Redetermination of the crystal structure of β-zinc molybdate from single-crystal X-ray diffraction data.

The crystal structure of the β-polymorph of ZnMoO4 was re-determined on the basis of single-crystal X-ray diffraction data. In comparison with previous powder X-ray diffraction studies [Katikaneani & Arunachalam (2005 ▸). Eur. J. Inorg. Chem. pp. 3080-3087; Cavalcante et al. (2013 ▸). Polyhedron, 54, 13-25], all atoms were refined with anisotropic displacement parameters, leading to a higher precision with respect to bond lengths and angles. β-ZnMoO4 adopts the wolframite structure type and is composed of distorted ZnO6 and MoO6 octa-hedra, both with point group symmetry 2. The distortion of the octa-hedra is reflected by variation of bond lengths and angles from 2.002 (3)-2.274 (4) Å, 80.63 (11)-108.8 (2)° for equatorial and 158.4 (2)- 162.81 (14)° for axial angles (ZnO6), and of 1.769 (3)-2.171 (3) Å, 73.39 (16)-104.7 (2), 150.8 (2)-164.89 (15)° (MoO6), respectively. In the crystal structure, the same type of MO6 octa-hedra share edges to built up zigzag chains extending parallel to [001]. The two types of chains are condensed by common vertices into a framework structure. The crystal structure can alternatively be described as derived from a distorted hexa-gonally closed packed arrangement of the O atoms, with Zn and Mo in half of the octa-hedral voids.

Related literature

Most molybdates of divalent cations crystallize either in the scheelite-type or in the wolframite-type (Macavei & Schulz, 1993 ▸). Zinc molybdate (ZnMoO4) is an inorganic semiconductor. It adopts the wolframite-type of structure (Keeling, 1957 ▸) and is dimorphic. The two phases, referred to as α- (triclinc symmetry) and β- (monoclinic symmetry), can be selectively obtained by controlling the synthetic conditions (Abrahams et al., 1967 ▸; Zhang et al., 2010 ▸). Previous crystal structure refinements of β-ZnMoO4, based on X-ray powder diffraction data, were reported by Cavalcante et al. (2013 ▸) and Katikaneani & Arunachalam (2005 ▸). For structure refinement of ZnWO4, isotypic with the title compound, see: Trots et al. (2009 ▸).

Experimental

Crystal data

ZnMoO4

M = 225.31

Monoclinic,

a = 4.6980 (3) Å

b = 5.7380 (4) Å

c = 4.8960 (4) Å

β = 90.311 (7)°

V = 131.98 (2) Å3

Z = 2

Mo Kα radiation

μ = 13.62 mm−1

T = 293 K

0.08 × 0.06 × 0.03 mm

Data collection

Oxford Diffraction Xcalibur CCD diffractometer

Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2014 ▸) T min = 0.905, T max = 1.000

1207 measured reflections

405 independent reflections

358 reflections with I > 2σ(I)

R int = 0.036

Refinement

R[F 2 > 2σ(F 2)] = 0.028

wR(F 2) = 0.068

S = 1.10

405 reflections

29 parameters

Δρmax = 1.20 e Å−3

Δρmin = −1.17 e Å−3

Data collection: CrysAlis CCD (Oxford Diffraction, 2014 ▸); cell refinement: CrysAlis RED (Oxford Diffraction, 2014 ▸); data reduction: CrysAlis RED; program(s) used to solve structure: SIR2011 (Burla et al., 2012 ▸); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ▸); molecular graphics: DIAMOND (Brandenburg & Putz, 1999 ▸); software used to prepare material for publication: WinGX (Farrugia, 2012 ▸), publCIF (Westrip, 2010 ▸) and PARST (Nardelli, 1995 ▸).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S205698901501186X/wm5159sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S205698901501186X/wm5159Isup2.hkl

Click here for additional data file.

4 . DOI: 10.1107/S205698901501186X/wm5159fig1.tif

A view of the crystal structure of β-ZnMoO4. Anisotropic displacement parameters are drawn at the 50% probability level.

CCDC reference: 1408028

Additional supporting information: crystallographic information; 3D view; checkCIF report

MoO4Zn	F(000) = 208
Mr = 225.31	Dx = 5.670 Mg m−3
Monoclinic, P2/c	Mo Kα radiation, λ = 0.71073 Å
a = 4.6980 (3) Å	Cell parameters from 570 reflections
b = 5.7380 (4) Å	θ = 3.6–31.1°
c = 4.8960 (4) Å	µ = 13.62 mm−1
β = 90.311 (7)°	T = 293 K
V = 131.98 (2) Å3	Prism, colourless
Z = 2	0.08 × 0.06 × 0.03 mm

Oxford Diffraction Xcalibur CCD diffractometer	405 independent reflections
Radiation source: Enhance (Mo) X-ray Source	358 reflections with I > 2σ(I)
Detector resolution: 10.2673 pixels mm-1	Rint = 0.036
ω– and φ–scans	θmax = 31.3°, θmin = 3.6°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2014)	h = −6→6
Tmin = 0.905, Tmax = 1.000	k = −8→8
1207 measured reflections	l = −6→6

Refinement on F2	29 parameters
Least-squares matrix: full	0 restraints
R[F2 > 2σ(F2)] = 0.028	w = 1/[σ2(Fo2) + (0.0209P)2 + 0.5403P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.068	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 1.20 e Å−3
405 reflections	Δρmin = −1.17 e Å−3

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.

	x	y	z	Uiso*/Ueq
Mo1	1.0000	0.81190 (10)	0.2500	0.00507 (18)
Zn1	1.5000	0.69182 (15)	0.7500	0.0092 (2)
O1	1.2538 (7)	0.6236 (6)	0.4014 (7)	0.0080 (7)
O2	0.7835 (7)	0.8950 (6)	0.5603 (7)	0.0058 (7)

	U11	U22	U33	U12	U13	U23
Mo1	0.0065 (3)	0.0045 (3)	0.0041 (3)	0.000	−0.0002 (2)	0.000
Zn1	0.0087 (4)	0.0116 (4)	0.0073 (4)	0.000	0.0009 (3)	0.000
O1	0.0089 (17)	0.0110 (16)	0.0041 (17)	0.0006 (14)	0.0003 (13)	−0.0004 (14)
O2	0.0088 (16)	0.0064 (14)	0.0021 (16)	−0.0005 (13)	0.0016 (12)	−0.0010 (13)

Mo1—O1i	1.769 (3)	Zn1—O2iv	2.002 (3)
Mo1—O1	1.769 (3)	Zn1—O2v	2.002 (3)
Mo1—O2	1.894 (3)	Zn1—O1vi	2.094 (3)
Mo1—O2i	1.894 (3)	Zn1—O1	2.094 (3)
Mo1—O2ii	2.171 (3)	Zn1—O1vii	2.274 (4)
Mo1—O2iii	2.171 (3)	Zn1—O1viii	2.274 (4)
O1i—Mo1—O1	104.7 (2)	O2iv—Zn1—O1	95.54 (14)
O1i—Mo1—O2	97.25 (15)	O2v—Zn1—O1	96.96 (14)
O1—Mo1—O2	100.46 (15)	O1vi—Zn1—O1	158.4 (2)
O1i—Mo1—O2i	100.46 (15)	O2iv—Zn1—O1vii	162.81 (14)
O1—Mo1—O2i	97.25 (15)	O2v—Zn1—O1vii	88.37 (13)
O2—Mo1—O2i	150.8 (2)	O1vi—Zn1—O1vii	82.25 (14)
O1i—Mo1—O2ii	164.89 (14)	O1—Zn1—O1vii	80.63 (11)
O1—Mo1—O2ii	88.90 (14)	O2iv—Zn1—O1viii	88.37 (13)
O2—Mo1—O2ii	73.39 (16)	O2v—Zn1—O1viii	162.81 (14)
O2i—Mo1—O2ii	84.01 (11)	O1vi—Zn1—O1viii	80.63 (11)
O1i—Mo1—O2iii	88.90 (14)	O1—Zn1—O1viii	82.24 (14)
O1—Mo1—O2iii	164.89 (15)	O1vii—Zn1—O1viii	74.53 (18)
O2—Mo1—O2iii	84.01 (11)	Mo1—O1—Zn1	126.54 (19)
O2i—Mo1—O2iii	73.39 (16)	Mo1—O1—Zn1viii	133.83 (18)
O2ii—Mo1—O2iii	78.49 (18)	Zn1—O1—Zn1viii	97.75 (14)
O2iv—Zn1—O2v	108.8 (2)	Mo1—O2—Zn1ix	125.93 (18)
O2iv—Zn1—O1vi	96.96 (14)	Mo1—O2—Mo1ii	106.61 (16)
O2v—Zn1—O1vi	95.54 (14)	Zn1ix—O2—Mo1ii	124.32 (17)