Vanadium nickel antimonide, VNi_0.26(2)Sb

Vanadium nickel antimonide, VNi_0.26 (2)Sb, adopts a partly filled NiAs-type structure. It has an ordered atomic arrangement, with V atoms coordinated octahedrally [V-Sb 2.8073 (3) Å] and Ni atoms coordinated trigonal bipyramidally [Ni-Sb 2.4553 (3)-2.7221 (3) Å] by Sb atoms.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](V-Sb) = 0.0003 Å
• R factor = 0.058
• wR factor = 0.115
• Data-to-parameter ratio = 9.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



DIFMN_02  Alert C The minimum difference density is < -0.1*ZMAX*0.75
          _refine_diff_density_min given =     -4.485
          Test value =     -3.825

DIFMN_03  Alert C The minimum difference density is < -0.1*ZMAX*0.75
          The relevant atom site should be identified.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

S1. Comment

Ternary vanadium antimonides VFeSb, VCoSb, and VNiSb have been reported in a cubic form (F43m, MgAgAs-type, a ternary ordered variant of CaF₂) and a hexagonal form (P6₃/mmc, Ni₂In-type, a filled variant of NiAs) (Evers et al., 1997; Krypyakevich & Markiv, 1963; Noda et al., 1979). Although these are simple structures, the atomic distribution in these compounds is often uncertain. An ordered arrangement has now been proposed for the cubic forms, but it remains to be established for the hexagonal forms (Evers et al., 1997). In hexagonal VFeSb and VCoSb, the transition metal atoms were assumed to be disordered over the 2a and 2 d sites, whereas Sb occupies the 2c site (Noda et al., 1979). Examination of cell parameters suggested that hexagonal VNiSb may really be a defect structure of composition V_0.6NiSb, but lack of single-crystal data has prevented definitive conclusions from being drawn (Evers et al., 1997). Contributing further to the complexity of the V—Ni—Sb system, we now report an alternative defect hexagonal structure, VNi_0.26 (2)Sb.

In VNi_0.26 (2)Sb, the V atoms occupy all octahedral interstices between hexagonal close packed (hcp) layers of Sb atoms (Fig. 1). Alternatively, the V atoms form trigonal prisms, half of which are centred by Sb atoms (Fig. 2). The remaining half of these trigonal prisms are then partially occupied at 0.26 (2) with Ni atoms. The c/a ratio of 1.280 is substantially contracted from the ideal value of 1.63, giving rise to strong metal-metal bonding [V–V 2.7221 (3) Å] along the c direction, as is typical of NiAs-type structures. The ordering of the transition metal atoms is consistent with longer distances to Sb from the larger V atom [V–Sb 2.8073 (3) Å (× 6)] and shorter ones from the smaller Ni atom [Ni–Sb 2.4553 (3) Å (× 3), 2.7221 (3) Å (× 2)]. These distances are comparable to those found in binary VSb (2.816 Å; Grison & Beck, 1962) and Ni_{1 + x}Sb (~2.3, \sim2.6 Å for the Ni atoms in the 2 d site) (Chen et al., 1978; Kjekshus & Walseth, 1969).

The cell parameters for VNi_0.26 (2)Sb are larger by ~0.03 Å than those for hexagonal VFeSb, VCoSb, and V_0.6NiSb (Evers et al., 1997; Noda et al., 1979). In contrast, a is smaller by ~0.03 Å and c is nearly identical when compared to the cell parameters in VSb (Grison & Beck, 1962) and V_{1 + x}Sb x = 0.4–0.5) (Bouwma et al., 1973; Meissner & Schubert, 1965). This suggests that VNi_0.26 (2)Sb can indeed be regarded as being derived from VSb with insertion of small amounts of Ni. In contrast, some degree of disorder is probably present in the other ternary antimonides, with a proportion of the V atoms occupying the smaller 2 d site.

S2. Experimental

A 0.25 g mixture of elemental vanadium, nickel, and antimony in a 9:1:7 molar ratio (V, 84 mg, 1.64 mmol, 99.5%, Cerac; Ni, 10 mg, 0.18 mmol, 99.9%, Cerac; Sb, 156 mg, 1.28 mmol, 99.995%, Aldrich) was reacted, in an attempt to prepare a target compound V₉NiSb₇ analogous to Nb₉PdAs₇ (Wang & Mar, 2001). The reactants were heated in an evacuated fused-silica tube at 1273 K for 3 d, cooled to 873 K over 1 d, and then cooled to room temperature over 1 d. Small black prismatic crystals were obtained which contained all three elements as determined by semiquantitative EDX (energy-dispersive X-ray) analysis on a Hitachi F2700 scanning electron microscope.

S3. Refinement

Weissenberg photography on the selected crystal confirmed that it was single, gave preliminary cell parameters, and revealed hexagonal symmetry. Space group P6₃/mmc was chosen upon recognition of the relationship to the NiAs-type structure and was verified by the systematic absences. The ambiguity lies in the distribution of V, Ni, and Sb in the three sites 2a (0,0,0; 0,0,1/2); 2c (1/3,2/3,1/4; 2/3,1/3,3/4), and 2 d (1/3,2/3,3/4; 2/3,1/3,1/4). All possible combinations were tested, but the only feasible model placed V in 2a, Sb in 2c, and Ni partially occupied in 2 d. When all occupancies were allowed to refine, they converged to values of 0.99 (24) for V, 0.27 (7) for Ni, and 1.00 (24) for Sb. In the final refinement, the occupancies were fixed at 1.00 for V and Sb, but converged to 0.26 (2) for Ni. The largest residual (Δρ_min = -4.485 e Å^-3) in the final difference electron-density map is located 1.36 Å from a V site.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT 6.02 (Bruker, 2000); program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: ATOMS (Dowty, 1999); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. VNi0.26 (2)Sb viewed approximately down the c axis, showing VSb6 octahedra. Here and in Fig. 2, the colour key is: V blue, Ni green, Sb red.
	Fig. 2. VNi0.26 (2)Sb viewed perpendicular to the c axis, showing NiSb5 trigonal bipyramids and SbV6 trigonal prisms. Displacement ellipsoids are drawn at the 50% probability level.

vanadium nickel antimonide

Crystal data

VNi01.26Sb	Dx = 7.332 Mg m^−3
Mr = 188.25	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/mmc	Cell parameters from 929 reflections
Hall symbol: -P 6c 2c	θ = 3.7–32.2°
a = 4.2527 (5) Å	µ = 23.53 mm^−1
c = 5.4443 (6) Å	T = 295 K
V = 85.27 (2) Å^3	Prism, black
Z = 2	0.19 × 0.16 × 0.14 mm
F(000) = 163

Data collection

Bruker Platform/SMART 1000 CCD diffractometer	78 independent reflections
Radiation source: fine-focus sealed tube	78 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
ω scans (0.2°)	θmax = 32.5°, θmin = 5.5°
Absorption correction: numerical (SHELXTL; Sheldrick, 1997)	h = −5→6
Tmin = 0.046, Tmax = 0.143	k = −6→6
1099 measured reflections	l = −8→8

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.058	Secondary atom site location: difference Fourier map
wR(F^2) = 0.115	w = 1/[σ^2(Fo^2) + 5.7913P] where P = (Fo^2 + 2Fc^2)/3
S = 1.33	(Δ/σ)max = 0.003
78 reflections	Δρmax = 1.67 e Å^−3
8 parameters	Δρmin = −4.49 e Å^−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	Occ. (<1)
V	0.0000	0.0000	0.0000	0.0204 (12)
Ni	0.6667	0.3333	0.2500	0.012 (4)	0.26 (2)
Sb	0.3333	0.6667	0.2500	0.0327 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
V	0.0210 (17)	0.0210 (17)	0.019 (2)	0.0105 (8)	0.000	0.000
Ni	0.010 (4)	0.010 (4)	0.015 (6)	0.005 (2)	0.000	0.000
Sb	0.0421 (11)	0.0421 (11)	0.0139 (9)	0.0211 (6)	0.000	0.000

Geometric parameters (Å, º)

V—V^i	2.7221 (3)	Ni—Sb^viii	2.7221 (3)
V—V^ii	2.7221 (3)	Ni—V^xii	2.8073 (3)
V—Sb^iii	2.8073 (3)	Ni—V^xiii	2.8073 (3)
V—Sb	2.8073 (3)	Ni—V^x	2.8073 (3)
V—Ni	2.8073 (3)	Ni—V^xiv	2.8073 (3)
V—Sb^iv	2.8073 (3)	Ni—V^i	2.8073 (3)
V—Ni^v	2.8073 (3)	Sb—Ni^xv	2.4553 (3)
V—Ni^iv	2.8073 (3)	Sb—Ni^v	2.4553 (3)
V—Ni^vi	2.8073 (3)	Sb—Ni^xi	2.7221 (3)
V—Sb^vii	2.8073 (3)	Sb—Ni^viii	2.7221 (3)
V—Sb^viii	2.8073 (3)	Sb—V^xvi	2.8073 (3)
V—Sb^ix	2.8073 (3)	Sb—V^xiii	2.8073 (3)
Ni—Sb^x	2.4553 (3)	Sb—V^xv	2.8073 (3)
Ni—Sb^vii	2.4553 (3)	Sb—V^xiv	2.8073 (3)
Ni—Sb	2.4553 (3)	Sb—V^i	2.8073 (3)
Ni—Sb^xi	2.7221 (3)
V^i—V—V^ii	180.0	Sb^vii—Ni—V^xiii	150.999 (4)
V^i—V—Sb^iii	119.001 (4)	Sb—Ni—V^xiii	64.068 (1)
V^ii—V—Sb^iii	60.999 (4)	Sb^xi—Ni—V^xiii	60.999 (4)
V^i—V—Sb	60.999 (4)	Sb^viii—Ni—V^xiii	119.001 (4)
V^ii—V—Sb	119.001 (4)	V—Ni—V^xiii	128.136 (2)
Sb^iii—V—Sb	81.523 (5)	V^xii—Ni—V^xiii	98.477 (5)
V^i—V—Ni	60.999 (4)	Sb^x—Ni—V^x	64.068 (1)
V^ii—V—Ni	119.001 (4)	Sb^vii—Ni—V^x	64.068 (1)
Sb^iii—V—Ni	128.136 (2)	Sb—Ni—V^x	150.999 (4)
Sb—V—Ni	51.864 (2)	Sb^xi—Ni—V^x	119.001 (4)
V^i—V—Sb^iv	119.001 (4)	Sb^viii—Ni—V^x	60.999 (4)
V^ii—V—Sb^iv	60.999 (4)	V—Ni—V^x	98.477 (5)
Sb^iii—V—Sb^iv	98.477 (5)	V^xii—Ni—V^x	58.003 (8)
Sb—V—Sb^iv	180.0	V^xiii—Ni—V^x	128.136 (2)
Ni—V—Sb^iv	128.136 (2)	Sb^x—Ni—V^xiv	64.068 (1)
V^i—V—Ni^v	60.999 (4)	Sb^vii—Ni—V^xiv	150.999 (4)
V^ii—V—Ni^v	119.001 (4)	Sb—Ni—V^xiv	64.068 (1)
Sb^iii—V—Ni^v	58.003 (8)	Sb^xi—Ni—V^xiv	119.001 (4)
Sb—V—Ni^v	51.864 (2)	Sb^viii—Ni—V^xiv	60.999 (4)
Ni—V—Ni^v	98.477 (5)	V—Ni—V^xiv	98.477 (5)
Sb^iv—V—Ni^v	128.136 (2)	V^xii—Ni—V^xiv	128.136 (2)
V^i—V—Ni^iv	119.001 (4)	V^xiii—Ni—V^xiv	58.003 (8)
V^ii—V—Ni^iv	60.999 (4)	V^x—Ni—V^xiv	98.477 (5)
Sb^iii—V—Ni^iv	51.864 (2)	Sb^x—Ni—V^i	150.999 (4)
Sb—V—Ni^iv	128.136 (2)	Sb^vii—Ni—V^i	64.068 (1)
Ni—V—Ni^iv	180.0	Sb—Ni—V^i	64.068 (1)
Sb^iv—V—Ni^iv	51.864 (2)	Sb^xi—Ni—V^i	60.999 (4)
Ni^v—V—Ni^iv	81.523 (5)	Sb^viii—Ni—V^i	119.001 (4)
V^i—V—Ni^vi	119.001 (4)	V—Ni—V^i	58.003 (8)
V^ii—V—Ni^vi	60.999 (4)	V^xii—Ni—V^i	98.477 (5)
Sb^iii—V—Ni^vi	121.997 (8)	V^xiii—Ni—V^i	98.477 (5)
Sb—V—Ni^vi	128.136 (2)	V^x—Ni—V^i	128.136 (2)
Ni—V—Ni^vi	81.523 (5)	V^xiv—Ni—V^i	128.136 (2)
Sb^iv—V—Ni^vi	51.864 (2)	Ni^xv—Sb—Ni^v	120.0
Ni^v—V—Ni^vi	180.0	Ni^xv—Sb—Ni	120.0
Ni^iv—V—Ni^vi	98.477 (5)	Ni^v—Sb—Ni	120.0
V^i—V—Sb^vii	60.999 (4)	Ni^xv—Sb—Ni^xi	90.0
V^ii—V—Sb^vii	119.001 (4)	Ni^v—Sb—Ni^xi	90.0
Sb^iii—V—Sb^vii	180.0	Ni—Sb—Ni^xi	90.0
Sb—V—Sb^vii	98.477 (5)	Ni^xv—Sb—Ni^viii	90.0
Ni—V—Sb^vii	51.864 (2)	Ni^v—Sb—Ni^viii	90.0
Sb^iv—V—Sb^vii	81.523 (5)	Ni—Sb—Ni^viii	90.0
Ni^v—V—Sb^vii	121.997 (8)	Ni^xi—Sb—Ni^viii	180.0
Ni^iv—V—Sb^vii	128.136 (2)	Ni^xv—Sb—V	150.999 (4)
Ni^vi—V—Sb^vii	58.003 (8)	Ni^v—Sb—V	64.068 (1)
V^i—V—Sb^viii	119.001 (4)	Ni—Sb—V	64.068 (1)
V^ii—V—Sb^viii	60.999 (4)	Ni^xi—Sb—V	119.001 (4)
Sb^iii—V—Sb^viii	98.477 (5)	Ni^viii—Sb—V	60.999 (4)
Sb—V—Sb^viii	81.523 (5)	Ni^xv—Sb—V^xvi	64.068 (1)
Ni—V—Sb^viii	58.003 (8)	Ni^v—Sb—V^xvi	64.068 (1)
Sb^iv—V—Sb^viii	98.477 (5)	Ni—Sb—V^xvi	150.999 (4)
Ni^v—V—Sb^viii	128.136 (2)	Ni^xi—Sb—V^xvi	60.999 (4)
Ni^iv—V—Sb^viii	121.997 (8)	Ni^viii—Sb—V^xvi	119.001 (4)
Ni^vi—V—Sb^viii	51.864 (2)	V—Sb—V^xvi	128.136 (2)
Sb^vii—V—Sb^viii	81.523 (5)	Ni^xv—Sb—V^xiii	64.068 (1)
V^i—V—Sb^ix	60.999 (4)	Ni^v—Sb—V^xiii	150.999 (4)
V^ii—V—Sb^ix	119.001 (4)	Ni—Sb—V^xiii	64.068 (1)
Sb^iii—V—Sb^ix	81.523 (5)	Ni^xi—Sb—V^xiii	60.999 (4)
Sb—V—Sb^ix	98.477 (5)	Ni^viii—Sb—V^xiii	119.001 (4)
Ni—V—Sb^ix	121.997 (8)	V—Sb—V^xiii	128.136 (2)
Sb^iv—V—Sb^ix	81.523 (5)	V^xvi—Sb—V^xiii	98.477 (5)
Ni^v—V—Sb^ix	51.864 (2)	Ni^xv—Sb—V^xv	64.068 (1)
Ni^iv—V—Sb^ix	58.003 (8)	Ni^v—Sb—V^xv	64.068 (1)
Ni^vi—V—Sb^ix	128.136 (2)	Ni—Sb—V^xv	150.999 (4)
Sb^vii—V—Sb^ix	98.477 (5)	Ni^xi—Sb—V^xv	119.001 (4)
Sb^viii—V—Sb^ix	180.0	Ni^viii—Sb—V^xv	60.999 (4)
Sb^x—Ni—Sb^vii	120.0	V—Sb—V^xv	98.477 (5)
Sb^x—Ni—Sb	120.0	V^xvi—Sb—V^xv	58.003 (8)
Sb^vii—Ni—Sb	120.0	V^xiii—Sb—V^xv	128.136 (2)
Sb^x—Ni—Sb^xi	90.0	Ni^xv—Sb—V^xiv	64.068 (1)
Sb^vii—Ni—Sb^xi	90.0	Ni^v—Sb—V^xiv	150.999 (4)
Sb—Ni—Sb^xi	90.0	Ni—Sb—V^xiv	64.068 (1)
Sb^x—Ni—Sb^viii	90.0	Ni^xi—Sb—V^xiv	119.001 (4)
Sb^vii—Ni—Sb^viii	90.0	Ni^viii—Sb—V^xiv	60.999 (4)
Sb—Ni—Sb^viii	90.0	V—Sb—V^xiv	98.477 (5)
Sb^xi—Ni—Sb^viii	180.0	V^xvi—Sb—V^xiv	128.136 (2)
Sb^x—Ni—V	150.999 (4)	V^xiii—Sb—V^xiv	58.003 (8)
Sb^vii—Ni—V	64.068 (1)	V^xv—Sb—V^xiv	98.477 (5)
Sb—Ni—V	64.068 (1)	Ni^xv—Sb—V^i	150.999 (4)
Sb^xi—Ni—V	119.001 (4)	Ni^v—Sb—V^i	64.068 (1)
Sb^viii—Ni—V	60.999 (4)	Ni—Sb—V^i	64.068 (1)
Sb^x—Ni—V^xii	64.068 (1)	Ni^xi—Sb—V^i	60.999 (4)
Sb^vii—Ni—V^xii	64.068 (1)	Ni^viii—Sb—V^i	119.001 (4)
Sb—Ni—V^xii	150.999 (4)	V—Sb—V^i	58.003 (8)
Sb^xi—Ni—V^xii	60.999 (4)	V^xvi—Sb—V^i	98.477 (5)
Sb^viii—Ni—V^xii	119.001 (4)	V^xiii—Sb—V^i	98.477 (5)
V—Ni—V^xii	128.136 (2)	V^xv—Sb—V^i	128.136 (2)
Sb^x—Ni—V^xiii	64.068 (1)	V^xiv—Sb—V^i	128.136 (2)

Symmetry codes: (i) −x, −y, z+1/2; (ii) −x, −y, z−1/2; (iii) −x, −y+1, −z; (iv) −x, −y, −z; (v) x−1, y, z; (vi) −x+1, −y, −z; (vii) x, y−1, z; (viii) −x+1, −y+1, −z; (ix) x−1, y−1, z; (x) x+1, y, z; (xi) −x+1, −y+1, −z+1; (xii) −x+1, −y, z+1/2; (xiii) −x+1, −y+1, z+1/2; (xiv) x+1, y+1, z; (xv) x, y+1, z; (xvi) −x, −y+1, z+1/2.