inorganic compounds
Potassium trinickel(II) orthophosphate diphosphate, KNi3(PO4)P2O7
aLaboratoire de Physico-Chimie des Matériaux Inorganiques, Faculté des Sciences Aïn Chock, Casablanca, Morocco, and bLaboratoire de Chimie du Solide Appliquée, Faculté des Sciences, Université Mohammed V-Agdal, Avenue Ibn Batouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: moutataouia_m@yahoo.fr
The structure of the title compound is characterized by the presence of two different anions, (PO4)3− and (P2O7)4− with an eclipsed conformation. The consists of edge-sharing [NiO6] octahedra forming an [Ni3O14] chain running parallel to [001]. Adjacent chains are connected through edges and apices to PO4 and P2O7 groups in such a way as to build a three-dimensional host lattice. The resulting framework presents intersecting tunnels running along [010] and [101] in which the 11-coordinated potassium cation is located. The of this new phosphate probably represents a new structural type.
CCDC reference: 977736
Related literature
For example of crystal structures with mixed phosphate anions, see: Ayed (2012); Palkina & Maksimova (1980); Nagornyi et al. (1996); Sanz et al. (1996, 1999, 2001).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2009); cell SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
CCDC reference: 977736
https://doi.org/10.1107/S1600536813034089/br2234sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813034089/br2234Isup2.hkl
KNi3(PO4)P2O7 is obtained during the preparation of NaK5Ni4Co(P2O7)4 diphosphate. The powder of this phosphate was prepared by solid state reaction, by mixing the nominal proportions reagents NaNO3, KNO3, Ni(NO3)2,6H2O, Co(NO3)2,6H2O and (NH4)H2PO4. The mixture is put into a platinum crucible, and subjected to thermal treatment (473 K, 673 K and 873 K) interspersed with grinding until a temperature of 1073 K. The final powder is brown colour.
The prepared powder by the solid route is gradually increased to a temperature above its melting point (1273 K) for 2 h, followed by slow cooling to about 5 K per hour to 673 K. Then, the power supply of the furnace is cut, and cooling is continued to room temperature. Single crystals of brown colour are obtained.
The highest peak and the deepest hole in the final Fourier map are at 0.70 Å and 0.84 Å, respectively, from O3 and Ni2. The not significant bonds and angles were removed from the
file.Despite the large number of new structures of transition metal phosphates determined in recent years, only a limited number of phosphates show the existence of P2O7 diphosphate and PO4 monophosphate groups in their structures. Of these compounds, we report AgCr2(PO4)(P2O7) discovered by Ayed (2012). The K2Ni4(PO4)2(P2O7), Na4Ni5(PO4)2(P2O7)2 and Na4MII3(PO4)2(P2O7), (MII = Mn, Co, Ni) compounds were respectively developed by Palkina & Maksimova (1980), Nagornyi et al. (1996) and Sanz et al. (1996, 1999 and 2001). In the present work, we report the synthesis and structural determination of the new mixed anion phosphate, KNi3(PO4)(P2O7), from single-crystal X-ray diffraction data.
The partial three-dimensional plot in Fig.1 shows the connection ion-oxygen polyhedra in the
of the title compound. In the PO4 tetrahedron, the P–O distances and O–P–O angles respectively between 1.5170—1.5916 (9) Å and 104.70—114.66 (5) Å are consistent with values found in the literature. In the P2O7 group, the values of the P–O distances are in the range of 1.4924—1.5659 (9) Å while the shared oxygen is at P2–O8–P3 between 1.5971—1.6408 (9) Å and the angle P2—O8—P3 = 125.38 (6)°. P2O7 adopts an eclipsed conformation as indicated by the dihedral angle of 7.42°, between the two plans through O5P2O8 and O8P3O9.In this structure the three independent nickel atoms occupy regular octahedra with Ni–O distances between 2.0027 (9) Å and 2.2284 (9) Å. The [Ni1O6], [Ni2O6] and [Ni3O6] octahedra share edges and form a chain directed along the c axis. The chains are linked together by PO4 and P2O7 tetrahedra and by sharing two edges of two octahedra in the way to form a layer perpendicular to the b axis. The potassium atom K1, is coordinated to eleven oxygen atoms building a very distorted polyhedron.
The resulting 3-D framework presents intersecting tunnels running along the [010] and [001] directions, where the potassium cation is located (Fig.2). Probably, the structure of this phosphate represents a new structural type.
For example of crystal structures with mixed phosphate anions, see: Ayed (2012); Palkina & Maksimova (1980); Nagornyi et al. (1996); Sanz et al. (1996, 1999, 2001).
Data collection: APEX2 (Bruker, 2009); cell
SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).KNi3(PO4)P2O7 | F(000) = 944 |
Mr = 484.14 | Dx = 3.977 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 3543 reflections |
a = 9.8591 (3) Å | θ = 3.2–35.0° |
b = 9.3953 (3) Å | µ = 8.09 mm−1 |
c = 9.9778 (3) Å | T = 296 K |
β = 118.965 (1)° | Block, brown |
V = 808.63 (4) Å3 | 0.25 × 0.18 × 0.12 mm |
Z = 4 |
Bruker X8 APEX diffractometer | 3543 independent reflections |
Radiation source: fine-focus sealed tube | 3352 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
φ and ω scans | θmax = 35.0°, θmin = 3.2° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −15→15 |
Tmin = 0.223, Tmax = 0.443 | k = −12→15 |
14936 measured reflections | l = −15→16 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.020 | w = 1/[σ2(Fo2) + (0.021P)2 + 0.5342P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.050 | (Δ/σ)max = 0.001 |
S = 1.06 | Δρmax = 0.69 e Å−3 |
3543 reflections | Δρmin = −0.91 e Å−3 |
164 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0100 (4) |
KNi3(PO4)P2O7 | V = 808.63 (4) Å3 |
Mr = 484.14 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 9.8591 (3) Å | µ = 8.09 mm−1 |
b = 9.3953 (3) Å | T = 296 K |
c = 9.9778 (3) Å | 0.25 × 0.18 × 0.12 mm |
β = 118.965 (1)° |
Bruker X8 APEX diffractometer | 3543 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 3352 reflections with I > 2σ(I) |
Tmin = 0.223, Tmax = 0.443 | Rint = 0.036 |
14936 measured reflections |
R[F2 > 2σ(F2)] = 0.020 | 164 parameters |
wR(F2) = 0.050 | 0 restraints |
S = 1.06 | Δρmax = 0.69 e Å−3 |
3543 reflections | Δρmin = −0.91 e Å−3 |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | ||
Ni1 | 0.861648 (18) | 0.127830 (16) | 0.624602 (19) | 0.00491 (4) | |
Ni2 | 1.007773 (18) | 0.632051 (17) | 0.603321 (18) | 0.00441 (4) | |
Ni3 | 0.679301 (17) | 0.131207 (17) | 0.264248 (18) | 0.00438 (4) | |
K1 | 0.50173 (3) | 0.73539 (3) | 0.41894 (4) | 0.01315 (6) | |
P1 | 0.82799 (3) | 0.83779 (3) | 0.43146 (3) | 0.00345 (5) | |
P2 | 0.69371 (3) | 0.42611 (3) | 0.42330 (3) | 0.00344 (6) | |
P3 | 0.85111 (3) | 0.44065 (3) | 0.75246 (3) | 0.00384 (6) | |
O1 | 0.96823 (10) | 0.77074 (9) | 0.41635 (10) | 0.00519 (14) | |
O2 | 0.82563 (10) | 1.00027 (9) | 0.43452 (10) | 0.00565 (14) | |
O3 | 0.84288 (10) | 0.77158 (10) | 0.57665 (10) | 0.00698 (15) | |
O4 | 0.68760 (10) | 0.77531 (10) | 0.28581 (10) | 0.00575 (14) | |
O5 | 0.54105 (10) | 0.47889 (10) | 0.30043 (10) | 0.00712 (15) | |
O6 | 0.83385 (10) | 0.49624 (10) | 0.41561 (10) | 0.00516 (14) | |
O7 | 0.70827 (10) | 0.26402 (9) | 0.43661 (10) | 0.00567 (14) | |
O8 | 0.70879 (10) | 0.48003 (10) | 0.58176 (10) | 0.00553 (14) | |
O9 | 0.81763 (10) | 0.52456 (10) | 0.86045 (10) | 0.00722 (15) | |
O10 | 0.85298 (11) | 0.28110 (10) | 0.76671 (11) | 0.00720 (15) | |
O11 | 0.99874 (10) | 0.49156 (10) | 0.74974 (10) | 0.00609 (15) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.00522 (7) | 0.00507 (8) | 0.00467 (7) | 0.00009 (4) | 0.00258 (6) | 0.00000 (5) |
Ni2 | 0.00475 (7) | 0.00416 (7) | 0.00444 (7) | 0.00088 (4) | 0.00232 (6) | 0.00091 (4) |
Ni3 | 0.00555 (7) | 0.00355 (8) | 0.00402 (7) | −0.00021 (4) | 0.00230 (6) | 0.00010 (4) |
K1 | 0.01425 (12) | 0.01237 (13) | 0.01689 (13) | 0.00032 (9) | 0.01076 (10) | 0.00072 (10) |
P1 | 0.00407 (11) | 0.00287 (12) | 0.00361 (12) | 0.00047 (8) | 0.00202 (9) | 0.00016 (9) |
P2 | 0.00370 (11) | 0.00332 (12) | 0.00354 (12) | −0.00001 (8) | 0.00194 (9) | −0.00022 (9) |
P3 | 0.00463 (11) | 0.00382 (12) | 0.00401 (12) | −0.00023 (9) | 0.00284 (9) | −0.00035 (9) |
O1 | 0.0048 (3) | 0.0046 (3) | 0.0073 (4) | 0.0006 (3) | 0.0038 (3) | 0.0003 (3) |
O2 | 0.0076 (3) | 0.0031 (4) | 0.0053 (3) | 0.0008 (3) | 0.0025 (3) | 0.0000 (3) |
O3 | 0.0092 (4) | 0.0073 (4) | 0.0064 (4) | 0.0025 (3) | 0.0053 (3) | 0.0023 (3) |
O4 | 0.0045 (3) | 0.0050 (4) | 0.0061 (3) | 0.0000 (3) | 0.0012 (3) | −0.0008 (3) |
O5 | 0.0053 (3) | 0.0072 (4) | 0.0058 (4) | 0.0007 (3) | 0.0003 (3) | −0.0002 (3) |
O6 | 0.0049 (3) | 0.0052 (4) | 0.0065 (4) | −0.0007 (3) | 0.0036 (3) | −0.0002 (3) |
O7 | 0.0077 (3) | 0.0034 (4) | 0.0060 (4) | 0.0002 (3) | 0.0034 (3) | −0.0003 (3) |
O8 | 0.0059 (3) | 0.0067 (4) | 0.0042 (3) | 0.0007 (3) | 0.0025 (3) | −0.0005 (3) |
O9 | 0.0086 (4) | 0.0084 (4) | 0.0062 (4) | 0.0006 (3) | 0.0048 (3) | −0.0020 (3) |
O10 | 0.0112 (4) | 0.0042 (4) | 0.0079 (4) | −0.0006 (3) | 0.0060 (3) | −0.0005 (3) |
O11 | 0.0052 (3) | 0.0068 (4) | 0.0074 (4) | 0.0002 (3) | 0.0039 (3) | 0.0019 (3) |
Ni1—O5i | 2.0509 (9) | K1—O5 | 2.7928 (10) |
Ni1—O10 | 2.0515 (9) | K1—O8x | 2.8966 (9) |
Ni1—O9ii | 2.0840 (9) | K1—O3 | 2.9627 (9) |
Ni1—O2iii | 2.1230 (9) | K1—O3viii | 2.9901 (9) |
Ni1—O1iv | 2.1335 (9) | K1—O7x | 3.0421 (9) |
Ni1—O7 | 2.1668 (9) | K1—O8 | 3.0578 (9) |
Ni2—O11 | 2.0027 (9) | K1—O11viii | 3.0633 (10) |
Ni2—O3 | 2.0033 (9) | K1—O10x | 3.0677 (10) |
Ni2—O4v | 2.0223 (9) | P1—O3 | 1.5170 (9) |
Ni2—O6iv | 2.0524 (9) | P1—O2 | 1.5273 (9) |
Ni2—O1 | 2.1508 (9) | P1—O4 | 1.5569 (9) |
Ni2—O6 | 2.2284 (9) | P1—O1 | 1.5916 (9) |
Ni3—O2iii | 2.0266 (9) | P2—O5 | 1.4924 (9) |
Ni3—O7 | 2.0299 (9) | P2—O7 | 1.5294 (9) |
Ni3—O11vi | 2.0666 (9) | P2—O6 | 1.5659 (9) |
Ni3—O4vii | 2.1069 (9) | P2—O8 | 1.5971 (9) |
Ni3—O1vii | 2.1314 (9) | P3—O9 | 1.4953 (9) |
Ni3—O6vii | 2.1494 (9) | P3—O10 | 1.5050 (10) |
K1—O4 | 2.7605 (9) | P3—O11 | 1.5447 (9) |
K1—O9viii | 2.7742 (10) | P3—O8 | 1.6408 (9) |
K1—O10ix | 2.7790 (10) | ||
O5i—Ni1—O10 | 93.40 (4) | O8x—K1—O3 | 135.18 (3) |
O5i—Ni1—O9ii | 96.96 (4) | O4—K1—O3viii | 63.64 (2) |
O10—Ni1—O9ii | 87.52 (4) | O9viii—K1—O3viii | 81.38 (3) |
O5i—Ni1—O2iii | 100.96 (4) | O10ix—K1—O3viii | 172.36 (3) |
O10—Ni1—O2iii | 165.64 (4) | O5—K1—O3viii | 66.47 (3) |
O9ii—Ni1—O2iii | 91.17 (4) | O8x—K1—O3viii | 90.21 (3) |
O5i—Ni1—O1iv | 87.13 (4) | O3—K1—O3viii | 116.18 (3) |
O10—Ni1—O1iv | 96.81 (3) | O4—K1—O7x | 172.06 (3) |
O9ii—Ni1—O1iv | 173.88 (4) | O9viii—K1—O7x | 64.66 (3) |
O2iii—Ni1—O1iv | 83.57 (3) | O10ix—K1—O7x | 64.03 (3) |
O5i—Ni1—O7 | 168.65 (4) | O5—K1—O7x | 117.91 (3) |
O10—Ni1—O7 | 86.48 (4) | O8x—K1—O7x | 49.54 (2) |
O9ii—Ni1—O7 | 94.38 (3) | O3—K1—O7x | 127.31 (3) |
O2iii—Ni1—O7 | 79.36 (3) | O3viii—K1—O7x | 116.17 (3) |
O1iv—Ni1—O7 | 81.62 (3) | O4—K1—O8 | 86.23 (3) |
O11—Ni2—O3 | 102.02 (4) | O9viii—K1—O8 | 161.82 (3) |
O11—Ni2—O4v | 87.49 (4) | O10ix—K1—O8 | 71.04 (3) |
O3—Ni2—O4v | 98.00 (4) | O5—K1—O8 | 49.77 (3) |
O11—Ni2—O6iv | 89.12 (4) | O8x—K1—O8 | 75.30 (3) |
O3—Ni2—O6iv | 167.61 (4) | O3—K1—O8 | 60.91 (2) |
O4v—Ni2—O6iv | 87.78 (4) | O3viii—K1—O8 | 115.80 (3) |
O11—Ni2—O1 | 168.14 (3) | O7x—K1—O8 | 100.50 (2) |
O3—Ni2—O1 | 72.17 (3) | O4—K1—O11viii | 56.81 (3) |
O4v—Ni2—O1 | 103.41 (4) | O9viii—K1—O11viii | 51.13 (2) |
O6iv—Ni2—O1 | 95.88 (3) | O10ix—K1—O11viii | 110.78 (3) |
O11—Ni2—O6 | 87.01 (4) | O5—K1—O11viii | 117.10 (3) |
O3—Ni2—O6 | 91.05 (4) | O8x—K1—O11viii | 140.19 (3) |
O4v—Ni2—O6 | 170.22 (4) | O3—K1—O11viii | 84.38 (2) |
O6iv—Ni2—O6 | 84.05 (4) | O3viii—K1—O11viii | 61.90 (2) |
O1—Ni2—O6 | 82.84 (3) | O7x—K1—O11viii | 115.62 (3) |
O2iii—Ni3—O7 | 84.95 (4) | O8—K1—O11viii | 140.86 (2) |
O2iii—Ni3—O11vi | 87.67 (4) | O4—K1—O10x | 123.00 (3) |
O7—Ni3—O11vi | 99.52 (4) | O9viii—K1—O10x | 58.37 (3) |
O2iii—Ni3—O4vii | 108.45 (4) | O10ix—K1—O10x | 120.20 (3) |
O7—Ni3—O4vii | 87.57 (4) | O5—K1—O10x | 92.99 (3) |
O11vi—Ni3—O4vii | 163.00 (4) | O8x—K1—O10x | 50.00 (2) |
O2iii—Ni3—O1vii | 178.03 (3) | O3—K1—O10x | 174.53 (3) |
O7—Ni3—O1vii | 95.54 (4) | O3viii—K1—O10x | 59.72 (2) |
O11vi—Ni3—O1vii | 94.13 (3) | O7x—K1—O10x | 56.48 (2) |
O4vii—Ni3—O1vii | 69.68 (3) | O8—K1—O10x | 123.62 (3) |
O2iii—Ni3—O6vii | 94.15 (3) | O11viii—K1—O10x | 90.32 (3) |
O7—Ni3—O6vii | 175.46 (3) | O3—P1—O2 | 112.71 (5) |
O11vi—Ni3—O6vii | 84.87 (3) | O3—P1—O4 | 111.59 (5) |
O4vii—Ni3—O6vii | 88.50 (3) | O2—P1—O4 | 112.35 (5) |
O1vii—Ni3—O6vii | 85.21 (3) | O3—P1—O1 | 103.97 (5) |
O4—K1—O9viii | 107.91 (3) | O2—P1—O1 | 114.83 (5) |
O4—K1—O10ix | 115.00 (3) | O4—P1—O1 | 100.53 (5) |
O9viii—K1—O10ix | 92.23 (3) | O5—P2—O7 | 114.66 (5) |
O4—K1—O5 | 69.69 (3) | O5—P2—O6 | 112.50 (5) |
O9viii—K1—O5 | 145.41 (3) | O7—P2—O6 | 112.05 (5) |
O10ix—K1—O5 | 120.66 (3) | O5—P2—O8 | 106.34 (5) |
O4—K1—O8x | 137.36 (3) | O7—P2—O8 | 105.67 (5) |
O9viii—K1—O8x | 99.93 (3) | O6—P2—O8 | 104.70 (5) |
O10ix—K1—O8x | 95.04 (3) | O9—P3—O10 | 117.00 (5) |
O5—K1—O8x | 69.04 (3) | O9—P3—O11 | 112.84 (5) |
O4—K1—O3 | 52.60 (3) | O10—P3—O11 | 109.97 (5) |
O9viii—K1—O3 | 118.50 (3) | O9—P3—O8 | 104.65 (5) |
O10ix—K1—O3 | 63.30 (3) | O10—P3—O8 | 106.73 (5) |
O5—K1—O3 | 88.24 (3) | O11—P3—O8 | 104.55 (5) |
Symmetry codes: (i) x+1/2, −y+1/2, z+1/2; (ii) −x+3/2, y−1/2, −z+3/2; (iii) x, y−1, z; (iv) −x+2, −y+1, −z+1; (v) x+1/2, −y+3/2, z+1/2; (vi) x−1/2, −y+1/2, z−1/2; (vii) −x+3/2, y−1/2, −z+1/2; (viii) x−1/2, −y+3/2, z−1/2; (ix) −x+3/2, y+1/2, −z+3/2; (x) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | KNi3(PO4)P2O7 |
Mr | 484.14 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 296 |
a, b, c (Å) | 9.8591 (3), 9.3953 (3), 9.9778 (3) |
β (°) | 118.965 (1) |
V (Å3) | 808.63 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 8.09 |
Crystal size (mm) | 0.25 × 0.18 × 0.12 |
Data collection | |
Diffractometer | Bruker X8 APEX |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.223, 0.443 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 14936, 3543, 3352 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.806 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.020, 0.050, 1.06 |
No. of reflections | 3543 |
No. of parameters | 164 |
Δρmax, Δρmin (e Å−3) | 0.69, −0.91 |
Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006), publCIF (Westrip, 2010).
Acknowledgements
The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.
References
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Despite the large number of new structures of transition metal phosphates determined in recent years, only a limited number of phosphates show the existence of P2O7 diphosphate and PO4 monophosphate groups in their structures. Of these compounds, we report AgCr2(PO4)(P2O7) discovered by Ayed (2012). The K2Ni4(PO4)2(P2O7), Na4Ni5(PO4)2(P2O7)2 and Na4MII3(PO4)2(P2O7), (MII = Mn, Co, Ni) compounds were respectively developed by Palkina & Maksimova (1980), Nagornyi et al. (1996) and Sanz et al. (1996, 1999 and 2001). In the present work, we report the synthesis and structural determination of the new mixed anion phosphate, KNi3(PO4)(P2O7), from single-crystal X-ray diffraction data.
The partial three-dimensional plot in Fig.1 shows the connection ion-oxygen polyhedra in the crystal structure of the title compound. In the PO4 tetrahedron, the P–O distances and O–P–O angles respectively between 1.5170—1.5916 (9) Å and 104.70—114.66 (5) Å are consistent with values found in the literature. In the P2O7 group, the values of the P–O distances are in the range of 1.4924—1.5659 (9) Å while the shared oxygen is at P2–O8–P3 between 1.5971—1.6408 (9) Å and the angle P2—O8—P3 = 125.38 (6)°. P2O7 adopts an eclipsed conformation as indicated by the dihedral angle of 7.42°, between the two plans through O5P2O8 and O8P3O9.
In this structure the three independent nickel atoms occupy regular octahedra with Ni–O distances between 2.0027 (9) Å and 2.2284 (9) Å. The [Ni1O6], [Ni2O6] and [Ni3O6] octahedra share edges and form a chain directed along the c axis. The chains are linked together by PO4 and P2O7 tetrahedra and by sharing two edges of two octahedra in the way to form a layer perpendicular to the b axis. The potassium atom K1, is coordinated to eleven oxygen atoms building a very distorted polyhedron.
The resulting 3-D framework presents intersecting tunnels running along the [010] and [001] directions, where the potassium cation is located (Fig.2). Probably, the structure of this phosphate represents a new structural type.