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The structure of the title compound, potassium trinickel arsenate diarsenate, is built up from corner- and edge-sharing NiO6 octahedra, AsO4 tetrahedra and As2O7 groups, giving rise to a polyhedral connectivity which produces large tunnels running along the crystallographic [010] direction. The K+ cations are located within these tunnels.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100000792/br1273sup1.cif
Contains datablocks I, bnsm5

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100000792/br1273Isup2.hkl
Contains datablock I

Comment top

Until now, in the system K2O-NiO-As2O5 only the structure of K4Ni7(AsO4)6 (Ben Smail et al., 1999) has been refined from single-crystal data. For KNiAsO4 (Buckley et al., 1988), the crystal structure has been determined by high-resolution powder neutron diffraction. In this paper we present the synthesis and structural determination of the new potassium nickel arsenate KNi3(AsO4)(As2O7) refined from single-crystal data. The structure of this compound, viewed along the b axis, is shown in Fig. 1. It contains parallel tunnels running along the [010] direction, wherein the K+ cations are located. The three-dimensional open anionic framework is made up of corner- and edge-sharing NiO6 octahedra, AsO4 tetrathedra and As2O7 groups. It can be described in terms of layers lying parallel to the (100) plane. These layers are connected to each other by corner sharing with the As3O4 tetrahedron of the As2As3O7 group and with the Ni3O6 octahedron. In each layer centrosymmetric pairs of Ni1O6, Ni2O6 and Ni3O6 octahedra share six edges to constitute an Ni6O24 unit. Each unit is connected to its four adjacent neighbours by eight corners (Fig. 2). The cohesion between these units is reinforced by As1O4 tetrahedra and As2As3O7 groups. Each As1O4 tetrahedron shares two edges, O8—O11 and O10—O11, with two adjacent NiO6 octahedra of one Ni6O24 unit and two corners, O3 and O10, with two NiO6 octahedra of another unit. The diarsenate group shares five corners, O1, O2, O4, O6 and O7, with three units of one layer and the sixth, O5, with one unit of another layer. The As2O7 group has no internal symmetry and a nearly eclipsed conformation, with O9 as the bridging oxygen. The As2—O9—As3 bridging angle is 120.4 (2)°. The average As—O bond distance is 1.649 (3) Å. Both values agree with those generally observed for As2O7 groups (Effenberger & Pertlik, 1993).

The As—O bond lengths range from 1.640?(3) to 1.788 (3) Å. These values compare well with those obtained in the two arsenate diarsenates previously reported: Ag5Cu(AsO4)(As2O7) (Effenberger & Pertlik, 1993) and Na5Bi2(AsO4)(As2O7)2 (Boughzala & Jouini, 1998).

The three Ni atoms in the asymmetric unit exhibit a normal octahedral coordination, with average Ni—O distances of 2.083 (3), 2.079 (3) and 2.086?(3) Å for Ni1, Ni2 and Ni3, respectively. These values are in the same range as those found in K4Ni7(AsO4)6 and KNiAsO4.

The K+ ion is eleven-coordinated. The K···O distances range between 2.809 (4) and 3.105 (4) Å, with a mean distance of 2.960?(9) Å. We note here that the structure of the rubidium cadmium vanadate, NaCd3(VO4)(V2O7) (Mertens & Müller-Buschbaum, 1997), although analogous in composition, is fundamentally different in structure from the arsenate studied in the present work.

Experimental top

The title compound was prepared by the reaction of NiO, As2O5 and K2CO3 in the molar ratio 0.5:1:1. The mixture was ground in an agate mortar and heated at 673 K for 12 h. After grinding, the mixture was heated at 968 K for 6 h, following by slow cooling at a rate of 10 K h-1 to 773 K and from 773 K to room temperature at 100 K h-1.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: DIAMOND (Brandenburg, 1997); software used to prepare material for publication: SHELXL93.

Figures top
[Figure 1] Fig. 1. A projection of the KNi3(AsO4)(As2O7) structure along the b axis.
[Figure 2] Fig. 2. A perspective view of a portion of the structure of KNi3(AsO4)(As2O7), showing the connections between the NiO6 octahedra, AsO4 tetrahedra and As2O7 groups.
potassium trinickel arsenate diarsenate top
Crystal data top
KNi3(AsO4)(As2O7)F(000) = 1160
Mr = 615.99Dx = 4.727 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 10.066 (1) Åθ = 11.5–17.0°
b = 9.681 (2) ŵ = 18.38 mm1
c = 10.234 (1) ÅT = 293 K
β = 119.780 (1)°Parallelepiped, green
V = 865.6 (2) Å30.14 × 0.07 × 0.05 mm
Z = 4
Data collection top
Enraf-Nonius CAD4
diffractometer
1851 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.023
Graphite monochromatorθmax = 30.0°, θmin = 2.3°
ω/2θ scansh = 014
Absorption correction: ψ-scan
(North et al., 1968)
k = 130
Tmin = 0.217, Tmax = 0.371l = 1412
2653 measured reflections2 standard reflections every 120 min
2526 independent reflections intensity decay: 0.6%
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)] = 0.032Calculated w = 1/[σ2(Fo2) + (0.0225P)2 + 1.2839P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.059(Δ/σ)max = 0.001
S = 1.10Δρmax = 1.08 e Å3
2526 reflectionsΔρmin = 1.21 e Å3
164 parametersExtinction correction: SHELXL93 (Sheldrick, 1993), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00219 (14)
Crystal data top
KNi3(AsO4)(As2O7)V = 865.6 (2) Å3
Mr = 615.99Z = 4
Monoclinic, P21/cMo Kα radiation
a = 10.066 (1) ŵ = 18.38 mm1
b = 9.681 (2) ÅT = 293 K
c = 10.234 (1) Å0.14 × 0.07 × 0.05 mm
β = 119.780 (1)°
Data collection top
Enraf-Nonius CAD4
diffractometer
1851 reflections with I > 2σ(I)
Absorption correction: ψ-scan
(North et al., 1968)
Rint = 0.023
Tmin = 0.217, Tmax = 0.3712 standard reflections every 120 min
2653 measured reflections intensity decay: 0.6%
2526 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.032164 parameters
wR(F2) = 0.0590 restraints
S = 1.10Δρmax = 1.08 e Å3
2526 reflectionsΔρmin = 1.21 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 on F2 for ALL reflections except for 0 with very negative F2 or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating _R_factor_obs 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
Ni10.91265 (7)0.13238 (6)0.73634 (7)0.0059 (1)
Ni20.09243 (7)0.12885 (6)0.10055 (7)0.0056 (1)
Ni30.73818 (7)0.13548 (6)0.38145 (7)0.0060 (1)
K0.4101 (1)0.2333 (1)0.9109 (1)0.0154 (2)
As10.09995 (6)0.15740 (5)0.43237 (5)0.0048 (1)
As20.77020 (6)0.07247 (5)0.08381 (5)0.0048 (1)
As30.59179 (6)0.05737 (5)0.73943 (5)0.0053 (1)
O10.7641 (4)0.2450 (3)0.0640 (4)0.0068 (6)
O20.5818 (4)0.2279 (4)0.7291 (4)0.0090 (7)
O30.8965 (4)0.0149 (3)0.5653 (4)0.0070 (6)
O40.7446 (4)0.0151 (4)0.2205 (4)0.0101 (7)
O50.5576 (4)0.0315 (4)0.3831 (4)0.0087 (7)
O60.7562 (4)0.0031 (4)0.7487 (4)0.0069 (6)
O70.0753 (4)0.0027 (3)0.9153 (4)0.0065 (6)
O80.2371 (4)0.2360 (4)0.5841 (4)0.0081 (7)
O90.6135 (4)0.0128 (4)0.9186 (4)0.0086 (7)
O100.0871 (4)0.2268 (3)0.2731 (4)0.0080 (7)
O110.9383 (4)0.2388 (3)0.4152 (4)0.0070 (7)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ni10.0062 (3)0.0050 (3)0.0054 (3)0.0000 (2)0.0021 (2)0.0002 (2)
Ni20.0056 (3)0.0054 (3)0.0055 (3)0.0000 (2)0.0025 (2)0.0005 (2)
Ni30.0055 (3)0.0059 (3)0.0056 (3)0.0002 (2)0.0020 (2)0.0002 (2)
K0.0115 (5)0.0140 (5)0.0188 (6)0.0000 (4)0.0061 (5)0.0002 (4)
As10.0046 (2)0.0044 (2)0.0047 (2)0.0002 (2)0.0017 (2)0.0002 (2)
As20.0040 (2)0.0050 (2)0.0046 (2)0.0000 (2)0.0016 (2)0.0002 (2)
As30.0035 (2)0.0060 (2)0.0051 (2)0.0001 (2)0.0011 (2)0.0005 (2)
O10.010 (2)0.005 (2)0.007 (2)0.000 (1)0.005 (1)0.000 (1)
O20.005 (2)0.006 (2)0.012 (2)0.001 (1)0.002 (1)0.000 (1)
O30.010 (2)0.003 (1)0.008 (2)0.002 (1)0.005 (1)0.000 (1)
O40.015 (2)0.008 (2)0.010 (2)0.002 (1)0.009 (2)0.000 (1)
O50.006 (2)0.014 (2)0.006 (2)0.006 (1)0.003 (1)0.004 (1)
O60.004 (2)0.008 (2)0.007 (2)0.002 (1)0.002 (1)0.001 (1)
O70.005 (2)0.006 (2)0.008 (2)0.001 (1)0.003 (1)0.001 (1)
O80.004 (2)0.009 (2)0.008 (2)0.001 (1)0.000 (1)0.004 (1)
O90.009 (2)0.011 (2)0.004 (2)0.004 (1)0.001 (1)0.001 (1)
O100.010 (2)0.008 (2)0.008 (2)0.002 (1)0.006 (1)0.001 (1)
O110.005 (2)0.008 (2)0.008 (2)0.000 (1)0.004 (1)0.001 (1)
Geometric parameters (Å, º) top
Ni1—O32.025 (3)K—O92.931 (4)
Ni1—O1i2.033 (3)K—O9ix3.032 (4)
Ni1—O62.064 (3)K—O8i3.055 (4)
Ni1—O10ii2.104 (3)K—O6x3.095 (4)
Ni1—O11i2.122 (3)K—O1xi3.102 (4)
Ni1—O7iii2.152 (3)K—O23.105 (4)
Ni1—As1ii2.8220 (8)K—As1i3.4056 (13)
Ni2—O6iv2.000 (3)As1—O81.663 (3)
Ni2—O8v2.026 (3)As1—O3iv1.669 (3)
Ni2—O102.028 (3)As1—O101.707 (3)
Ni2—O7vi2.056 (3)As1—O11xii1.737 (3)
Ni2—O11vii2.173 (3)As1—Ni2i2.7165 (9)
Ni2—O7viii2.188 (3)As1—Ni1vii2.8220 (8)
Ni2—As1v2.7165 (9)As1—Kv3.4055 (13)
Ni2—Kv3.4649 (13)As2—O41.640 (3)
Ni3—O42.045 (4)As2—O11.680 (3)
Ni3—O2v2.054 (3)As2—O7iv1.713 (3)
Ni3—O52.085 (3)As2—O9viii1.741 (3)
Ni3—O1i2.101 (3)As2—Kiv3.4867 (14)
Ni3—O32.112 (3)As2—Kviii3.5102 (13)
Ni3—O112.118 (3)As3—O5iv1.643 (3)
Ni3—Kv3.6875 (14)As3—O21.654 (3)
K—O5i2.809 (4)As3—O61.694 (3)
K—O4iv2.817 (4)As3—O91.788 (3)
K—O2i2.854 (4)As3—Kxiii3.4900 (14)
K—O10i2.856 (4)As3—Kv3.5565 (13)
K—O82.904 (4)
O3—Ni1—O1i82.48 (13)O2v—Ni3—O588.54 (14)
O3—Ni1—O688.63 (14)O4—Ni3—O1i172.16 (14)
O1i—Ni1—O698.75 (14)O2v—Ni3—O1i91.74 (14)
O3—Ni1—O10ii102.71 (13)O5—Ni3—O1i89.00 (13)
O1i—Ni1—O10ii88.03 (14)O4—Ni3—O395.23 (14)
O6—Ni1—O10ii167.51 (13)O2v—Ni3—O3170.49 (14)
O3—Ni1—O11i177.16 (14)O5—Ni3—O390.04 (14)
O1i—Ni1—O11i97.30 (13)O1i—Ni3—O378.83 (13)
O6—Ni1—O11i94.19 (13)O4—Ni3—O1189.58 (13)
O10ii—Ni1—O11i74.45 (13)O2v—Ni3—O1197.36 (13)
O3—Ni1—O7iii96.25 (13)O5—Ni3—O11171.45 (13)
O1i—Ni1—O7iii177.92 (13)O1i—Ni3—O1184.65 (13)
O6—Ni1—O7iii82.84 (13)O3—Ni3—O1183.12 (13)
O10ii—Ni1—O7iii90.64 (13)O8—As1—O3iv116.2 (2)
O11i—Ni1—O7iii83.88 (13)O8—As1—O10110.2 (2)
O6iv—Ni2—O8v99.97 (14)O3iv—As1—O10113.4 (2)
O6iv—Ni2—O1088.06 (14)O8—As1—O11xii100.9 (2)
O8v—Ni2—O1095.83 (14)O3iv—As1—O11xii117.9 (2)
O6iv—Ni2—O7vi86.91 (14)O10—As1—O11xii95.9 (2)
O8v—Ni2—O7vi171.69 (14)O4—As2—O1115.3 (2)
O10—Ni2—O7vi89.00 (14)O4—As2—O7iv112.2 (2)
O6iv—Ni2—O11vii171.94 (13)O1—As2—O7iv113.7 (2)
O8v—Ni2—O11vii77.17 (13)O4—As2—O9viii105.4 (2)
O10—Ni2—O11vii99.68 (13)O1—As2—O9viii104.6 (2)
O7vi—Ni2—O11vii95.39 (13)O7iv—As2—O9viii104.3 (2)
O6iv—Ni2—O7viii90.81 (14)O5iv—As3—O2118.0 (2)
O8v—Ni2—O7viii92.22 (13)O5iv—As3—O6112.3 (2)
O10—Ni2—O7viii171.94 (13)O2—As3—O6109.9 (2)
O7vi—Ni2—O7viii82.97 (14)O5iv—As3—O9104.8 (2)
O11vii—Ni2—O7viii81.84 (13)O2—As3—O9106.2 (2)
O4—Ni3—O2v94.27 (14)O6—As3—O9104.4 (2)
O4—Ni3—O596.18 (14)
Symmetry codes: (i) x, y+1/2, z+1/2; (ii) x+1, y+1/2, z+1/2; (iii) x+1, y, z; (iv) x+1, y, z+1; (v) x, y+1/2, z1/2; (vi) x, y, z+1; (vii) x1, y+1/2, z1/2; (viii) x, y, z1; (ix) x+1, y, z+2; (x) x+1, y+1/2, z+3/2; (xi) x, y, z+1; (xii) x1, y, z; (xiii) x+1, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaKNi3(AsO4)(As2O7)
Mr615.99
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)10.066 (1), 9.681 (2), 10.234 (1)
β (°) 119.780 (1)
V3)865.6 (2)
Z4
Radiation typeMo Kα
µ (mm1)18.38
Crystal size (mm)0.14 × 0.07 × 0.05
Data collection
DiffractometerEnraf-Nonius CAD4
diffractometer
Absorption correctionψ-scan
(North et al., 1968)
Tmin, Tmax0.217, 0.371
No. of measured, independent and
observed [I > 2σ(I)] reflections
2653, 2526, 1851
Rint0.023
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.059, 1.10
No. of reflections2526
No. of parameters164
Δρmax, Δρmin (e Å3)1.08, 1.21

Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1994), CAD-4 EXPRESS, MolEN (Fair, 1990), SHELXS86 (Sheldrick, 1990), SHELXL93 (Sheldrick, 1993), DIAMOND (Brandenburg, 1997), SHELXL93.

Selected bond lengths (Å) top
Ni1—O32.025 (3)Ni3—O1i2.101 (3)
Ni1—O1i2.033 (3)Ni3—O32.112 (3)
Ni1—O62.064 (3)Ni3—O112.118 (3)
Ni1—O10ii2.104 (3)As1—O81.663 (3)
Ni1—O11i2.122 (3)As1—O3iv1.669 (3)
Ni1—O7iii2.152 (3)As1—O101.707 (3)
Ni2—O6iv2.000 (3)As1—O11ix1.737 (3)
Ni2—O8v2.026 (3)As2—O41.640 (3)
Ni2—O102.028 (3)As2—O11.680 (3)
Ni2—O7vi2.056 (3)As2—O7iv1.713 (3)
Ni2—O11vii2.173 (3)As2—O9viii1.741 (3)
Ni2—O7viii2.188 (3)As3—O5iv1.643 (3)
Ni3—O42.045 (4)As3—O21.654 (3)
Ni3—O2v2.054 (3)As3—O61.694 (3)
Ni3—O52.085 (3)As3—O91.788 (3)
Symmetry codes: (i) x, y+1/2, z+1/2; (ii) x+1, y+1/2, z+1/2; (iii) x+1, y, z; (iv) x+1, y, z+1; (v) x, y+1/2, z1/2; (vi) x, y, z+1; (vii) x1, y+1/2, z1/2; (viii) x, y, z1; (ix) x1, y, z.
 

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