Structure refinement of (NH4)3Al2(PO4)3 prepared by ionothermal synthesis in phospho-nium based ionic liquids - a redetermination.

After crystallization during ionothermal syntheses in phospho-nium-containing ionic liquids, the structure of (NH4)3Al2(PO4)3 [tri-ammonium dialuminum tris-(phosphate)] was refined on the basis of powder X-ray diffraction data from a synchrotron source. (NH4)3Al2(PO4)3 is a member of the structural family with formula A 3Al2(PO4)3, where A is a group 1 element, and of which the NH4, K, and Rb forms were previously known. The NH4 form is isostructural with the K form, and was previously solved from single-crystal X-ray data when the material (SIZ-2) crystallized from a choline-containing eutectic mixture [Cooper et al. (2004 ▸). Nature, 430, 1012-1017]. Our independent refinement incorporates NH4 groups and shows that these NH4 groups are hydrogen bonded to framework O atoms present in rings containing 12 T sites in a channel along the c-axis direction. We describe structural details of (NH4)3Al2(PO4)3 and discuss differences with respect to isostructural forms. © Nicholas et al. 2019.

Chemical context

Following the discovery of the microporous AlPO4-n series of materials (Wilson et al., 1982 ▸), many efforts have been directed toward the synthesis of novel phases utilizing traditional hydro­thermal (Wilson, 2007 ▸; Yu & Xu, 2006 ▸) and solvothermal syntheses (Das et al., 2012 ▸). Recently, ionothermal synthesis has been added to the stable of synthetic methods. Ionothermal synthesis is an extension of the solvothermal method of synthesis using an ionic liquid as the solvent (replacing, for example, water or ethyl­ene glycol) where a portion of the organic structure-directing agent from a typical zeolite synthesis is derived from the ionic liquid (Morris, 2009 ▸). Many new materials have been synthesized by ionothermal synthesis, with new aluminophosphate materials among the most common (Parnham & Morris, 2007 ▸; Xing et al., 2008 ▸, 2010 ▸).

An important issue in ionothermal synthesis is control of water (Ma et al., 2008 ▸). Excess water often leads to synthesis of dense AlPO4 phases such as the one with a tridymite-type of structure, which we observed as well during syntheses utilizing 85%wt H3PO4. To control the level of water in the synthesis, thereby allowing easy recycling of the ionic liquid solvent and to intentionally prepare ammonium aluminophosphates, we used (NH4)2HPO4 as the phospho­rous source in the synthesis. Ammonium is a good structure-directing agent for aluminophosphate frameworks; multiple ammonium aluminum phosphates are known (Byrne et al., 2009 ▸; Vaughan et al., 2012 ▸). In the current phospho­nium-based ionothermal synthesis, the presence of an ammonium cation in the relative absence of water provokes the formation of a 2/3 Al/P framework with the formula (NH4)3Al2(PO4)3. A structurally unrelated compound with the formula (NH4)3Al2(PO4)3 has previously been synthesized via a solvothermal approach (Medina et al., 2004 ▸).

The aluminophosphate database at Jilin (Li et al., 2019 ▸) currently lists 21 framework structures with a 2:3 ratio of Al:P. A framework with sub-stoichiometric Al content is by necessity anionically charged and must be cation-balanced, so most of the known frameworks, such as UT-3, UT-4 and UT-5 (Oliver et al., 1996 ▸) are charge-balanced by organo­ammonium cations. Low-water-content syntheses clearly favor 2:3 compounds as most of the known materials are synthesized from low-water-content preparations.

Structural commentary and survey of related compounds

The (NH4)3Al2(PO4)3 phase synthesized here is related to the series of A 3Al2(PO4)3 materials synthesized via high-temperature solid-state methods (Devi & Vidyasagar, 2000 ▸) with varying monocations on the A site. Additionally, an independent synthesis previously yielded a (NH4)3Al2(PO4)3 material called SIZ-2 whose structure was solved and refined from single-crystal data (Cooper et al., 2004 ▸) and possesses nearly the same structure as refined from the current powder data of (NH4)3Al2(PO4)3. A polyhedral representation of the crystal structure of (NH4)3Al2(PO4)3 is shown in Fig. 1 ▸. SIZ-2 crystallized from a choline chloride/urea eutectic mixture where decomposition of urea was proposed to be the source of ammonium in the structure. The refinement of Cooper et al. (2004 ▸) included the ammonium N atoms, but made no attempt to find or model the corresponding H atoms.

Figure 1

Polyhedral representation of (NH4)3Al2(PO4)3, showing the overall connectivity and ion channels in the crystal structure. Al is in the center of blue tetra­hedra, P in gray tetra­hedra, and N is represented by blue spheres.

Devi & Vidyasagar (2000 ▸) utilized Li, Na, K, Rb, Cs, and Tl as the A cation and succeeded in crystallizing compounds with A = Na, K, Rb, Tl. The thallium derivative yielded a completely different structure with trigonal–bipyramidal coordination of Al. The A = Na structure was not solved, but apparently crystallizes in an unrelated ortho­rhom­bic space-group type from that observed for A = K, Rb in their work, and for A = NH4 here. Devi & Vidyasagar (2000 ▸) utilized (NH4)2HPO4 as the phosphate source in their high-temperature preparations of A 3Al2(PO4)3, but did not obtain (NH4)3Al2(PO4)3, likely due to the volatility of NH3 at high temperatures.

As in the K and Rb forms of the A 3Al2(PO4)3 series, aluminum and phospho­rus are both tetra­hedrally coordinated and connected through corners throughout the (NH4)3Al2(PO4)3 structure. The NH4 + cations reside in a channel along the c-axis direction made from a 12 T-site ring of alternating AlO4 and PO4 tetra­hedra (Fig. 2 ▸). The NH4 + groups occupy the available space and none of the ionic liquid solvent is present within the pores of the (NH4)3Al2(PO4)3 framework. Without the NH4 + groups, the structure would have 24% void volume. The framework is triply negatively charged and charge-balanced by the ammonium cations. Three of the six phosphate groups in the ring protrude inward such that the closest contact distance between the H atom of an ammonium group and the O atom of the nearest phosphate is between 1.83 and 1.87 Å, indicating significant hydrogen-bonding inter­actions. The full range of H⋯O hydrogen-bond lengths is between 1.83 and 1.97 Å (Table 1 ▸).

Figure 2

Ball and stick representation of (NH4)3Al2(PO4)3 showing the 12-membered ring with three phosphate groups protruding inward with close contact to ammonium cations.

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H11⋯O9i	0.95 (4)	2.39 (4)	3.250 (10)	151 (3)
N1—H11⋯O11	0.95 (4)	2.35 (5)	3.163 (8)	143 (3)
N1—H12⋯O1ii	0.95 (4)	1.88 (4)	2.791 (10)	159 (3)
N1—H13⋯O5	0.95 (4)	2.14 (4)	2.934 (10)	141 (3)
N1—H14⋯O9iii	0.95 (4)	1.83 (4)	2.776 (9)	173 (3)
N2—H21⋯O5iv	0.95 (4)	1.96 (4)	2.896 (10)	170 (4)
N2—H22⋯O8v	0.95 (4)	2.31 (3)	3.216 (10)	158 (4)
N2—H23⋯O9iv	0.95 (4)	1.89 (5)	2.738 (9)	148 (4)
N2—H24⋯O11vi	0.96 (4)	1.86 (4)	2.818 (9)	174 (5)
N3—H31⋯O5vi	0.96 (4)	1.97 (4)	2.821 (9)	147 (3)
N3—H32⋯O11vi	0.952 (15)	1.85 (2)	2.728 (8)	153 (4)
N3—H33⋯O1v	0.95 (3)	1.90 (3)	2.823 (9)	164 (4)
N3—H34⋯O12	0.96 (3)	2.37 (4)	2.925 (8)	117 (4)

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

Crystallizing in space-group type Pna21, (NH4)3Al2(PO4)3 is isostructural to, but with a slightly larger unit cell than the K form synthesized by Devi & Vidyasagar (2000 ▸). Lattice expansion of ∼0.1–0.2 Å occurs along each of the three axes, leading to an overall 6.6% increase in cell volume from 1245 to 1327 Å3. A lattice expansion is no surprise as the ionic radius of NH4 + is between 1.4 and 1.67 Å depending on the coordination number (Sidey, 2016 ▸). This is slightly larger than the reported 1.37 to 1.55 Å range for K+ (Shannon, 1976 ▸). Much of the relative lattice expansion for (NH4)3Al2(PO4)3 occurs along the a and c axes. Tilting of tetra­hedra accounts for a significantly smaller expansion of the long b axis. In addition, an isostructural K/As form is also known where two-thirds of the phosphate groups have been replaced by arsenate (Boughzala et al., 1997 ▸). Arsenate included on the phosphate sites increases the cell volume to 1307 Å3, just smaller than that recorded here for (NH4)3Al2(PO4)3. The pure arsenate form K3Al2(AsO4)3 was reported by Stöger & Weil (2012 ▸), which has a cell volume of 1328 Å3, essentially equivalent to that here.

An overlay plot of atomic positions of (NH4)3Al2(PO4)3 (red) versus SIZ-2 (blue) shows that although the independent refinements of the two (NH4)3Al2(PO4)3 materials were performed via different methods at different temperatures, most atom positions are similar, with no more than about 0.004 fractional position differences along the a or c axes (for these axes, about 0.03–0.04 Å, Fig. 3 ▸). One area stands out in the A 3Al2(PO4)3 series. Fig. 4 ▸ shows the key area surrounding O11 where the largest position movement is observed in the two independent refinements of (NH4)3Al2(PO4)3.

Figure 3

Atomic position overlay plot of SIZ-2 (blue) and (NH4)3Al2(PO4)3 (red) showing that most atom positions are within 0.03 Å of each other. The most significant difference is in the O11 position.

Figure 4

Ball and stick representation of the key area surrounding O11 where the largest position movement takes place in the two independent refinements of (NH4)3Al2(PO4)3.

The P3—O11 bond is always among the shortest P—O bonds found in the crystal structure, here at 1.487 (5) Å. Two clusters of P—O bond lengths occur; one at about 1.49 Å and another at 1.55 Å. These distances are relatively typical for aluminophosphates (Richardson & Vogt, 1992 ▸; Wei et al., 2012 ▸). Each of the O atoms protruding into the pore possess short P—O bonds and hydrogen bonds to two ammonium ions (Table 1 ▸). In particular, N2, N3, O11, and P3 are effectively in a plane so that with the hydrogen bonding present in our refined model from N3 and N2 through the attached H atoms to O11, O11 moves closer to P3 while N2 and N3 move slightly further away versus the positions in the SIZ-2 refinement. Table 2 ▸ shows respective O—A and P—O distances for the four isostructural A 3Al2(PO4)3 compounds. Other bond lengths and angles are otherwise relatively unremarkable versus other members of the structural class although we note that As/P—O distances are longer than P—O as expected.

Table 2

Key atomic distances (Å) in related A 3Al2(PO4)3 structures

Compound	O11—A1	O11—A2	O11—A3	O11—P3	Reference
(NH4)3Al2(PO4)3	3.162	2.818	2.727	1.487	This work
SIZ-2 (A = NH4)	3.090	2.834	2.688	1.496	Cooper et al. (2004 ▸)
K3Al2(PO4)3	2.754	2.824	2.722	1.487	Devi & Vidyasagar (2000 ▸)
K3Al2(AsO4)2(PO4)	3.025	2.743	2.621	1.673	Boughzala et al. (1997 ▸)

For each of the compounds, the atomic numbering scheme of the current (NH4)3Al2(PO4)3 refinement has been utilized. For the first two compounds, A = NH4, while for the second two, A = K. For the As-containing compound, the P3 site is reported to have the highest occupancy of As at 0.86.

Rb3Al2(PO4)3 is structurally related to the NH4 and K forms, but crystallizes in a higher symmetry space-group type (Cmc21), accompanied with higher overall coordination numbers around Rb+ and a mirror plane perpendicular to a. The ionic radius of Rb+ is similar to that of NH4 +, reported as 1.52–1.63 Å (Shannon, 1976 ▸). Lithium and cesium forms of the series have not yet been synthesized, likely because of the relatively small and large, respectively, ionic radii versus those of the fitting A cations. Our initial attempts at ion-exchange of (NH4)3Al2(PO4)3 with LiNO3 or CsNO3 in aqueous solution to form the Li or Cs form failed, with partial structural degradation and no ion-exchange observed.

Synthesis and crystallization

In a typical preparation, 1.65 g (NH4)2HPO4 was added to a 125 ml polytetra­fluoro­ethene (PTFE) lined autoclave containing 24.02 g of ethyl tri(but­yl)phospho­nium di­ethyl phosphate. The mixture was stirred at room temperature for 2 min. To this mixture were added 0.49 g of Al(OH)3, and the contents were stirred at room temperature for 2 min. The contents of the autoclave were digested at 423 K for 24 h prior to isolating the product by filtration. Analytical results show this material has a molar ratio Al:P of 0.725. The X-ray diffraction pattern is shown in Fig. 5 ▸. Scanning electron microscopy (SEM) revealed agglomerated stacks of irregularly shaped blocky crystals of from 500 nm to 2–4 µm in length (Fig. 6 ▸). Calcination of (NH4)3Al2(PO4)3 at temperatures of 773 K or higher causes the formation of an AlPO4 phase with a tridymite-type structure. Ethyl tributyl phospho­nium diethyl phosphate (Cyphos 169) was acquired from Cytec; aluminum hydroxide was acquired from Pfaltz and Bauer.

Figure 5

XRD pattern (λ = 0.373811 Å) of (NH4)3Al2(PO4)3 synthesized ionothermally in ethyl tri­butyl­phospho­nium di­ethyl­phosphate and Rietveld residuals following structure refinement. Part A shows the fit to the overall pattern, and inset B shows the fit to high-angle regions.

Figure 6

SEM image of polycrystalline (NH4)3Al2(PO4)3 synthesized ionothermally in ethyl tri­butyl­phospho­nium diethyl phosphate and used for structure refinement.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. Following initial survey scans on in-house Cu source powder XRD instruments, final data were acquired from samples packed in thin glass capillaries on 11-BM at the Advanced Photon Source at Argonne National Laboratory. Starting atomic positions for the refinement were adapted from the literature examples. Starting positions for the ammonium cations were located in a difference-Fourier map and subsequently refined using GSAS (Larson & Von Dreele, 2000 ▸) as tetra­hedral rigid bodies with N—H bond lengths held at 0.9526 Å and tetra­hedrality enforced, leading to H⋯H distances of 1.5556 Å. No soft constraints were applied to the framework positions. All atoms in the structure were refined with a common U iso parameter. Two low-intensity reflections in the region 4.00–4.22°/2θ were excluded from the refinement as belonging to an impurity phase after assessment of multiple (NH4)3Al2(PO4)3 batches. Refinement trials with a higher symmetry model (space-group type Cmc21) were attempted but showed poor agreement with the experimental data, with R wp > 0.16.

Table 3

Experimental details

Crystal data
Chemical formula	(NH4)3Al2(PO4)3
M r	392.99
Crystal system, space group	Orthorhombic, P n a21
Temperature (K)	100
a, b, c (Å)	8.98884 (6), 17.01605 (10), 8.67653 (5)
V (Å3)	1327.11 (2)
Z	4
Radiation type	Synchrotron, λ = 0.373811 Å
μ (mm−1)	0.12
Specimen shape, size (mm)	Cylinder, 0.70 × 0.70
Data collection
Diffractometer	11BM synchrotron
Specimen mounting	Capillary
Data collection mode	Transmission
Scan method	Continuous
2θ values (°)	2θmin = 2.45, 2θmax = 20, 2θstep = 0.001
Refinement
R factors and goodness of fit	R p = 0.082, R wp = 0.101, R exp = 0.060, R(F 2) = 0.03552, χ2 = 2.856
No. of parameters	95
No. of restraints	20
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
(Δ/σ)max	0.17

Computer programs: local program at 11BM, GSAS (Larson & Von Dreele, 2000 ▸), coordinates from an isotypic structure, CrystalMaker (Palmer, 2005 ▸), publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989019015330/wm5528sup1.cif

CCDC references: 1965580, 1965580

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

(NH4)3Al2(PO4)3	V = 1327.11 (2) Å3
Mr = 392.99	Z = 4
Orthorhombic, Pna21	Synchrotron radiation, λ = 0.373811 Å
Hall symbol: P 2c -2n	µ = 0.12 mm−1
a = 8.98884 (6) Å	T = 100 K
b = 17.01605 (10) Å	white
c = 8.67653 (5) Å	cylinder, 0.70 × 0.70 mm

11BM_synchrotron diffractometer	Scan method: continuous
Specimen mounting: capillary	2θmin = 2.45°, 2θmax = 20°, 2θstep = 0.001°
Data collection mode: transmission

Least-squares matrix: full	Profile function: CW Profile function number 4 with 18 terms Pseudovoigt profile coefficients as parameterized in P. Thompson, D.E. Cox & J.B. Hastings (1987). J. Appl. Cryst.,20,79-83. Asymmetry correction of L.W. Finger, D.E. Cox & A. P. Jephcoat (1994). J. Appl. Cryst.,27,892-900. Microstrain broadening by P.W. Stephens, (1999). J. Appl. Cryst.,32,281-289. #1(GU) = 1.163 #2(GV) = -0.126 #3(GW) = 0.063 #4(GP) = 0.000 #5(LX) = 0.143 #6(ptec) = -0.01 #7(trns) = 0.00 #8(shft) = 0.0000 #9(sfec) = 0.00 #10(S/L) = 0.0011 #11(H/L) = 0.0011 #12(eta) = 0.7694 #13(S400 ) = 1.1E-01 #14(S040 ) = 2.8E-03 #15(S004 ) = 1.0E-01 #16(S220 ) = 1.3E-02 #17(S202 ) = -9.0E-03 #18(S022 ) = 6.9E-03 Peak tails are ignored where the intensity is below 0.0010 times the peak Aniso. broadening axis 1.0 0.0 0.0
Rp = 0.082	95 parameters
Rwp = 0.101	20 restraints
Rexp = 0.060	H atoms treated by a mixture of independent and constrained refinement
R(F2) = 0.03552	(Δ/σ)max = 0.17
49495 data points	Background function: GSAS Background function number 1 with 11 terms. Shifted Chebyshev function of 1st kind 1: 111.086 2: -42.2923 3: 17.4011 4: -1.76183 5: -7.25556 6: 2.97020 7: 2.60010 8: -3.84672 9: 5.91765 10: -3.48127 11: 1.19076

	x	y	z	Uiso*/Ueq
P1	0.1689 (3)	0.21458 (16)	−0.0138 (5)	0.0086 (3)*
P2	0.3100 (3)	0.29952 (16)	0.4927 (5)	0.0086 (3)*
P3	0.2594 (3)	0.5033 (2)	0.0861	0.0086 (3)*
Al1	0.3631 (4)	0.33375 (18)	0.1361 (5)	0.0086 (3)*
Al2	0.1295 (4)	0.17048 (19)	0.6462 (5)	0.0086 (3)*
O1	0.2886 (7)	0.1552 (3)	0.0117 (8)	0.0086 (3)*
O2	0.0384 (8)	0.2046 (3)	0.1014 (8)	0.0086 (3)*
O3	0.2289 (7)	0.3006 (3)	0.0100 (8)	0.0086 (3)*
O4	0.1017 (7)	0.2138 (4)	0.8252 (8)	0.0086 (3)*
O5	0.1953 (7)	0.3602 (3)	0.5464 (8)	0.0086 (3)*
O6	0.4625 (7)	0.3234 (3)	0.5425 (8)	0.0086 (3)*
O7	0.2776 (8)	0.2165 (3)	0.5518 (7)	0.0086 (3)*
O8	0.3087 (7)	0.2962 (4)	0.3126 (8)	0.0086 (3)*
O9	0.1072 (5)	0.4838 (3)	0.1404 (8)	0.0086 (3)*
O10	0.3228 (7)	0.5700 (4)	0.1747 (7)	0.0086 (3)*
O11	0.2604 (6)	0.5218 (3)	0.9186 (6)	0.0086 (3)*
O12	0.3716 (7)	0.4348 (3)	0.1188 (9)	0.0086 (3)*
N1	0.0164 (8)	0.3978 (4)	0.8194 (9)	0.0086 (3)*
H11	0.076 (5)	0.425 (3)	0.893 (4)	0.0086 (3)*
H12	−0.058 (4)	0.368 (3)	0.871 (5)	0.0086 (3)*
H13	0.077 (5)	0.364 (2)	0.760 (5)	0.0086 (3)*
H14	−0.030 (5)	0.435 (2)	0.753 (5)	0.0086 (3)*
N2	0.9630 (8)	0.3743 (4)	0.3168 (9)	0.0086 (3)*
H21	1.036 (4)	0.363 (3)	0.393 (5)	0.0086 (3)*
H22	0.915 (6)	0.3268 (16)	0.287 (6)	0.0086 (3)*
H23	1.009 (5)	0.397 (3)	0.229 (4)	0.0086 (3)*
H24	0.891 (5)	0.410 (3)	0.358 (6)	0.0086 (3)*
N3	0.6786 (6)	0.4917 (4)	0.1118 (7)	0.0086 (3)*
H31	0.755 (4)	0.530 (2)	0.095 (6)	0.0086 (3)*
H32	0.668 (5)	0.483 (3)	0.2196 (14)	0.0086 (3)*
H33	0.704 (5)	0.4438 (18)	0.062 (5)	0.0086 (3)*
H34	0.587 (3)	0.511 (3)	0.071 (5)	0.0086 (3)*

P1—Al1	2.975 (5)	O3—P1	1.573 (6)
P1—Al2i	3.064 (5)	O3—Al1	1.724 (7)
P1—O1	1.493 (6)	O4—P1iv	1.522 (7)
P1—O2	1.550 (7)	O4—Al2	1.737 (7)
P1—O3	1.573 (6)	O5—P2	1.532 (6)
P1—O4i	1.522 (7)	O5—H21viii	1.953 (13)
P2—Al2	3.038 (4)	O5—H31ix	1.97 (3)
P2—O5	1.532 (6)	O6—P2	1.493 (7)
P2—O6	1.493 (7)	O6—Al2iii	1.753 (7)
P2—O7	1.532 (6)	O7—P2	1.532 (6)
P2—O8	1.563 (6)	O7—Al2	1.748 (7)
P3—Al1	3.062 (5)	O8—P2	1.563 (6)
P3—Al2ii	3.060 (5)	O8—Al1	1.730 (7)
P3—O9	1.484 (5)	O9—P3	1.484 (5)
P3—O10	1.485 (6)	O9—H14x	1.828 (10)
P3—O11i	1.487 (5)	O9—H23viii	1.88 (3)
P3—O12	1.567 (6)	O10—P3	1.485 (6)
Al1—P1	2.975 (5)	O10—Al2ii	1.780 (7)
Al1—P3	3.062 (5)	O11—P3iv	1.487 (5)
Al1—O2iii	1.732 (7)	O11—H24ix	1.868 (10)
Al1—O3	1.724 (7)	O11—H32ix	1.84 (2)
Al1—O8	1.730 (7)	O12—P3	1.567 (6)
Al1—O12	1.727 (6)	O12—Al1	1.727 (6)
Al2—P1iv	3.064 (5)	N1—H11	0.9526 (1)
Al2—P2	3.038 (4)	N1—H12	0.9526 (1)
Al2—P3v	3.060 (5)	N1—H13	0.9526 (1)
Al2—O4	1.737 (7)	N1—H14	0.9526
Al2—O6vi	1.753 (7)	N2—H21	0.9526 (1)
Al2—O7	1.748 (7)	N2—H22	0.9526 (1)
Al2—O10v	1.780 (7)	N2—H23	0.9526 (1)
O1—P1	1.493 (6)	N2—H24	0.9526 (1)
O1—H12vii	1.88 (2)	N3—H31	0.9526 (1)
O1—H33vi	1.897 (15)	N3—H32	0.9526 (1)
O2—P1	1.550 (7)	N3—H33	0.9526 (1)
O2—Al1vi	1.732 (7)	N3—H34	0.9526 (1)
O1—P1—O2	112.1 (4)	O6vi—Al2—O10v	109.6 (3)
O1—P1—O3	111.3 (4)	O7—Al2—O10v	108.1 (3)
O1—P1—O4i	114.6 (4)	P1—O2—Al1vi	147.3 (5)
O2—P1—O3	106.1 (4)	P1—O3—Al1	128.9 (4)
O2—P1—O4i	106.9 (4)	P1iv—O4—Al2	140.1 (4)
O3—P1—O4i	105.4 (4)	P2—O6—Al2iii	161.9 (5)
O5—P2—O6	110.3 (4)	P2—O7—Al2	135.6 (5)
O5—P2—O7	113.1 (4)	P2—O8—Al1	150.4 (4)
O5—P2—O8	108.9 (4)	P3—O10—Al2ii	139.0 (5)
O6—P2—O7	109.2 (4)	P3—O12—Al1	136.7 (5)
O6—P2—O8	107.8 (4)	H11—N1—H12	109.4713 (9)
O7—P2—O8	107.4 (4)	H11—N1—H13	109.4719 (6)
O9—P3—O10	111.1 (4)	H11—N1—H14	109.4706
O9—P3—O11i	111.3 (4)	H12—N1—H13	109.4715 (1)
O9—P3—O12	111.7 (4)	H12—N1—H14	109.4704
O10—P3—O11i	110.0 (4)	H13—N1—H14	109.4715 (5)
O10—P3—O12	103.2 (3)	H21—N2—H22	109.4716 (7)
O11i—P3—O12	109.3 (4)	H21—N2—H23	109.4710 (4)
O2iii—Al1—O3	113.8 (4)	H21—N2—H24	109.4716 (4)
O2iii—Al1—O8	105.8 (4)	H22—N2—H23	109.4707
O2iii—Al1—O12	108.6 (4)	H22—N2—H24	109.4717 (8)
O3—Al1—O8	104.1 (3)	H23—N2—H24	109.4706 (7)
O3—Al1—O12	107.6 (4)	H31—N3—H32	109.4709
O8—Al1—O12	117.2 (4)	H31—N3—H33	109.4710 (5)
O4—Al2—O6vi	108.1 (3)	H31—N3—H34	109.4709 (1)
O4—Al2—O7	109.8 (3)	H32—N3—H33	109.4717
O4—Al2—O10v	108.5 (4)	H32—N3—H34	109.472
O6vi—Al2—O7	112.6 (4)	H33—N3—H34	109.4709

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···O9iv	0.95 (4)	2.39 (4)	3.250 (10)	151 (3)
N1—H11···O11	0.95 (4)	2.35 (5)	3.163 (8)	143 (3)
N1—H12···O1xi	0.95 (4)	1.88 (4)	2.791 (10)	159 (3)
N1—H13···O5	0.95 (4)	2.14 (4)	2.934 (10)	141 (3)
N1—H14···O9xii	0.95 (4)	1.83 (4)	2.776 (9)	173 (3)
N2—H21···O5xiii	0.95 (4)	1.96 (4)	2.896 (10)	170 (4)
N2—H22···O8iii	0.95 (4)	2.31 (3)	3.216 (10)	158 (4)
N2—H23···O9xiii	0.95 (4)	1.89 (5)	2.738 (9)	148 (4)
N2—H24···O11xiv	0.96 (4)	1.86 (4)	2.818 (9)	174 (5)
N3—H31···O5xiv	0.96 (4)	1.97 (4)	2.821 (9)	147 (3)
N3—H32···O11xiv	0.952 (15)	1.85 (2)	2.728 (8)	153 (4)
N3—H33···O1iii	0.95 (3)	1.90 (3)	2.823 (9)	164 (4)
N3—H34···O12	0.96 (3)	2.37 (4)	2.925 (8)	117 (4)