The title compound, (NH4)ZnPO4–HEX, is built up from a three-dimensional network of ZnO4 and PO4 tetrahedra [dav(Zn—O) = 1.9400 (7) Å and dav(P—O) = 1.5396 (7) Å], fused together via Zn—O—P links [θav = 133.47 (4)°]. An undisordered linear Zn—O—P bond occurs (all three atoms lie on a threefold axis). Extra-framework NH4+ cations, which interact with the [ZnPO4]− framework by hydrogen bonds, complete the crystal structure.
Supporting information
A mixture of N2H4 (2.35 g, 73 mmol), zinc acetate (2.20 g, 10 mmol), 85%
H3PO4 (4.6 g, 40 mmol) and water (9.08 g, 500 mmol) was placed in a
plastic bottle (initial pH = 6.5) and heated to 343 K for 14 d. Numerous
bicapped,hexagonal rods (maximum size 1 mm) of the title compound were
recovered by vacuum filtration and drying in air. Elemental analysis (Found: N
7.85, 2.22%; calculated 7.86%, H 2.24%) was consistent with the crystal
structure.
All H atoms were located from diffence maps and their atomic coordinates and
isotropic thermal factors were freely refined.
Data collection: local routines; cell refinement: local routines; data reduction: local routines; program(s) used to solve structure: SHELXS86 (Sheldrick, 1986); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software Inc., 1999); software used to prepare material for publication: SHELXL97.
Crystal data top
(NH4)·(ZnPO4) | Dx = 2.745 Mg m−3 |
Mr = 178.38 | Melting point: decomposes before melting K |
Hexagonal, P63 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 6c | Cell parameters from 20 reflections |
a = 10.702 (2) Å | θ = 13.3–13.7° |
c = 8.703 (2) Å | µ = 5.95 mm−1 |
V = 863.2 (3) Å3 | T = 10 K |
Z = 8 | Hexagonal prism, colourless |
F(000) = 704 | 0.20 × 0.20 × 0.20 mm |
Data collection top
Huber diffractometer | 3026 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.026 |
Graphite monochromator | θmax = 37.6°, θmin = 3.2° |
θ/2θ scans | h = 0→18 |
Absorption correction: analytical (ABSORB; Hall et al., 1995) | k = −18→15 |
Tmin = 0.824, Tmax = 0.952 | l = −14→14 |
9471 measured reflections | 3 standard reflections every 97 reflections |
3049 independent reflections | intensity decay: none |
Refinement top
Refinement on F2 | Hydrogen site location: difference Fourier map |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.013 | w = 1/[σ2(Fo2) + (0.013P)2 + 0.062P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.031 | (Δ/σ)max = 0.003 |
S = 1.15 | Δρmax = 0.38 e Å−3 |
3049 reflections | Δρmin = −0.58 e Å−3 |
109 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.0329 (5) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.000 (5) |
Crystal data top
(NH4)·(ZnPO4) | Z = 8 |
Mr = 178.38 | Mo Kα radiation |
Hexagonal, P63 | µ = 5.95 mm−1 |
a = 10.702 (2) Å | T = 10 K |
c = 8.703 (2) Å | 0.20 × 0.20 × 0.20 mm |
V = 863.2 (3) Å3 | |
Data collection top
Huber diffractometer | 3026 reflections with I > 2σ(I) |
Absorption correction: analytical (ABSORB; Hall et al., 1995) | Rint = 0.026 |
Tmin = 0.824, Tmax = 0.952 | 3 standard reflections every 97 reflections |
9471 measured reflections | intensity decay: none |
3049 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.013 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.031 | Δρmax = 0.38 e Å−3 |
S = 1.15 | Δρmin = −0.58 e Å−3 |
3049 reflections | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
109 parameters | Absolute structure parameter: 0.000 (5) |
1 restraint | |
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 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 (Å2) top | x | y | z | Uiso*/Ueq | |
N1 | 0.05046 (8) | 0.53438 (8) | 0.75371 (10) | 0.00646 (10) | |
N2 | 0.0000 | 0.0000 | 0.74956 (16) | 0.00664 (18) | |
Zn1 | 0.822249 (9) | 0.674521 (9) | 0.951768 (11) | 0.00320 (2) | |
Zn2 | 0.6667 | 0.3333 | 0.57517 (2) | 0.00317 (3) | |
P1 | 0.81947 (2) | 0.67342 (2) | 0.57189 (3) | 0.00309 (4) | |
P2 | 0.6667 | 0.3333 | 0.96623 (5) | 0.00338 (6) | |
O1 | 1.02517 (7) | 0.81712 (7) | 0.97324 (7) | 0.00520 (10) | |
O2 | 0.77303 (7) | 0.68119 (7) | 0.73743 (7) | 0.00543 (9) | |
O3 | 0.69860 (7) | 0.72409 (7) | 1.07217 (8) | 0.00558 (9) | |
O4 | 0.77175 (7) | 0.48534 (7) | 1.03021 (8) | 0.00556 (9) | |
O5 | 0.71408 (7) | 0.52403 (7) | 0.50269 (8) | 0.00567 (9) | |
O6 | 0.6667 | 0.3333 | 0.79295 (13) | 0.00863 (19) | |
H11 | 0.084 (3) | 0.574 (2) | 0.838 (3) | 0.018 (5)* | |
H12 | 0.110 (3) | 0.528 (2) | 0.697 (3) | 0.019 (5)* | |
H13 | −0.0144 (18) | 0.4453 (18) | 0.769 (2) | 0.004 (3)* | |
H14 | 0.011 (2) | 0.578 (2) | 0.702 (3) | 0.017 (5)* | |
H21 | 0.0000 | 0.0000 | 0.642 (4) | 0.022 (9)* | |
H22 | −0.082 (2) | −0.026 (2) | 0.789 (2) | 0.020 (5)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0068 (2) | 0.0064 (2) | 0.0065 (3) | 0.0035 (2) | −0.0003 (2) | −0.0004 (2) |
N2 | 0.0065 (3) | 0.0065 (3) | 0.0069 (4) | 0.00325 (13) | 0.000 | 0.000 |
Zn1 | 0.00284 (4) | 0.00291 (4) | 0.00376 (4) | 0.00136 (3) | −0.00003 (3) | 0.00007 (3) |
Zn2 | 0.00291 (4) | 0.00291 (4) | 0.00367 (6) | 0.00146 (2) | 0.000 | 0.000 |
P1 | 0.00267 (7) | 0.00279 (8) | 0.00370 (9) | 0.00129 (6) | −0.00002 (6) | 0.00023 (6) |
P2 | 0.00327 (8) | 0.00327 (8) | 0.00359 (15) | 0.00164 (4) | 0.000 | 0.000 |
O1 | 0.0039 (2) | 0.0052 (2) | 0.0065 (2) | 0.00225 (18) | −0.00124 (16) | 0.00025 (17) |
O2 | 0.0054 (2) | 0.0070 (2) | 0.0037 (2) | 0.00299 (19) | 0.00018 (17) | −0.00011 (16) |
O3 | 0.0064 (2) | 0.0043 (2) | 0.0073 (2) | 0.00359 (18) | 0.0020 (2) | 0.00118 (19) |
O4 | 0.0051 (2) | 0.0030 (2) | 0.0079 (2) | 0.00144 (19) | −0.00142 (18) | −0.00023 (18) |
O5 | 0.0063 (2) | 0.0036 (2) | 0.0060 (2) | 0.00169 (19) | −0.00147 (19) | −0.00037 (18) |
O6 | 0.0111 (3) | 0.0111 (3) | 0.0036 (4) | 0.00556 (14) | 0.000 | 0.000 |
Geometric parameters (Å, º) top
N1—H11 | 0.83 (2) | Zn2—O5i | 1.9455 (7) |
N1—H12 | 0.84 (2) | Zn2—O5ii | 1.9455 (7) |
N1—H13 | 0.865 (17) | Zn2—O5 | 1.9455 (7) |
N1—H14 | 0.89 (2) | P1—O2 | 1.5398 (7) |
N2—H21 | 0.93 (4) | P1—O3iii | 1.5423 (7) |
N2—H22 | 0.85 (2) | P1—O1iv | 1.5423 (7) |
Zn1—O4 | 1.9399 (7) | P1—O5 | 1.5451 (7) |
Zn1—O1 | 1.9406 (8) | P2—O6 | 1.5081 (13) |
Zn1—O2 | 1.9494 (7) | P2—O4i | 1.5465 (7) |
Zn1—O3 | 1.9577 (7) | P2—O4 | 1.5465 (7) |
Zn2—O6 | 1.8953 (12) | P2—O4ii | 1.5465 (7) |
| | | |
H11—N1—H12 | 114 (2) | O2—P1—O3iii | 109.70 (4) |
H11—N1—H13 | 109 (2) | O2—P1—O1iv | 109.75 (4) |
H12—N1—H13 | 103.1 (18) | O3iii—P1—O1iv | 108.40 (4) |
H11—N1—H14 | 112.1 (19) | O2—P1—O5 | 109.40 (4) |
H12—N1—H14 | 109 (2) | O3iii—P1—O5 | 110.27 (4) |
H13—N1—H14 | 109.1 (18) | O1iv—P1—O5 | 109.30 (4) |
H21—N2—H22 | 113.6 (13) | O6—P2—O4i | 111.10 (3) |
O4—Zn1—O1 | 113.90 (3) | O6—P2—O4 | 111.10 (3) |
O4—Zn1—O2 | 115.82 (3) | O4i—P2—O4 | 107.79 (3) |
O1—Zn1—O2 | 106.26 (3) | O6—P2—O4ii | 111.10 (3) |
O4—Zn1—O3 | 102.77 (3) | O4i—P2—O4ii | 107.79 (3) |
O1—Zn1—O3 | 112.18 (3) | O4—P2—O4ii | 107.79 (3) |
O2—Zn1—O3 | 105.70 (3) | P1v—O1—Zn1 | 131.77 (4) |
O6—Zn2—O5i | 108.92 (2) | P1—O2—Zn1 | 142.46 (4) |
O6—Zn2—O5ii | 108.92 (2) | P1vi—O3—Zn1 | 133.60 (4) |
O5i—Zn2—O5ii | 110.02 (2) | P2—O4—Zn1 | 130.37 (4) |
O6—Zn2—O5 | 108.92 (2) | P1—O5—Zn2 | 129.17 (4) |
O5i—Zn2—O5 | 110.02 (2) | P2—O6—Zn2 | 180.0 |
O5ii—Zn2—O5 | 110.02 (2) | | |
Symmetry codes: (i) −x+y+1, −x+1, z; (ii) −y+1, x−y, z; (iii) x−y+1, x, z−1/2; (iv) y, −x+y+1, z−1/2; (v) x−y+1, x, z+1/2; (vi) y, −x+y+1, z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H11···O5vii | 0.83 (3) | 1.97 (2) | 2.7843 (13) | 165 (2) |
N1—H12···O4viii | 0.84 (3) | 1.98 (3) | 2.8018 (14) | 169 (3) |
N1—H13···O2ix | 0.864 (17) | 2.070 (17) | 2.8553 (12) | 150.7 (19) |
N1—H14···O3x | 0.89 (2) | 1.90 (2) | 2.7702 (14) | 166 (2) |
N2—H22···O1ix | 0.85 (2) | 2.10 (2) | 2.8670 (15) | 150.3 (17) |
Symmetry codes: (vii) x−y, x, z+1/2; (viii) −x+1, −y+1, z−1/2; (ix) −x+y, −x+1, z; (x) x−y, x, z−1/2. |
Experimental details
Crystal data |
Chemical formula | (NH4)·(ZnPO4) |
Mr | 178.38 |
Crystal system, space group | Hexagonal, P63 |
Temperature (K) | 10 |
a, c (Å) | 10.702 (2), 8.703 (2) |
V (Å3) | 863.2 (3) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 5.95 |
Crystal size (mm) | 0.20 × 0.20 × 0.20 |
|
Data collection |
Diffractometer | Huber diffractometer |
Absorption correction | Analytical (ABSORB; Hall et al., 1995) |
Tmin, Tmax | 0.824, 0.952 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9471, 3049, 3026 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.857 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.013, 0.031, 1.15 |
No. of reflections | 3049 |
No. of parameters | 109 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.38, −0.58 |
Absolute structure | Flack H D (1983), Acta Cryst. A39, 876-881 |
Absolute structure parameter | 0.000 (5) |
Selected geometric parameters (Å, º) topZn1—O4 | 1.9399 (7) | P1—O2 | 1.5398 (7) |
Zn1—O1 | 1.9406 (8) | P1—O3iii | 1.5423 (7) |
Zn1—O2 | 1.9494 (7) | P1—O1iv | 1.5423 (7) |
Zn1—O3 | 1.9577 (7) | P1—O5 | 1.5451 (7) |
Zn2—O6 | 1.8953 (12) | P2—O6 | 1.5081 (13) |
Zn2—O5i | 1.9455 (7) | P2—O4i | 1.5465 (7) |
Zn2—O5ii | 1.9455 (7) | P2—O4 | 1.5465 (7) |
Zn2—O5 | 1.9455 (7) | P2—O4ii | 1.5465 (7) |
| | | |
P1v—O1—Zn1 | 131.77 (4) | P2—O4—Zn1 | 130.37 (4) |
P1—O2—Zn1 | 142.46 (4) | P1—O5—Zn2 | 129.17 (4) |
P1vi—O3—Zn1 | 133.60 (4) | P2—O6—Zn2 | 180.0 |
Symmetry codes: (i) −x+y+1, −x+1, z; (ii) −y+1, x−y, z; (iii) x−y+1, x, z−1/2; (iv) y, −x+y+1, z−1/2; (v) x−y+1, x, z+1/2; (vi) y, −x+y+1, z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H11···O5vii | 0.83 (3) | 1.97 (2) | 2.7843 (13) | 165 (2) |
N1—H12···O4viii | 0.84 (3) | 1.98 (3) | 2.8018 (14) | 169 (3) |
N1—H13···O2ix | 0.864 (17) | 2.070 (17) | 2.8553 (12) | 150.7 (19) |
N1—H14···O3x | 0.89 (2) | 1.90 (2) | 2.7702 (14) | 166 (2) |
N2—H22···O1ix | 0.85 (2) | 2.10 (2) | 2.8670 (15) | 150.3 (17) |
Symmetry codes: (vii) x−y, x, z+1/2; (viii) −x+1, −y+1, z−1/2; (ix) −x+y, −x+1, z; (x) x−y, x, z−1/2. |
MZnPO4 phases (M = univalent cation) built up from a three-dimensional framework of vertex-sharing ZnO4 and PO4 tetrahedra are of interest for their physical properties (Blum et al., 1986), their phase transition behaviour (Kahlenberg, 1998; Hammond, Barbier & Gallardo, 1998), and their structural relationship to polymorphs of silica and aluminosilicate zeolites (Harrison, 2000). Here, we describe the low-temperature (10 K) structure of the hexagonal form (Averbuch-Pouchot & Durif, 1968) of ammonium zinc phosphate, NH4ZnPO4. We have named this phase NH4ZnPO4—HEX in order to distinguish it from monoclinic NH4ZnPO4—ABW (Bu et al., 1997).
There are 12 framework (2 Zn, 2 P, 8 O) and eight extra-framework (2 N, 6 H) atoms in this structure. The geometrical parameters for the ZnO4 and PO4 tetrahedra [dav(Zn—O) = 1.9400 (7) Å; dav(P—O) = 1.5396 (7) Å]. are typical (Bu et al., 1997). The linkage of these moieties by Zn—O—P bonds results in a strictly alternating array of Zn and P tetrahedral nodes with an average Zn—O—P bond angle of 133.47 (4)° excluding the linear Zn2—O6—P2 bond.
The framework structure of NH4ZnPO4—HEX is built up from infinite sheets of tetrahedral six rings arrayed normal to [0001] (Figure 2). Topologically, this linkage pattern of Zn and P atoms via O atom bridges may be described as layers of simple 63 hexagonal nets (Hyde & O'Keeffe, 1996). The fourth Zn—O or P—O vertex points approximately either up (U) or down (D) with respect to the the [0001] direction. Using the up/down classification (Liebau, 1985), two types of six ring may be identified as UDUDUD and UUUDDD. In this structure, there are three UUUDDD rings for every UDUDUD ring in any [0001] sheet.
The extra-framework ammonium cations occupy the [0001] channels and interact with the [ZnPO4]- framework by N—H···O hydrogen bonds (Table 2). N1 occupies the UUUDDD channels and makes four N—H···O hydrogen bonds to framework oxygen species. N2 occupies the UDUDUD channels, and makes three equivalent H bonds, as N2—H22···O1. The N2—H21 moiety which occupies the threefold axis does not participate in any H bonds: all these bonds point the same way in this polar crystal structure. Framework atoms O1—O5 act as H bond acceptors, with only O6 not involved in these guest-framework interactions.
NH4ZnPO4—HEX is isostructural with NH4CoPO4 (Feng et al., 1997) and α-AgZnPO4 (Hammond et al., 1998). As noted recently (Hammond et al., 1998; Harrison, 2000) the NH4ZnPO4—HEX structure is not isostructural with hexagonal nepheline types such as β-(Na3/4K1/4)AlGeO4 (Hammond & Barbier, 1998) which have the same space group and similar lattice parameters to NH4ZnPO4—HEX. The nepheline types contain just one topologically distinct six-ring (type UDUDUD), as adopted by the tridymite form of SiO2.
A notable feature of the NH4ZnPO4—HEX structure is the symmetry constrained, linear Zn2—O6—P2 bond. At 10 K, there is negligible anisotropy in the thermal motion of O6, which has a ratio of longest-to-shortest ellipsoid axes, U3/U1, of 3.11, compared to an average of 2.53 for the other five O atoms. Conversely, in α-AgZnPO4 (Hammond et al., 1998), the equivalent linear Zn—O—P bond is disordered over three equivalent positions about the threefold axis [resulting Zn—O—P bond angle = 165.8 (4)°]. It was suggested that Ag—O bonding may play a role in promoting this situation, whereas for NH4ZnPO4—HEX, the linear Zn—O6—P bond is the only one not involved in interactions with the ammonium cation.