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The 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 (\overline{6}2m), Ag (2/m), C (m), N (m), O (m2m) and H (m).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807029133/pk2030sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807029133/pk2030Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 290 K
  • Mean [sigma](N-C) = 0.006 Å
  • R factor = 0.019
  • wR factor = 0.047
  • Data-to-parameter ratio = 10.8

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Tb1
Alert level G ABSTM02_ALERT_3_G The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.320 0.438 Tmin and Tmax expected: 0.232 0.405 RR = 1.275 Please check that your absorption correction is appropriate. REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values From the CIF: _diffrn_reflns_theta_max 25.30 From the CIF: _reflns_number_total 260 From the CIF: _diffrn_reflns_limit_ max hkl 6. 6. 22. From the CIF: _diffrn_reflns_limit_ min hkl 0. 0. -22. TEST1: Expected hkl limits for theta max Calculated maximum hkl 8. 8. 22. Calculated minimum hkl -8. -8. -22. PLAT794_ALERT_5_G Check Predicted Bond Valency for Tb1 (3) 3.60
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 1 ALERT level C = Check and explain 3 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

Comment top

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).

Related literature top

The title compound is isostructural with the previously reported gold analog, Tb[Au(CN)2]3.3H2O (Tanner et al., 2005). These compounds contain the Eu[Ag(CN)2]3.3H2O structure type (Assefa et al., 1994, 1995), which has also been reported for several other tris(dicyanoargentate)lanthanide trihydrates or tris(dicyanoaurate)lanthanide trihydrates (Colis, Larochelle et al., 2005). Detailed spectroscopic properties have been reported for the title compound (Rawashdeh-Omary et al., 2000; Tanner et al., 2005).

For related literature, see: Ahrland et al. (1985); Colis, Staples et al. (2005).

Experimental top

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%.

Refinement top

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).

Structure description top

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).

The title compound is isostructural with the previously reported gold analog, Tb[Au(CN)2]3.3H2O (Tanner et al., 2005). These compounds contain the Eu[Ag(CN)2]3.3H2O structure type (Assefa et al., 1994, 1995), which has also been reported for several other tris(dicyanoargentate)lanthanide trihydrates or tris(dicyanoaurate)lanthanide trihydrates (Colis, Larochelle et al., 2005). Detailed spectroscopic properties have been reported for the title compound (Rawashdeh-Omary et al., 2000; Tanner et al., 2005).

For related literature, see: Ahrland et al. (1985); Colis, Staples et al. (2005).

Computing details top

Data collection: CAD-4-PC (Enraf-Nonius, 1993); cell refinement: CAD-4-PC; data reduction: XCAD4-PC (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).

Figures top
[Figure 1] Fig. 1. An illustration of the coordination environment around the terbium and silver atoms. 50% thermal ellipsoids are shown.
[Figure 2] Fig. 2. A view of the packing diagram of I viewed perpendicular to the c axis. Hydrogen atoms not shown.
Poly[triaquahexa-µ-cyanido-terbium(III)trisilver(I)] top
Crystal data top
[Ag3Tb(CN)6(H2O)3]Dx = 3.251 Mg m3
Mr = 692.70Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/mcmCell parameters from 25 reflections
Hall symbol: -P 6c 2θ = 8.3–21.1°
a = 6.6692 (11) ŵ = 9.04 mm1
c = 18.371 (2) ÅT = 290 K
V = 707.63 (19) Å3Prism, colorless
Z = 20.29 × 0.14 × 0.10 mm
F(000) = 628
Data collection top
Enraf–Nonius CAD-4
diffractometer
226 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.056
Graphite monochromatorθmax = 25.3°, θmin = 2.2°
θ/2θ scansh = 06
Absorption correction: analytical
(XPREP; Bruker, 2000)
k = 06
Tmin = 0.320, Tmax = 0.438l = 2222
849 measured reflections3 standard reflections every 120 min
260 independent reflections intensity decay: 3%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.019H-atom parameters constrained
wR(F2) = 0.047 w = 1/[σ2(Fo2) + (0.0134P)2 + 0.104P]
where P = (Fo2 + 2Fc2)/3
S = 1.14(Δ/σ)max < 0.001
260 reflectionsΔρmax = 0.68 e Å3
24 parametersΔρmin = 0.51 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0152 (8)
Crystal data top
[Ag3Tb(CN)6(H2O)3]Z = 2
Mr = 692.70Mo Kα radiation
Hexagonal, P63/mcmµ = 9.04 mm1
a = 6.6692 (11) ÅT = 290 K
c = 18.371 (2) Å0.29 × 0.14 × 0.10 mm
V = 707.63 (19) Å3
Data collection top
Enraf–Nonius CAD-4
diffractometer
226 reflections with I > 2σ(I)
Absorption correction: analytical
(XPREP; Bruker, 2000)
Rint = 0.056
Tmin = 0.320, Tmax = 0.4383 standard reflections every 120 min
849 measured reflections intensity decay: 3%
260 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0190 restraints
wR(F2) = 0.047H-atom parameters constrained
S = 1.14Δρmax = 0.68 e Å3
260 reflectionsΔρmin = 0.51 e Å3
24 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Tb11.00000.00000.25000.0141 (3)
Ag10.50000.00000.00000.0364 (3)
N10.7414 (6)0.00000.1502 (2)0.0287 (9)
C10.6558 (8)0.00000.0970 (2)0.0277 (11)
O11.3630 (8)0.00000.25000.0471 (16)
H11.41990.00000.20860.057*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Tb10.0161 (3)0.0161 (3)0.0101 (3)0.00803 (15)0.0000.000
Ag10.0416 (4)0.0406 (5)0.0265 (3)0.0203 (2)0.01559 (18)0.000
N10.0273 (16)0.038 (3)0.0243 (18)0.0190 (13)0.0030 (15)0.000
C10.0262 (18)0.033 (3)0.026 (2)0.0166 (15)0.0024 (18)0.000
O10.041 (2)0.097 (5)0.022 (2)0.049 (3)0.0000.000
Geometric parameters (Å, º) top
Tb1—O12.421 (5)Ag1—Ag1i3.3346 (5)
Tb1—N12.517 (4)N1—C11.132 (6)
Ag1—C12.063 (5)O1—H10.8500
O1ii—Tb1—O1iii120.000 (1)N1ii—Tb1—N1v139.92 (7)
O1ii—Tb1—O1120.000 (1)O1ii—Tb1—N1vi69.96 (3)
O1iii—Tb1—O1120.0O1iii—Tb1—N1vi133.26 (9)
O1ii—Tb1—N1iv133.26 (9)O1—Tb1—N1vi69.96 (3)
O1iii—Tb1—N1iv69.96 (3)N1iv—Tb1—N1vi72.81 (14)
O1—Tb1—N1iv69.96 (3)N1—Tb1—N1vi139.92 (7)
O1ii—Tb1—N169.96 (3)N1iii—Tb1—N1vi93.48 (18)
O1iii—Tb1—N169.96 (3)N1ii—Tb1—N1vi139.92 (7)
O1—Tb1—N1133.26 (9)N1v—Tb1—N1vi72.81 (14)
N1iv—Tb1—N1139.92 (7)C1—Ag1—C1vii180.00 (12)
O1ii—Tb1—N1iii69.96 (3)C1—Ag1—Ag1i104.59 (7)
O1iii—Tb1—N1iii133.26 (9)C1vii—Ag1—Ag1i75.41 (7)
O1—Tb1—N1iii69.96 (3)C1—Ag1—Ag1viii75.41 (7)
N1iv—Tb1—N1iii139.92 (7)C1vii—Ag1—Ag1viii104.59 (7)
N1—Tb1—N1iii72.81 (14)Ag1i—Ag1—Ag1viii180.0
O1ii—Tb1—N1ii133.26 (9)C1—Ag1—Ag1ix75.41 (7)
O1iii—Tb1—N1ii69.96 (3)C1vii—Ag1—Ag1ix104.59 (7)
O1—Tb1—N1ii69.96 (3)Ag1i—Ag1—Ag1ix60.0
N1iv—Tb1—N1ii93.48 (18)Ag1viii—Ag1—Ag1ix120.0
N1—Tb1—N1ii72.81 (14)C1—Ag1—Ag1x104.59 (7)
N1iii—Tb1—N1ii72.81 (14)C1vii—Ag1—Ag1x75.41 (7)
O1ii—Tb1—N1v69.96 (3)Ag1i—Ag1—Ag1x120.0
O1iii—Tb1—N1v69.96 (3)Ag1viii—Ag1—Ag1x60.0
O1—Tb1—N1v133.26 (9)Ag1ix—Ag1—Ag1x180.0
N1iv—Tb1—N1v72.81 (14)C1—N1—Tb1167.0 (4)
N1—Tb1—N1v93.48 (18)N1—C1—Ag1180.0 (4)
N1iii—Tb1—N1v139.92 (7)Tb1—O1—H1116.5
Symmetry codes: (i) y, xy1, z; (ii) x+y+2, x+1, z; (iii) y+1, xy1, z; (iv) x+y+2, x+1, z+1/2; (v) x, y, z+1/2; (vi) y+1, xy1, z+1/2; (vii) x+1, y, z; (viii) y+1, xy, z; (ix) x+y+1, x, z; (x) x+y+1, x+1, z.

Experimental details

Crystal data
Chemical formula[Ag3Tb(CN)6(H2O)3]
Mr692.70
Crystal system, space groupHexagonal, P63/mcm
Temperature (K)290
a, c (Å)6.6692 (11), 18.371 (2)
V3)707.63 (19)
Z2
Radiation typeMo Kα
µ (mm1)9.04
Crystal size (mm)0.29 × 0.14 × 0.10
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionAnalytical
(XPREP; Bruker, 2000)
Tmin, Tmax0.320, 0.438
No. of measured, independent and
observed [I > 2σ(I)] reflections
849, 260, 226
Rint0.056
(sin θ/λ)max1)0.601
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.019, 0.047, 1.14
No. of reflections260
No. of parameters24
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.68, 0.51

Computer programs: CAD-4-PC (Enraf-Nonius, 1993), CAD-4-PC, XCAD4-PC (Harms, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1998), publCIF (Westrip, 2007).

 

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