A layered fluorinated gallium phosphate organically templated by propane-1,3-diaminium, an analog of the aluminophosphate MIL-12: Ga₂(PO₄)F₅·C₃H₁₂N₂

Crystals of the oxyfluorinated gallium phosphate MIL-12 (digallium phosphate penta­fluoride propane-1,3-diaminium), (C₃H₁₂N₂)[Ga₂(PO₄)F₅], were synthesized hydro­thermally at 453 K under autogenous pressure using propane-1,3-diamine as the structure-directing agent. The title compound is isomorphous with the aluminium phosphate having the MIL-12 structural type. The structure is built up from a two-dimensional anionic network inter­calated by the diamine species. The inorganic layer is composed of corner-linked GaO₂F₄ octa­hedra and PO₄ tetra­hedra. The diprotonated diamine group is located on a mirror plane, between the inorganic sheets, and inter­acts preferentially via hydrogen bonding through the ammonium groups and the terminal F and bridging O atoms of the inorganic layer. One of the Ga atoms lies on an inversion centre and the other lies on a mirror plane, as does the P atom, two of the phosphate O atoms and one of the F atoms.

S1. Comment

Microporous metal phosphates have been studied intensively because of their potential applications in diverse areas such as catalysis, gas separation and ionic exchangers. In the past decade, the preparations of a large number of open-framework phosphates containing aluminium or gallium have been reported (Cheetham et al., 1999), and structural analyses of several aluminium phosphates have shown that they possess three-dimensional networks identical to those encountered in the aluminosilicate zeolite family. The substitution of gallium for aluminium in these compounds and the use of HF as mineralizing agent have led to the discovery of novel oxyfluorinated extra large-pore open-framework structures. In the series, it was shown that different key parameters play a significant role in the formation of such three-dimensional frameworks. For instance, the reaction pH has a drastic effect on the synthesis of phases with different structures. A typical example is the study of the chemical system including gallium, phosphoric acid, hydrofluoric acid, water and propane-1,3-diamine as structure-directing agent (Ferey, 1995).

Following this study, the concentration of the fluoride ions was considered. For high F content (i.e. F/Ga = 2 or 2.5), the phase called MIL-12 (MIL stands for materials of Institut Lavoisier) occurred at very low pH in this specific system. The present paper deals with the single-crystal structure characterization of the gallium phosphate MIL-12 or Ga₂(PO₄)F₅·C₃H₁₂N₂, prepared in the presence of propane-1,3-diamine as templating molecule. The structure of this solid is similar to that of the layered aluminium phosphate MIL-12 (Simon et al., 1999) intercalating the same diamine and characterized by powder X-ray diffraction techniques.

The structure (Fig. 1) of MIL-12 is built up from the connection by vertices of PO₄ tetrahedra with GaO₂F₄ octahedra (Fig. 2). The unique phosphorus crystallographic site is coordinated by four O atoms, with P—O distances ranging from 1.523 (3) to 1.550 (2) Å, as expected for the phosphates groups. The two crystallographically inequivalent Ga atoms are octahedrally coordinated by four F and two O atoms. The Ga—O distances range from 1.897 (3) to 1.9259 (18) Å and the O atoms are in trans positions. The position of the F atoms was deduced from the single-crystal X-ray diffraction and chemical analyses, and there exist two types of configuration. For atom Ga1 on special position 2e, two F atoms are terminal with shorter Ga—F distances [Ga1—F3 = 1.8621 (18) Å], whereas the two other bridge the Ga atoms to each other with Ga1—F2 distances of 1.9979 (17) Å. Such a Ga—F bond difference was observed previously in another fluorinated gallium phosphate, GaPO₄—CJ2 (Ferey et al., 1993), and in pseudo-KTP structures (Loiseau et al., 2000), in which terminal and brigding F atoms occur. For atom Ga2, on special position 2c, four F atoms bridge the Ga atoms to each other [Ga2—F2 = 1.9140 (16) and Ga2—F1 = 1.9425 (9) Å].

The Ga2O₂F₄ species are linked via atom F1 in such a way as to form infinite straight chains of trans-connected octahedra running along the b axis. These chains are connected together through the phosphate groups (via O atoms) and with the Ga1O₂F₄ species (via F atoms), and this type of connection results in the formation of an inorganic sheet, [Ga₂(PO₄)F₅]²⁻, in the ab plane (Fig. 3). The terminal F3 atoms point alternately downward and upward in the layer, toward the interacalated organic propane-1,3-diamine molecules, which are perpendicular to the inorganic sheet (in the mirror plane). The diamine species is diprotonated ([H₃N(CH₂)₃NH₃]²⁺), and the resulting positive charges balance the negative ones of the anionic layer. One of the diamine atoms (N2) is linked to the terminal atom F3 through very strong hydrogen-bond interactions [N2—H1N2···F3 = 1.84 (3) Å] and is weakly linked to atom O2 [N2—H2N2···O2= 2.14 (4) Å; Table 2]. The other ammonium N atom (N1) mainly interacts with atom O3 via an N1—H1N1···O3 hydrogen bond [2.06 (3) Å]. A similar layer-like atomic arrangement was reported previously in the aluminium phosphate MIL-12 (Simon et al., 1999b), in which the Al atoms replace the Ga atoms.

S2. Experimental

The title compound was prepared hydrothermally from a mixture of gallium oxide (Ga₂O₃, 99.999%), phosphoric acid (H₃PO₄, 85%), hydrofluoric acid (HF, 40%), propane-1,3-diamine (C₃H₁₀N₂, 98%) and deionized water with the molar ratio 0.5:1:2 (or 2.5):0.4:40. This mixture was sealed in a teflon-lined Parr autoclave and then heated for 26 h at 453 K under autogeneous pressure. The pH was 1–2 during the synthesis. After cooling to room temperature, the solid was separated from the liquid phase by filtration, washed with water and then dried in air. A single-crystal was selected optically for the diffraction study and glued to a glass fiber. The presence of fluorine was deduced from the consideration of the thermal parameter analysis. It was confirmed by bond valence calculations (O'Keeffe & Brese, 1992) and was in agreement with the chemical analysis (observed: 23.0 wt%; calculated: 23.4 wt% for 5 F/2Ga).

S3. Refinement

H atoms bonded to C atoms were included as riding atoms, with C—H distances of 0.97 Å.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1996); software used to prepare material for publication: SHELXTL (Siemens, 1995).

Figures

	Fig. 1. : A displacement ellipsoid plot (50% probability level) of the structure of MIL-12.
	Fig. 2. : A polyhedral projection of the structure of Ga2(PO4)F5·C3H12N2 (MIL-12 type) along [100], showing the inorganic layer intercalated by the propane-1,3-diammonium molecules. Grey circles: N; black circles: C; small open circles: H; grey octahedra: GaO2F4; white tetrahedra: PO4.
	Fig. 3. : A polyhedral projection of the inorganic anionic [Ga2(PO4)F5]^2− sheet along [001]. Grey octahedra: GaO2F4; white tetrahedra: PO4; open circles: O; grey circles: F.

Digallium phosphate pentafluoride propane-1,3-diaminium

Crystal data

Ga2(PO4)F5·C3H12N2	F(000) = 396
Mr = 405.56	Dx = 2.721 Mg m^−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 2320 reflections
a = 6.2082 (1) Å	θ = 1.8–29.5°
b = 7.2183 (1) Å	µ = 5.69 mm^−1
c = 11.2335 (3) Å	T = 293 K
β = 100.477 (2)°	Platelet, colourless
V = 495.01 (2) Å^3	0.12 × 0.03 × 0.01 mm
Z = 2

Data collection

Siemens SMART CCD area-detector diffractometer	1374 independent reflections
Radiation source: fine-focus sealed tube	1160 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
ϕ and ω scans	θmax = 29.5°, θmin = 1.8°
Absorption correction: empirical (using intensity measurements) (SADABS; Blessing, 1995, 1997)	h = −8→8
Tmin = 0.549, Tmax = 0.945	k = −9→7
3501 measured reflections	l = −13→14

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.028	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.072	w = 1/[σ^2(Fo^2) + (0.0485P)^2 + 0.1108P] where P = (Fo^2 + 2Fc^2)/3
S = 0.90	(Δ/σ)max = 0.001
1374 reflections	Δρmax = 0.62 e Å^−3
109 parameters	Δρmin = −0.62 e Å^−3
4 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0112 (18)

Special details

Experimental. 'Blessing, Acta Cryst. (1995) A51, 33–38' 'Blessing, J. Appl. Cryst. (1997) 30, 421–6'

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	Occ. (<1)
Ga1	0.29474 (7)	0.2500	0.76145 (4)	0.01062 (14)
Ga2	0.0000	0.5000	0.5000	0.00958 (14)
P	0.21386 (16)	0.7500	0.32810 (9)	0.0097 (2)
F1	−0.0128 (4)	0.7500	0.5623 (2)	0.0157 (5)
F2	0.2330 (3)	0.4409 (3)	0.63092 (15)	0.0159 (4)
F3	0.3566 (3)	0.4363 (3)	0.87730 (16)	0.0211 (4)
O1	0.0076 (4)	0.7500	0.2298 (2)	0.0144 (6)
O2	0.4065 (5)	0.7500	0.2614 (3)	0.0163 (6)
O3	0.2201 (3)	0.5759 (3)	0.40942 (17)	0.0128 (4)
N1	0.4291 (7)	0.2500	0.3392 (4)	0.0238 (8)
H1N1	0.394 (6)	0.157 (5)	0.378 (3)	0.027 (11)*
H2N1	0.562 (8)	0.2500	0.337 (7)	0.06 (2)*
N2	−0.2315 (7)	0.2500	0.0117 (4)	0.0235 (8)
H1N2	−0.284 (7)	0.146 (5)	0.046 (4)	0.041 (12)*
H2N2	−0.287 (11)	0.2500	−0.070 (4)	0.05 (2)*
C1	0.3374 (8)	0.2500	0.2057 (4)	0.0264 (10)
H1A	0.3901	0.1414	0.1690	0.032*	0.50
H1B	0.3901	0.3586	0.1690	0.032*	0.50
C2	0.0889 (8)	0.2500	0.1799 (4)	0.0234 (10)
H2A	0.0341	0.1410	0.2152	0.028*	0.50
H2B	0.0341	0.3590	0.2152	0.028*	0.50
C3	0.0113 (8)	0.2500	0.0433 (4)	0.0245 (10)
H3A	0.0682	0.3587	0.0087	0.029*	0.50
H3B	0.0682	0.1413	0.0087	0.029*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ga1	0.0085 (2)	0.0121 (2)	0.0113 (2)	0.000	0.00198 (15)	0.000
Ga2	0.0106 (2)	0.0083 (2)	0.0098 (2)	0.00003 (15)	0.00204 (15)	0.00099 (15)
P	0.0085 (4)	0.0103 (5)	0.0105 (5)	0.000	0.0023 (3)	0.000
F1	0.0233 (13)	0.0097 (11)	0.0154 (12)	0.000	0.0069 (10)	0.000
F2	0.0133 (8)	0.0178 (9)	0.0155 (8)	−0.0017 (7)	−0.0003 (6)	0.0047 (7)
F3	0.0205 (9)	0.0217 (9)	0.0212 (9)	−0.0023 (8)	0.0043 (7)	−0.0094 (8)
O1	0.0088 (13)	0.0217 (16)	0.0124 (13)	0.000	0.0015 (10)	0.000
O2	0.0115 (14)	0.0222 (16)	0.0163 (14)	0.000	0.0058 (11)	0.000
O3	0.0134 (9)	0.0113 (9)	0.0148 (10)	0.0018 (8)	0.0056 (8)	0.0027 (8)
N1	0.019 (2)	0.021 (2)	0.032 (2)	0.000	0.0057 (17)	0.000
N2	0.024 (2)	0.023 (2)	0.023 (2)	0.000	0.0033 (16)	0.000
C1	0.027 (2)	0.029 (3)	0.026 (2)	0.000	0.0106 (19)	0.000
C2	0.024 (2)	0.027 (2)	0.020 (2)	0.000	0.0070 (18)	0.000
C3	0.024 (2)	0.029 (3)	0.020 (2)	0.000	0.0055 (18)	0.000

Geometric parameters (Å, º)

Ga1—F3^i	1.8621 (18)	O1—Ga1^ii	1.897 (3)
Ga1—F3	1.8621 (18)	O2—Ga1^iii	1.918 (3)
Ga1—O1^ii	1.897 (3)	N1—C1	1.504 (7)
Ga1—O2^iii	1.918 (3)	N1—H1N1	0.85 (3)
Ga1—F2^i	1.9979 (17)	N1—H2N1	0.83 (4)
Ga1—F2	1.9979 (17)	N2—C3	1.485 (6)
Ga2—F2^ii	1.9140 (16)	N2—H1N2	0.93 (3)
Ga2—F2	1.9140 (16)	N2—H2N2	0.92 (4)
Ga2—O3^ii	1.9259 (18)	C1—C2	1.517 (7)
Ga2—O3	1.9259 (18)	C1—H1A	0.9700
Ga2—F1^ii	1.9425 (9)	C1—H1B	0.9700
Ga2—F1	1.9425 (9)	C2—C3	1.523 (7)
P—O2	1.523 (3)	C2—H2A	0.9700
P—O1	1.532 (3)	C2—H2B	0.9700
P—O3	1.550 (2)	C3—H3A	0.9700
F1—Ga2^iv	1.9425 (9)	C3—H3B	0.9700
F3^i—Ga1—F3	92.46 (12)	O2—P—O3^v	110.63 (10)
F3^i—Ga1—O1^ii	92.52 (8)	O1—P—O3^v	110.69 (10)
F3—Ga1—O1^ii	92.52 (8)	O3—P—O3^v	108.34 (16)
F3^i—Ga1—O2^iii	90.67 (8)	Ga2^iv—F1—Ga2	136.56 (13)
F3—Ga1—O2^iii	90.67 (8)	Ga2—F2—Ga1	137.31 (9)
O1^ii—Ga1—O2^iii	175.39 (12)	P—O1—Ga1^ii	131.89 (17)
F3^i—Ga1—F2^i	90.14 (8)	P—O2—Ga1^iii	158.6 (2)
F3—Ga1—F2^i	177.04 (8)	P—O3—Ga2	126.72 (12)
O1^ii—Ga1—F2^i	88.77 (8)	C1—N1—H1N1	115 (3)
O2^iii—Ga1—F2^i	87.89 (8)	C1—N1—H2N1	99 (5)
F3^i—Ga1—F2	177.04 (8)	H1N1—N1—H2N1	112 (4)
F3—Ga1—F2	90.14 (8)	C3—N2—H1N2	109 (3)
O1^ii—Ga1—F2	88.77 (8)	C3—N2—H2N2	115 (4)
O2^iii—Ga1—F2	87.89 (8)	H1N2—N2—H2N2	108 (4)
F2^i—Ga1—F2	87.22 (10)	N1—C1—C2	112.2 (4)
F2^ii—Ga2—F2	180.0	N1—C1—H1A	109.2
F2^ii—Ga2—O3^ii	87.69 (8)	C2—C1—H1A	109.2
F2—Ga2—O3^ii	92.31 (8)	N1—C1—H1B	109.2
F2^ii—Ga2—O3	92.31 (8)	C2—C1—H1B	109.2
F2—Ga2—O3	87.69 (8)	H1A—C1—H1B	107.9
O3^ii—Ga2—O3	180.0	C3—C2—C1	108.5 (4)
F2^ii—Ga2—F1^ii	90.27 (9)	C3—C2—H2A	110.0
F2—Ga2—F1^ii	89.73 (9)	C1—C2—H2A	110.0
O3^ii—Ga2—F1^ii	90.32 (9)	C3—C2—H2B	110.0
O3—Ga2—F1^ii	89.69 (9)	C1—C2—H2B	110.0
F2^ii—Ga2—F1	89.73 (9)	H2A—C2—H2B	108.4
F2—Ga2—F1	90.27 (9)	N2—C3—C2	111.2 (4)
O3^ii—Ga2—F1	89.68 (9)	N2—C3—H3A	109.4
O3—Ga2—F1	90.31 (9)	C2—C3—H3A	109.4
F1^ii—Ga2—F1	179.999 (1)	N2—C3—H3B	109.4
O2—P—O1	105.87 (16)	C2—C3—H3B	109.4
O2—P—O3	110.63 (10)	H3A—C3—H3B	108.0
O1—P—O3	110.69 (10)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O3^i	0.85 (3)	2.06 (3)	2.866 (3)	157 (4)
N2—H1N2···F3^vi	0.93 (3)	1.84 (3)	2.764 (3)	174 (4)
N2—H2N2···O2^vii	0.92 (4)	2.14 (4)	3.062 (5)	178 (6)

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