supplementary materials


Acta Cryst. (2012). E68, i91    [ doi:10.1107/S1600536812045667 ]

The layered polyphosphide Ag3.73(4)Zn2.27(4)P16

M. Köpf, O. Osters, M. Bawohl and T. Nilges

Abstract top

The silver zinc hexadecaphosphide Ag3.73(4)Zn2.27(4)P16 is the first polyphosphide in the ternary system Ag/Zn/P. It was synthesized from stoichiometric mixtures of Ag, Zn and P in the molar ratio 4:2:16, using AgI as a mineralizing agent in a gas-phase-assisted reaction. Ag3.73(4)Zn2.27(4)P16 crystallizes in the Cu5InP16 structure type. The asymmetric unit contains two Ag/Zn sites with mixed occupancies and four P sites. One of the Ag/Zn sites is located on a twofold rotation axis. The polyanionic [P16]-substructure consists of corrugated six-membered rings that are connected into a layer via the 1-, 2-, 4- and 5-positions of the rings by a bridging P atom in each case. The layers extend parallel to the bc plane and are stacked along the a axis. Both Ag/Zn sites are tetrahedrally coordinated by P atoms.

Comment top

Herein we report on Ag3.73 (4)Zn2.27 (4)P16 (silver zinc hexadecaphosphide), the first ternary compound in the system Ag/Zn/P. It crystallizes isostructurally to Cu5InP16 in space group C2/c (Lange et al., 2008). The asymmetric unit is built up by two mixed-occupied Ag/Zn sites and four P sites. Both Ag/Zn sites are tetrahedrally coordinated by four P atoms featuring bond lengths of 2.4386 (7) to 2.5432 (7) Å. The bond lengths of the (Ag1/Zn1) site to phosphorus range from 2.4386 (7) to 2.4836 (7) Å while slightly longer bond lengths of 2.4551 (7) to 2.5432 (7) Å are observed for (Ag2/Zn2). This finding is consistent with the higher amount of zinc on the (Ag1/Zn1) site leading to somewhat shorter bond lengths. For comparison, Zn—P bond length range from 2.36 to 2.40 Å in ZnP2 (Zanin et al., 2003) and ZnP4 (Dommann et al., 1989) while common Ag—P distances in polyphosphides are observed from 2.47 to 2.61 Å in Ag3P11 (Möller & Jeitschko, 1981) and 2.50 to 2.69 Å in AgP2 (Olofsson, 1965), respectively. Mixed-occupied Ag/Zn sites are not uncommon and are observed, for example, in intermetallic phases like Ag4.5Zn4.5 (or better AgZn; Edmunds & Qurashi, 1951). All P—P distances in Ag3.73 (4)Zn2.27 (4)P16, ranging from 2.1909 (9) to 2.2328 (9) Å, are within the expected range for polyphosphides (Bawohl & Nilges, 2009).

Related literature top

For background to and structures of related polyphosphides, see: Bawohl & Nilges (2009); Dommann et al. (1989); Edmunds & Qurashi (1951); Lange et al. (2008); Möller & Jeitschko (1981); Olofsson (1965); Zanin et al. (2003). For background to the extinction correction, see: Becker & Coppens (1974).

Experimental top

Ag3.73 (4)Zn2.27 (4)P16 was prepared by reaction from the elements Ag (ChemPur, powder, 99.9%), Zn (Sigma-Aldrich, pices, 99.9%), and P (ChemPur, powder, 99.999%) in the stoichiometric ratio of 4:2:16 in a 500 mg batch. As mineralizing agent, 10 mg AgI (ChemPur, powder, 99.9%) per 500 mg total sample weight was added. The reaction was carried out in evacuated ampoules in a muffle furnace at 823 K during 14 days using a heating ratio of 70 K/h. The sample was cooled down slowly at a rate of 5 K/h. For X-ray powder phase analyses a fraction of the sample was ground. Phase purity has been substantiated. Single crystals of suitable size for a single-crystal structure determination could be separated from the bulk phase. The sample was stable under atmospheric conditions for months.

Refinement top

The mixed-occupied Ag/Zn sites are located on Wyckoff positions 4e and 8f. The refinement of the Ag and Zn content was constrained to an overall full occupancy according to the sum of the two elements, each of them located on the same coordinates and with the same displacement parameters. The ratio of the two elements has been refined unrestricted.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2011); cell refinement: X-AREA (Stoe & Cie, 2011); data reduction: X-AREA (Stoe & Cie, 2011); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis 2007); program(s) used to refine structure: JANA2006 (Petřiček et al., 2006); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The crystal structure of Ag3.73 (4)Zn2.27 (4)P16, viewed along the c axis. The mixed Ag/Zn sites are drawn in turqueous and P atoms in blue, respectively. The displacement ellipsoids are shown at the 90% probability level.
Silver zinc hexadecaphosphide top
Crystal data top
Ag3.73Zn2.27P16F(000) = 966
Mr = 1046.3Dx = 4.17 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 4528 reflections
a = 11.492 (1) Åθ = 2.8–30.5°
b = 9.9604 (8) ŵ = 9.05 mm1
c = 7.7106 (9) ÅT = 293 K
β = 109.585 (9)°Isomorphic, black
V = 831.5 (2) Å30.02 × 0.02 × 0.02 mm
Z = 2
Data collection top
IPDS Stoe 2T
diffractometer
1265 independent reflections
Radiation source: X-ray tube1135 reflections with I > 3σ(I)
Plane graphite monochromatorRint = 0.015
Detector resolution: 6.67 pixels mm-1θmax = 30.5°, θmin = 2.8°
rotation method scansh = 1616
Absorption correction: numerical
(X-AREA; Stoe & Cie, 2011)
k = 1314
Tmin = 0.730, Tmax = 0.771l = 1010
4398 measured reflections
Refinement top
Refinement on F214 constraints
R[F2 > 2σ(F2)] = 0.018Weighting scheme based on measured s.u.'s w = 1/(σ2(I) + 0.0004I2)
wR(F2) = 0.042(Δ/σ)max = 0.038
S = 1.39Δρmax = 0.56 e Å3
1265 reflectionsΔρmin = 0.66 e Å3
54 parametersExtinction correction: B-C type 1 Gaussian isotropic (Becker & Coppens, 1974)
0 restraintsExtinction coefficient: 0.084 (5)
Crystal data top
Ag3.73Zn2.27P16V = 831.5 (2) Å3
Mr = 1046.3Z = 2
Monoclinic, C2/cMo Kα radiation
a = 11.492 (1) ŵ = 9.05 mm1
b = 9.9604 (8) ÅT = 293 K
c = 7.7106 (9) Å0.02 × 0.02 × 0.02 mm
β = 109.585 (9)°
Data collection top
IPDS Stoe 2T
diffractometer
1265 independent reflections
Absorption correction: numerical
(X-AREA; Stoe & Cie, 2011)
1135 reflections with I > 3σ(I)
Tmin = 0.730, Tmax = 0.771Rint = 0.015
4398 measured reflectionsθmax = 30.5°
Refinement top
R[F2 > 2σ(F2)] = 0.018Δρmax = 0.56 e Å3
wR(F2) = 0.042Δρmin = 0.66 e Å3
S = 1.39Absolute structure: ?
1265 reflectionsFlack parameter: ?
54 parametersRogers parameter: ?
0 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Ag100.41699 (3)0.250.01075 (10)0.422 (6)
Zn100.41699 (3)0.250.01075 (10)0.578 (6)
Ag20.089927 (17)0.13768 (2)0.08750 (3)0.01608 (7)0.721 (7)
Zn20.089927 (17)0.13768 (2)0.08750 (3)0.01608 (7)0.279 (7)
P10.16624 (5)0.56752 (5)0.05996 (7)0.00731 (15)
P20.24029 (5)0.32264 (5)0.24701 (7)0.00785 (15)
P30.09157 (4)0.27552 (6)0.07194 (7)0.00827 (15)
P40.33325 (5)0.48032 (5)0.14361 (8)0.00915 (15)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ag10.01067 (15)0.01146 (16)0.01117 (17)00.00506 (10)0
Zn10.01067 (15)0.01146 (16)0.01117 (17)00.00506 (10)0
Ag20.01637 (11)0.01572 (12)0.01331 (12)0.00637 (6)0.00121 (7)0.00034 (6)
Zn20.01637 (11)0.01572 (12)0.01331 (12)0.00637 (6)0.00121 (7)0.00034 (6)
P10.0079 (2)0.0074 (2)0.0071 (2)0.00021 (16)0.00310 (17)0.00069 (17)
P20.0090 (2)0.0076 (2)0.0072 (2)0.00064 (16)0.00309 (17)0.00022 (18)
P30.0077 (2)0.0082 (2)0.0093 (3)0.00004 (16)0.00342 (18)0.00121 (17)
P40.0096 (2)0.0104 (2)0.0080 (2)0.00069 (17)0.00363 (17)0.00171 (18)
Geometric parameters (Å, º) top
Ag1—P12.4836 (7)Ag2—P4iii2.5280 (7)
Ag1—P1i2.4836 (7)P1—P2iv2.2328 (9)
Ag1—P32.4385 (7)P1—P3v2.1909 (9)
Ag1—P3i2.4385 (7)P1—P42.2095 (9)
Ag2—P22.5432 (7)P2—P3vi2.1976 (8)
Ag2—P32.4551 (7)P2—P42.1941 (9)
Ag2—P4ii2.5115 (7)
P1—Ag1—P1i105.73 (2)Ag2—P2—P4132.64 (3)
P1—Ag1—P3114.11 (2)P1vii—P2—P3vi104.18 (3)
P1—Ag1—P3i106.81 (2)P1vii—P2—P4103.43 (3)
P1i—Ag1—P3106.81 (2)P3vi—P2—P496.77 (3)
P1i—Ag1—P3i114.11 (2)Ag1—P3—Ag298.66 (2)
P3—Ag1—P3i109.40 (2)Ag1—P3—Zn298.66 (2)
P2—Ag2—P399.36 (2)Ag1—P3—P1v99.15 (3)
P2—Ag2—P4ii93.38 (2)Ag1—P3—P2viii110.66 (3)
P2—Ag2—P4iii109.66 (2)Ag2—P3—P1v124.46 (3)
P3—Ag2—P4ii140.08 (2)Ag2—P3—P2viii119.19 (3)
P3—Ag2—P4iii110.23 (2)P1v—P3—P2viii102.39 (3)
P4ii—Ag2—P4iii100.52 (2)Ag2ix—P4—Ag2iii139.72 (3)
Ag1—P1—P2iv106.99 (3)Ag2ix—P4—Zn2iii139.72 (3)
Ag1—P1—P3v111.18 (3)Ag2ix—P4—P1108.81 (3)
Ag1—P1—P4119.67 (3)Ag2ix—P4—P2103.06 (3)
P2iv—P1—P3v104.82 (3)Ag2iii—P4—Zn2ix139.72 (3)
P2iv—P1—P4103.40 (3)Ag2iii—P4—P196.17 (3)
P3v—P1—P4109.44 (3)Ag2iii—P4—P2104.53 (3)
Ag2—P2—P1vii109.17 (3)P1—P4—P297.28 (3)
Ag2—P2—P3vi107.16 (3)
Symmetry codes: (i) x, y, z+1/2; (ii) x1/2, y1/2, z1/2; (iii) x1/2, y+1/2, z; (iv) x, y+1, z+1/2; (v) x, y+1, z; (vi) x1/2, y+1/2, z1/2; (vii) x, y+1, z1/2; (viii) x+1/2, y+1/2, z+1/2; (ix) x1/2, y+1/2, z1/2.
Acknowledgements top

The authors thank the German Science Foundation (DFG) for the kind support of project NI1095/1–2.

references
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