Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103010497/gd1248sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103010497/gd1248Isup2.hkl |
CCDC reference: 217129
Clear single crystals of [Et4N][Cd(en)]4[Fe(CN)6]3 were prepared by slow addition of a 0.1 M aqueous solution of K3[Fe(CN)6] (7.5 ml, 1 mmol) to a solution of CdCl2·2.5H2O (1 mmol) with en and [Et4N]Br in the 1:3:1 molar ratio. The next day, the solution was filtered to remove the formed turbidity. From the yellow filtrate, red cube-like crystals appeared after several days. The crystals were filtered off, washed with a small amount of water and ethanol, and dried in air (yield 30%). IR (Nicolet Magma 750 s pectrometer cm−1, KBr disc): ν(NH2): 3372 s, 3331 s, 3273 s, 3210 w; ν(CH3): 2965 m; ν(CH2): 2988 w; ν(CN): 2137 v.s., 2115 v.s.; δ(NH2): 1601 s; δ(CH2): 1487 m, 1458 m, 1441 m ν(Fe—C): 588 m.
H atoms were treated as riding atoms, with C—H distances of 0.98 or 0.99 Å and N—H distances of 0.92 Å.
Data collection: X-AREA WinExpose (Stoe 2002); cell refinement: X-AREA WinCell (Stoe 2002); data reduction: X-AREA WinIntegrate (Stoe 2002); program(s) used to solve structure: SHELXS86 (Sheldrick, 1985); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Crystal Impact 1999).
(C8H20N)[Cd4Fe3(CN)18(C2H8N2)4] | Dx = 1.969 Mg m−3 Dm = 1.945 Mg m−3 Dm measured by flotation |
Mr = 1456.18 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, I41/acd | Cell parameters from 56335 reflections |
Hall symbol: -I 4bd 2c | θ = 1.8–29.5° |
a = 13.6532 (3) Å | µ = 2.62 mm−1 |
c = 52.696 (2) Å | T = 120 K |
V = 9823.1 (5) Å3 | Cube, red |
Z = 8 | 0.14 × 0.13 × 0.13 mm |
F(000) = 5720 |
IPDS-II (Stoe) diffractometer | 3360 independent reflections |
Radiation source: fine-focus sealed tube | 3012 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
Detector resolution: 150 pixels mm-1 | θmax = 29.4°, θmin = 2.3° |
Integration method scans | h = −18→18 |
Absorption correction: multi-scan SHELXTL XPREP (Sheldrick 1996) | k = −18→18 |
Tmin = 0.630, Tmax = 0.712 | l = −63→71 |
40110 measured reflections |
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)] = 0.023 | H-atom parameters constrained |
wR(F2) = 0.064 | Calculated w = 1/[σ2(Fo2) + (0.05P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
3360 reflections | Δρmax = 0.91 e Å−3 |
166 parameters | Δρmin = −0.75 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00043 (3) |
(C8H20N)[Cd4Fe3(CN)18(C2H8N2)4] | Z = 8 |
Mr = 1456.18 | Mo Kα radiation |
Tetragonal, I41/acd | µ = 2.62 mm−1 |
a = 13.6532 (3) Å | T = 120 K |
c = 52.696 (2) Å | 0.14 × 0.13 × 0.13 mm |
V = 9823.1 (5) Å3 |
IPDS-II (Stoe) diffractometer | 3360 independent reflections |
Absorption correction: multi-scan SHELXTL XPREP (Sheldrick 1996) | 3012 reflections with I > 2σ(I) |
Tmin = 0.630, Tmax = 0.712 | Rint = 0.029 |
40110 measured reflections |
R[F2 > 2σ(F2)] = 0.023 | 0 restraints |
wR(F2) = 0.064 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.91 e Å−3 |
3360 reflections | Δρmin = −0.75 e Å−3 |
166 parameters |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Cd | 0.201002 (9) | 0.077013 (9) | 0.049791 (2) | 0.01540 (6) | |
Fe1 | 0.5000 | 0.2500 | 0.023752 (7) | 0.01427 (9) | |
Fe2 | 0.0000 | 0.2500 | 0.1250 | 0.01310 (10) | |
C1 | 0.44386 (13) | 0.38024 (13) | 0.02735 (4) | 0.0179 (3) | |
N1 | 0.41029 (13) | 0.45557 (12) | 0.03177 (3) | 0.0239 (3) | |
C2 | 0.58882 (13) | 0.29413 (13) | −0.00270 (4) | 0.0184 (3) | |
N2 | 0.63758 (12) | 0.32475 (12) | −0.01865 (3) | 0.0211 (3) | |
C3 | 0.39962 (14) | 0.21183 (14) | 0.04771 (4) | 0.0191 (3) | |
N3 | 0.33518 (12) | 0.18756 (14) | 0.06024 (3) | 0.0252 (4) | |
C4 | −0.10062 (14) | 0.14938 (14) | 0.1250 | 0.0179 (5) | |
N4 | −0.16019 (13) | 0.08981 (13) | 0.1250 | 0.0276 (5) | |
C5 | 0.06942 (12) | 0.18042 (12) | 0.09824 (4) | 0.0169 (3) | |
N5 | 0.10872 (12) | 0.14058 (12) | 0.08196 (3) | 0.0201 (3) | |
N6 | 0.25080 (14) | −0.05894 (13) | 0.07325 (3) | 0.0236 (3) | |
H6A | 0.2565 | −0.0427 | 0.0901 | 0.028* | 0.720 (7) |
H6B | 0.2056 | −0.1086 | 0.0717 | 0.028* | 0.720 (7) |
H6E | 0.2826 | −0.0374 | 0.0876 | 0.028* | 0.280 (7) |
H6F | 0.1960 | −0.0928 | 0.0784 | 0.028* | 0.280 (7) |
C6 | 0.3497 (3) | −0.0917 (3) | 0.06279 (6) | 0.0294 (8) | 0.720 (7) |
H6C | 0.4016 | −0.0472 | 0.0690 | 0.035* | 0.720 (7) |
H6D | 0.3646 | −0.1586 | 0.0689 | 0.035* | 0.720 (7) |
C7 | 0.3486 (2) | −0.0910 (2) | 0.03437 (6) | 0.0258 (8) | 0.720 (7) |
H7A | 0.4131 | −0.1126 | 0.0278 | 0.031* | 0.720 (7) |
H7B | 0.2983 | −0.1372 | 0.0281 | 0.031* | 0.720 (7) |
N7 | 0.32791 (12) | 0.00410 (13) | 0.02550 (3) | 0.0228 (3) | |
H7C | 0.3092 | 0.0012 | 0.0087 | 0.027* | 0.720 (7) |
H7D | 0.3835 | 0.0420 | 0.0265 | 0.027* | 0.720 (7) |
H7G | 0.3027 | −0.0333 | 0.0125 | 0.027* | 0.280 (7) |
H7H | 0.3688 | 0.0509 | 0.0188 | 0.027* | 0.280 (7) |
C6A | 0.3123 (6) | −0.1231 (6) | 0.06027 (15) | 0.0209 (17)* | 0.280 (7) |
H6G | 0.2738 | −0.1646 | 0.0485 | 0.025* | 0.280 (7) |
H6H | 0.3470 | −0.1662 | 0.0724 | 0.025* | 0.280 (7) |
C7A | 0.3843 (5) | −0.0625 (5) | 0.04571 (14) | 0.0172 (17)* | 0.280 (7) |
H7E | 0.4217 | −0.0203 | 0.0575 | 0.021* | 0.280 (7) |
H7F | 0.4313 | −0.1058 | 0.0368 | 0.021* | 0.280 (7) |
C8 | 0.02904 (15) | −0.16559 (14) | 0.10794 (4) | 0.0241 (4) | |
H8A | 0.0814 | −0.1883 | 0.0964 | 0.029* | |
H8B | −0.0281 | −0.1476 | 0.0974 | 0.029* | |
N8 | 0.0000 | −0.2500 | 0.1250 | 0.0190 (6) | |
C9 | 0.06458 (18) | −0.07477 (14) | 0.12152 (5) | 0.0309 (5) | |
H9A | 0.0817 | −0.0245 | 0.1090 | 0.046* | |
H9B | 0.1224 | −0.0909 | 0.1317 | 0.046* | |
H9C | 0.0126 | −0.0500 | 0.1326 | 0.046* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cd | 0.01661 (8) | 0.01582 (8) | 0.01378 (9) | 0.00122 (4) | 0.00015 (4) | −0.00017 (4) |
Fe1 | 0.01455 (16) | 0.01453 (16) | 0.01373 (18) | −0.00063 (12) | 0.000 | 0.000 |
Fe2 | 0.01381 (14) | 0.01381 (14) | 0.0117 (2) | 0.00061 (16) | 0.000 | 0.000 |
C1 | 0.0168 (8) | 0.0189 (8) | 0.0180 (9) | 0.0014 (6) | 0.0007 (6) | 0.0005 (6) |
N1 | 0.0257 (8) | 0.0226 (8) | 0.0234 (9) | 0.0008 (6) | 0.0042 (7) | 0.0018 (6) |
C2 | 0.0186 (8) | 0.0180 (8) | 0.0185 (9) | −0.0002 (6) | −0.0018 (6) | −0.0008 (6) |
N2 | 0.0229 (7) | 0.0211 (7) | 0.0192 (8) | −0.0015 (6) | 0.0009 (6) | 0.0010 (6) |
C3 | 0.0199 (8) | 0.0202 (8) | 0.0170 (9) | −0.0014 (7) | −0.0006 (6) | −0.0021 (6) |
N3 | 0.0227 (8) | 0.0320 (9) | 0.0210 (9) | −0.0069 (6) | 0.0018 (6) | −0.0039 (7) |
C4 | 0.0205 (7) | 0.0205 (7) | 0.0128 (11) | 0.0006 (9) | −0.0008 (6) | 0.0008 (6) |
N4 | 0.0321 (8) | 0.0321 (8) | 0.0185 (13) | −0.0115 (10) | −0.0031 (7) | 0.0031 (7) |
C5 | 0.0175 (7) | 0.0162 (7) | 0.0169 (9) | −0.0001 (6) | 0.0002 (6) | 0.0009 (6) |
N5 | 0.0202 (7) | 0.0202 (7) | 0.0197 (8) | 0.0001 (6) | 0.0025 (6) | 0.0001 (6) |
N6 | 0.0304 (9) | 0.0233 (8) | 0.0170 (8) | 0.0032 (6) | 0.0002 (7) | 0.0027 (6) |
C6 | 0.0268 (17) | 0.0333 (17) | 0.0282 (17) | 0.0115 (14) | 0.0017 (12) | 0.0054 (12) |
C7 | 0.0273 (15) | 0.0213 (14) | 0.0286 (17) | 0.0044 (10) | 0.0035 (12) | −0.0001 (11) |
N7 | 0.0239 (8) | 0.0265 (9) | 0.0180 (8) | −0.0019 (6) | 0.0028 (6) | −0.0017 (7) |
N6A | 0.0304 (9) | 0.0233 (8) | 0.0170 (8) | 0.0032 (6) | 0.0002 (7) | 0.0027 (6) |
N7A | 0.0239 (8) | 0.0265 (9) | 0.0180 (8) | −0.0019 (6) | 0.0028 (6) | −0.0017 (7) |
C8 | 0.0263 (9) | 0.0232 (9) | 0.0227 (10) | 0.0011 (7) | 0.0015 (7) | 0.0038 (7) |
N8 | 0.0199 (8) | 0.0199 (8) | 0.0171 (16) | 0.000 | 0.000 | 0.000 |
C9 | 0.0337 (11) | 0.0215 (9) | 0.0374 (13) | −0.0034 (7) | 0.0028 (9) | 0.0007 (8) |
Cd—N5 | 2.2833 (16) | N6—H6A | 0.9200 |
Cd—N2i | 2.2893 (17) | N6—H6B | 0.9200 |
Cd—N6 | 2.3314 (17) | C6—C7 | 1.498 (5) |
Cd—N7 | 2.3731 (17) | C6—H6C | 0.9900 |
Cd—N3 | 2.4366 (17) | C6—H6D | 0.9900 |
Cd—N1ii | 2.4412 (17) | C7—N7 | 1.409 (3) |
Fe1—C3 | 1.9349 (19) | C7—H7A | 0.9900 |
Fe1—C3iii | 1.9349 (19) | C7—H7B | 0.9900 |
Fe1—C2iii | 1.9432 (19) | N7—H7C | 0.9200 |
Fe1—C2 | 1.9432 (19) | N7—H7D | 0.9200 |
Fe1—C1 | 1.9457 (17) | C6A—C7A | 1.497 (11) |
Fe1—C1iii | 1.9457 (17) | C6A—H6G | 0.9900 |
Fe2—C4 | 1.943 (3) | C6A—H6H | 0.9900 |
Fe2—C4iv | 1.943 (3) | C7A—H7E | 0.9900 |
Fe2—C5iv | 1.9467 (18) | C7A—H7F | 0.9900 |
Fe2—C5 | 1.9467 (18) | C8—C9 | 1.512 (3) |
Fe2—C5v | 1.9467 (18) | C8—N8 | 1.515 (2) |
Fe2—C5vi | 1.9467 (18) | C8—H8A | 0.9900 |
C1—N1 | 1.150 (2) | C8—H8B | 0.9900 |
N1—Cdvii | 2.4412 (17) | N8—C8ix | 1.515 (2) |
C2—N2 | 1.151 (3) | N8—C8x | 1.515 (2) |
N2—Cdviii | 2.2893 (17) | N8—C8xi | 1.515 (2) |
C3—N3 | 1.149 (3) | C9—H9A | 0.9800 |
C4—N4 | 1.150 (4) | C9—H9B | 0.9800 |
C5—N5 | 1.149 (3) | C9—H9C | 0.9800 |
N6—C6 | 1.525 (4) | ||
N5—Cd—N2i | 95.78 (6) | N4—C4—Fe2 | 180.0 (2) |
N5—Cd—N6 | 94.01 (6) | N5—C5—Fe2 | 178.10 (17) |
N2i—Cd—N6 | 163.09 (6) | C5—N5—Cd | 172.76 (15) |
N5—Cd—N7 | 164.31 (6) | C6—N6—Cd | 107.46 (15) |
N2i—Cd—N7 | 97.78 (6) | C6—N6—H6A | 110.2 |
N6—Cd—N7 | 74.88 (6) | Cd—N6—H6A | 110.2 |
N5—Cd—N3 | 90.67 (6) | C6—N6—H6B | 110.2 |
N2i—Cd—N3 | 94.79 (6) | Cd—N6—H6B | 110.2 |
N6—Cd—N3 | 98.86 (6) | H6A—N6—H6B | 108.5 |
N7—Cd—N3 | 80.38 (6) | C7—C6—N6 | 110.6 (2) |
N5—Cd—N1ii | 101.74 (6) | C7—C6—H6C | 109.5 |
N2i—Cd—N1ii | 83.33 (6) | N6—C6—H6C | 109.5 |
N6—Cd—N1ii | 81.20 (6) | C7—C6—H6D | 109.5 |
N7—Cd—N1ii | 87.69 (6) | N6—C6—H6D | 109.5 |
N3—Cd—N1ii | 167.57 (6) | H6C—C6—H6D | 108.1 |
C3—Fe1—C3iii | 98.55 (11) | N7—C7—C6 | 109.8 (2) |
C3—Fe1—C2iii | 86.70 (8) | N7—C7—H7A | 109.7 |
C3iii—Fe1—C2iii | 173.48 (8) | C6—C7—H7A | 109.7 |
C3—Fe1—C2 | 173.48 (8) | N7—C7—H7B | 109.7 |
C3iii—Fe1—C2 | 86.70 (8) | C6—C7—H7B | 109.7 |
C2iii—Fe1—C2 | 88.35 (11) | H7A—C7—H7B | 108.2 |
C3—Fe1—C1 | 84.46 (8) | C7—N7—Cd | 110.74 (16) |
C3iii—Fe1—C1 | 88.24 (8) | C7—N7—H7C | 109.5 |
C2iii—Fe1—C1 | 96.17 (8) | Cd—N7—H7C | 109.5 |
C2—Fe1—C1 | 91.86 (8) | C7—N7—H7D | 109.5 |
C3—Fe1—C1iii | 88.24 (8) | Cd—N7—H7D | 109.5 |
C3iii—Fe1—C1iii | 84.46 (8) | H7C—N7—H7D | 108.1 |
C2iii—Fe1—C1iii | 91.86 (8) | C7A—C6A—H6G | 110.2 |
C2—Fe1—C1iii | 96.17 (8) | C7A—C6A—H6H | 110.2 |
C1—Fe1—C1iii | 168.81 (11) | H6G—C6A—H6H | 108.5 |
C4—Fe2—C4iv | 180.00 (8) | C6A—C7A—H7E | 109.7 |
C4—Fe2—C5iv | 90.05 (5) | C6A—C7A—H7F | 109.7 |
C4iv—Fe2—C5iv | 89.95 (5) | H7E—C7A—H7F | 108.2 |
C4—Fe2—C5 | 89.95 (5) | C9—C8—N8 | 115.29 (17) |
C4iv—Fe2—C5 | 90.05 (5) | C9—C8—H8A | 108.5 |
C5iv—Fe2—C5 | 87.15 (11) | N8—C8—H8A | 108.5 |
C4—Fe2—C5v | 90.05 (5) | C9—C8—H8B | 108.5 |
C4iv—Fe2—C5v | 89.95 (5) | N8—C8—H8B | 108.5 |
C5iv—Fe2—C5v | 179.91 (12) | H8A—C8—H8B | 107.5 |
C5—Fe2—C5v | 92.85 (11) | C8ix—N8—C8 | 107.17 (16) |
C4—Fe2—C5vi | 89.95 (5) | C8ix—N8—C8x | 110.64 (8) |
C4iv—Fe2—C5vi | 90.05 (5) | C8—N8—C8x | 110.64 (8) |
C5iv—Fe2—C5vi | 92.85 (11) | C8ix—N8—C8xi | 110.64 (8) |
C5—Fe2—C5vi | 179.91 (12) | C8—N8—C8xi | 110.64 (8) |
C5v—Fe2—C5vi | 87.15 (11) | C8x—N8—C8xi | 107.17 (16) |
N1—C1—Fe1 | 173.86 (18) | C8—C9—H9A | 109.5 |
C1—N1—Cdvii | 159.14 (16) | C8—C9—H9B | 109.5 |
N2—C2—Fe1 | 175.91 (17) | H9A—C9—H9B | 109.5 |
C2—N2—Cdviii | 162.76 (15) | C8—C9—H9C | 109.5 |
N3—C3—Fe1 | 174.36 (17) | H9A—C9—H9C | 109.5 |
C3—N3—Cd | 128.64 (15) | H9B—C9—H9C | 109.5 |
Symmetry codes: (i) x−1/2, −y+1/2, −z; (ii) −x+1/2, y−1/2, z; (iii) −x+1, −y+1/2, z; (iv) −x, −y+1/2, z; (v) −y+1/4, −x+1/4, −z+1/4; (vi) y−1/4, x+1/4, −z+1/4; (vii) −x+1/2, y+1/2, z; (viii) x+1/2, −y+1/2, −z; (ix) −x, −y−1/2, z; (x) y+1/4, −x−1/4, −z+1/4; (xi) −y−1/4, x−1/4, −z+1/4. |
Experimental details
Crystal data | |
Chemical formula | (C8H20N)[Cd4Fe3(CN)18(C2H8N2)4] |
Mr | 1456.18 |
Crystal system, space group | Tetragonal, I41/acd |
Temperature (K) | 120 |
a, c (Å) | 13.6532 (3), 52.696 (2) |
V (Å3) | 9823.1 (5) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 2.62 |
Crystal size (mm) | 0.14 × 0.13 × 0.13 |
Data collection | |
Diffractometer | IPDS-II (Stoe) diffractometer |
Absorption correction | Multi-scan SHELXTL XPREP (Sheldrick 1996) |
Tmin, Tmax | 0.630, 0.712 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 40110, 3360, 3012 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.690 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.023, 0.064, 1.03 |
No. of reflections | 3360 |
No. of parameters | 166 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.91, −0.75 |
Computer programs: X-AREA WinExpose (Stoe 2002), X-AREA WinCell (Stoe 2002), X-AREA WinIntegrate (Stoe 2002), SHELXS86 (Sheldrick, 1985), SHELXL97 (Sheldrick, 1997), DIAMOND (Crystal Impact 1999).
Cd—N5 | 2.2833 (16) | C1—N1 | 1.150 (2) |
Cd—N2i | 2.2893 (17) | C2—N2 | 1.151 (3) |
Cd—N6 | 2.3314 (17) | C3—N3 | 1.149 (3) |
Cd—N7 | 2.3731 (17) | C4—N4 | 1.150 (4) |
Cd—N3 | 2.4366 (17) | C5—N5 | 1.149 (3) |
Cd—N1ii | 2.4412 (17) | N6—C6 | 1.525 (4) |
Fe1—C3 | 1.9349 (19) | C6—C7 | 1.498 (5) |
Fe1—C2 | 1.9432 (19) | C7—N7 | 1.409 (3) |
Fe1—C1 | 1.9457 (17) | C8—C9 | 1.512 (3) |
Fe2—C4 | 1.943 (3) | C8—N8 | 1.515 (2) |
Fe2—C5 | 1.9467 (18) | ||
N5—Cd—N2i | 95.78 (6) | C4—Fe2—C5 | 89.95 (5) |
N6—Cd—N7 | 74.88 (6) | C5iii—Fe2—C5iv | 179.91 (12) |
N5—Cd—N3 | 90.67 (6) | C1—N1—Cdv | 159.14 (16) |
N5—Cd—N1ii | 101.74 (6) | C2—N2—Cdvi | 162.76 (15) |
N3—Cd—N1ii | 167.57 (6) | C3—N3—Cd | 128.64 (15) |
C3—Fe1—C2 | 173.48 (8) | C5—N5—Cd | 172.76 (15) |
C3—Fe1—C1 | 84.46 (8) | C6—N6—Cd | 107.46 (15) |
C2—Fe1—C1 | 91.86 (8) |
Symmetry codes: (i) x−1/2, −y+1/2, −z; (ii) −x+1/2, y−1/2, z; (iii) −x, −y+1/2, z; (iv) −y+1/4, −x+1/4, −z+1/4; (v) −x+1/2, y+1/2, z; (vi) x+1/2, −y+1/2, −z. |
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Because of their structural diversity, cyano complexes are suitable for use in the study of various physical phenomena associated with magnetism, such as spin crossover, photomagnetism, spin dynamics in low-dimensional systems and high-temperature magnetic ordering (Dunbar & Heintz, 1997; Verdaguer et al., 1999; Ohba & Okawa, 2000). The synthetic design of cyano complexes can be based on the so called `brick and mortar' method (Willet et al., 1993), in which complex cations form `bricks' and complex cyano anions behave as `mortar', linking the cations via bridging cyano ligands. The desired dimensionality of the coordination polymer can be achieved by a suitable choice of the number and types of `blocking' ligands coordinated to the central cation, leaving only some coordination sites free for N-bonded cyano ligands from the anion.
We are interested in the synthesis, characterization, crystal chemistry and magnetostructural correlations of low-dimensional magnetic systems (Černák et al., 2002). In continuation of this study and taking into account the known structure of the diamagnetic one-dimensional coordination polymer Cd(en)2Ni(CN)4 (en = ethylenediamine), which displays two polymorphs, (one monoclinic and one orthorhombic; Yuge et al., 1995), we have tried to replace the square tetracyanonickelate anion by the octahedral hexacyanoferrate(III) anion. From the aqueous system [NEt4]Br - Cd2+ - en - [Fe(CN)6]3− (Et is ethyl), we have isolated the title compound, [Et4N][Cd(en)]4[Fe(CN)6]3, (I), which contains only one en ligand coordinated to the central Cd atom. Our attempts to prepare compounds with a higher en/Cd ratio (such as 1:1) by raising the initial en/Cd ratio (to 6:1) failed. From similar systems, [Cd(tet)]2[Fe(CN)6]·3H2O (tet = triethylenetetramine), with a one-dimensional structure (Zhang et al., 2000), and [Cd(tren)]3[Fe(CN)5NO] [tren is tris(2-aminoethyl)amine], with a three-dimensional structure (Zhang et al., 2002), were isolated.
The X-ray structure analysis reveals that the structure of (I) consists of a three-dimensional negatively charged framework of composition {[Cd(en)]4[Fe(CN)6]3}nn-, which encapsulates the [Et4N]+ cations. A similar negatively charged three-dimensional framework based on a cyanometallate system, with tetraalkylammonium ions placed in the voids, was descrbided for [N(CH3)4]2[Mn(H2O)]3[Mo(CN)7]2·2H2O (Larionovova et al., 2002).
A perspective view of the asymmetric unit of (I) is shown in Fig. 1, and selected bond lengths and angles are listed in Table 1. There are two crystallographically independent FeIII atoms in the structure (Fig. 1), both of which are hexacoordinated by C-bonded cyano groups. In the coordination polyhedron of atom Fe1 placed in the layer, all six cyano groups exhibit bridging character. Atom Fe2 is coordinated by two terminal (in axial positions) and four bridging cyano groups. The Fe—C bond lengths in both anions range between 1.935 (2) and 1.947 (2) Å. Similar distances, ranging between 1.942 (8) and 1.949 (5) Å, were found in [Ni(pn)2]2[Fe(CN)6]ClO4·2H2O (pn is 1,2-diaminopropane; Ohba et al., 1995). The Fe—C—N angles deviate only slightly from linearity (maximum 6.3 °), which accounts for the presence of π back donation.
The CdII atom exhibits a distorted octahedral coordination, involving one disordered chelate-like en ligand and four N-bonded bridging cyano groups. Three of the latter link the Cd atom to three neighbouring Fe1(CN)6 groups, thus forming double layers (Fig. 2), with composition [{Cd(en)}2(µ-NC)6Fe], parallel to the a,b plane at heights z = 0, 1/4, 1/2 and 3/4 (Fig. 3). The fourth cyano group makes the connection between these layers over the Fe2(CN)6 anions. The Cd—N bond distances are in the range 2.283—2.441 Å; the octahedron around the Cd atom is axially elongated and involves two longer Cd—N(CN) bonds in the layer [mean 2.439 (3) Å]. The remaining two pairs of Cd—N bonds [Cd—N(en) and Cd—N(CN)] in the equatorial plane exhibit a mean value of 2.32 (4) Å (Table 1). The N—Cd—N angles are rather variable; the lowest value, 74.88 (6) °, is found for the N—Cd—N angle within the chelate ring. A similar value, 75.9 (1) °, was found in the monoclinic form of Cd(en)2Ni(CN)4 (Yuge et al., 1995). The en ligand is in δ conformation (more populated position, 72%) and has geometric parameters exhibiting usual values (Yuge et al., 1995).
The Fe(CN)6 groups connecting the Fe1/Cd double layers at z = 1/8, 3/8, 5/8 and 7/8 (Fig. 3) have Fe2···Fe2 separations of 9.65 Å. In the large cavities of these layers, the NEt4 cations alternate with the Fe2-atom octahedra. By operation of the 41 screw axis, the building units are stacked along the c axis (combined with 90° rotations), giving rise to the large translation period along c (>5 nm).
As a consequence of the formation of a three-dimensional framework, some of the Cd—N—C units are strongly bent, the lowest value being 128.6 (2) °. Such values are not uncommon in polymeric cyano complexes (Zhang et al., 2000). The cyano groups exhibit usual distances (Sharpe et al., 1976). The [Et4N]+ cations are placed in the holes of the three-dimensional framework (Fig. 3). The N—C and C—C bonds show normal values (Li et al., 2001).
Note that, in the IR spectrum, two absorption bands are present in the 2000–2200 cm−1 region, which can be assigned to the presence of terminal (2115 cm−1, weak) and bridging (2137 cm−1, strong) cyano groups (Nakamoto, 1997).