KNb1.75V0.25PS10

Jaemin Yu; Hoseop Yun

doi:10.1107/S1600536811004430

. 2011 Feb 12;67(Pt 3):i24. doi: 10.1107/S1600536811004430

KNb_1.75V_0.25PS₁₀

Jaemin Yu ^a,^*, Hoseop Yun ^a

PMCID: PMC3051977 PMID: 21522232

Abstract

The title compound, potassium diniobium vanadium phosphorus decasulfide, KNb_1.75V_0.25PS₁₀, was obtained by reaction of the elements with a eutectic mixture of KCl/LiCl. It is isostructural with the quaternary KNb₂PS₁₀, but the Nb sites are occupied by statistically disordered Nb (87.5%) and V (12.5%) atoms. The structure is composed of anionic _∞ ¹[M ₂PS₁₀]⁻ chains (M = Nb/V) separated from each other by K⁺ ions. The chain is composed of [MS₈] distorted bicapped trigonal prisms and [PS₄] tetrahedra. There are no interchain bonding interactions. The crystal used for the X-ray analysis was a racemic twin.

Related literature

For related ternary compounds, see: Brec et al. (1983a ▶,b ▶). For related quaternary compounds, see: Goh et al. (2002 ▶); Do & Yun (1996 ▶); Kim & Yun (2002 ▶); Kwak et al. (2007 ▶); Bang et al. (2008 ▶); Do & Yun (2009 ▶). For related pentanary compounds, see: Kwak & Yun (2008 ▶); Dong et al. (2005a ▶,b ▶); Park & Yun (2010 ▶). For typical Nb⁴⁺—Nb⁴⁺ bond lengths, see: Angenault et al. (2000 ▶)

Experimental

Crystal data

KNb_1.75V_0.25PS₁₀
M _r = 2264.39
Orthorhombic,
a = 12.9696 (3) Å
b = 7.5229 (2) Å
c = 13.3248 (4) Å
V = 1300.09 (6) Å³
Z = 1
Mo Kα radiation
μ = 3.73 mm⁻¹
T = 290 K
0.36 × 0.06 × 0.06 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.649, T _max = 1.000
11855 measured reflections
2970 independent reflections
2859 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.019
wR(F ²) = 0.042
S = 1.07
2970 reflections
130 parameters
1 restraint
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.28 e Å⁻³
Absolute structure: Flack (1983 ▶), 1417 Friedel pairs
Flack parameter: 0.47 (4)

Data collection: RAPID-AUTO (Rigaku, 2006 ▶); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: locally modified version of ORTEP (Johnson, 1965 ▶); software used to prepare material for publication: STRUCTURE TIDY (Gelato & Parthé, 1987 ▶) and WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811004430/fj2392sup1.cif

e-67-00i24-sup1.cif^{(15KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811004430/fj2392Isup2.hkl

e-67-00i24-Isup2.hkl^{(142.8KB, hkl)}

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

Acknowledgments

This work was supported by the Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2010–0029617). Use was made of the X-ray facilities supported by Ajou University.

supplementary crystallographic information

Comment

Ternary group 5 metal thiophosphates have been reported to have mostly low-dimensional structures. Especially the Nb₂PS₁₀ phase has a two-dimensional layered structure (Brec et al., 1983a) and V₂PS₁₀ adopts a one-dimensional chain structure (Brec et al., 1983b). Due to empty spaces and the orbitals which can accommodate electrons, they have been of potential importance as cathode materials for secondary batteries and a number of quaternary alkali metal Nb thiophosphates, ANb₂PS₁₀ (A=monovalent metals) have been investigated. Among them are NaNb₂PS₁₀ (Goh et al., 2002), KNb₂PS₁₀ (Do & Yun, 1996), RbNb₂PS₁₀ (Kim & Yun, 2002), CsNb₂PS₁₀ (Kwak et al., 2007), TlNb₂PS₁₀ (Bang et al., 2008), Ag_0.88Nb₂PS₁₀ (Do & Yun, 2009), K_0.34Cu_0.5Nb₂PS₁₀ (Kwak & Yun, 2008), K_0.5Ag_0.5Nb₂PS₁₀ (Dong et al., 2005a), Rb_0.38Ag_0.5Nb₂PS₁₀ (Dong et al., 2005b), and Cs_0.5Ag_0.5Nb₂PS₁₀ (Park & Yun, 2010). It is interesting that no V analogue of these phases has been discovered yet. As a result of efforts to find new phases in this family, we report the synthesis and characterization of a new mixed-metal quintenary thiophosphate, KNb_{2 -}_xV_xPS₁₀ (x=0.25).

The structure of KNb_{2 -}_xV_xPS₁₀ is isostructural with the quaternary KNb₂PS₁₀ and detailed description of the structure is given previously (Do & Yun, 1996). The title compound is made up of the bicapped trigonal biprismatic [M₂S₁₂] unit (M=Nb/V) and the tetrahedral [PS₄] group. The M sites are occupied by the statistically disordered Nb(~87.5%) and V(~12.5%) atoms. The bicapped biprismatic [M₂S₁₂] units and its neighboring tetrahedral [PS₄] groups are given in Figure 1. These [M₂S₁₂] units are linked together to form the one-dimensional chains by sharing the S₂^2- prism edge. The one-dimensional chain composed of M, P, and S extends along [100] and can be described as ∞¹[M₂PS₁₀^-1].

The M atoms associate in pairs with M—M interactions alternating in the sequence of one short (2.8851 (3) Å) and one long (3.7590 (3) Å) distances. The short distance is typical of Nb⁴⁺—Nb⁴⁺ bonding interactions (Angenault et al., 2000). There are no interchain bonding interactions except the van der Waals forces and the K⁺ ions in this van der Waals gap stabilize the structure through the electrostatic interactions (Figure 2). Finally, the classical charge balance of this phase can be represented by [K⁺][M⁴⁺]₂[PS₄^3-][S₂^2-]₃ and this is consistent with the highly resistive and diamagnetic nature of the compound.

Experimental

The compound KNb_{2 -}_xV_xPS₁₀ was prepared by the reaction of the elemental Nb, V, P, and S with the use of the reactive alkali metal halides. A combination of the pure elements, Nb powder (CERAC 99.9%), V powder (CERAC 99.5%), P powder(CERAC99.95%), and S powder (Aldrich 99.999%) were mixed in a fused silica tube in a molar ratio of Nb: V: P: S = 1:1:1:5 with the eutectic mixture of KCl/LiCl. The mass ratio of the reactants and the halides flux was 2:1. The tube was evacuated to 0.133 Pa, sealed and heated gradually (50 K/h) to 650 K, where it was kept for 72 h. The tube was cooled to 423 K at 3 K/h and then was quenched to room temperature. The excess halides were removed with distilled water and black needle shaped crystals were obtained. The crystals are stable in air and water. A microprobe analysis of the crystals was made with an EDAX equipped scanning electron microscope (Jeol JSM-6700 F). Analysis of these crystals showed only the presence of K, Nb, V, P, and S. A quantitative analysis performed with standards gave the ratio of Nb: V = 87: 13, which corresponds to KNb_1.74V_0.26PS₁₀.