ▸), forming an anionic [La(SO₄)₂(H₂O)]⁻ framework by sharing common edges and vertices (Fig. 2 ▸). The NH₄ ⁺ counter-cations are situated in the cavities of this framework.

Figure 1.

The principal building units, LaO₉ polyhedra and SO₄ tetra­hedra, in the crystal structure of (NH₄)[La(SO₄)₂(H₂O)], showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) 1 − x, − + y,  − z; (ii) 1 − x,  + y,  − z; (iii) 1 − x, 2 − y, −z; (iv) 2 − x, 2 − y, 1 − z; (v) x,  − y,  + z.]

Figure 2.

The connection of LaO₉ polyhedra and SO₄ tetra­hedra in the crystal structure of (NH₄)[La(SO₄)₂(H₂O)], viewed along the a axis.

The La³⁺ cation is coordinated by eight O atoms from six different sulfate tetra­hedra. Two tetra­hedra are in a bidentate coordination mode and four tetra­hedra are in a monodentate mode. The distorted tricapped trigonal–prismatic coordination sphere is completed by one O atom from a water mol­ecule. The La—O bond lengths, ranging from 2.472 (3) to 2.637 (3) Å with 2.496 (3) Å to the water mol­ecule, and the O—La—O angles, ranging from 53.55 (8) to 145.43 (9)°, are similar to the analogous distances found in NaLa(SO₄)₂·H₂O (Blackburn & Gerkin, 1995 ▸). The ninefold coordination of La³⁺ in NH₄[La(SO₄)₂(H₂O)] is typical for the majority of monohydrated alkali rare earth sulfate complexes and of rare earth complexes in general. For early members of the rare earth sulfate series, the coordination number of nine is realized, e.g. for Ce, Pr, La and Nd (Blackburn & Gerkin, 1994 ▸, 1995 ▸; Iskhakova et al., 1985b ▸, 1988 ▸). For later members of the sulfate series, such as Gd (Sarukhanyan et al., 1984b ▸), the coordination number decreases to eight, presumably in association with the lanthanide contraction. There are two sulfur atoms (S1, S2) in the asymmetric unit of the title compound, both with very similar S—O bond lengths in the ranges 1.465 (3)–1.488 (3) and 1.468 (3)–1.490 (3) Å, respectively. The range of O—S—O bond angles, 106.04 (16)–110.89 (19)° for S1 and 104.70 (16)–111.52 (17)° for S2, reflect the distortion of the two sulfate tetra­hedra. Each SO₄ anion bridges three La³⁺ cations (Fig. 2 ▸).

Supra­molecular features  

The bridging modes of the O atoms result in the formation of a three-dimensional anionic framework, stabilized by O—H⋯O hydrogen-bonding inter­actions between the aqua ligand and the two SO₄ tetra­hedra (Table 1 ▸) whereby each sulfate tetra­hedron establishes one hydrogen bond with the water mol­ecule via the oxygen atom (O6 and O3) corres­ponding to the longest S—O bonds. The N atoms are situated in the cavities of this framework. Although the H atoms of the ammonium cation could not be located, the N⋯O distances between 2.865 (5) and 3.036 (5) Å strongly suggest N—H⋯O hydrogen bonds of medium strength (Table 1 ▸). It appears most likely that the number of O atoms (six) in the vicinity of the N atom is the reason for the disorder of the ammonium cation.

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
O1WH11O3i	0.84(5)	1.94(5)	2.717(5)	153(5)
O1WH21O6ii	0.85(3)	1.95(3)	2.778(4)	168(5)
N1O1iii			2.942(5)
N1O6ii			3.036(5)
N1O3iv			2.914(5)
N1O8v			2.943(5)
N1O5vi			2.865(5)
N1O4			2.866(5)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) .

Synthesis and crystallization  

The title compound was obtained during the attempted preparation of a complex resulting from the hydro­thermal reaction of La₂O₃ (0.1 g, 1 mmol) with 37%wt sulfuric acid and 3-amino­benzoic acid (0.048 g, 1 mmol) in the presence of NH₄OH in 10 ml water. The mixture was kept in a 23 ml Teflon-lined steel autoclave at 433 K for 3 d. After this treatment, the autoclave was cooled slowly to room temperature. Slow evaporation of the solvent at room temperature led to the formation of prismatic colourless crystals of the title compound.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The oxygen-bound hydrogen atoms were located in a difference Fourier map and were refined with restraints of the O—H bond length [0.85 (1) Å] and H⋯H distances (1.39 Å) and with U _iso(H) = 1.5U _eq(O). The ammonium hydrogen atoms could not be located reliably by difference Fourier methods. Several disorder models considering the hydrogen-bonding environment (see Table 1 ▸) failed, eventually leading to the exclusion of the ammonium hydrogen atoms from the refinement. The maximum and minimum peaks in the final difference Fourier map are 0.93 and 0.72 Å, respectively, from atom La1.

Table 2. Experimental details.

Crystal data
Chemical formula	NH4[La(SO4)2(H2O)]
M r	367.07
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	100
a, b, c ()	8.4919(16), 9.978(2), 11.9268(19)
()	128.511(10)
V (3)	790.7(3)
Z	4
Radiation type	Mo K
(mm1)	5.96
Crystal size (mm)	0.30 0.20 0.10
Data collection
Diffractometer	Nonius KappaCCD
Absorption correction	For a sphere (Dwiggins, 1975 ▸)
T min, T max	0.419, 0.431
No. of measured, independent and observed [I > 2(I)] reflections	2414, 2414, 2362
(sin /)max (1)	0.715
Refinement
R[F 2 > 2(F 2)], wR(F 2), S	0.027, 0.081, 1.26
No. of reflections	2414
No. of parameters	124
No. of restraints	3
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
max, min (e 3)	1.81, 1.48

Computer programs: COLLECT (Nonius, 1998 ▸), DENZO and SCALEPACK (Otwinowski Minor, 1997 ▸), SIR92 (Altomare et al., 1993 ▸), SHELXL97 (Sheldrick, 2008 ▸), ORTEP-3 for Windows and WinGX (Farrugia, 2012 ▸) and DIAMOND (Brandenburg Berndt, 1999 ▸).

Diffraction data were collected some time ago, and merged in the corresponding crystal class. Unfortunately, the original measurement data got lost; experiments to repeat the crystal growth were unsuccessful. Therefore the crystal structure was finally solved and refined with the merged data set.

Supplementary Material

CCDC reference: 1401662

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Crystal data

NH4[La(SO4)2(H2O)]	F(000) = 680
Mr = 367.07	Dx = 3.083 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2542 reflections
a = 8.4919 (16) Å	θ = 3–30.5°
b = 9.978 (2) Å	µ = 5.96 mm−1
c = 11.9268 (19) Å	T = 100 K
β = 128.511 (10)°	Prism, colourless
V = 790.7 (3) Å3	0.30 × 0.20 × 0.10 × 0.10 (radius) mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	2414 independent reflections
Radiation source: fine-focus sealed tube	2362 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.0000
Detector resolution: 9 pixels mm-1	θmax = 30.5°, θmin = 3.0°
CCD scans	h = −12→0
Absorption correction: for a sphere (Dwiggins, 1975)	k = −14→0
Tmin = 0.419, Tmax = 0.431	l = −12→17
2414 measured reflections

Refinement

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)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.081	H atoms treated by a mixture of independent and constrained refinement
S = 1.26	w = 1/[σ2(Fo2) + (0.0427P)2 + 2.7376P] where P = (Fo2 + 2Fc2)/3
2414 reflections	(Δ/σ)max = 0.001
124 parameters	Δρmax = 1.81 e Å−3
3 restraints	Δρmin = −1.48 e Å−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
La1	0.71683 (3)	0.839390 (18)	0.248314 (19)	0.01052 (8)
S1	0.74128 (12)	1.09162 (8)	0.42791 (8)	0.01163 (15)
S2	0.70608 (12)	0.91270 (8)	−0.02026 (8)	0.01129 (15)
O1	0.6085 (4)	1.0290 (3)	−0.1156 (3)	0.0179 (5)
O2	0.8105 (5)	0.8337 (3)	−0.0602 (3)	0.0189 (5)
O3	0.8535 (4)	0.9585 (3)	0.1310 (3)	0.0156 (5)
O8	0.9057 (4)	1.1402 (3)	0.5727 (3)	0.0182 (5)
O4	0.5597 (4)	0.8301 (3)	−0.0221 (3)	0.0188 (5)
O7	0.5667 (4)	1.1797 (3)	0.3641 (3)	0.0229 (6)
O6	0.6873 (4)	0.9516 (3)	0.4347 (3)	0.0185 (5)
O5	0.8062 (4)	1.0870 (3)	0.3387 (3)	0.0192 (5)
O1W	0.8711 (5)	0.6537 (3)	0.2059 (3)	0.0241 (6)
H11	0.982 (5)	0.615 (6)	0.266 (4)	0.036*
H21	0.820 (8)	0.632 (6)	0.121 (2)	0.036*
N1	0.2567 (6)	0.6458 (4)	−0.2302 (4)	0.0244 (7)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
La1	0.01098 (11)	0.00981 (11)	0.01113 (11)	−0.00037 (5)	0.00706 (9)	−0.00028 (5)
S1	0.0106 (3)	0.0110 (3)	0.0114 (3)	0.0009 (3)	0.0059 (3)	−0.0005 (3)
S2	0.0118 (3)	0.0111 (3)	0.0101 (3)	0.0008 (3)	0.0064 (3)	0.0000 (2)
O1	0.0212 (12)	0.0144 (11)	0.0173 (11)	0.0055 (10)	0.0116 (10)	0.0056 (9)
O2	0.0214 (13)	0.0207 (14)	0.0180 (13)	0.0035 (10)	0.0140 (12)	−0.0013 (9)
O3	0.0158 (11)	0.0162 (11)	0.0111 (10)	−0.0037 (9)	0.0066 (9)	−0.0028 (9)
O8	0.0141 (12)	0.0206 (12)	0.0141 (12)	−0.0009 (10)	0.0059 (10)	−0.0041 (10)
O4	0.0181 (13)	0.0212 (13)	0.0174 (12)	−0.0061 (9)	0.0111 (11)	−0.0018 (9)
O7	0.0139 (12)	0.0207 (13)	0.0217 (13)	0.0068 (10)	0.0049 (11)	−0.0025 (10)
O6	0.0240 (13)	0.0145 (11)	0.0174 (12)	−0.0029 (10)	0.0130 (11)	−0.0002 (9)
O5	0.0246 (13)	0.0181 (12)	0.0211 (12)	−0.0020 (10)	0.0174 (11)	−0.0016 (10)
O1W	0.0289 (16)	0.0220 (14)	0.0177 (13)	0.0126 (11)	0.0127 (12)	0.0010 (10)
N1	0.0248 (16)	0.0252 (18)	0.0296 (18)	−0.0037 (13)	0.0201 (15)	−0.0006 (13)

Geometric parameters (Å, º)

La1—O7i	2.472 (3)	S1—O8	1.471 (3)
La1—O1W	2.496 (3)	S1—O5	1.472 (3)
La1—O8ii	2.521 (3)	S1—O6	1.488 (3)
La1—O1iii	2.533 (3)	S2—O1	1.468 (3)
La1—O2iv	2.563 (3)	S2—O2	1.470 (3)
La1—O3	2.596 (3)	S2—O4	1.480 (3)
La1—O5	2.612 (3)	S2—O3	1.490 (3)
La1—O4	2.614 (3)	O1W—H11	0.845 (10)
La1—O6	2.637 (3)	O1W—H21	0.844 (10)
S1—O7	1.465 (3)
O7i—La1—O1W	82.44 (12)	O7i—La1—O6	99.16 (10)
O7i—La1—O8ii	143.78 (10)	O1W—La1—O6	145.43 (9)
O1W—La1—O8ii	71.36 (10)	O8ii—La1—O6	89.43 (9)
O7i—La1—O1iii	71.36 (10)	O1iii—La1—O6	70.57 (9)
O1W—La1—O1iii	139.83 (10)	O2iv—La1—O6	71.00 (9)
O8ii—La1—O1iii	143.55 (9)	O3—La1—O6	124.69 (8)
O7i—La1—O2iv	72.90 (10)	O5—La1—O6	53.55 (8)
O1W—La1—O2iv	76.67 (10)	O4—La1—O6	144.28 (9)
O8ii—La1—O2iv	76.96 (10)	O7—S1—O8	109.04 (17)
O1iii—La1—O2iv	121.24 (9)	O7—S1—O5	110.89 (19)
O7i—La1—O3	127.89 (10)	O8—S1—O5	110.49 (17)
O1W—La1—O3	76.32 (10)	O7—S1—O6	110.19 (18)
O8ii—La1—O3	70.11 (9)	O8—S1—O6	110.17 (16)
O1iii—La1—O3	96.07 (9)	O5—S1—O6	106.04 (16)
O2iv—La1—O3	142.55 (9)	O7—S1—La1	119.80 (13)
O7i—La1—O5	140.16 (10)	O8—S1—La1	131.15 (12)
O1W—La1—O5	137.02 (11)	O5—S1—La1	52.71 (11)
O8ii—La1—O5	71.62 (9)	O6—S1—La1	53.78 (11)
O1iii—La1—O5	72.00 (9)	O1—S2—O2	109.67 (16)
O2iv—La1—O5	114.84 (9)	O1—S2—O4	111.40 (17)
O3—La1—O5	71.17 (8)	O2—S2—O4	111.52 (17)
O7i—La1—O4	74.43 (10)	O1—S2—O3	109.85 (16)
O1W—La1—O4	69.69 (10)	O2—S2—O3	109.59 (17)
O8ii—La1—O4	116.81 (9)	O4—S2—O3	104.70 (16)
O1iii—La1—O4	74.17 (9)	La1—O1W—H11	128 (4)
O2iv—La1—O4	135.44 (9)	La1—O1W—H21	119 (4)
O3—La1—O4	53.65 (8)	H11—O1W—H21	112 (3)
O5—La1—O4	109.69 (9)

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) −x+2, −y+2, −z+1; (iii) −x+1, −y+2, −z; (iv) x, −y+3/2, z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H11···O3v	0.84 (5)	1.94 (5)	2.717 (5)	153 (5)
O1W—H21···O6vi	0.85 (3)	1.95 (3)	2.778 (4)	168 (5)
N1···O1vii			2.942 (5)
N1···O6vi			3.036 (5)
N1···O3viii			2.914 (5)
N1···O8i			2.943 (5)
N1···O5iii			2.865 (5)
N1···O4			2.866 (5)

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (iii) −x+1, −y+2, −z; (v) −x+2, y−1/2, −z+1/2; (vi) x, −y+3/2, z−1/2; (vii) −x+1, y−1/2, −z−1/2; (viii) x−1, −y+3/2, z−1/2.