Ni2Si(P2O7)2

Yahya Toubi; Rachid Essehli; Michal Dušek; Karla Fejfarová; Brahim El Bali

doi:10.1107/S1600536809021734

. 2009 Jun 27;65(Pt 7):i55. doi: 10.1107/S1600536809021734

Ni₂Si(P₂O₇)₂

Yahya Toubi ^a, Rachid Essehli ^a, Michal Dušek ^b, Karla Fejfarová ^b, Brahim El Bali ^a,^*

PMCID: PMC2969362 PMID: 21582648

Abstract

Dinickel(II) silicon bis[diphosphate(4−)], Ni₂Si(P₂O₇)₂, is isotypic with other phosphates of the formula M ₂Si(P₂O₇)₂ (M = Co, Cd). All atoms except Si (site symmetry 2) are found in general positions. Ni₂O₁₀ dimers formed from edge-sharing NiO₆ octahedra are linked by corners and O—P—O bridges, forming slabs parallel to (100), which are in turn interconnected by O—Si—O contacts.

Related literature

For the structures of isotypic compounds, see: Glaum & Schmidt (1996 ▶) for Co₂Si(P₂O₇)₂ and Trojan et al. (1987 ▶) for Cd₂Si(P₂O₇)₂. For bond-length and angle data, see: Bostroem (1987 ▶); Durif (1995 ▶). For the extinction correction, see: Becker & Coppens (1974 ▶).

Experimental

Crystal data

Ni₂Si(P₂O₇)₂
M _r = 493.3
Monoclinic,
a = 16.8615 (9) Å
b = 4.8948 (2) Å
c = 12.1925 (5) Å
β = 103.693 (4)°
V = 977.69 (8) Å³
Z = 4
Mo Kα radiation
μ = 4.72 mm⁻¹
T = 295 K
0.27 × 0.16 × 0.07 mm

Data collection

Oxford Diffraction Xcalibur diffractometer with Atlas (Gemini ultra Cu) detector
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2006 ▶) T _min = 0.438, T _max = 0.829
4978 measured reflections
1013 independent reflections
877 reflections with I > 3σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.016
wR(F ²) = 0.045
S = 1.34
1013 reflections
97 parameters
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2006 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: Superflip (Palatinus & Chapuis, 2007 ▶); program(s) used to refine structure: JANA2006 (Petříček et al., 2006 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: JANA2006.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809021734/mg2073sup1.cif

e-65-00i55-sup1.cif^{(14KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809021734/mg2073Isup2.hkl

e-65-00i55-Isup2.hkl^{(44.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Ni1—O1	1.9631 (18)
Ni1—O4ⁱ	2.2351 (17)
Ni1—O4ⁱⁱ	2.1436 (14)
Ni1—O5ⁱⁱⁱ	2.1271 (17)
Ni1—O5^iv	2.1509 (14)
Ni1—O6	1.9660 (18)
Si1—O2^v	1.6018 (18)
Si1—O2^vi	1.6018 (18)
Si1—O7	1.5881 (16)
Si1—O7^vii	1.5881 (16)
P1—O1	1.4759 (17)
P1—O2	1.564 (2)
P1—O3^viii	1.5888 (15)
P1—O4	1.5132 (16)
P2—O3	1.5873 (19)
P2—O5	1.5017 (17)
P2—O6	1.4768 (18)
P2—O7	1.5458 (16)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) .

Acknowledgments

We thank the Grant Agency of the Czech Republic (grant No. 202/06/0757) for support.

supplementary crystallographic information

Comment

Although the isostructural silicodiphosphates M₂Si(P₂O₇)₂ have been reported for M = Fe, Ni, Co, Cu, and Cd, full single-crystal structure determinations have been carried out only for the Co and Cd members (Glaum & Schmidt, 1996; Trojan et al., 1987). The structure of Ni₂Si(P₂O₇)₂ is reported herein. Its cell parameters are consistent with those obtained earlier from Guinier photographs (Glaum & Schmidt, 1996). The three-dimensional framework is built up of NiO₆ octahedra, SiO₄ tetrahedra, and P₂O₇ diphosphate groups. Ni₂O₁₀ dimers, formed from pairs of edge-sharing NiO₆ octahedra, are interconnected through corners (O4) and O–P–O bridges of the diphosphate groups to generate slabs that lie parallel to (100) (Fig. 1). Neighboring slabs are connected through O–Si–O linkages from the SiO₄ groups (Fig. 2). The NiO₆ octahedron, whose apices are formed from one bidentate and four monodentate P₂O₇ groups (Fig. 3), is strongly distorted, with an average Ni–O distance [2.098 (2) Å] that is between those in Ni₂P₂O₇ (2.114 Å) and Ni₂SiO₄ (2.080 Å) (Bostroem, 1987). The P₂O₇ group adopts a nearly eclipsed conformation, with an average P–O distance [1.532 (2) Å] that is similar to other diphosphates (Durif, 1995) and a rather small P–O–P angle [132.51 (12) °] owing to its bidentate coordination to the Ni center.

Experimental

Ni₂Si(P₂O₇)₂ in the form of powder was prepared by stoichiometric reaction of SiO₂ (99.9%, Aldrich) and Ni₂P₄O₁₂ (the latter being obtained from a reaction of NiO and NH₄H₂PO₄ in a 2:4 ratio at 750 °C for 24 h under O₂ atmosphere). The mixture was heated at 500 °C under Ar atmosphere for 2 days and 700 °C for 36 h with intermediate grindings to ensure complete reaction. Subsequent melting at 1300 °C followed by slow cooling to room temperature at a rate of 5 ° h^-1 resulted in green crystals of the title compound.