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Redetermination of AgPO3

aDepartment of Inorganic Chemistry, Taras Shevchenko National University, 64 Volodymyrska Street, 01601 Kyiv, Ukraine, and bSTC `Institute for Single Crystals', NAS of Ukraine, 60 Lenin Avenue, 61001 Kharkiv, Ukraine
*Correspondence e-mail: tereb@bigmir.ru

(Received 19 January 2011; accepted 31 January 2011; online 9 February 2011)

Single crystals of silver(I) polyphosphate(V), AgPO3, were prepared via a phospho­ric acid melt method using a solution of Ag3PO4 in H3PO4. In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961[Jost, K. H. (1961). Acta Cryst. 14, 779-784.]). Acta Cryst. 14, 779–784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO5] polyhedra, giving rise to multidirectional ribbons, and from two types of PO4 tetra­hedra linked into meandering chains (PO3)n spreading parallel to the b axis with a repeat unit of four tetra­hedra. The calculated bond-valence sum value of one of the two AgI ions indicates a significant strain of the structure.

Related literature

For a previous crystallographic study of AgPO3, see: Jost (1961[Jost, K. H. (1961). Acta Cryst. 14, 779-784.]). For the isotypic A-form of the Kurrol salt NaPO3, see: McAdam et al. (1968[McAdam, A., Jost, K. H. & Beagley, B. (1968). Acta Cryst. B24, 1621-1622.]). Properties of glassy silver phosphates have been reported by Portier et al. (1990[Portier, L. J., Tanguy, B., Videau, J. J., Allal, M. A. A., Morcos, J. & Salardenne, J. (1990). Active Passive Elec. Compd, 14, 81-94.]) and Novita et al. (2009[Novita, D. I., Boolchand, P., Malki, M. & Micoulaut, M. (2009). J. Phys. Condens. Matter, 21, 205106.]). For long-chain polyphosphates AgMIII(PO3)4 (MIII = La, Gd, Eu), see: El Masloumi et al. (2005[El Masloumi, M., Imaz, I., Chaminade, J.-P., Videau, J.-J., Couzi, M., Mesnaoui, M. & Maazaz, M. (2005). J. Solid State Chem. 178, 3581-3588.]); Naıli et al. (2006[Naıli, H., Ettis, H. & Mhiri, T. (2006). J. Alloys Compd, 424, 400-407.]); Ayadi et al. (2009[Ayadi, M., Férid, M. & Moine, B. (2009). Acta Cryst. E65, i13.]). For AgMII (PO3)3 (MII = Mg, Zn, Ba), see: Belharouak et al. (1999[Belharouak, I., Aouad, H., Mesnaoui, M., Maazaz, M., Parent, C., Tanguy, B., Gravereau, P. & Le Flem, G. (1999). J. Solid State Chem. 145, 97-103.]); for AgMI(PO3)2 (MI = K, Rb, Cs, Tl), see: Averbuch-Pouchot (1993[Averbuch-Pouchot, M. T. (1993). J. Solid State Chem. 102, 93-99.]). For background to the bond-valence method, see: Brown & Altermatt (1985[Brown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244-247.]).

Experimental

Crystal data
  • AgPO3

  • Mr = 186.84

  • Monoclinic, P 21 /n

  • a = 11.9335 (3) Å

  • b = 6.0667 (1) Å

  • c = 7.3278 (2) Å

  • β = 93.491 (2)°

  • V = 529.53 (2) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 7.96 mm−1

  • T = 293 K

  • 0.10 × 0.08 × 0.04 mm

Data collection
  • Oxford Diffraction Xcalibur-3 CCD diffractometer

  • Absorption correction: multi-scan (Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.]) Tmin = 0.465, Tmax = 0.733

  • 22720 measured reflections

  • 2333 independent reflections

  • 2208 reflections with I > 2σ(I)

  • Rint = 0.042

Refinement
  • R[F2 > 2σ(F2)] = 0.024

  • wR(F2) = 0.058

  • S = 1.08

  • 2333 reflections

  • 92 parameters

  • Δρmax = 1.43 e Å−3

  • Δρmin = −1.86 e Å−3

Table 1
Selected geometric parameters (Å, °)

Ag1—O3i 2.441 (2)
Ag1—O1 2.460 (2)
Ag1—O6ii 2.491 (2)
Ag1—O1iii 2.511 (2)
Ag1—O6 2.540 (2)
Ag2—O5iv 2.3708 (19)
Ag2—O5v 2.3756 (19)
Ag2—O3 2.3968 (19)
Ag2—O6ii 2.487 (2)
Ag2—O3iv 2.750 (2)
P1—O1 1.490 (2)
P1—O3 1.4952 (19)
P1—O4vi 1.5889 (17)
P1—O2 1.6033 (17)
P2—O5 1.479 (2)
P2—O6 1.4924 (19)
P2—O4 1.5909 (17)
P2—O2 1.6074 (18)
P1—O2—P2 124.88 (11)
P1vii—O4—P2 135.91 (11)
Symmetry codes: (i) x, y-1, z; (ii) -x, -y+1, -z+1; (iii) [-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iv) -x, -y+2, -z+1; (v) x, y, z+1; (vi) [-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (vii) [-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].

Data collection: CrysAlis CCD (Oxford Diffraction, 2006[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Brandenburg, 1999[Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]) and enCIFer (Allen et al., 2004[Allen, F. H., Johnson, O., Shields, G. P., Smith, B. R. & Towler, M. (2004). J. Appl. Cryst. 37, 335-338.]).

Supporting information


Comment top

Glassy silver polyphosphates as a part of complex oxide-chalcogenide systems have various applications in the field of solid electrolytes (Portier et al., 1990; Novita et al., 2009). Much attention has therefore been paid to phase equilibrium studies within AgPO3M(PO3)n systems, where M is a rare earth (Ayadi et al., 2009; Naili et al., 2006, El Masloumi et al., 2005), a divalent (Belharouak et al., 1999) or a monovalent metal (Averbuch-Pouchot, 1993).

The title compound is isotypic with the A-form of the Kurrol salt NaPO3 (McAdam et al., 1968). AgPO3 has been previously structurally studied based on single crystal Weissenberg photographs (Jost, 1961). The current study mainly confirms the previous results, but with significantly higher precision and with anisotropic displacement parameters refined for all atoms.

The structure of AgPO3 features two types of penta-coordinated AgI ions: Ag1 is located in a distorted trigonal bipyramid and Ag2 in a irregular tetragonal pyramid of oxygen atoms (Fig. 1). Calculated values of bond valence sums (BVS; Brown & Altermatt, 1985) were found to be quite different: 0.96 valence units (v.u.) for Ag2 and 0.87 v.u. for Ag1. The observed deviation of the BVS of the latter atom from its chemical valence (expected 1) is due to a high polyhedral distortion caused by the presence of rigid (PO3)n chains. In this case the BVS values may be seen as a degree of silver "underbonding" and have a concomitant effect on physical properties of the title compound or glassy materials containing silver polyphosphate. The next-nearest coordination spheres of Ag1 include six adjacent silver atoms, resulting in edge-sharing Ag1 and Ag2 polyhedra and other four polyhedra connected through corners. As a result of this linkage, two polyhedral ribbons appear. One spreads parallel to the a-axis through interconnected [Ag1O5] polyhedra by sharing a common edge and vertex alternatively, and another spreads parallel to the b-axis and consist of corner-sharing [Ag1O5] polyhedra. Ag2 is remotely surrounded by one Ag1 and two Ag2, resulting in a ribbon of edge-sharing [Ag2O5] polyhedra that run parallel to the c-axis. Intersecting these ribbons leads to a three-dimensional network penetrated with tunnels having eight-sided windows. Helical chains (PO3)n with a repeating unit of four phosphate tetrahedra are located within the tunnels and spiral along the 21 axes parallel to the b-axis. Due to the centrosymmetric nature of the structure, adjacent chains are left- and right-helices. As is characteristic for catena-polyphosphates (Averbuch-Pouchot, 1993), each of the two PO4 tetrahedra displays two types of P—O bond lengths: P—O terminal ranging from 1.479 (2) to 1.4952 (19) Å and P—O bridging from 1.5889 (17) to 1.6074 (18) Å. The corresponding BVS are 4.92 v.u. and 4.95 v.u. for P1 and P2, respectively. The BVS per doubled formula (corresponds to the crystallographically independent atoms in a cell) of positively charged atoms equals to 11.72 v.u., while the chemical charge of the remaining O atoms is equal to -12 valences. This difference is an additional indication of the strain in the structure caused by the presence of rigid phosphate chains.

Related literature top

For a previous crystallographic study of AgPO3, see: Jost (1961). For the isotypic A-form of the Kurrol salt NaPO3, see: McAdam et al. (1968). Properties of glassy silver phosphates have been reported by Portier et al. (1990) and Novita et al. (2009). For long-chain polyphosphates AgMIII(PO3)4 (MIII = La, Gd, Eu), see: El Masloumi et al. (2005); Naıli et al. (2006); Ayadi et al. (2009). For AgMII (PO3)3 (MII = Mg, Zn, Ba), see: Belharouak et al. (1999); for AgMI(PO3)2 (MI = K, Rb, Cs, Tl), see: Averbuch-Pouchot (1993). For background to the bond-valence method, see: Brown & Altermatt (1985).

Experimental top

AgPO3 was prepared by crystallizing a solution of Ag3PO4 in H3PO4 (84 %wt) at a molar ratio Ag/P = 0.01. The thermal treatment included heating the mixture in a graphite crucible at 473 K for 6 h and then cooling to room temperature. After leaching with water, the product consisted of colorless prismatic crystals.

Refinement top

The highest peak and the deepest hole in the final difference map are located at 0.56 Å from Ag1 (1.432 e/Å3) and 0.56 Å from Ag1 (-1.858 e/Å3), respectively

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and enCIFer (Allen et al., 2004).

Figures top
[Figure 1] Fig. 1. The connectivity of the Ag and P atoms in the structure of AgPO3 with displacement ellipsoids disolayed at the 50% probability level. [Symmetry codes: (i) 0.5 - x, 1/2 + y, 0.5 - z; (ii) -x, -1 + y, z; (iii) 0.5 - x,1/2 + y, 1.5 - z; (iv) -x, 1 - y, 1 - z; (v) x, y, 1 + z; (vi) -x, 2 - y, 1 - z;].
[Figure 2] Fig. 2. A view of the crystal structure of AgPO3 down the b-axis, emphasizing the tunnels with eight-sided windows where the helical polyphosphate chains reside.
Silver(I) polyphosphate top
Crystal data top
AgPO3F(000) = 688
Mr = 186.84Dx = 4.687 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 22720 reflections
a = 11.9335 (3) Åθ = 3.2–35.0°
b = 6.0667 (1) ŵ = 7.96 mm1
c = 7.3278 (2) ÅT = 293 K
β = 93.491 (2)°Prism, colorless
V = 529.53 (2) Å30.10 × 0.08 × 0.04 mm
Z = 8
Data collection top
Oxford Diffraction Xcalibur-3 CCD
diffractometer
2333 independent reflections
Radiation source: fine-focus sealed tube2208 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.042
ϕ and ω scansθmax = 35°, θmin = 3.2°
Absorption correction: multi-scan
(Blessing, 1995)
h = 1919
Tmin = 0.465, Tmax = 0.733k = 99
22720 measured reflectionsl = 1111
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.024 w = 1/[σ2(Fo2) + (0.0212P)2 + 1.7313P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.058(Δ/σ)max = 0.001
S = 1.08Δρmax = 1.43 e Å3
2333 reflectionsΔρmin = 1.86 e Å3
92 parametersExtinction correction: SHELXL97 (Sheldrick, 2008)
0 restraintsExtinction coefficient: 0.0034 (3)
Crystal data top
AgPO3V = 529.53 (2) Å3
Mr = 186.84Z = 8
Monoclinic, P21/nMo Kα radiation
a = 11.9335 (3) ŵ = 7.96 mm1
b = 6.0667 (1) ÅT = 293 K
c = 7.3278 (2) Å0.10 × 0.08 × 0.04 mm
β = 93.491 (2)°
Data collection top
Oxford Diffraction Xcalibur-3 CCD
diffractometer
2333 independent reflections
Absorption correction: multi-scan
(Blessing, 1995)
2208 reflections with I > 2σ(I)
Tmin = 0.465, Tmax = 0.733Rint = 0.042
22720 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02492 parameters
wR(F2) = 0.0580 restraints
S = 1.08Δρmax = 1.43 e Å3
2333 reflectionsΔρmin = 1.86 e Å3
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
xyzUiso*/Ueq
Ag10.127313 (18)0.33468 (3)0.61230 (3)0.02461 (6)
Ag20.03023 (2)0.89757 (4)0.77035 (3)0.02748 (6)
P10.22766 (5)0.81768 (10)0.48624 (7)0.01372 (10)
P20.11152 (5)0.61417 (10)0.18002 (8)0.01331 (10)
O10.25346 (18)0.6554 (3)0.6355 (3)0.0241 (4)
O20.22388 (14)0.6980 (3)0.2909 (2)0.0179 (3)
O30.12509 (15)0.9578 (3)0.4956 (3)0.0218 (3)
O40.16402 (14)0.4679 (3)0.0265 (2)0.0169 (3)
O50.05294 (17)0.7997 (3)0.0843 (3)0.0234 (3)
O60.04724 (16)0.4744 (3)0.3047 (3)0.0220 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ag10.02707 (10)0.02043 (10)0.02611 (10)0.00056 (7)0.00023 (7)0.00252 (7)
Ag20.03883 (12)0.02340 (11)0.02121 (9)0.00423 (8)0.01011 (8)0.00068 (7)
P10.0138 (2)0.0153 (2)0.0121 (2)0.00206 (17)0.00169 (16)0.00000 (17)
P20.0124 (2)0.0141 (2)0.0134 (2)0.00133 (17)0.00096 (16)0.00069 (17)
O10.0312 (9)0.0223 (9)0.0183 (7)0.0081 (7)0.0021 (7)0.0064 (6)
O20.0155 (6)0.0225 (8)0.0157 (6)0.0010 (6)0.0008 (5)0.0059 (6)
O30.0169 (7)0.0268 (9)0.0220 (8)0.0031 (6)0.0041 (6)0.0047 (7)
O40.0161 (6)0.0200 (8)0.0145 (6)0.0058 (6)0.0000 (5)0.0042 (5)
O50.0278 (9)0.0208 (8)0.0211 (8)0.0108 (7)0.0020 (6)0.0000 (6)
O60.0218 (8)0.0243 (9)0.0204 (7)0.0050 (7)0.0061 (6)0.0000 (7)
Geometric parameters (Å, º) top
Ag1—O3i2.441 (2)P1—O4vii1.5889 (17)
Ag1—O12.460 (2)P1—O21.6033 (17)
Ag1—O6ii2.491 (2)P2—O51.479 (2)
Ag1—O1iii2.511 (2)P2—O61.4924 (19)
Ag1—O62.540 (2)P2—O41.5909 (17)
Ag1—Ag2i3.1431 (3)P2—O21.6074 (18)
Ag2—O5iv2.3708 (19)O1—Ag1viii2.511 (2)
Ag2—O5v2.3756 (19)O3—Ag1vi2.441 (2)
Ag2—O32.3968 (19)O4—P1ix1.5889 (17)
Ag2—O6ii2.487 (2)O5—Ag2iv2.3708 (19)
Ag2—O3iv2.750 (2)O5—Ag2x2.3756 (19)
Ag2—Ag1vi3.1431 (3)O6—Ag2ii2.487 (2)
P1—O11.490 (2)O6—Ag1ii2.491 (2)
P1—O31.4952 (19)
O3i—Ag1—O1139.36 (7)O3—P1—O4vii110.36 (11)
O3i—Ag1—O6ii121.99 (6)O1—P1—O2110.46 (11)
O1—Ag1—O6ii97.63 (7)O3—P1—O2108.66 (10)
O3i—Ag1—O1iii81.11 (6)O4vii—P1—O2100.72 (9)
O1—Ag1—O1iii88.56 (4)O5—P2—O6118.48 (12)
O6ii—Ag1—O1iii117.80 (6)O5—P2—O4106.52 (10)
O3i—Ag1—O690.36 (7)O6—P2—O4110.79 (11)
O1—Ag1—O689.59 (6)O5—P2—O2110.76 (12)
O6ii—Ag1—O677.68 (6)O6—P2—O2108.33 (10)
O1iii—Ag1—O6164.51 (6)O4—P2—O2100.46 (9)
O3i—Ag1—Ag2i48.87 (5)P1—O1—Ag1111.96 (11)
O1—Ag1—Ag2i151.61 (4)P1—O1—Ag1viii109.67 (10)
O6ii—Ag1—Ag2i88.27 (5)Ag1—O1—Ag1viii135.28 (8)
O1iii—Ag1—Ag2i64.42 (5)P1—O2—P2124.88 (11)
O6—Ag1—Ag2i118.78 (4)P1—O3—Ag2112.45 (11)
O5iv—Ag2—O5v77.57 (7)P1—O3—Ag1vi123.86 (11)
O5iv—Ag2—O3119.43 (7)Ag2—O3—Ag1vi81.04 (6)
O5v—Ag2—O3145.04 (7)P1ix—O4—P2135.91 (11)
O5iv—Ag2—O6ii129.94 (7)P2—O5—Ag2iv125.12 (11)
O5v—Ag2—O6ii90.36 (7)P2—O5—Ag2x132.23 (11)
O3—Ag2—O6ii98.10 (6)Ag2iv—O5—Ag2x102.43 (7)
O5iv—Ag2—Ag1vi71.68 (5)P2—O6—Ag2ii125.33 (11)
O5v—Ag2—Ag1vi123.01 (5)P2—O6—Ag1ii110.73 (11)
O3—Ag2—Ag1vi50.09 (5)Ag2ii—O6—Ag1ii99.83 (6)
O6ii—Ag2—Ag1vi145.52 (4)P2—O6—Ag1123.59 (11)
O1—P1—O3118.36 (12)Ag2ii—O6—Ag190.46 (7)
O1—P1—O4vii106.84 (10)Ag1ii—O6—Ag1102.32 (6)
Symmetry codes: (i) x, y1, z; (ii) x, y+1, z+1; (iii) x+1/2, y1/2, z+3/2; (iv) x, y+2, z+1; (v) x, y, z+1; (vi) x, y+1, z; (vii) x+1/2, y+1/2, z+1/2; (viii) x+1/2, y+1/2, z+3/2; (ix) x+1/2, y1/2, z+1/2; (x) x, y, z1.

Experimental details

Crystal data
Chemical formulaAgPO3
Mr186.84
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)11.9335 (3), 6.0667 (1), 7.3278 (2)
β (°) 93.491 (2)
V3)529.53 (2)
Z8
Radiation typeMo Kα
µ (mm1)7.96
Crystal size (mm)0.10 × 0.08 × 0.04
Data collection
DiffractometerOxford Diffraction Xcalibur-3 CCD
diffractometer
Absorption correctionMulti-scan
(Blessing, 1995)
Tmin, Tmax0.465, 0.733
No. of measured, independent and
observed [I > 2σ(I)] reflections
22720, 2333, 2208
Rint0.042
(sin θ/λ)max1)0.807
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.058, 1.08
No. of reflections2333
No. of parameters92
Δρmax, Δρmin (e Å3)1.43, 1.86

Computer programs: CrysAlis CCD (Oxford Diffraction, 2006), CrysAlis RED (Oxford Diffraction, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999), WinGX (Farrugia, 1999) and enCIFer (Allen et al., 2004).

Selected geometric parameters (Å, º) top
Ag1—O3i2.441 (2)Ag2—O3iv2.750 (2)
Ag1—O12.460 (2)P1—O11.490 (2)
Ag1—O6ii2.491 (2)P1—O31.4952 (19)
Ag1—O1iii2.511 (2)P1—O4vi1.5889 (17)
Ag1—O62.540 (2)P1—O21.6033 (17)
Ag2—O5iv2.3708 (19)P2—O51.479 (2)
Ag2—O5v2.3756 (19)P2—O61.4924 (19)
Ag2—O32.3968 (19)P2—O41.5909 (17)
Ag2—O6ii2.487 (2)P2—O21.6074 (18)
P1—O2—P2124.88 (11)P1vii—O4—P2135.91 (11)
Symmetry codes: (i) x, y1, z; (ii) x, y+1, z+1; (iii) x+1/2, y1/2, z+3/2; (iv) x, y+2, z+1; (v) x, y, z+1; (vi) x+1/2, y+1/2, z+1/2; (vii) x+1/2, y1/2, z+1/2.
 

References

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