Acta Cryst. (2008). E64, i85-i86 [ doi:10.1107/S1600536808039664 ]
The title compound, NH4YbP2O7, crystallizes in the KAlP2O7 structure type and consists of distorted YbO6 octahedra and bent P2O74- diphosphate units forming together a three-dimensional network. There are channels in the structure running along the c axis, where the NH4+ cations are located. They are connected via N-H
O hydrogen bonds to the terminal O atoms of the diphosphate anions.
Three solutions have been mixed in a beaker to prepare the title compound: NH4OH (20 ml, 0.1 mmol), YbCl3.6H2O (20 ml, 0.1 mmol) and Na4P2O7 (20 ml, 0.1 mmol). The pH of the mixture was controlled with diluted hydrochloric acid to be slightly acidic, and the solution was stirred for two hours at room temperature. Crystals suitable for X-ray analysis were formed after a few days.
All hydrogen atoms were discernible in difference Fourier maps and could be refined to reasonable geometry. The N—H distances were restrained to 0.87 Å with σ of 0.02. The isotropic atomic displacement parameters of all hydrogen atoms were refined with 1.2×Ueq of the N atom.
Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: JANA2006 (Petříček et al., 2007); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: JANA2006 (Petříček et al., 2007).
![[Figure 1]](./wm2208fig1thm.gif)
| Fig. 1. Part of the structure of NH4YbP2O7. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) 1 - x,-1/2 + y, 1.5 - z; (ii) x, 0.5 - y, -1/2 + z; (iii) x, 0.5 - y, 1/2 + z; (iv) 2 - x, -1/2 + y, 1.5 - z; (v) 1 - x, 1 - y, 1 - z; (vi} -1 + x, 0.5 - y, -1/2 + z; (vii) -1 + x, y, z.] |
![[Figure 2]](./wm2208fig2thm.gif)
| Fig. 2. The packing of NH4YbP2O7 viewed along c. Colors: Pink (P2O7), grey (YbO6), blue balls (N), black balls (H). |
| NH4YbP2O7 | F(000) = 668 |
| Mr = 365 | Dx = 3.502 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 8929 reflections |
| a = 7.6468 (2) Å | θ = 2.8–26.5° |
| b = 10.9119 (2) Å | µ = 13.97 mm−1 |
| c = 8.6129 (3) Å | T = 120 K |
| β = 105.645 (3)° | Prism, colorless |
| V = 692.04 (3) Å3 | 0.26 × 0.08 × 0.07 mm |
| Z = 4 |
| Oxford Diffraction XCalibur 2 with Sapphire 2 area detector diffractometer | 1437 independent reflections |
| Radiation source: X-ray tube | 1362 reflections with I > 3σ(I) |
| graphite | Rint = 0.023 |
| Detector resolution: 8.3438 pixels mm-1 | θmax = 26.5°, θmin = 2.8° |
| Rotation method data acquisition using ω scans | h = −9→9 |
| Absorption correction: analytical [implemented in CrysAlis RED (Oxford Diffraction, 2008), according to Clark & Reid (1995)] | k = −13→13 |
| Tmin = 0.169, Tmax = 0.545 | l = −10→10 |
| 8574 measured reflections |
| Refinement on F2 | Only H-atom coordinates refined |
| R[F2 > 2σ(F2)] = 0.016 | Weighting scheme based on measured s.u.'s w = 1/[σ2(I) + 0.0016I2] |
| wR(F2) = 0.061 | (Δ/σ)max = 0.039 |
| S = 1.32 | Δρmax = 0.58 e Å−3 |
| 1437 reflections | Δρmin = −0.50 e Å−3 |
| 113 parameters | Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974) |
| 4 restraints | Extinction coefficient: 170 (60) |
| 4 constraints |
| NH4YbP2O7 | V = 692.04 (3) Å3 |
| Mr = 365 | Z = 4 |
| Monoclinic, P21/c | Mo Kα radiation |
| a = 7.6468 (2) Å | µ = 13.97 mm−1 |
| b = 10.9119 (2) Å | T = 120 K |
| c = 8.6129 (3) Å | 0.26 × 0.08 × 0.07 mm |
| β = 105.645 (3)° |
| Oxford Diffraction XCalibur 2 with Sapphire 2 area detector diffractometer | 1437 independent reflections |
| Absorption correction: analytical [implemented in CrysAlis RED (Oxford Diffraction, 2008), according to Clark & Reid (1995)] | 1362 reflections with I > 3σ(I) |
| Tmin = 0.169, Tmax = 0.545 | Rint = 0.023 |
| 8574 measured reflections | θmax = 26.5° |
| R[F2 > 2σ(F2)] = 0.016 | Only H-atom coordinates refined |
| wR(F2) = 0.061 | Δρmax = 0.58 e Å−3 |
| S = 1.32 | Δρmin = −0.50 e Å−3 |
| 1437 reflections | Absolute structure: ? |
| 113 parameters | Flack parameter: ? |
| 4 restraints | Rogers parameter: ? |
Refinement. The refinement was carried out against all reflections. The conventional R-factor is always based on F. The goodness of fit as well as the weighted R-factor are based on F and F2 for refinement carried out on F and F2, respectively. The threshold expression is used only for calculating R-factors etc. and it is not relevant to the choice of reflections for refinement. The program used for refinement, Jana2006, uses the weighting scheme based on the experimental expectations, see _refine_ls_weighting_details, that does not force S to be one. Therefore the values of S are usually larger than the ones from the SHELX program. |
| x | y | z | Uiso*/Ueq | ||
| Yb1 | 0.73470 (3) | 0.100256 (15) | 0.753623 (18) | 0.00555 (9) | |
| P1 | 0.63175 (18) | 0.40147 (9) | 0.81812 (14) | 0.0080 (4) | |
| P2 | 0.93914 (15) | 0.36312 (10) | 0.68708 (13) | 0.0070 (3) | |
| O1 | 0.5777 (4) | 0.2746 (3) | 0.7457 (4) | 0.0124 (10) | |
| O2 | 0.6416 (6) | 0.4080 (3) | 0.9940 (5) | 0.0254 (14) | |
| O3 | 0.8335 (4) | 0.4300 (3) | 0.8037 (4) | 0.0126 (9) | |
| O4 | 0.5107 (4) | 0.5010 (3) | 0.7202 (3) | 0.0097 (9) | |
| O5 | 0.9555 (4) | 0.2277 (3) | 0.7359 (4) | 0.0121 (10) | |
| O6 | 0.8260 (6) | 0.3855 (3) | 0.5169 (5) | 0.0183 (12) | |
| O7 | 1.1241 (4) | 0.4235 (3) | 0.7273 (4) | 0.0142 (10) | |
| N1 | 0.3131 (6) | 0.3233 (4) | 0.4381 (5) | 0.0183 (13) | |
| H1 | 0.281 (7) | 0.348 (5) | 0.523 (4) | 0.0219* | |
| H2 | 0.365 (7) | 0.385 (3) | 0.403 (6) | 0.0219* | |
| H3 | 0.206 (4) | 0.306 (5) | 0.375 (5) | 0.0219* | |
| H4 | 0.373 (7) | 0.267 (4) | 0.501 (5) | 0.0219* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Yb1 | 0.00611 (15) | 0.00443 (15) | 0.00616 (16) | −0.00018 (5) | 0.00173 (9) | 0.00025 (5) |
| P1 | 0.0101 (6) | 0.0088 (6) | 0.0056 (5) | 0.0056 (4) | 0.0027 (5) | −0.0006 (4) |
| P2 | 0.0066 (5) | 0.0058 (5) | 0.0084 (5) | −0.0016 (4) | 0.0017 (4) | 0.0016 (4) |
| O1 | 0.0142 (16) | 0.0076 (15) | 0.0178 (16) | 0.0019 (12) | 0.0085 (13) | 0.0023 (12) |
| O2 | 0.034 (3) | 0.039 (2) | 0.0043 (17) | 0.0210 (17) | 0.0062 (17) | 0.0013 (14) |
| O3 | 0.0073 (15) | 0.0117 (14) | 0.0158 (16) | 0.0000 (12) | −0.0019 (13) | −0.0036 (13) |
| O4 | 0.0093 (14) | 0.0097 (13) | 0.0102 (14) | 0.0026 (12) | 0.0028 (11) | 0.0041 (12) |
| O5 | 0.0088 (15) | 0.0113 (15) | 0.0166 (16) | −0.0007 (12) | 0.0041 (12) | 0.0045 (12) |
| O6 | 0.017 (2) | 0.0277 (19) | 0.0086 (18) | −0.0005 (14) | 0.0015 (15) | 0.0090 (14) |
| O7 | 0.0093 (16) | 0.0101 (13) | 0.0228 (17) | −0.0036 (13) | 0.0035 (14) | 0.0014 (12) |
| N1 | 0.017 (2) | 0.021 (2) | 0.013 (2) | −0.0069 (17) | −0.0014 (17) | 0.0046 (16) |
| Yb1—O1 | 2.240 (3) | P1—O4 | 1.525 (3) |
| Yb1—O2i | 2.158 (4) | P2—O3 | 1.622 (4) |
| Yb1—O4ii | 2.230 (3) | P2—O5 | 1.532 (3) |
| Yb1—O5 | 2.224 (3) | P2—O6 | 1.507 (4) |
| Yb1—O6iii | 2.191 (4) | P2—O7 | 1.514 (3) |
| Yb1—O7iv | 2.195 (3) | N1—H1 | 0.87 (5) |
| P1—O1 | 1.529 (3) | N1—H2 | 0.87 (5) |
| P1—O2 | 1.498 (5) | N1—H3 | 0.87 (3) |
| P1—O3 | 1.611 (4) | N1—H4 | 0.86 (4) |
| O1—Yb1—O2i | 88.83 (13) | O2—P1—O3 | 106.3 (2) |
| O1—Yb1—O4ii | 87.53 (11) | O2—P1—O4 | 112.5 (2) |
| O1—Yb1—O5 | 82.94 (12) | O3—P1—O4 | 105.70 (17) |
| O1—Yb1—O6iii | 89.43 (12) | O3—P2—O5 | 106.33 (19) |
| O1—Yb1—O7iv | 175.63 (13) | O3—P2—O6 | 106.2 (2) |
| O2i—Yb1—O4ii | 91.87 (14) | O3—P2—O7 | 104.64 (18) |
| O2i—Yb1—O5 | 89.99 (15) | O5—P2—O6 | 113.98 (18) |
| O2i—Yb1—O6iii | 178.23 (14) | O5—P2—O7 | 110.79 (17) |
| O2i—Yb1—O7iv | 93.37 (13) | O6—P2—O7 | 114.1 (2) |
| O4ii—Yb1—O5 | 170.25 (11) | P1—O3—P2 | 127.40 (19) |
| O4ii—Yb1—O6iii | 88.39 (13) | P1—O4—H2v | 115.2 (13) |
| O4ii—Yb1—O7iv | 88.63 (12) | P2—O5—H3vi | 109.5 (14) |
| O5—Yb1—O6iii | 89.47 (13) | H1—N1—H2 | 108 (5) |
| O5—Yb1—O7iv | 100.82 (12) | H1—N1—H3 | 99 (4) |
| O6iii—Yb1—O7iv | 88.39 (12) | H1—N1—H4 | 85 (5) |
| O1—P1—O2 | 113.0 (2) | H2—N1—H3 | 113 (4) |
| O1—P1—O3 | 107.61 (19) | H2—N1—H4 | 123 (5) |
| O1—P1—O4 | 111.26 (16) | H3—N1—H4 | 119 (4) |
| Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x+1, y−1/2, −z+3/2; (iii) x, −y+1/2, z+1/2; (iv) −x+2, y−1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) x+1, −y+1/2, z+1/2. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1···O7vii | 0.87 (4) | 2.52 (5) | 3.381 (5) | 168 (4) |
| N1—H2···O4v | 0.88 (4) | 2.03 (5) | 2.888 (5) | 166 (4) |
| N1—H3···O5viii | 0.87 (4) | 2.00 (4) | 2.873 (6) | 177 (7) |
| N1—H4···O1 | 0.86 (5) | 2.26 (4) | 2.916 (5) | 132 (4) |
| Symmetry codes: (vii) x−1, y, z; (v) −x+1, −y+1, −z+1; (viii) x−1, −y+1/2, z−1/2. |
| Yb1—O1 | 2.240 (3) | P1—O2 | 1.498 (5) |
| Yb1—O2i | 2.158 (4) | P1—O3 | 1.611 (4) |
| Yb1—O4ii | 2.230 (3) | P1—O4 | 1.525 (3) |
| Yb1—O5 | 2.224 (3) | P2—O3 | 1.622 (4) |
| Yb1—O6iii | 2.191 (4) | P2—O5 | 1.532 (3) |
| Yb1—O7iv | 2.195 (3) | P2—O6 | 1.507 (4) |
| P1—O1 | 1.529 (3) | P2—O7 | 1.514 (3) |
| P1—O3—P2 | 127.40 (19) |
| Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x+1, y−1/2, −z+3/2; (iii) x, −y+1/2, z+1/2; (iv) −x+2, y−1/2, −z+3/2. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1···O7v | 0.87 (4) | 2.52 (5) | 3.381 (5) | 168 (4) |
| N1—H2···O4vi | 0.88 (4) | 2.03 (5) | 2.888 (5) | 166 (4) |
| N1—H3···O5vii | 0.87 (4) | 2.00 (4) | 2.873 (6) | 177 (7) |
| N1—H4···O1 | 0.86 (5) | 2.26 (4) | 2.916 (5) | 132 (4) |
| Symmetry codes: (v) x−1, y, z; (vi) −x+1, −y+1, −z+1; (vii) x−1, −y+1/2, z−1/2. |
We acknowledge the Grant Agency of the Czech Republic for grant No. 202/06/0757.
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Rare earth phosphates have many potential applications in the field of optical materials including laser phosphors (Yamada et al., 1974; Hong, 1975; Bimberg et al., 1975). Their crystal structures depend on the ionic radii of the alkali metal and the rare earth ions. The two AYbP2O7 (A = Cs (Jansen et al., 1991), K (Horchani-Naifer & Férid, 2007)) structures known so far belong to the KAlP2O7 structure type (Ng & Calvo, 1973) and crystallize in space group P21/c. For the correspondent isoformular sodium rare earth diphosphates, several other structures have been described, for instance NaYP2O7 in space group P21 (Hamady & Jouini, 1996), NaLnP2O7 (Ln = Eu (Férid, Horchani & Amami, 2004), Yb (Ferid et al., 2004)) in space group P21/n, and NaLnP2O7 (Ln = La (Férid & Horchani-Naifer, 2004), Ce (Horchani-Naifer & Férid, 2005) in space group Pnma. KYP2O7 is dimorphic and can adopt the KAlP2O7 structure type (Yuan et al., 2007), or a structure in space group Cmcm (Hamady et al., 1994).
In the present paper we report the crystal structure of NH4YbP2O7. This compound is isotypic with NH4LuP2O7 (Man-Rong et al. 2005), KYbP2O7 (Horchani-Naifer & Férid, 2007) and CsYbP2O7 (Jansen et al., 1991). The Yb atom is coordinated by six oxygen atoms forming a distorted octahedron that belong to five symmetry-related P2O74- anions (Fig. 1). The average Yb—O bond lenght is 2.206 Å (Table 1). The diphosphate anion is bent with a bridging angle of 127.40 (19) °. The three-dimensional network of YbO6 and P2O74- units forms channels running along the c direcion in which the NH4+ cations are located (Fig. 2). Each NH4+ cation is connected via N—H···O hydrogen bonds to four different P2O74- anions (Table 2).