Acta Cryst. (2007). E63, i162 [ doi:10.1107/S1600536807029133 ]
![[mu]](/logos/entities/mu_rmgif.gif)
-cyanido-terbium(III)trisilver(I)]: a 4f-4d bimetallic coordination polymerThe title compound, [Ag3Tb(CN)6(H2O)3]n, consists of hydrated Tb3+ cations that are linked with dicyanoargentate anions into a three-dimensional network. The resultant TbN6O3 coordination polyhedra have a tricapped trigonal prismatic geometry. Six N atoms from the dicyanoargentate groups form the corners of the trigonal prisms, while the O atoms of three water molecules reside in the capping positions to complete the coordination environment around terbium. Argentophilic interactions give rise to a two-dimensional network of Ag atoms. All of the atoms in the structure are located on special crystallographic positions. Only one unique atom of each type is found in the structure. The site symmetry of each is: Tb (
2m), Ag (2/m), C (m), N (m), O (m2m) and H (m).
Tb(NO3)3.xH2O (99.9%) and KAg(CN)2 (99.9%) were purchased from Alfa Aesar. An aqueous Tb3+ solution (0.13 M) was prepared from the Tb(NO3)3.xH2O. The reaction involved placing a sealed quartz tube containing 0.10 ml of the aqueous Tb3+ solution and 7.7 mg (39 µmol) of the KAg(CN)2 into a preheated box oven. The tube was left in the oven at 393 K for 3 d. Colorless single crystals of Tb[Ag(CN)2]3·3H2O in the form of hexagonal plates were isolated as the sole solid product contained in a colorless mother liquor. The observed yield was 51%.
The unique H-atom in the structure was located in a Fourier difference map and then fixed at a distance of 0.85 Å from the oxygen atom. The coordinates of the H atom were restrained to ensure a reasonable geometry for the water molecule and Uiso(H) was fixed at 1.2Ueq(O).
Data collection: CAD-4-PC (Enraf-Nonius, 1993); cell refinement: CAD-4-PC; data reduction: XCAD4PC (Harms, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: publCIF (Westrip, 2007).
![[Figure 1]](./pk2030fig1thm.gif)
| Fig. 1. An illustration of the coordination environment around the terbium and silver atoms. 50% thermal ellipsoids are shown. |
![[Figure 2]](./pk2030fig2thm.gif)
| Fig. 2. A view of the packing diagram of I viewed perpendicular to the c axis. Hydrogen atoms not shown. |
| [Ag3Tb(CN)6(H2O)3] | Z = 2 |
| Mr = 692.70 | F000 = 628 |
| Hexagonal, P63/mcm | Dx = 3.251 Mg m−3 |
| Hall symbol: -P 6c 2 | Mo Kα radiation λ = 0.71073 Å |
| a = 6.6692 (11) Å | Cell parameters from 25 reflections |
| b = 6.6692 (11) Å | θ = 8.3–21.1º |
| c = 18.371 (2) Å | µ = 9.04 mm−1 |
| α = 90º | T = 290 (2) K |
| β = 90º | Prism, colorless |
| γ = 120º | 0.29 × 0.14 × 0.10 mm |
| V = 707.63 (19) Å3 |
| Enraf–Nonius CAD-4 diffractometer | Rint = 0.056 |
| Radiation source: fine-focus sealed tube | θmax = 25.3º |
| Monochromator: graphite | θmin = 2.2º |
| T = 290(2) K | h = 0→6 |
| θ/2θ scans | k = 0→6 |
| Absorption correction: analytical (XPREP; Bruker, 2000) | l = −22→22 |
| Tmin = 0.320, Tmax = 0.438 | 3 standard reflections |
| 849 measured reflections | every 120 min |
| 260 independent reflections | intensity decay: 3% |
| 226 reflections with I > 2σ(I) |
| Refinement on F2 | Hydrogen site location: difference Fourier map |
| Least-squares matrix: full | H-atom parameters constrained |
| R[F2 > 2σ(F2)] = 0.019 | w = 1/[σ2(Fo2) + (0.0134P)2 + 0.104P] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.047 | (Δ/σ)max < 0.001 |
| S = 1.14 | Δρmax = 0.68 e Å−3 |
| 260 reflections | Δρmin = −0.51 e Å−3 |
| 24 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0152 (8) |
| Secondary atom site location: difference Fourier map |
| [Ag3Tb(CN)6(H2O)3] | γ = 120º |
| Mr = 692.70 | V = 707.63 (19) Å3 |
| Hexagonal, P63/mcm | Z = 2 |
| a = 6.6692 (11) Å | Mo Kα |
| b = 6.6692 (11) Å | µ = 9.04 mm−1 |
| c = 18.371 (2) Å | T = 290 (2) K |
| α = 90º | 0.29 × 0.14 × 0.10 mm |
| β = 90º |
| Enraf–Nonius CAD-4 diffractometer | 226 reflections with I > 2σ(I) |
| Absorption correction: analytical (XPREP; Bruker, 2000) | Rint = 0.056 |
| Tmin = 0.320, Tmax = 0.438 | 3 standard reflections |
| 849 measured reflections | every 120 min |
| 260 independent reflections | intensity decay: 3% |
| R[F2 > 2σ(F2)] = 0.019 | 24 parameters |
| wR(F2) = 0.047 | H-atom parameters constrained |
| S = 1.14 | Δρmax = 0.68 e Å−3 |
| 260 reflections | Δρmin = −0.51 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 | ||
| Tb1 | 1.0000 | 0.0000 | 0.2500 | 0.0141 (3) | |
| Ag1 | 0.5000 | 0.0000 | 0.0000 | 0.0364 (3) | |
| N1 | 0.7414 (6) | 0.0000 | 0.1502 (2) | 0.0287 (9) | |
| C1 | 0.6558 (8) | 0.0000 | 0.0970 (2) | 0.0277 (11) | |
| O1 | 1.3630 (8) | 0.0000 | 0.2500 | 0.0471 (16) | |
| H1 | 1.4199 | 0.0000 | 0.2086 | 0.057* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Tb1 | 0.0161 (3) | 0.0161 (3) | 0.0101 (3) | 0.00803 (15) | 0.000 | 0.000 |
| Ag1 | 0.0416 (4) | 0.0406 (5) | 0.0265 (3) | 0.0203 (2) | −0.01559 (18) | 0.000 |
| N1 | 0.0273 (16) | 0.038 (3) | 0.0243 (18) | 0.0190 (13) | −0.0030 (15) | 0.000 |
| C1 | 0.0262 (18) | 0.033 (3) | 0.026 (2) | 0.0166 (15) | −0.0024 (18) | 0.000 |
| O1 | 0.041 (2) | 0.097 (5) | 0.022 (2) | 0.049 (3) | 0.000 | 0.000 |
| Tb1—O1 | 2.421 (5) | Ag1—Ag1i | 3.3346 (5) |
| Tb1—N1 | 2.517 (4) | N1—C1 | 1.132 (6) |
| Ag1—C1 | 2.063 (5) | O1—H1 | 0.8500 |
| O1ii—Tb1—O1iii | 120.000 (1) | N1ii—Tb1—N1v | 139.92 (7) |
| O1ii—Tb1—O1 | 120.000 (1) | O1ii—Tb1—N1vi | 69.96 (3) |
| O1iii—Tb1—O1 | 120.0 | O1iii—Tb1—N1vi | 133.26 (9) |
| O1ii—Tb1—N1iv | 133.26 (9) | O1—Tb1—N1vi | 69.96 (3) |
| O1iii—Tb1—N1iv | 69.96 (3) | N1iv—Tb1—N1vi | 72.81 (14) |
| O1—Tb1—N1iv | 69.96 (3) | N1—Tb1—N1vi | 139.92 (7) |
| O1ii—Tb1—N1 | 69.96 (3) | N1iii—Tb1—N1vi | 93.48 (18) |
| O1iii—Tb1—N1 | 69.96 (3) | N1ii—Tb1—N1vi | 139.92 (7) |
| O1—Tb1—N1 | 133.26 (9) | N1v—Tb1—N1vi | 72.81 (14) |
| N1iv—Tb1—N1 | 139.92 (7) | C1—Ag1—C1vii | 180.00 (12) |
| O1ii—Tb1—N1iii | 69.96 (3) | C1—Ag1—Ag1i | 104.59 (7) |
| O1iii—Tb1—N1iii | 133.26 (9) | C1vii—Ag1—Ag1i | 75.41 (7) |
| O1—Tb1—N1iii | 69.96 (3) | C1—Ag1—Ag1viii | 75.41 (7) |
| N1iv—Tb1—N1iii | 139.92 (7) | C1vii—Ag1—Ag1viii | 104.59 (7) |
| N1—Tb1—N1iii | 72.81 (14) | Ag1i—Ag1—Ag1viii | 180.0 |
| O1ii—Tb1—N1ii | 133.26 (9) | C1—Ag1—Ag1ix | 75.41 (7) |
| O1iii—Tb1—N1ii | 69.96 (3) | C1vii—Ag1—Ag1ix | 104.59 (7) |
| O1—Tb1—N1ii | 69.96 (3) | Ag1i—Ag1—Ag1ix | 60.0 |
| N1iv—Tb1—N1ii | 93.48 (18) | Ag1viii—Ag1—Ag1ix | 120.0 |
| N1—Tb1—N1ii | 72.81 (14) | C1—Ag1—Ag1x | 104.59 (7) |
| N1iii—Tb1—N1ii | 72.81 (14) | C1vii—Ag1—Ag1x | 75.41 (7) |
| O1ii—Tb1—N1v | 69.96 (3) | Ag1i—Ag1—Ag1x | 120.0 |
| O1iii—Tb1—N1v | 69.96 (3) | Ag1viii—Ag1—Ag1x | 60.0 |
| O1—Tb1—N1v | 133.26 (9) | Ag1ix—Ag1—Ag1x | 180.0 |
| N1iv—Tb1—N1v | 72.81 (14) | C1—N1—Tb1 | 167.0 (4) |
| N1—Tb1—N1v | 93.48 (18) | N1—C1—Ag1 | 180.0 (4) |
| N1iii—Tb1—N1v | 139.92 (7) | Tb1—O1—H1 | 116.5 |
| Symmetry codes: (i) −y, x−y−1, z; (ii) −x+y+2, −x+1, z; (iii) −y+1, x−y−1, z; (iv) −x+y+2, −x+1, −z+1/2; (v) x, y, −z+1/2; (vi) −y+1, x−y−1, −z+1/2; (vii) −x+1, −y, −z; (viii) −y+1, x−y, z; (ix) −x+y+1, −x, z; (x) −x+y+1, −x+1, z. |
The authors gladly acknowledge the Department of Energy and Oak Ridge National Laboratory for the loan of a Nonius CAD-4 X-ray diffractometer.
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Compounds containing lanthanide ions and dicyanometallate (e.g. dicyanoargentate, dicyanoaurate) anions have been extensively studied in recent years due to the interesting structural and optical properties of these systems (Tanner et al., 2005; Colis & Staples et al., 2005). It has been shown in both Tb[Ag(CN)2]3·3H2O and Tb[Au(CN)2]3·3H2O that donor-acceptor energy transfer processes occur. In these systems, exclusive excitation of the donor dicyanoaurate or dicyanoargentate moieties leads to sensitized luminescence from the acceptor Tb(III) (Rawashdeh-Omary et al., 2000; Tanner et al., 2005). The sensitized luminescence is reportedly much stronger in Tb[Ag(CN)2]3·3H2O than in Tb[Au(CN)2]3·3H2O due to a larger spectral overlap between the [Ag(CN)2−] emission and the Tb(III) absorption (Rawashdeh-Omary et al., 2000). However, while the structure of Tb[Au(CN)2]3·3H2O has been previously reported (Tanner et al., 2005), the structure of Tb[Ag(CN)2]3·3H2O has not. For this reason, a structural study of the title compound was undertaken.
Fig. 1 shows the coordination geometry around the terbium atom and the atomic labeling scheme. The environment of the Tb ion consists of six N-bound CN− groups coordinated approximately end-on, resulting in a trigonal prismatic arrangement. Only the N atoms are shown in Fig. 1, but the overall cyanide coordination is clearly evident in the packing diagram shown in Fig. 2. Three water molecules cap the three rectangular faces of the prism. The result is a tricapped trigonal prismatic coordination geometry around the Tb3+ with a D3h site symmetry. The three O atoms of the water molecules are coplanar with the Tb atom, by symmetry. Each silver atom is coordinated to the carbon atoms of two cyanide anions, resulting in nearly linear Ag(CN)2− units as found in other dicyanoargentates. This arrangement is shown in the packing diagram of Fig. 2. In the structure, the [TbN6O3] polyhedra are arranged in layers found in the crystallographic ab plane. As shown in Fig. 2, these alternating layers of Ag atoms and Tb polyhedra are bridged with cyanide linkages resulting in an overall three-dimensional framework. The silver atoms form a Kagomé lattice, also found in the ab plane, that separates the layers of terbium polyhedra. Every Ag atom has four nearest Ag neighbors, with a uniform Ag···Ag separation of 3.3346 (5) Å. The overall structural features are unchanged in the title compound as compared with the isostructural Tb[Au(CN)2]3·3H2O. The title compound contains a larger cell volume than Tb[Au(CN)2]3·3H2O due largely to the greater Ag···Ag separation as compared to the shorter Au···Au separation of 3.31 (1) Å (Tanner et al., 2005). This is consistent with the well established observation that aurophilic interactions are stronger than argentophilic interactions (Ahrland et al., 1985).