A triclinic polymorph of dicadmium divanadate(V).

The title compound, Cd2V2O7, was obtained under hydro-thermal conditions. Different from the known monoclinic form, the new polymorph of Cd2V2O7 has triclinic symmetry and is isotypic with Ca2V2O7. The building units of the crystal structure are two Cd(2+) cations, with coordination numbers of six and seven, and two V atoms with a tetra-hedral and a significantly distorted trigonal-pyramidal coordination environment, respectively. Two VO5 pyramids share an edge and each pyramid is connected to one VO4 tetra-hedron via a corner atom, forming an isolated V4O14 (8-) anion. These anions are arranged in sheets parallel to (-211) and are linked through the Cd(2+) cations into a three-dimensional framework structure.

Related literature

For Ca2V2O7, isotypic with the title compound, see: Trunov et al. (1983 ▶). For the structure of the monoclinic polymorph of Cd2V2O7, see: Au & Calvo (1967 ▶). For the thermal stability of the monoclinic polymorph, see: Krasnenko & Rotermel (2010 ▶). For applications of vanadates, see: Jin et al. (2013 ▶); Valverde et al. (2012 ▶). For bond-valence analysis, see: Brown & Altermatt (1985 ▶).

Experimental

Crystal data

Cd2V2O7

M = 438.68

Triclinic,

a = 6.5974 (2) Å

b = 6.8994 (2) Å

c = 6.9961 (2) Å

α = 83.325 (1)°

β = 63.898 (1)°

γ = 80.145 (1)°

V = 281.45 (1) Å3

Z = 2

Mo Kα radiation

μ = 10.65 mm−1

T = 296 K

0.29 × 0.17 × 0.12 mm

Data collection

Bruker X8 APEX diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.164, T max = 0.376

10113 measured reflections

2134 independent reflections

2077 reflections with I > 2σ(I)

R int = 0.025

Refinement

R[F 2 > 2σ(F 2)] = 0.016

wR(F 2) = 0.037

S = 1.21

2134 reflections

100 parameters

Δρmax = 0.70 e Å−3

Δρmin = −1.53 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536813028869/wm2776sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813028869/wm2776Isup2.hkl

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

Cd2V2O7	Z = 2
Mr = 438.68	F(000) = 396
Triclinic, P1	Dx = 5.176 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.5974 (2) Å	Cell parameters from 2717 reflections
b = 6.8994 (2) Å	θ = 3.0–33.1°
c = 6.9961 (2) Å	µ = 10.65 mm−1
α = 83.325 (1)°	T = 296 K
β = 63.898 (1)°	Block, colourless
γ = 80.145 (1)°	0.29 × 0.17 × 0.12 mm
V = 281.45 (1) Å3

Bruker X8 APEX diffractometer	2134 independent reflections
Radiation source: fine-focus sealed tube	2077 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
φ and ω scans	θmax = 33.1°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −10→10
Tmin = 0.164, Tmax = 0.376	k = −10→10
10113 measured reflections	l = −10→10

Refinement on F2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.016	Secondary atom site location: difference Fourier map
wR(F2) = 0.037	w = 1/[σ2(Fo2) + (0.0148P)2 + 0.2572P] where P = (Fo2 + 2Fc2)/3
S = 1.21	(Δ/σ)max = 0.001
2134 reflections	Δρmax = 0.70 e Å−3
100 parameters	Δρmin = −1.53 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.

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 > 2σ(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.

	x	y	z	Uiso*/Ueq
Cd1	0.24214 (2)	0.336697 (18)	0.83258 (2)	0.00767 (4)
Cd2	0.74980 (2)	0.034380 (18)	0.75748 (2)	0.00845 (4)
V1	0.71038 (5)	0.16450 (4)	0.25864 (4)	0.00469 (5)
V2	0.22836 (5)	0.45517 (4)	0.34409 (5)	0.00542 (5)
O1	0.8612 (2)	0.3328 (2)	0.0816 (2)	0.0100 (2)
O2	0.8622 (2)	0.0439 (2)	0.3907 (2)	0.0099 (2)
O3	0.4592 (2)	0.2893 (2)	0.4363 (2)	0.0092 (2)
O4	0.6546 (2)	−0.00638 (19)	0.1233 (2)	0.0086 (2)
O5	0.2714 (2)	0.29481 (19)	0.1660 (2)	0.0093 (2)
O6	0.3839 (2)	0.6438 (2)	0.2436 (2)	0.0104 (2)
O7	−0.0496 (2)	0.5892 (2)	0.3678 (2)	0.0100 (2)

	U11	U22	U33	U12	U13	U23
Cd1	0.00672 (6)	0.00774 (6)	0.00900 (6)	−0.00006 (4)	−0.00431 (4)	0.00047 (4)
Cd2	0.00779 (6)	0.00795 (6)	0.00808 (6)	0.00031 (4)	−0.00277 (4)	0.00069 (4)
V1	0.00423 (11)	0.00515 (11)	0.00483 (11)	−0.00033 (8)	−0.00222 (9)	−0.00007 (9)
V2	0.00472 (11)	0.00635 (12)	0.00446 (11)	−0.00089 (9)	−0.00115 (9)	−0.00065 (9)
O1	0.0089 (5)	0.0096 (5)	0.0098 (5)	−0.0031 (4)	−0.0025 (5)	0.0023 (4)
O2	0.0080 (5)	0.0124 (6)	0.0090 (5)	0.0009 (4)	−0.0044 (4)	0.0003 (4)
O3	0.0070 (5)	0.0116 (6)	0.0079 (5)	0.0021 (4)	−0.0032 (4)	−0.0013 (4)
O4	0.0110 (6)	0.0068 (5)	0.0095 (5)	−0.0012 (4)	−0.0054 (5)	−0.0014 (4)
O5	0.0128 (6)	0.0079 (5)	0.0083 (5)	0.0002 (4)	−0.0057 (5)	−0.0015 (4)
O6	0.0081 (5)	0.0079 (5)	0.0147 (6)	−0.0021 (4)	−0.0046 (5)	0.0014 (4)
O7	0.0056 (5)	0.0157 (6)	0.0064 (5)	0.0026 (4)	−0.0020 (4)	0.0004 (4)

Cd1—O7i	2.2401 (13)	Cd2—O4ii	2.4562 (14)
Cd1—O4ii	2.2898 (13)	V1—O1	1.6882 (13)
Cd1—O6iii	2.3083 (14)	V1—O2	1.7028 (14)
Cd1—O1iii	2.3345 (14)	V1—O3	1.7265 (13)
Cd1—O1iv	2.3476 (13)	V1—O4	1.7708 (13)
Cd1—O5v	2.4043 (13)	V2—O5	1.6612 (14)
Cd1—O3	2.5300 (13)	V2—O6	1.6885 (14)
Cd2—O6iii	2.2449 (14)	V2—O7	1.8530 (13)
Cd2—O5ii	2.2858 (13)	V2—O7i	1.8535 (13)
Cd2—O2vi	2.2894 (14)	V2—O3	2.0348 (13)
Cd2—O2	2.3327 (14)	V2—V2i	2.8482 (6)
Cd2—O4v	2.3459 (13)
O7i—Cd1—O4ii	114.29 (5)	O2vi—Cd2—O2	74.71 (5)
O7i—Cd1—O6iii	131.24 (5)	O6iii—Cd2—O4v	96.72 (5)
O4ii—Cd1—O6iii	83.66 (5)	O5ii—Cd2—O4v	75.42 (5)
O7i—Cd1—O1iii	85.81 (5)	O2vi—Cd2—O4v	102.17 (5)
O4ii—Cd1—O1iii	157.35 (5)	O2—Cd2—O4v	174.49 (5)
O6iii—Cd1—O1iii	90.73 (5)	O6iii—Cd2—O4ii	81.30 (5)
O7i—Cd1—O1iv	76.73 (5)	O5ii—Cd2—O4ii	75.69 (5)
O4ii—Cd1—O1iv	94.46 (5)	O2vi—Cd2—O4ii	160.52 (5)
O6iii—Cd1—O1iv	149.98 (5)	O2—Cd2—O4ii	98.40 (5)
O1iii—Cd1—O1iv	79.55 (5)	O4v—Cd2—O4ii	83.09 (5)
O7i—Cd1—O5v	153.49 (5)	O1—V1—O2	109.38 (7)
O4ii—Cd1—O5v	74.22 (5)	O1—V1—O3	107.57 (7)
O6iii—Cd1—O5v	73.06 (5)	O2—V1—O3	109.85 (7)
O1iii—Cd1—O5v	83.15 (5)	O1—V1—O4	109.71 (7)
O1iv—Cd1—O5v	77.60 (5)	O2—V1—O4	109.65 (7)
O7i—Cd1—O3	62.10 (5)	O3—V1—O4	110.65 (6)
O4ii—Cd1—O3	86.49 (5)	O5—V2—O6	114.25 (7)
O6iii—Cd1—O3	75.19 (5)	O5—V2—O7	99.11 (7)
O1iii—Cd1—O3	113.31 (5)	O6—V2—O7	98.25 (7)
O1iv—Cd1—O3	134.73 (5)	O5—V2—O7i	121.64 (7)
O5v—Cd1—O3	144.28 (4)	O6—V2—O7i	123.74 (7)
O6iii—Cd2—O5ii	156.37 (5)	O7—V2—O7i	79.57 (6)
O6iii—Cd2—O2vi	116.20 (5)	O5—V2—O3	92.06 (6)
O5ii—Cd2—O2vi	87.38 (5)	O6—V2—O3	93.85 (6)
O6iii—Cd2—O2	88.75 (5)	O7—V2—O3	158.40 (6)
O5ii—Cd2—O2	99.75 (5)	O7i—V2—O3	78.83 (6)