Crystal structure of bis-(propane-1,3-diaminium) hexa-fluorido-aluminate di-aqua-tetra-fluorido-aluminate tetra-hydrate.

The title compound, (C3H12N2)2[AlF6][AlF4(H2O)2]·4H2O, was obtained by a solvothermal method in ethanol as solvent and with aluminium hydroxide, HF and 1,3-di-amino-propane as educts. The asymmetric unit contains a quarter each of two crystallographically independent propane-1,3-di-ammonium dicat-ions, [AlF6](3-) and [AlF4(H2O)2](-) anions and four water mol-ecules. The cations, anions and three of the independent water mol-ecules are situated on special positions mm, while the fourth water mol-ecule is disordered about a mirror plane. In the crystal, inter-molecular N-H⋯F and O-H⋯F hydrogen bonds link the cations and anions into a three-dimensional framework with the voids filled by water mol-ecules, which generate O-H⋯O hydrogen bonds and further consolidate the packing.

Chemical context

Hybrid organic–inorganic fluoride compounds are composed of both organic and inorganic moieties. The search for new compounds in this class of materials is still intense due to their applications in many domains such as gas storage, catalysis, separation, ion-exchange and biomedicine (Horcajada et al., 2012 ▶; Stock & Biswas, 2012 ▶). Various hybrid materials containing fluorine organic ligands have been described in the literature (Ben Ali et al., 2007 ▶). The dimensionality of the metal fluoride entities are 0D (isolated polyanions) (Adil, Ben Ali et al., 2006 ▶; Adil, Leblanc & Maisonneuve, 2006 ▶; Fourquet et al., 1987 ▶) , 1D (chains) or 2D (layers) (Adil et al., 2010 ▶). The structural architecture of hybrid materials mainly depends on the metal and an organic part. However, other physical and physicochemical factors affect the resulting products such as the synthesis method (temperature, concentration, time of heating etc.) (Su et al., 2010 ▶). This work is a continuation of an exploration of chemical systems including metal fluoride and amine, and the study of their structures.

Structural commentary

The asymmetric unit of the title compound contains aluminum atoms located in two crystallographically independent sites with different environments, [Al2F6] and [Al1F4(H2O)2], and two independent 1,3-propane di­amine (dap) dications (Fig. 1 ▶). The Al—F distances in the two octa­hedra range from 1.768 (2) to 1.809 (3) Å while the Al1—OW1 distance is longer [1.944 (4) Å]. The [AlF6] octa­hedron is regular whereas [AlF4(H2O)2] exhibits a pronounced distortion due to the strong influence of the crystal field created by the heteroligands (F−/H2O). The value of the calculated valences (3.08 for Al1 and 3.01 for Al2) of the individual Al3+ cations (Brese & O’Keeffe, 1991 ▶) is in good agreement with the theoretical value, whereas those for the F− anions are equal to 0.5. These anions complete their valence by establishing strong hydrogen bonds.

Figure 1

A portion of the crystal structure of the title compound showing the atom labelling and 50% probability displacement ellipsoids. Dashed lines denote hydrogen bonds. [Symmetry codes: (i)  − x,  − y, −1 − z; (ii) 1 − x, y, z; (iii) x, y, −z; (v)  − x,  − y, 1 + z; (vi) −x, y, z; (vii) x, −y, −1 − z; (viii) x, y, 1 + z.]

Supra­molecular features

Each [AlF4(H2O)2] octa­hedron is linked via N—H⋯F or O—H⋯F hydrogen bonds (Table 1 ▶) to one type of the organic cations (Fig. 2 ▶), with the formation of infinite chains parallel to the a axis. These chains are linked to each other by the AlF6 3− dications and form infinite (H2dap)[AlF4(H2O)2] layers parallel to the ac plane (Fig. 3 ▶) . These layers are connected by the second organic cations and form a three-dimensional framework showing cavities, which are filled with the lattice water mol­ecules.

Table 1

Hydrogen-bond geometry (, )

DHA	DH	HA	D A	DHA
N1H1AF2	0.89	1.79	2.679(6)	177
N1H1BF5i	0.89	1.99	2.846(5)	161
N1H1CF5ii	0.89	1.99	2.846(5)	161
N2H2AF3	0.89	1.84	2.722(6)	173
N2H2BF1iii	0.89	2.00	2.841(5)	158
Ow1H1F5iv	0.83(4)	1.74(4)	2.569(5)	178
Ow2H2F3	0.84(4)	2.10(4)	2.880(5)	178
Ow4H4Ow5v	0.84(4)	2.13	2.910(5)	154

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

Figure 2

The environment of the AlF4(H2O)2 octa­hedron. Dashed lines denote hydrogen bonds.

Figure 3

The crystal packing of the title compound, viewed approximately along [001].

Database survey

In the Cambridge Structural Database (Version 5.35; Groom & Allen, 2014 ▶) numerous Class I fluorido­aluminates with isolated (poly)anions or extended 1D inorganic chains, 2D inorganic layers or 3D networks are mentioned. Eight compounds with AlF6 3− anions exist (Grottel et al., 1992 ▶; Rother et al., 1996 ▶, 1998 ▶; Touret et al., 2001 ▶; Adil et al., 2009 ▶; Bentrup et al., 1996 ▶) and seven compounds containing the AlF5(H2O)2− anion (Cadiau et al., 2008 ▶; Petrosyants et al., 1997 ▶; Schröder et al., 1993 ▶). However, to our knowledge, no fluorido­aluminate hybrid compounds containing both the AlF6 3− and AlF5(H2O)2− anions have been reported.

Synthesis and crystallization

The title compound was prepared from a starting mixture of AlF3 (0.5 g) in 40% HF (1.5 ml) and ethanol (5 ml). 1,3-Di­amino­propane (0.54 ml) was added and mild hydro­thermal conditions (463 K) were applied in a Teflon-lined autoclave (25 ml). The resulting product was washed with ethanol and dried in air giving colourless single crystals.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▶. The H atoms of the NH3 and CH2 groups of the organic mol­ecule were fixed geometrically [N—H = 0.89 (1) and C—H = 0.97 (1) Å with U iso(H) = 1.2U eq(N,C)]. All H atoms of the water mol­ecules were located from a Fourier difference map. The O—H distances and H—O—H angles were fixed [O—H = 0.84 (1) and H⋯H = 1.34 (1) Å with U iso(H) =1.5U eq(O)]. The water mol­ecule OW5 is disordered over two positions with the occupanies fixed to 0.5.

Table 2

Experimental details

Crystal data
Chemical formula	(C3H12N2)2[AlF6][AlF4(H2O)2]4H2O
M r	504.35
Crystal system, space group	Orthorhombic, C m m m
Temperature (K)	293
a, b, c ()	12.975(5), 25.115(9), 6.452(9)
V (3)	2103(3)
Z	4
Radiation type	Mo K
(mm1)	0.26
Crystal size (mm)	0.24 0.12 0.05
Data collection
Diffractometer	Siemens AED2
No. of measured, independent and observed [I > 2(I)] reflections	1371, 1371, 939
(sin /)max (1)	0.649
Refinement
R[F 2 > 2(F 2)], wR(F 2), S	0.047, 0.148, 1.12
No. of reflections	1371
No. of parameters	105
No. of restraints	10
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
max, min (e 3)	0.46, 0.48

Computer programs: STADI4 and X-RED (Stoe Cie, 2002 ▶), SHELXS97 (Sheldrick, 2008 ▶), SHELXL97 (Sheldrick, 2008 ▶) within WinGX (Farrugia, 2012 ▶), DIAMOND (Brandenburg, 2006 ▶) and publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536814024155/cv5471sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814024155/cv5471Isup2.hkl

CCDC reference: 1032262

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

(C3H12N2)2[AlF6][AlF4(H2O)2]·4H2O	F(000) = 1056
Mr = 504.35	Dx = 1.593 Mg m−3
Orthorhombic, Cmmm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2 2	Cell parameters from 32 reflections
a = 12.975 (5) Å	θ = 2–27.5°
b = 25.115 (9) Å	µ = 0.26 mm−1
c = 6.452 (9) Å	T = 293 K
V = 2103 (3) Å3	Platelets, colourless
Z = 4	0.24 × 0.12 × 0.05 mm

Siemens AED2 diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 27.5°, θmin = 1.6°
Graphite monochromator	h = 0→16
2θ/ω scan	k = 0→32
1371 measured reflections	l = 0→8
1371 independent reflections	3 standard reflections every 120 min
939 reflections with I > 2σ(I)	intensity decay: 4%

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)] = 0.047	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.148	w = 1/[σ2(Fo2) + (0.0452P)2 + 2.9098P] where P = (Fo2 + 2Fc2)/3
S = 1.12	(Δ/σ)max < 0.001
1371 reflections	Δρmax = 0.46 e Å−3
105 parameters	Δρmin = −0.48 e Å−3
10 restraints	Extinction correction: WinGX (Farrugia, 2012), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0022 (7)

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.

	x	y	z	Uiso*/Ueq	Occ. (<1)
Al1	0.0000	0.37606 (7)	0.0000	0.0234 (4)
Al2	0.2500	0.2500	−0.5000	0.0245 (4)
F1	0.0000	0.42435 (10)	0.2015 (4)	0.0382 (6)
F2	0.13615 (17)	0.37342 (11)	0.0000	0.0374 (6)
F3	0.2107 (2)	0.18091 (10)	−0.5000	0.0493 (8)
F5	0.15743 (14)	0.26362 (8)	−0.7007 (3)	0.0447 (5)
N1	0.3125 (2)	0.31814 (15)	0.0000	0.0325 (8)
H1A	0.2551	0.3375	0.0000	0.049*
H1B	0.3141	0.2977	0.1126	0.049*	0.50
H1C	0.3141	0.2977	−0.1126	0.049*	0.50
N2	0.3447 (3)	0.09755 (14)	−0.5000	0.0331 (8)
H2A	0.3055	0.1266	−0.5000	0.050*
H2B	0.3843	0.0974	−0.6126	0.050*	0.50
H2C	0.3843	0.0974	−0.3874	0.050*	0.50
C1	0.4029 (3)	0.35390 (18)	0.0000	0.0375 (11)
H1D	0.4014	0.3765	0.1219	0.045*	0.50
H1E	0.4014	0.3765	−0.1219	0.045*	0.50
C2	0.5000	0.3205 (2)	0.0000	0.0336 (14)
H2D	0.5000	0.2977	0.1215	0.040*	0.50
H2E	0.5000	0.2977	−0.1215	0.040*	0.50
C3	0.2784 (3)	0.04975 (18)	−0.5000	0.0415 (11)
H3A	0.2346	0.0501	−0.6217	0.050*	0.50
H3B	0.2346	0.0501	−0.3783	0.050*	0.50
C4	0.3432 (5)	0.0000	−0.5000	0.0427 (16)
H4A	0.3872	0.0000	−0.6215	0.051*	0.50
H4B	0.3872	0.0000	−0.3785	0.051*	0.50
OW1	0.0000	0.32173 (12)	0.2146 (6)	0.0400 (8)
OW2	0.0000	0.1449 (3)	−0.5000	0.080 (2)
OW3	0.3272 (7)	0.0000	0.0000	0.104 (3)
OW4	0.3732 (11)	0.5000	0.0000	0.200 (6)
OW5	0.5000	0.5374 (6)	0.342 (2)	0.110 (4)	0.50
H1	0.0517 (4)	0.3034 (11)	0.241 (9)	0.165*
H2	0.0517 (4)	0.1650 (8)	−0.5000	0.165*
H3	0.3669 (15)	0.0267 (2)	0.0000	0.165*
H4	0.4125 (17)	0.5000	−0.1039 (8)	0.165*
H5	0.5516 (4)	0.526 (5)	0.408 (12)	0.165*	0.50

	U11	U22	U33	U12	U13	U23
Al1	0.0187 (8)	0.0233 (8)	0.0282 (9)	0.000	0.000	0.000
Al2	0.0230 (8)	0.0257 (8)	0.0248 (8)	0.0074 (7)	0.000	0.000
F1	0.0469 (14)	0.0332 (13)	0.0346 (13)	0.000	0.000	−0.0076 (11)
F2	0.0190 (11)	0.0373 (14)	0.0560 (16)	−0.0036 (10)	0.000	0.000
F3	0.0445 (16)	0.0282 (14)	0.075 (2)	0.0027 (12)	0.000	0.000
F5	0.0370 (9)	0.0582 (13)	0.0388 (10)	0.0178 (8)	−0.0120 (8)	−0.0007 (9)
N1	0.0211 (16)	0.043 (2)	0.0338 (18)	0.0014 (15)	0.000	0.000
N2	0.0342 (19)	0.0262 (17)	0.039 (2)	0.0023 (15)	0.000	0.000
C1	0.027 (2)	0.030 (2)	0.056 (3)	0.0028 (17)	0.000	0.000
C2	0.020 (3)	0.029 (3)	0.053 (4)	0.000	0.000	0.000
C3	0.027 (2)	0.033 (2)	0.064 (3)	0.0040 (18)	0.000	0.000
C4	0.028 (3)	0.029 (3)	0.071 (5)	0.000	0.000	0.000
OW1	0.0266 (14)	0.0385 (16)	0.055 (2)	0.000	0.000	0.0203 (16)
OW2	0.065 (4)	0.104 (6)	0.070 (4)	0.000	0.000	0.000
OW3	0.121 (7)	0.090 (6)	0.102 (6)	0.000	0.000	0.000
OW4	0.209 (14)	0.204 (17)	0.188 (13)	0.000	0.000	0.000
OW5	0.101 (8)	0.110 (9)	0.119 (10)	0.000	0.000	0.032 (8)

Al1—F2i	1.768 (2)	N2—H2C	0.8900
Al1—F2	1.768 (2)	C1—C2	1.514 (5)
Al1—F1	1.778 (3)	C1—H1D	0.9700
Al1—F1ii	1.778 (3)	C1—H1E	0.9700
Al1—OW1	1.944 (4)	C2—C1vi	1.514 (5)
Al1—OW1ii	1.944 (4)	C2—H2D	0.9700
Al2—F5iii	1.799 (2)	C2—H2E	0.9700
Al2—F5	1.799 (2)	C3—C4	1.505 (5)
Al2—F5iv	1.799 (2)	C3—H3A	0.9700
Al2—F5v	1.799 (2)	C3—H3B	0.9700
Al2—F3	1.809 (3)	C4—C3vii	1.505 (5)
Al2—F3iii	1.809 (3)	C4—H4A	0.9700
N1—C1	1.476 (6)	C4—H4B	0.9700
N1—H1A	0.8900	OW1—H1	0.831 (10)
N1—H1B	0.8900	OW2—H2	0.840 (10)
N1—H1C	0.8900	OW3—H3	0.846 (10)
N2—C3	1.477 (6)	OW4—H4	0.842 (10)
N2—H2A	0.8900	OW5—H5	0.840 (10)
N2—H2B	0.8900
F2i—Al1—F2	175.7 (2)	H1A—N1—H1C	109.5
F2i—Al1—F1	91.47 (7)	H1B—N1—H1C	109.5
F2—Al1—F1	91.47 (7)	C3—N2—H2A	109.5
F2i—Al1—F1ii	91.47 (7)	C3—N2—H2B	109.5
F2—Al1—F1ii	91.47 (7)	H2A—N2—H2B	109.5
F1—Al1—F1ii	94.0 (2)	C3—N2—H2C	109.5
F2i—Al1—OW1	88.49 (7)	H2A—N2—H2C	109.5
F2—Al1—OW1	88.49 (7)	H2B—N2—H2C	109.5
F1—Al1—OW1	87.59 (16)	N1—C1—C2	108.9 (4)
F1ii—Al1—OW1	178.44 (16)	N1—C1—H1D	109.9
F2i—Al1—OW1ii	88.49 (7)	C2—C1—H1D	109.9
F2—Al1—OW1ii	88.49 (7)	N1—C1—H1E	109.9
F1—Al1—OW1ii	178.44 (16)	C2—C1—H1E	109.9
F1ii—Al1—OW1ii	87.60 (16)	H1D—C1—H1E	108.3
OW1—Al1—OW1ii	90.8 (2)	C1vi—C2—C1	112.7 (5)
F5iii—Al2—F5	180.00 (14)	C1vi—C2—H2D	109.1
F5iii—Al2—F5iv	87.92 (14)	C1—C2—H2D	109.1
F5—Al2—F5iv	92.08 (14)	C1vi—C2—H2E	109.1
F5iii—Al2—F5v	92.08 (14)	C1—C2—H2E	109.1
F5—Al2—F5v	87.92 (14)	H2D—C2—H2E	107.8
F5iv—Al2—F5v	180.00 (13)	N2—C3—C4	110.5 (4)
F5iii—Al2—F3	90.34 (9)	N2—C3—H3A	109.6
F5—Al2—F3	89.66 (9)	C4—C3—H3A	109.6
F5iv—Al2—F3	89.66 (9)	N2—C3—H3B	109.6
F5v—Al2—F3	90.34 (9)	C4—C3—H3B	109.6
F5iii—Al2—F3iii	89.66 (9)	H3A—C3—H3B	108.1
F5—Al2—F3iii	90.34 (9)	C3vii—C4—C3	112.2 (5)
F5iv—Al2—F3iii	90.34 (9)	C3vii—C4—H4A	109.2
F5v—Al2—F3iii	89.66 (9)	C3—C4—H4A	109.2
F3—Al2—F3iii	180.0	C3vii—C4—H4B	109.2
C1—N1—H1A	109.5	C3—C4—H4B	109.2
C1—N1—H1B	109.5	H4A—C4—H4B	107.9
H1A—N1—H1B	109.5	Al1—OW1—H1	122 (2)
C1—N1—H1C	109.5

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···F2	0.89	1.79	2.679 (6)	177
N1—H1B···F5viii	0.89	1.99	2.846 (5)	161
N1—H1C···F5iii	0.89	1.99	2.846 (5)	161
N2—H2A···F3	0.89	1.84	2.722 (6)	173
N2—H2B···F1ix	0.89	2.00	2.841 (5)	158
Ow1—H1···F5x	0.83 (4)	1.74 (4)	2.569 (5)	178
Ow2—H2···F3	0.84 (4)	2.10 (4)	2.880 (5)	178
Ow4—H4···Ow5ii	0.84 (4)	2.13	2.910 (5)	154