Cu(4.35)Cd(1.65)As(16): the first polyarsenic compound in the Cu-Cd-As system.

The first polyarsenic compound in the Cu-Cd-As system was obtained by solid-state reaction of the elements and has a refined composition of Cu(4.35 (2))Cd(1.65 (2))As(16) (tetra-copper dicadmium hexa-deca-arsenide). It adopts the Cu(5)InP(16) structure type. The asymmetric unit consists of one Cu site, a split Cu/Cd site and four As sites. The polyanionic structure can be described as being composed of As(6) rings in chair conformations which are connected in the 1-, 2-, 4- and 5-positions. The resulting layers evolve along the c axis perpendicular to the ab plane. One Cu atom exhibits site symmetry 2 and is tetra-hedrally coordinated by four As atoms. The other Cu atom, representing the split site, and the corresponding Cd atom have different coordination spheres. While the Cu atom is tetra-hedrally coordinated by four As atoms, the Cd atom has a [3 + 1] coordination with a considerably longer Cd-As distance.

Related literature

For Cu5InP16, see: Lange et al. (2008 ▶). For related polyphosphides, see: Pöttgen et al. (2006 ▶). For polyarsenides, see: Bauhofer et al. (1981 ▶); Jeitschko et al. (2000 ▶); Emmerling & Röhr (2002 ▶); Emmerling et al. (2004 ▶); Hönle et al. (2002 ▶). For binary Cu–Cd phases, see: Brandon et al. (1974 ▶); Kreiner & Schaepers (1997 ▶); von Heidenstamm et al. (1968 ▶). For related structures, see: Mansmann (1965 ▶); Clark & Range (1976 ▶). For crystallographic background, see: Becker & Coppens (1974 ▶).

Experimental

Crystal data

Cu4.35Cd1.65As16

M = 1660.8

Monoclinic,

a = 11.8324 (6) Å

b = 10.4423 (4) Å

c = 8.0903 (4) Å

β = 110.480 (4)°

V = 936.44 (8) Å3

Z = 2

Mo Kα radiation

μ = 34.73 mm−1

T = 293 K

0.030 × 0.020 × 0.004 mm

Data collection

Stoe IPDS 2T diffractometer

Absorption correction: numerical (X-AREA; Stoe & Cie, 2011 ▶) T min = 0.205, T max = 0.785

12811 measured reflections

1268 independent reflections

1113 reflections with I > 3σ(I)

R int = 0.053

Refinement

R[F 2 > 2σ(F 2)] = 0.036

wR(F 2) = 0.072

S = 1.83

1268 reflections

56 parameters

Δρmax = 1.50 e Å−3

Δρmin = −1.67 e Å−3

Data collection: X-AREA (Stoe & Cie, 2011 ▶); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: Superflip (Palatinus & Chapuis, 2007 ▶) embedded in JANA2006 (Petřiček et al., 2006 ▶); program(s) used to refine structure: JANA2006; molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811042127/wm2539sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811042127/wm2539Isup2.hkl

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

Cu4.35Cd1.65As16	F(000) = 1467
Mr = 1660.8	Dx = 5.888 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 12419 reflections
a = 11.8324 (6) Å	θ = 3.7–29.7°
b = 10.4423 (4) Å	µ = 34.73 mm−1
c = 8.0903 (4) Å	T = 293 K
β = 110.480 (4)°	Plate, black
V = 936.44 (8) Å3	0.03 × 0.02 × 0.004 mm
Z = 2

Stoe IPDS 2T diffractometer	1268 independent reflections
Radiation source: X-ray tube	1113 reflections with I > 3σ(I)
plane graphite	Rint = 0.053
Detector resolution: 6.67 pixels mm-1	θmax = 29.3°, θmin = 3.7°
ω scans	h = −16→16
Absorption correction: numerical (X-AREA; Stoe & Cie, 2011)	k = −14→14
Tmin = 0.205, Tmax = 0.785	l = −11→11
12811 measured reflections

Refinement on F2	6 constraints
R[F2 > 2σ(F2)] = 0.036	Weighting scheme based on measured s.u.'s w = 1/[σ2(I) + 0.0004I2]
wR(F2) = 0.072	(Δ/σ)max = 0.007
S = 1.83	Δρmax = 1.50 e Å−3
1268 reflections	Δρmin = −1.67 e Å−3
56 parameters	Extinction correction: B-C type 1 Gaussian isotropic (Becker & Coppens, 1974)
0 restraints	Extinction coefficient: 0.021 (2)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cu1	0	0.41450 (10)	0.25	0.0156 (3)
Cu2	−0.0942 (5)	0.1309 (5)	−0.0886 (9)	0.0198 (9)	0.587 (6)
Cd2	−0.0713 (4)	0.1064 (5)	−0.0867 (7)	0.0198 (9)	0.413 (6)
As1	−0.15337 (5)	0.56586 (5)	0.08461 (8)	0.01309 (19)
As2	−0.23875 (5)	0.30964 (6)	−0.22826 (8)	0.01406 (19)
As3	0.07426 (6)	0.27955 (6)	0.07165 (9)	0.0171 (2)
As4	−0.33882 (6)	0.48506 (7)	−0.13511 (9)	0.0232 (2)

	U11	U22	U33	U12	U13	U23
Cu1	0.0132 (5)	0.0182 (5)	0.0157 (5)	0	0.0055 (4)	0
Cu2	0.0171 (16)	0.0237 (16)	0.0194 (4)	−0.0067 (9)	0.0076 (10)	−0.0062 (10)
Cd2	0.0171 (16)	0.0237 (16)	0.0194 (4)	−0.0067 (9)	0.0076 (10)	−0.0062 (10)
As1	0.0115 (3)	0.0139 (3)	0.0130 (3)	−0.0003 (2)	0.0033 (2)	0.0001 (2)
As2	0.0126 (3)	0.0143 (3)	0.0143 (3)	0.0015 (2)	0.0034 (2)	0.0016 (2)
As3	0.0153 (3)	0.0172 (3)	0.0198 (3)	0.0025 (2)	0.0074 (2)	0.0046 (2)
As4	0.0128 (3)	0.0296 (3)	0.0265 (4)	−0.0031 (3)	0.0061 (3)	−0.0155 (3)

Cu1—As1	2.4254 (9)	Cd2—As2	2.856 (5)
Cu1—As1i	2.4254 (9)	Cd2—As3	2.516 (5)
Cu1—As3	2.3931 (9)	Cd2—As4ii	2.475 (5)
Cu1—As3i	2.3931 (9)	Cd2—As4iii	2.569 (6)
Cu2—Cd2	0.370 (8)	As1—As2v	2.4644 (10)
Cu2—As2	2.516 (5)	As1—As3vi	2.4307 (10)
Cu2—As3	2.501 (5)	As1—As4	2.4408 (8)
Cu2—As4ii	2.589 (6)	As2—As3vii	2.4242 (8)
Cu2—As4iii	2.524 (7)	As2—As4	2.4392 (10)
Cd2—Cd2iv	2.845 (7)
As1—Cu1—As1i	98.67 (4)	As3vi—As1—As4	105.22 (3)
As1—Cu1—As3	114.38 (2)	Cu2—As2—Cd2	3.1 (2)
As1—Cu1—As3i	110.77 (2)	Cu2—As2—As1viii	107.87 (17)
As1i—Cu1—As3	110.77 (2)	Cu2—As2—As3vii	109.44 (12)
As1i—Cu1—As3i	114.38 (2)	Cu2—As2—As4	138.19 (17)
As3—Cu1—As3i	107.85 (4)	Cd2—As2—As1viii	105.21 (13)
Cd2—Cu2—As2	155.1 (16)	Cd2—As2—As3vii	108.99 (10)
Cd2—Cu2—As3	88.1 (11)	Cd2—As2—As4	141.07 (12)
Cd2—Cu2—As4ii	68.2 (12)	As1viii—As2—As3vii	105.49 (3)
Cd2—Cu2—As4iii	92.7 (15)	As1viii—As2—As4	98.12 (3)
As2—Cu2—As3	93.76 (19)	As3vii—As2—As4	93.81 (3)
As2—Cu2—As4ii	95.40 (19)	Cu1—As3—Cu2	106.49 (17)
As2—Cu2—As4iii	110.1 (3)	Cu1—As3—Cd2	113.57 (14)
As3—Cu2—As4ii	139.5 (3)	Cu1—As3—As1vi	102.24 (3)
As3—Cu2—As4iii	108.6 (2)	Cu1—As3—As2ix	105.39 (3)
As4ii—Cu2—As4iii	105.0 (2)	Cu2—As3—Cd2	8.44 (18)
Cu2—Cd2—Cd2iv	149.6 (16)	Cu2—As3—As1vi	121.65 (17)
Cu2—Cd2—As2	21.8 (14)	Cu2—As3—As2ix	118.91 (13)
Cu2—Cd2—As3	83.5 (11)	Cd2—As3—As1vi	122.14 (14)
Cu2—Cd2—As4ii	103.9 (12)	Cd2—As3—As2ix	111.47 (11)
Cu2—Cd2—As4iii	79.0 (15)	As1vi—As3—As2ix	100.07 (3)
Cd2iv—Cd2—As2	170.7 (3)	Cu2x—As4—Cu2iii	145.40 (19)
Cd2iv—Cd2—As3	97.37 (17)	Cu2x—As4—Cd2x	7.97 (17)
Cd2iv—Cd2—As4ii	92.32 (19)	Cu2x—As4—Cd2iii	138.18 (18)
Cd2iv—Cd2—As4iii	71.60 (19)	Cu2x—As4—As1	110.54 (12)
As2—Cd2—As3	85.72 (15)	Cu2x—As4—As2	102.12 (16)
As2—Cd2—As4ii	89.91 (14)	Cu2iii—As4—Cd2x	138.99 (18)
As2—Cd2—As4iii	99.07 (19)	Cu2iii—As4—Cd2iii	8.26 (17)
As3—Cd2—As4ii	146.1 (3)	Cu2iii—As4—As1	94.09 (12)
As3—Cd2—As4iii	106.8 (2)	Cu2iii—As4—As2	99.75 (14)
As4ii—Cd2—As4iii	107.07 (19)	Cd2x—As4—Cd2iii	132.39 (17)
Cu1—As1—As2v	113.16 (3)	Cd2x—As4—As1	118.43 (12)
Cu1—As1—As3vi	111.70 (3)	Cd2x—As4—As2	101.77 (14)
Cu1—As1—As4	119.01 (3)	Cd2iii—As4—As1	96.10 (10)
As2v—As1—As3vi	106.52 (3)	Cd2iii—As4—As2	107.52 (12)
As2v—As1—As4	99.93 (3)	As1—As4—As2	94.29 (3)

Table 1

Selected bond lengths (Å)

Cu1—As1	2.4254 (9)
Cu1—As3	2.3931 (9)
Cu2—As2	2.516 (5)
Cu2—As3	2.501 (5)
Cu2—As4i	2.589 (6)
Cu2—As4ii	2.524 (7)
Cd2—As2	2.856 (5)
Cd2—As3	2.516 (5)
Cd2—As4i	2.475 (5)
Cd2—As4ii	2.569 (6)

Symmetry codes: (i) ; (ii) .