Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801009679/br6023sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801009679/br6023Isup2.hkl |
Potassium thiocyanate was obtained from Fluka Chemie AG and silver thiocyanate by the Aldrich Chemical Company Inc. Potassium silver thiocyanate was made by dissolving 1670 mg KSCN into 3.3 ml deionized water and then dissolving 1230 mg AgSCN into that solution at room temperature. After slow evaporation at room temperature, white crystals of Ag K(SCN)2 formed after two days. The crystal used for analysis was mounted on a glass fibre.
Data collection: CAD-4 Software (Enra-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2000).
AgK(SCN)2 | Dx = 2.666 Mg m−3 |
Mr = 263.13 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 25 reflections |
a = 6.719 (1) Å | θ = 14.6–25.4° |
b = 18.024 (1) Å | µ = 4.23 mm−1 |
c = 10.826 (2) Å | T = 293 K |
V = 1311.0 (3) Å3 | Prism, colourless |
Z = 8 | 0.2 × 0.2 × 0.1 mm |
F(000) = 992 |
Enraf Nonius CAD-4 diffractometer | 1137 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.000 |
Graphite monochromator | θmax = 30.0°, θmin = 2.3° |
ω/2θ scans | h = 0→9 |
Absorption correction: ψ scan (North et al., 1968) | k = 0→25 |
Tmin = 0.56, Tmax = 0.65 | l = 0→15 |
1897 measured reflections | 2 standard reflections every 60 min |
1897 independent reflections | intensity decay: none |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.036 | w = 1/[σ2(Fo2) + (0.046P)2 + 0.2326P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.095 | (Δ/σ)max = 0.001 |
S = 1.00 | Δρmax = 0.98 e Å−3 |
1897 reflections | Δρmin = −0.64 e Å−3 |
74 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0148 (6) |
AgK(SCN)2 | V = 1311.0 (3) Å3 |
Mr = 263.13 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 6.719 (1) Å | µ = 4.23 mm−1 |
b = 18.024 (1) Å | T = 293 K |
c = 10.826 (2) Å | 0.2 × 0.2 × 0.1 mm |
Enraf Nonius CAD-4 diffractometer | 1137 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.000 |
Tmin = 0.56, Tmax = 0.65 | 2 standard reflections every 60 min |
1897 measured reflections | intensity decay: none |
1897 independent reflections |
R[F2 > 2σ(F2)] = 0.036 | 74 parameters |
wR(F2) = 0.095 | 0 restraints |
S = 1.00 | Δρmax = 0.98 e Å−3 |
1897 reflections | Δρmin = −0.64 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 > 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 | ||
Ag1 | 0.17017 (6) | 0.50256 (2) | 0.37237 (4) | 0.04619 (16) | |
K1 | 0.35256 (14) | 0.26974 (6) | 0.37357 (9) | 0.0381 (2) | |
S1 | 0.54341 (18) | 0.53295 (7) | 0.34950 (10) | 0.0339 (3) | |
S2 | 0.01889 (16) | 0.39124 (6) | 0.48980 (9) | 0.0304 (2) | |
C1 | 0.5208 (7) | 0.6245 (3) | 0.3470 (4) | 0.0327 (10) | |
C2 | −0.1691 (7) | 0.3682 (2) | 0.3970 (4) | 0.0304 (9) | |
N1 | 0.5050 (7) | 0.6887 (2) | 0.3502 (4) | 0.0486 (11) | |
N2 | −0.3002 (6) | 0.3505 (3) | 0.3362 (4) | 0.0477 (11) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ag1 | 0.0487 (3) | 0.0437 (2) | 0.0462 (2) | −0.01424 (18) | 0.00546 (18) | 0.00078 (17) |
K1 | 0.0318 (5) | 0.0402 (5) | 0.0423 (5) | −0.0018 (4) | −0.0006 (5) | 0.0033 (5) |
S1 | 0.0335 (6) | 0.0353 (6) | 0.0328 (5) | −0.0006 (5) | −0.0002 (5) | 0.0067 (5) |
S2 | 0.0307 (5) | 0.0301 (5) | 0.0303 (5) | −0.0007 (5) | −0.0013 (4) | −0.0009 (4) |
C1 | 0.028 (2) | 0.041 (3) | 0.029 (2) | −0.0031 (18) | 0.0040 (19) | −0.0011 (17) |
C2 | 0.032 (2) | 0.0234 (19) | 0.036 (2) | −0.0034 (17) | 0.0054 (19) | −0.0041 (16) |
N1 | 0.042 (2) | 0.042 (2) | 0.062 (3) | 0.001 (2) | 0.006 (2) | 0.000 (2) |
N2 | 0.034 (2) | 0.056 (3) | 0.053 (3) | −0.008 (2) | 0.0007 (19) | −0.016 (2) |
Ag1—S1 | 2.5788 (13) | K1—K1viii | 4.3915 (13) |
Ag1—S2 | 2.5836 (11) | S1—C1 | 1.658 (5) |
Ag1—S1i | 2.6068 (12) | S1—Ag1v | 2.6068 (12) |
Ag1—S2ii | 2.7393 (11) | S2—C2 | 1.666 (4) |
K1—N2iii | 2.779 (4) | S2—Ag1ii | 2.7393 (11) |
K1—N1iv | 2.823 (5) | S2—K1ix | 3.4431 (15) |
K1—N2v | 2.885 (4) | C1—N1 | 1.162 (6) |
K1—N1vi | 2.986 (4) | C2—N2 | 1.145 (6) |
K1—N1vii | 3.228 (4) | C2—K1i | 3.429 (4) |
K1—S2 | 3.3771 (15) | C2—K1ix | 3.518 (4) |
K1—C2v | 3.429 (4) | N1—K1x | 2.823 (5) |
K1—S2viii | 3.4431 (15) | N1—K1xi | 2.986 (4) |
K1—C2viii | 3.518 (4) | N1—K1vii | 3.228 (4) |
K1—K1i | 4.2947 (13) | N2—K1xii | 2.779 (4) |
K1—K1v | 4.2947 (13) | N2—K1i | 2.885 (4) |
S1—Ag1—S2 | 126.49 (4) | N2iii—K1—K1v | 41.63 (9) |
S1—Ag1—S1i | 100.64 (3) | N1iv—K1—K1v | 127.57 (10) |
S2—Ag1—S1i | 119.21 (4) | N2v—K1—K1v | 77.75 (9) |
S1—Ag1—S2ii | 110.78 (4) | N1vi—K1—K1v | 40.88 (9) |
S2—Ag1—S2ii | 95.29 (3) | N1vii—K1—K1v | 110.20 (8) |
S1i—Ag1—S2ii | 101.75 (4) | S2—K1—K1v | 138.71 (3) |
N2iii—K1—N1iv | 166.46 (13) | C2v—K1—K1v | 60.06 (8) |
N2iii—K1—N2v | 85.41 (12) | S2viii—K1—K1v | 90.79 (2) |
N1iv—K1—N2v | 83.55 (12) | C2viii—K1—K1v | 118.18 (7) |
N2iii—K1—N1vi | 82.47 (12) | K1i—K1—K1v | 102.93 (4) |
N1iv—K1—N1vi | 86.95 (12) | N2iii—K1—K1viii | 62.19 (10) |
N2v—K1—N1vi | 73.88 (13) | N1iv—K1—K1viii | 128.54 (10) |
N2iii—K1—N1vii | 76.39 (12) | N2v—K1—K1viii | 147.59 (9) |
N1iv—K1—N1vii | 117.10 (11) | N1vi—K1—K1viii | 100.44 (9) |
N2v—K1—N1vii | 135.84 (13) | N1vii—K1—K1viii | 39.95 (8) |
N1vi—K1—N1vii | 140.36 (15) | S2—K1—K1viii | 112.37 (4) |
N2iii—K1—S2 | 105.79 (10) | C2v—K1—K1viii | 130.47 (8) |
N1iv—K1—S2 | 78.70 (10) | S2viii—K1—K1viii | 49.26 (3) |
N2v—K1—S2 | 74.35 (10) | C2viii—K1—K1viii | 58.47 (7) |
N1vi—K1—S2 | 146.32 (10) | K1i—K1—K1viii | 170.65 (3) |
N1vii—K1—S2 | 72.61 (8) | K1v—K1—K1viii | 77.878 (1) |
N2iii—K1—C2v | 68.90 (12) | C1—S1—Ag1 | 97.11 (16) |
N1iv—K1—C2v | 98.93 (11) | C1—S1—Ag1v | 102.95 (15) |
N2v—K1—C2v | 18.45 (10) | Ag1—S1—Ag1v | 111.19 (4) |
N1vi—K1—C2v | 64.77 (11) | C2—S2—Ag1 | 101.23 (15) |
N1vii—K1—C2v | 133.15 (11) | C2—S2—Ag1ii | 98.67 (15) |
S2—K1—C2v | 87.39 (8) | Ag1—S2—Ag1ii | 84.71 (3) |
N2iii—K1—S2viii | 103.37 (11) | C2—S2—K1 | 96.73 (14) |
N1iv—K1—S2viii | 83.03 (9) | Ag1—S2—K1 | 93.39 (3) |
N2v—K1—S2viii | 151.45 (11) | Ag1ii—S2—K1 | 164.56 (4) |
N1vi—K1—S2viii | 80.34 (9) | C2—S2—K1ix | 78.65 (14) |
N1vii—K1—S2viii | 72.63 (8) | Ag1—S2—K1ix | 173.46 (5) |
S2—K1—S2viii | 127.00 (3) | Ag1ii—S2—K1ix | 101.79 (4) |
C2v—K1—S2viii | 144.81 (8) | K1—S2—K1ix | 80.16 (3) |
N2iii—K1—C2viii | 120.51 (13) | N1—C1—S1 | 177.4 (4) |
N1iv—K1—C2viii | 70.26 (11) | N2—C2—S2 | 177.6 (4) |
N2v—K1—C2viii | 153.82 (11) | N2—C2—K1i | 52.9 (3) |
N1vi—K1—C2viii | 103.90 (11) | S2—C2—K1i | 127.7 (2) |
N1vii—K1—C2viii | 61.46 (10) | N2—C2—K1ix | 103.9 (3) |
S2—K1—C2viii | 99.66 (8) | S2—C2—K1ix | 73.67 (15) |
C2v—K1—C2viii | 165.37 (10) | K1i—C2—K1ix | 103.62 (10) |
S2viii—K1—C2viii | 27.67 (7) | C1—N1—K1x | 126.5 (4) |
N2iii—K1—K1i | 124.46 (11) | C1—N1—K1xi | 115.7 (3) |
N1iv—K1—K1i | 43.82 (9) | K1x—N1—K1xi | 95.30 (13) |
N2v—K1—K1i | 39.79 (9) | C1—N1—K1vii | 103.4 (3) |
N1vi—K1—K1i | 75.24 (9) | K1x—N1—K1vii | 92.81 (12) |
N1vii—K1—K1i | 144.00 (8) | K1xi—N1—K1vii | 122.88 (15) |
S2—K1—K1i | 73.31 (2) | C2—N2—K1xii | 135.1 (4) |
C2v—K1—K1i | 55.56 (8) | C2—N2—K1i | 108.7 (3) |
S2viii—K1—K1i | 121.44 (2) | K1xii—N2—K1i | 98.58 (13) |
C2viii—K1—K1i | 114.05 (7) |
Symmetry codes: (i) x−1/2, y, −z+1/2; (ii) −x, −y+1, −z+1; (iii) x+1, y, z; (iv) −x+1/2, y−1/2, z; (v) x+1/2, y, −z+1/2; (vi) −x+1, y−1/2, −z+1/2; (vii) −x+1, −y+1, −z+1; (viii) x+1/2, −y+1/2, −z+1; (ix) x−1/2, −y+1/2, −z+1; (x) −x+1/2, y+1/2, z; (xi) −x+1, y+1/2, −z+1/2; (xii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | AgK(SCN)2 |
Mr | 263.13 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 293 |
a, b, c (Å) | 6.719 (1), 18.024 (1), 10.826 (2) |
V (Å3) | 1311.0 (3) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 4.23 |
Crystal size (mm) | 0.2 × 0.2 × 0.1 |
Data collection | |
Diffractometer | Enraf Nonius CAD-4 diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.56, 0.65 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1897, 1897, 1137 |
Rint | 0.000 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.095, 1.00 |
No. of reflections | 1897 |
No. of parameters | 74 |
Δρmax, Δρmin (e Å−3) | 0.98, −0.64 |
Computer programs: CAD-4 Software (Enra-Nonius, 1989), CAD-4 Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 2000).
Ag1—S1 | 2.5788 (13) | K1—N1vii | 3.228 (4) |
Ag1—S2 | 2.5836 (11) | K1—S2 | 3.3771 (15) |
Ag1—S1i | 2.6068 (12) | K1—S2viii | 3.4431 (15) |
Ag1—S2ii | 2.7393 (11) | S1—C1 | 1.658 (5) |
K1—N2iii | 2.779 (4) | S2—C2 | 1.666 (4) |
K1—N1iv | 2.823 (5) | C1—N1 | 1.162 (6) |
K1—N2v | 2.885 (4) | C2—N2 | 1.145 (6) |
K1—N1vi | 2.986 (4) | ||
S1—Ag1—S2 | 126.49 (4) | S2—Ag1—S2ii | 95.29 (3) |
S1—Ag1—S1i | 100.64 (3) | S1i—Ag1—S2ii | 101.75 (4) |
S2—Ag1—S1i | 119.21 (4) | N1—C1—S1 | 177.4 (4) |
S1—Ag1—S2ii | 110.78 (4) | N2—C2—S2 | 177.6 (4) |
Symmetry codes: (i) x−1/2, y, −z+1/2; (ii) −x, −y+1, −z+1; (iii) x+1, y, z; (iv) −x+1/2, y−1/2, z; (v) x+1/2, y, −z+1/2; (vi) −x+1, y−1/2, −z+1/2; (vii) −x+1, −y+1, −z+1; (viii) x+1/2, −y+1/2, −z+1. |
There has been considerable investigation into thiocyanates. A valuable synthetic study was published about 100 years ago (Wells, 1902) and treated mostly double and triple thiocyanates. At that time, most studies were synthetic and analytical. Many crystal structure determinations relating to metal thiocyanates have been solved since. Silver forms simple thiocyanate AgSCN, which has two polymorphic forms, Pmnn and C2/c. There are also double silver thiocyanates, and triple thiocyanates such as Cs3Sr[Ag2(SCN)7] and Cs3Ba[Ag2(SCN)7]. These two triple thiocyanates have also interesting optical, electro-optic and electrostrictive properties (Bohaty & Fröhlich, 1992).
Although potassium silver thiocyanate, Ag K(SCN)2, has been known for 150 years, there is little data available in the literature. The unit cell has been published (Chateau et al., 1962). Potassium silver thiocyanate, Ag K(SCN)2, is not isostructural with AgNH4(SCN)2, unlike many potassium and ammonium compounds.
Potassium is seven-coordinated, with five N and two S atoms around the K atom. The coordination polyhedron is a distorted monocapped trigonal prism, as shown in Fig. 1. N1 is the capping atom which is at a distance of 2.986 (4) Å from K1.
Four S atoms surround the Ag atom in the form of a tetrahedron. The tetrahedron is slightly distorted: Ag—S distances vary between 2.579 (1) and 2.739 (1) Å. The six S—Ag—S angles vary between 95.29 (3) and 126.49 (4)°.
There are two different thiocyanate groups in the structure. The bond lengths and angles are normal and similar in both groups, but differ in coordination. In thiocyanate group one (S1/C1/N1), the S atom is connected to two Ag atoms and the N atom to three K atoms, whereas in thiocyanate group two (S2/C2/N2), the S atom is connected to two Ag atoms and two K atoms and the N atom to two K atoms.
The structure forms a three-dimensional network. It can be thought of as consisting of infinite AgS2 layers, so that the tetrahedra around the Ag atoms are approximately at planes xz with y = 0.0 and 0.5 (Fig. 2) and the potassium polyhedra approximately at planes xz with y = 0.25 and 0.75. Tetrahedra around the Ag atoms share one common edge and two common corners so that one tetrahedron is connected to three other tetrahedra. The monocapped trigonal prisms around the K atoms share four common edges and two common corners. These layers are held together by the thiocyanate groups (Fig. 3).