Nickel vanadium tellurium oxide, NiV₂Te₂O₁₀

Single crystals of nickel(II) divanadium(V) ditellurium(IV) decaoxide, NiV₂Te₂O₁₀, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound crystallizes in the triclinic system (space group P). The Ni atoms are positioned in the 1c position on the inversion centre, while the V and Te atoms are in general positions 2i. The crystal structure is layered, the building units within a (010) layer being distorted VO₆ octa­hedra and NiO₆ octa­hedra. The metal-oxide layers are connected by distorted TeO₄E square pyramids (E being the 5s² lone electron pair of Te^IV) to form the framework. The structure contains corner-sharing NiO₆ octa­hedra, corner- and edge-sharing TeO₄E square pyramids, and corner- and edge-sharing VO₆ octa­hedra. NiV₂Te₂O₁₀ is the first oxide containing all of the cations Ni^II, V^V and Te^IV.

S1. Comment

The crystal chemistry of transition metal tellurates has proved to be rich, and a number of compounds with various crystal structures have previously been described, for example, NiTe₂O₅ (Platte & Trömel, 1981), Ni₂Te₃O₈ (Feger et al., 1999), V₄Te₄O₁₈ (Xiao et al., 2003) and MnV₂TeO₇ (Feger & Kolis, 1998). The latter is a good example of a framework compound where the stereochemically active lone pairs on Te^IV are located in voids in the structure.

The synthesis and crystal structure of the new compound NiV₂Te₂O₁₀ is a result of an ongoing investigation of oxide and oxohalide compounds containing transition metal cations as well as p-element cations with stereochemically active lone electron pairs, such as Te^IV, Se^IV, Sb^III and Bi^III. The present compound is to the best of our knowledge the first oxide to contain all three of Ni^II, V^V and Te^IV. The stereochemically active lone electron pairs occupy space similar to that required for an oxygen ion in the crystal structure. This means that the lone electron pairs open up the crystal structure, very often leading to a low-dimensional arrangement of the transition metal cations in such compounds.

NiV₂Te₂O₁₀ crystallizes in the centrosymmetric triclinic space group P1. The V^V atoms are surrounded by six O atoms forming a very distorted octahedron with one V1═O4 vanadyl double bond equal to 1.643 (4) Å and one long V1—O5^vii bond [symmetry code: (vii) -x, -y +1, -z+ 1] equal to 2.332 (4) Å (Fig. 1). As a consequence, the V atom is located above the equatorial plane of the octahedron. Bond valence sum analysis (Brown & Altermatt, 1985) confirms this choice, with the calculated valence (V^V, Ro = 1.803) equal to 5.04. The VO₆ octahedra are connected via O5···O5^vii and O1···O1^vi edge sharing [symmetry code: (vi) - x + 1,-y + 1,-z + 1] to form chains along [100]. The Ni^II ions are in a regular octahedral environment. The NiO₆ octahedra are not connected to one another but bridge the chains by corner sharing to four different distorted VO₆ octahedra to form metal–oxide layers parallel to (010) (Fig. 2). The Te^IV ion has one-sided TeO₄ coordination owing to presence of the 5s² stereochemically active lone pair, E, and two such units share edges to form Te₂O₆E₂ units, where the Te···Teⁱⁱ [symmetry code: (ii) -x + 1, -y + 2, -z] distance is 3.312 (6) Å. The crystal structure can be described as being layered, and the Te₂O₆E₂ groups connect the metal–oxide layers by corner sharing (Fig. 3). The stereochemically active Te^IV lone pairs are located in voids in the structure.

Related literature

For related literature, see: Brown & Altermatt (1985); Feger & Kolis (1998); Feger et al. (1999); Platte & Trömel (1981); Xiao et al. (2003).

S2. Experimental

Single crystals of NiV₂Te₂O₁₀ are non-hygroscopic and were synthesized via chemical vapour transport reactions in sealed evacuated silica tubes. The starting materials were NiO (Alfa Aesar, 99%), NiCl₂ (Sigma–Aldrich, 98%), V₂O₅ (ABCR, 99.9%) and TeO₂ (Sigma–Aldrich, >99%) mixed in the molar ratio 1:1:1:2. The starting mixture was loaded at one end of a silica tube, which was subsequently evacuated, sealed and heat treated in a muffle furnace at 793 K for 72 h. The synthesized products were a mixture of red–brown NiV₂Te₂O₁₀ single crystals and a yellow–brown powder of undetermined composition. The crystals subject to analyses were selected manually on the basis of colour and morphology. Attempts to synthesize the compound from a stoichiometric mixture were unsuccessful.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Bergerhoff, 2001); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Figures

	Fig. 1. : A displacement ellipsoid diagram showing the coordination around the three cations. Atomic displacement parameters are given at the 50% probability level. [Symmetry codes: (i) x, y + 1, z; (ii) -x + 1, -y + 2, -z; (iii) -x, -y + 1, -z; (iv) x - 1, y, z; (v) -x + 1, -y + 1, -z; (vi) -x + 1, -y + 1, -z + 1; (vii) -x, -y + 1, -z + 1.]
	Fig. 2. : A metal–oxide slab [NiV2O10^8-] parallell to (010). Atomic displacement parameters are given at the 50% probability level.
	Fig. 3. : The structure of NiV2Te2O10, viewed along [100].

nickel(II) divanadium(V) ditellurium(IV) decaoxide

Crystal data

NiV2Te2O10	Z = 1
Mr = 575.79	F(000) = 258
Triclinic, P1	Dx = 5.349 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 4.7961 (2) Å	Cell parameters from 6322 reflections
b = 6.3747 (3) Å	θ = 3.7–33.1°
c = 6.5643 (5) Å	µ = 13.21 mm^−1
α = 84.651 (2)°	T = 293 K
β = 69.490 (3)°	Block, red
γ = 72.011 (4)°	0.07 × 0.06 × 0.05 mm
V = 178.76 (2) Å^3

Data collection

Oxford Xcalibur3 Diffractometer	723 independent reflections
Radiation source: fine-focus sealed tube	713 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.066
fσcan	θmax = 26.4°, θmin = 4.7°
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2005) Version 1.171.32.9 (release 17-07-2007 CrysAlis171 .NET) (compiled Aug 17 2007,17:36:27) Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by (Clark & Reid, 1995).	h = −5→5
Tmin = 0.413, Tmax = 0.599	k = −7→7
6322 measured reflections	l = −8→8

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.026	w = 1/[σ^2(Fo^2) + (0.0574P)^2 + 0.6923P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.071	(Δ/σ)max = 0.001
S = 1.00	Δρmax = 1.40 e Å^−3
723 reflections	Δρmin = −1.43 e Å^−3
71 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.025 (3)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Te1	0.28022 (7)	0.90950 (4)	0.22439 (4)	0.0074 (2)
Ni1	0.0000	0.5000	0.0000	0.0079 (3)
V1	0.3566 (2)	0.39027 (13)	0.36931 (13)	0.0073 (3)
O1	0.3976 (9)	0.6785 (5)	0.4266 (6)	0.0087 (7)
O2	0.7021 (8)	0.8269 (6)	0.0383 (6)	0.0091 (7)
O3	0.2849 (9)	0.1152 (6)	0.4111 (6)	0.0110 (7)
O4	0.6536 (9)	0.3494 (6)	0.1404 (6)	0.0116 (7)
O5	0.0397 (9)	0.5282 (6)	0.2934 (6)	0.0097 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Te1	0.0086 (3)	0.0059 (3)	0.0075 (3)	−0.00089 (15)	−0.00297 (17)	−0.00158 (14)
Ni1	0.0091 (5)	0.0066 (5)	0.0078 (5)	−0.0012 (3)	−0.0032 (4)	−0.0015 (3)
V1	0.0090 (5)	0.0057 (4)	0.0077 (4)	−0.0013 (3)	−0.0037 (3)	−0.0017 (3)
O1	0.0109 (18)	0.0066 (16)	0.0094 (17)	−0.0028 (13)	−0.0040 (13)	−0.0020 (13)
O2	0.0069 (17)	0.0085 (16)	0.0073 (16)	0.0016 (13)	0.0004 (13)	−0.0019 (12)
O3	0.018 (2)	0.0055 (16)	0.0103 (17)	−0.0032 (14)	−0.0050 (14)	−0.0018 (12)
O4	0.013 (2)	0.0117 (18)	0.0100 (17)	−0.0050 (14)	−0.0018 (14)	0.0002 (13)
O5	0.0105 (18)	0.0084 (16)	0.0094 (16)	0.0005 (13)	−0.0046 (13)	−0.0024 (12)

Geometric parameters (Å, º)

Te1—O3^i	1.887 (4)	Ni1—O2^v	2.111 (3)
Te1—O2	1.895 (4)	Ni1—O2^iv	2.111 (3)
Te1—O1	1.974 (3)	V1—O4	1.643 (4)
Te1—O2^ii	2.291 (3)	V1—O5	1.719 (4)
Ni1—O5^iii	2.030 (3)	V1—O3	1.867 (3)
Ni1—O5	2.030 (3)	V1—O1	1.990 (3)
Ni1—O4^iv	2.068 (4)	V1—O1^vi	2.013 (4)
Ni1—O4^v	2.068 (4)	V1—O5^vii	2.332 (4)
O3^i—Te1—O2	100.90 (16)	O4^iv—Ni1—O2^iv	96.46 (14)
O3^i—Te1—O1	87.35 (14)	O4^v—Ni1—O2^iv	83.54 (14)
O2—Te1—O1	88.71 (15)	O2^v—Ni1—O2^iv	180.0
O3^i—Te1—O2^ii	88.12 (14)	O4—V1—O5	104.26 (18)
O2—Te1—O2^ii	75.81 (15)	O4—V1—O3	101.90 (17)
O1—Te1—O2^ii	162.74 (15)	O5—V1—O3	97.29 (17)
O5^iii—Ni1—O5	180.0 (2)	O4—V1—O1	92.69 (17)
O5^iii—Ni1—O4^iv	88.92 (14)	O5—V1—O1	89.50 (16)
O5—Ni1—O4^iv	91.08 (14)	O3—V1—O1	161.79 (15)
O5^iii—Ni1—O4^v	91.08 (14)	O4—V1—O1^vi	97.48 (17)
O5—Ni1—O4^v	88.92 (14)	O5—V1—O1^vi	153.89 (16)
O4^iv—Ni1—O4^v	180.00 (16)	O3—V1—O1^vi	92.13 (15)
O5^iii—Ni1—O2^v	89.18 (14)	O1—V1—O1^vi	75.04 (15)
O5—Ni1—O2^v	90.82 (14)	O4—V1—O5^vii	173.77 (16)
O4^iv—Ni1—O2^v	83.54 (14)	O5—V1—O5^vii	78.60 (16)
O4^v—Ni1—O2^v	96.46 (14)	O3—V1—O5^vii	83.07 (15)
O5^iii—Ni1—O2^iv	90.82 (14)	O1—V1—O5^vii	81.74 (14)
O5—Ni1—O2^iv	89.18 (14)	O1^vi—V1—O5^vii	78.44 (14)

Symmetry codes: (i) x, y+1, z; (ii) −x+1, −y+2, −z; (iii) −x, −y+1, −z; (iv) x−1, y, z; (v) −x+1, −y+1, −z; (vi) −x+1, −y+1, −z+1; (vii) −x, −y+1, −z+1.