metal-organic compounds
Bis(N,N,N-trimethylethanaminium) bis(1,4-tetraselenido-κ2Se1,Se4)cadmate
aDepartment of Chemistry, University of Incheon, Incheon 406-772, Republic of Korea
*Correspondence e-mail: kimkw@incheon.ac.kr
The title compound, (EtMe3N)2[Cd(Se4)2], which has been prepared by reaction of CdI2, K2Se4 and EtMe3NI in dimethylformamide, is the first example of a [Cd(Se4)2]2− anion stabilized by alkylammonium counter-ions. The Cd atom in the complex [Cd(Se4)2]2− anion is tetrahedrally coordinated by two chelating tetraselenide ligands, and both CdSe4 rings exhibit an envelope conformation.
Related literature
For general background to [Cd(Se4)2]2− complexes, see: Kanatzidis & Huang (1994); Ansari et al. (1990); Barrie et al. (1994). For related structures, see: Adel et al. (1988); Kräuter et al. (1989); Magull et al. (1992); Banda et al. (1989). For applications of soluble cadmium–chalcogen compounds, see: Khanna et al. (2006); Nesheva (2001); Dhingra et al. (1991).
Experimental
Crystal data
|
Data collection: APEX2 (Bruker, 2005); cell SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
10.1107/S1600536811007227/zl2349sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811007227/zl2349Isup2.hkl
All synthetic experiments were performed under an atmosphere of dry argon or nitrogen using either a
or a Schlenk line. To a 50 ml DMF solution of 0.59 g (1.5 mmol) K2Se4 and 0.32 g (1.5 mmol) EtMe3NI, a 10 ml DMF solution of 0.27 g (0.75 mmol) CdI2 was added dropwise over a 20 min period. 60 ml ether were slowly layered over the filtrate solution, after removing undissolved precipitates by filtration. Upon standing at room temperature for 3 days, dark purple crystals were obtained. These crystals were isolated and washed with ether several times. More crystals were obtained upon layering additional 50 ml ether over the solution after isolation of the first crop of crystals. The overall yield was 65%, based on the CdI2 used. SEM/EDAX analyses on the crystals of (EtMe3N)2[Cd(Se4)2] showed an average Cd:Se atomic ratio of 1:7.2.H atoms were positioned geometrically and treated as riding, with C—H = 0.97 (CH2) and 0.96 (CH3) Å with Uiso(H) = 1.2 (1.5 for methyl) Ueq(C). H atoms of the CH3 were positioned to be staggered with respect to the shortest other bond to the atom to which the CH3 is attached.
Data collection: APEX2 (Bruker, 2005); cell
SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).(C5H14N)2[Cd(Se4)2] | F(000) = 1688 |
Mr = 920.42 | Dx = 2.589 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 12.5125 (2) Å | Cell parameters from 9912 reflections |
b = 11.3273 (2) Å | θ = 2.4–28.1° |
c = 16.7290 (3) Å | µ = 13.25 mm−1 |
β = 95.174 (1)° | T = 173 K |
V = 2361.39 (7) Å3 | Polyhedral block, dark purple |
Z = 4 | 0.30 × 0.27 × 0.16 mm |
Bruker APEXII CCD ULTRA diffractometer | 5876 independent reflections |
Radiation source: Turbo X-ray | 4911 reflections with I > 2σ(I) |
Multilyar monochromator | Rint = 0.074 |
ϕ and ω scans | θmax = 28.3°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −16→16 |
Tmin = 0.010, Tmax = 0.041 | k = −15→15 |
40764 measured reflections | l = −22→20 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.032 | H-atom parameters constrained |
wR(F2) = 0.081 | w = 1/[σ2(Fo2) + (0.0326P)2 + 1.8487P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
5876 reflections | Δρmax = 0.88 e Å−3 |
191 parameters | Δρmin = −1.85 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008) |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00141 (10) |
(C5H14N)2[Cd(Se4)2] | V = 2361.39 (7) Å3 |
Mr = 920.42 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 12.5125 (2) Å | µ = 13.25 mm−1 |
b = 11.3273 (2) Å | T = 173 K |
c = 16.7290 (3) Å | 0.30 × 0.27 × 0.16 mm |
β = 95.174 (1)° |
Bruker APEXII CCD ULTRA diffractometer | 5876 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 4911 reflections with I > 2σ(I) |
Tmin = 0.010, Tmax = 0.041 | Rint = 0.074 |
40764 measured reflections |
R[F2 > 2σ(F2)] = 0.032 | 0 restraints |
wR(F2) = 0.081 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.88 e Å−3 |
5876 reflections | Δρmin = −1.85 e Å−3 |
191 parameters |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 | 0.28864 (2) | 0.52306 (3) | 0.255978 (17) | 0.02603 (9) | |
Se1 | 0.29708 (3) | 0.75340 (4) | 0.28334 (3) | 0.03026 (11) | |
Se2 | 0.47862 (3) | 0.76914 (4) | 0.32974 (3) | 0.03032 (11) | |
Se3 | 0.49898 (3) | 0.60822 (4) | 0.41770 (3) | 0.03229 (11) | |
Se4 | 0.47131 (3) | 0.44849 (4) | 0.32945 (3) | 0.03102 (11) | |
Se5 | 0.28100 (3) | 0.40649 (4) | 0.11800 (2) | 0.03112 (11) | |
Se6 | 0.09505 (3) | 0.40696 (5) | 0.08845 (3) | 0.03800 (12) | |
Se7 | 0.03406 (3) | 0.34066 (4) | 0.20879 (3) | 0.03345 (11) | |
Se8 | 0.08684 (3) | 0.49621 (4) | 0.29446 (3) | 0.03304 (11) | |
N1 | 0.2702 (3) | 0.1209 (3) | 0.3584 (2) | 0.0271 (7) | |
N2 | 0.1899 (2) | 0.6780 (3) | 0.5421 (2) | 0.0273 (7) | |
C1 | 0.2527 (4) | 0.2362 (4) | 0.3994 (3) | 0.0363 (10) | |
H1A | 0.2383 | 0.2217 | 0.4539 | 0.054* | |
H1B | 0.1929 | 0.2766 | 0.3718 | 0.054* | |
H1C | 0.3159 | 0.2842 | 0.3988 | 0.054* | |
C2 | 0.1710 (4) | 0.0470 (5) | 0.3612 (3) | 0.0451 (12) | |
H2A | 0.1575 | 0.034 | 0.4161 | 0.068* | |
H2B | 0.1811 | −0.0275 | 0.3356 | 0.068* | |
H2C | 0.111 | 0.0873 | 0.3337 | 0.068* | |
C3 | 0.2907 (4) | 0.1413 (5) | 0.2737 (3) | 0.0500 (14) | |
H3A | 0.354 | 0.1888 | 0.2718 | 0.075* | |
H3B | 0.2305 | 0.1815 | 0.2463 | 0.075* | |
H3C | 0.301 | 0.0669 | 0.248 | 0.075* | |
C4 | 0.3621 (3) | 0.0540 (4) | 0.4028 (3) | 0.0316 (9) | |
H4A | 0.3443 | 0.0394 | 0.4572 | 0.038* | |
H4B | 0.3687 | −0.022 | 0.377 | 0.038* | |
C5 | 0.4685 (4) | 0.1152 (5) | 0.4065 (3) | 0.0462 (12) | |
H5A | 0.5223 | 0.0659 | 0.4341 | 0.069* | |
H5B | 0.4643 | 0.1886 | 0.4347 | 0.069* | |
H5C | 0.4871 | 0.1302 | 0.353 | 0.069* | |
C6 | 0.1112 (4) | 0.7104 (5) | 0.5999 (3) | 0.0426 (11) | |
H6A | 0.1461 | 0.7101 | 0.6534 | 0.064* | |
H6B | 0.0535 | 0.6542 | 0.5963 | 0.064* | |
H6C | 0.0832 | 0.7877 | 0.5874 | 0.064* | |
C7 | 0.2779 (4) | 0.7675 (5) | 0.5477 (3) | 0.0489 (13) | |
H7A | 0.3118 | 0.7692 | 0.6015 | 0.073* | |
H7B | 0.2486 | 0.8439 | 0.534 | 0.073* | |
H7C | 0.3299 | 0.7469 | 0.5112 | 0.073* | |
C8 | 0.1357 (4) | 0.6786 (6) | 0.4594 (3) | 0.0561 (15) | |
H8A | 0.0804 | 0.6196 | 0.4549 | 0.084* | |
H8B | 0.1873 | 0.6618 | 0.4217 | 0.084* | |
H8C | 0.1045 | 0.7549 | 0.4479 | 0.084* | |
C9 | 0.2423 (4) | 0.5611 (5) | 0.5627 (3) | 0.0434 (12) | |
H9A | 0.2962 | 0.5465 | 0.5257 | 0.052* | |
H9B | 0.2791 | 0.5665 | 0.6162 | 0.052* | |
C10 | 0.1678 (5) | 0.4572 (5) | 0.5604 (4) | 0.0588 (15) | |
H10A | 0.2083 | 0.3867 | 0.5732 | 0.088* | |
H10B | 0.1312 | 0.4502 | 0.5077 | 0.088* | |
H10C | 0.1162 | 0.4684 | 0.5989 | 0.088* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd1 | 0.02102 (14) | 0.02943 (17) | 0.02811 (16) | −0.00364 (11) | 0.00481 (11) | 0.00007 (11) |
Se1 | 0.02386 (19) | 0.0284 (2) | 0.0385 (2) | 0.00127 (16) | 0.00277 (16) | 0.00038 (17) |
Se2 | 0.02108 (19) | 0.0273 (2) | 0.0435 (3) | −0.00169 (16) | 0.00789 (16) | −0.00507 (17) |
Se3 | 0.0269 (2) | 0.0401 (3) | 0.0298 (2) | 0.00456 (18) | 0.00195 (16) | −0.00306 (17) |
Se4 | 0.02296 (19) | 0.0274 (2) | 0.0426 (3) | 0.00099 (16) | 0.00250 (17) | 0.00039 (17) |
Se5 | 0.0253 (2) | 0.0401 (3) | 0.0292 (2) | −0.00149 (17) | 0.00922 (16) | −0.00414 (17) |
Se6 | 0.0279 (2) | 0.0541 (3) | 0.0313 (2) | 0.0017 (2) | −0.00101 (17) | −0.00473 (19) |
Se7 | 0.01889 (19) | 0.0374 (3) | 0.0446 (3) | −0.00443 (17) | 0.00541 (16) | −0.00307 (19) |
Se8 | 0.0223 (2) | 0.0426 (3) | 0.0357 (2) | −0.00182 (17) | 0.01091 (16) | −0.00686 (18) |
N1 | 0.0189 (15) | 0.0344 (19) | 0.0293 (18) | 0.0003 (14) | 0.0093 (13) | −0.0002 (14) |
N2 | 0.0223 (15) | 0.0346 (19) | 0.0260 (17) | −0.0016 (14) | 0.0074 (12) | −0.0010 (14) |
C1 | 0.033 (2) | 0.029 (2) | 0.049 (3) | 0.0038 (18) | 0.0139 (19) | 0.0045 (19) |
C2 | 0.025 (2) | 0.044 (3) | 0.066 (3) | −0.007 (2) | 0.009 (2) | −0.006 (2) |
C3 | 0.043 (3) | 0.080 (4) | 0.029 (3) | 0.013 (3) | 0.011 (2) | 0.011 (2) |
C4 | 0.028 (2) | 0.032 (2) | 0.035 (2) | 0.0071 (18) | 0.0075 (17) | 0.0023 (17) |
C5 | 0.025 (2) | 0.051 (3) | 0.062 (3) | 0.000 (2) | −0.002 (2) | 0.001 (2) |
C6 | 0.032 (2) | 0.058 (3) | 0.040 (3) | −0.002 (2) | 0.0186 (19) | −0.011 (2) |
C7 | 0.049 (3) | 0.047 (3) | 0.054 (3) | −0.019 (2) | 0.024 (2) | −0.010 (2) |
C8 | 0.048 (3) | 0.088 (5) | 0.032 (3) | 0.007 (3) | −0.002 (2) | 0.001 (3) |
C9 | 0.029 (2) | 0.042 (3) | 0.060 (3) | 0.004 (2) | 0.006 (2) | 0.008 (2) |
C10 | 0.055 (3) | 0.043 (3) | 0.081 (4) | −0.007 (3) | 0.022 (3) | 0.002 (3) |
Cd1—Se4 | 2.6347 (5) | C3—H3A | 0.96 |
Cd1—Se1 | 2.6494 (5) | C3—H3B | 0.96 |
Cd1—Se5 | 2.6535 (5) | C3—H3C | 0.96 |
Cd1—Se8 | 2.6789 (5) | C4—C5 | 1.497 (6) |
Se1—Se2 | 2.3402 (5) | C4—H4A | 0.97 |
Se2—Se3 | 2.3419 (6) | C4—H4B | 0.97 |
Se3—Se4 | 2.3411 (6) | C5—H5A | 0.96 |
Se5—Se6 | 2.3346 (6) | C5—H5B | 0.96 |
Se6—Se7 | 2.3401 (7) | C5—H5C | 0.96 |
Se7—Se8 | 2.3289 (6) | C6—H6A | 0.96 |
N1—C3 | 1.481 (6) | C6—H6B | 0.96 |
N1—C1 | 1.500 (6) | C6—H6C | 0.96 |
N1—C2 | 1.501 (6) | C7—H7A | 0.96 |
N1—C4 | 1.515 (5) | C7—H7B | 0.96 |
N2—C8 | 1.485 (6) | C7—H7C | 0.96 |
N2—C6 | 1.487 (5) | C8—H8A | 0.96 |
N2—C7 | 1.494 (6) | C8—H8B | 0.96 |
N2—C9 | 1.504 (6) | C8—H8C | 0.96 |
C1—H1A | 0.96 | C9—C10 | 1.499 (7) |
C1—H1B | 0.96 | C9—H9A | 0.97 |
C1—H1C | 0.96 | C9—H9B | 0.97 |
C2—H2A | 0.96 | C10—H10A | 0.96 |
C2—H2B | 0.96 | C10—H10B | 0.96 |
C2—H2C | 0.96 | C10—H10C | 0.96 |
Se4—Cd1—Se1 | 102.462 (15) | H3B—C3—H3C | 109.5 |
Se4—Cd1—Se5 | 102.001 (17) | C5—C4—N1 | 114.9 (4) |
Se1—Cd1—Se5 | 129.652 (18) | C5—C4—H4A | 108.5 |
Se4—Cd1—Se8 | 130.416 (18) | N1—C4—H4A | 108.5 |
Se1—Cd1—Se8 | 95.396 (16) | C5—C4—H4B | 108.5 |
Se5—Cd1—Se8 | 101.053 (16) | N1—C4—H4B | 108.5 |
Se2—Se1—Cd1 | 98.899 (19) | H4A—C4—H4B | 107.5 |
Se1—Se2—Se3 | 101.33 (2) | C4—C5—H5A | 109.5 |
Se4—Se3—Se2 | 101.76 (2) | C4—C5—H5B | 109.5 |
Se3—Se4—Cd1 | 96.841 (19) | H5A—C5—H5B | 109.5 |
Se6—Se5—Cd1 | 98.053 (19) | C4—C5—H5C | 109.5 |
Se5—Se6—Se7 | 102.31 (2) | H5A—C5—H5C | 109.5 |
Se8—Se7—Se6 | 100.97 (2) | H5B—C5—H5C | 109.5 |
Se7—Se8—Cd1 | 99.156 (19) | N2—C6—H6A | 109.5 |
C3—N1—C1 | 110.3 (4) | N2—C6—H6B | 109.5 |
C3—N1—C2 | 109.4 (4) | H6A—C6—H6B | 109.5 |
C1—N1—C2 | 108.5 (3) | N2—C6—H6C | 109.5 |
C3—N1—C4 | 111.0 (3) | H6A—C6—H6C | 109.5 |
C1—N1—C4 | 110.3 (3) | H6B—C6—H6C | 109.5 |
C2—N1—C4 | 107.4 (3) | N2—C7—H7A | 109.5 |
C8—N2—C6 | 109.4 (3) | N2—C7—H7B | 109.5 |
C8—N2—C7 | 109.1 (4) | H7A—C7—H7B | 109.5 |
C6—N2—C7 | 108.6 (4) | N2—C7—H7C | 109.5 |
C8—N2—C9 | 111.8 (4) | H7A—C7—H7C | 109.5 |
C6—N2—C9 | 111.6 (4) | H7B—C7—H7C | 109.5 |
C7—N2—C9 | 106.2 (4) | N2—C8—H8A | 109.5 |
N1—C1—H1A | 109.5 | N2—C8—H8B | 109.5 |
N1—C1—H1B | 109.5 | H8A—C8—H8B | 109.5 |
H1A—C1—H1B | 109.5 | N2—C8—H8C | 109.5 |
N1—C1—H1C | 109.5 | H8A—C8—H8C | 109.5 |
H1A—C1—H1C | 109.5 | H8B—C8—H8C | 109.5 |
H1B—C1—H1C | 109.5 | C10—C9—N2 | 115.3 (4) |
N1—C2—H2A | 109.5 | C10—C9—H9A | 108.4 |
N1—C2—H2B | 109.5 | N2—C9—H9A | 108.4 |
H2A—C2—H2B | 109.5 | C10—C9—H9B | 108.4 |
N1—C2—H2C | 109.5 | N2—C9—H9B | 108.4 |
H2A—C2—H2C | 109.5 | H9A—C9—H9B | 107.5 |
H2B—C2—H2C | 109.5 | C9—C10—H10A | 109.5 |
N1—C3—H3A | 109.5 | C9—C10—H10B | 109.5 |
N1—C3—H3B | 109.5 | H10A—C10—H10B | 109.5 |
H3A—C3—H3B | 109.5 | C9—C10—H10C | 109.5 |
N1—C3—H3C | 109.5 | H10A—C10—H10C | 109.5 |
H3A—C3—H3C | 109.5 | H10B—C10—H10C | 109.5 |
Experimental details
Crystal data | |
Chemical formula | (C5H14N)2[Cd(Se4)2] |
Mr | 920.42 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 173 |
a, b, c (Å) | 12.5125 (2), 11.3273 (2), 16.7290 (3) |
β (°) | 95.174 (1) |
V (Å3) | 2361.39 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 13.25 |
Crystal size (mm) | 0.30 × 0.27 × 0.16 |
Data collection | |
Diffractometer | Bruker APEXII CCD ULTRA diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.010, 0.041 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 40764, 5876, 4911 |
Rint | 0.074 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.081, 1.03 |
No. of reflections | 5876 |
No. of parameters | 191 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.88, −1.85 |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006), WinGX (Farrugia, 1999).
Acknowledgements
This work was supported by a University of Incheon Research Grant in 2006. The authors thank Dr Ji-Eun Lee at the Central Instrument Facility of Gyeongsang National University for the X-ray measurements.
References
Adel, J., Weller, F. & Dehnicke, K. (1988). Z. Naturforsch. Teil B, 43, 1094–1100. CAS Google Scholar
Ansari, M. A., Mahler, C. H., Chorghade, G. S., Lu, Y.-J. & Ibers, J. A. (1990). Inorg. Chem. 29, 3832–3839. CSD CrossRef CAS Web of Science Google Scholar
Banda, R. M. H., Cusick, J., Scudder, M. L., Craig, D. C. & Dance, I. G. (1989). Polyhedron, 8, 1995–1998. CAS Google Scholar
Barrie, P. J., Clark, R. J. H., Withnall, R., Chung, D.-Y., Kim, K.-W. & Kanatzidis, M. G. (1994). Inorg. Chem. 33, 1212–1216. CrossRef CAS Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dhingra, S., Kim, K.-W. & Kanatzidis, M. G. (1991). Mater. Res. Soc. Symp. Proc. 204, 163–168. CrossRef CAS Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Kanatzidis, M. G. & Huang, S.-P. (1994). Coord. Chem. Rev. 130, 509–621. CrossRef CAS Google Scholar
Khanna, P. K., Singh, N., Charan, S., Lonkar, S. P., Reddy, A. S., Patil, Y. & Viswanath, A. K. (2006). Mater. Chem. Phys. 97, 288–294. CrossRef CAS Google Scholar
Kräuter, G., Weller, F. & Dehnicke, K. (1989). Z. Naturforsch. Teil B, 44, 444–454. Google Scholar
Magull, S., Dehnicke, K. & Fenske, D. (1992). Z. Anorg. Allg. Chem. 608, 17–22. CrossRef CAS Google Scholar
Nesheva, D. (2001). Handbook of Surfaces and Interfaces of Materials, Vol. 3, edited by H. S. Nalwa, pp. 239–279. San Diego: Academic Press. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Within metal polychalcogenide chemistry, the bis(tetrachalcogenido)metallate [M(Q4)2]2- (Q = S, Se, Te) anions are among the most well known molecular complexes (Kanatzidis & Huang (1994); Ansari et al. (1990)). For the [Cd(Se4)2]2- anion, there are four structurally characterized complexes: stabilized with [Na(15-crown-5]+ (Adel et al. (1988)), [Li3(12-crown-4)3(CH3COO]2+ (Kräuter et al. (1989)), [Ba(18-crown-6)(DMF)4]2+ (Magull et al. (1992)), and [Ph4P]+ (Banda et al. (1989)). So far, no alkylammonium salt of the [Cd(Se4)2]2- anion had been structurally characterized. Compared to alkali metal-crown ether complexes and arylphosphonium salts, an alkylammonium salt could be preferable for the application as a precursor of Cd/Se binary and related materials (Khanna et al. (2006); Nesheva (2001); Dhingra et al. (1991)), and also for 77Se solid-state NMR measurements (Barrie et al. (1994)). The title compound is the first example of an alkylammonium [Cd(Se4)2]2- salt, containing EtMe3N+ cations as the counterion.
The structure of the [Cd(Se4)2]2- anion in (EtMe3N)2[Cd(Se4)2] is essentially the same as that of the [Na(15-crown-5]+, [Li3(12-crown-4)3(CH3COO]2+, [Ba(18-crown-6)(DMF)4]2+, and [Ph4P]+ salts. As shown in Fig. 1, a Cd atom is tetrahedrally coordinated by two chelating tetraselenide ligands, and all eight Se atoms occupy distinct crystallographic sites. The Cd—Se distances and Se—Se distances are typical, ranging from 2.6347 (5) Å to 2.6789 (5) Å, and from 2.3289 (6) Å to 2.3419 (6) Å, respectively, similar to those found in the previously characterized four [Cd(Se4)2]2- complexes. Both CdSe4 rings in [Cd(Se4)2]2- exhibit the envelope conformation. In one CdSe4 ring, the Cd1, Se1, Se2, and Se4 atoms are considered to be in a plane with a mean deviation of 0.12 (4) Å, while the Se3 atom lies 1.24 Å below it. Similarly, in the other CdSe4 ring, the Cd1, Se5, Se7, and Se8 atoms are in a plane with a mean deviation of 0.15 (6) Å, and the Se6 atom lies 1.17 Å below it. The dihedral angle between the two planes in [Cd(Se4)2]2- is found to be 112.12°.