Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107023463/fa3083sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107023463/fa3083Isup2.hkl |
CCDC reference: 609776
H-atom positions were calculated; they were refined riding on the corresponding C atoms, with Uiso(H) constrained to 1.2Ueq of the related C atom.
Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXP in SHELXTL/PC (Sheldrick, 1990) and SCHAKAL (Keller, 1999); software used to prepare material for publication: SCHAKAL and publCIF (Westrip, 2007).
[Hg(CN)2]2·C16H10 | Dx = 2.619 Mg m−3 |
Mr = 707.50 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Cmc21 | Cell parameters from 30 reflections |
a = 11.9893 (3) Å | θ = 4.0–25.0° |
b = 17.3480 (4) Å | µ = 17.10 mm−1 |
c = 8.6266 (2) Å | T = 293 K |
V = 1794.25 (7) Å3 | Lamina, pink |
Z = 4 | 0.24 × 0.12 × 0.10 mm |
F(000) = 1272 |
Bruker P4 APEX diffractometer | 2251 independent reflections |
Radiation source: fine-focus sealed tube | 2105 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
ϕ scans | θmax = 28.3°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −15→15 |
Tmin = 0.072, Tmax = 0.181 | k = −23→23 |
10971 measured reflections | l = −11→10 |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.021 | w = 1/[σ2(Fo2) + (0.0208P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.044 | (Δ/σ)max < 0.001 |
S = 1.01 | Δρmax = 0.69 e Å−3 |
2251 reflections | Δρmin = −1.07 e Å−3 |
128 parameters | Extinction correction: refined, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.00131 (4) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983) |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.030 (14) |
[Hg(CN)2]2·C16H10 | V = 1794.25 (7) Å3 |
Mr = 707.50 | Z = 4 |
Orthorhombic, Cmc21 | Mo Kα radiation |
a = 11.9893 (3) Å | µ = 17.10 mm−1 |
b = 17.3480 (4) Å | T = 293 K |
c = 8.6266 (2) Å | 0.24 × 0.12 × 0.10 mm |
Bruker P4 APEX diffractometer | 2251 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2105 reflections with I > 2σ(I) |
Tmin = 0.072, Tmax = 0.181 | Rint = 0.036 |
10971 measured reflections |
R[F2 > 2σ(F2)] = 0.021 | H-atom parameters constrained |
wR(F2) = 0.044 | Δρmax = 0.69 e Å−3 |
S = 1.01 | Δρmin = −1.07 e Å−3 |
2251 reflections | Absolute structure: Flack (1983) |
128 parameters | Absolute structure parameter: 0.030 (14) |
1 restraint |
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 | ||
Hg1 | 0.5000 | 0.38506 (3) | −0.37350 (4) | 0.02913 (13) | |
Hg2 | 0.5000 | 0.13641 (2) | 0.07906 (4) | 0.02965 (12) | |
C11 | 0.5000 | 0.4584 (5) | −0.5572 (9) | 0.0309 (19) | |
N11 | 0.5000 | 0.4995 (7) | −0.6578 (10) | 0.050 (2) | |
C12 | 0.5000 | 0.3046 (5) | −0.2022 (10) | 0.031 (2) | |
N12 | 0.5000 | 0.2600 (6) | −0.1063 (11) | 0.047 (3) | |
C21 | 0.3303 (4) | 0.1319 (3) | 0.0887 (7) | 0.0322 (12) | |
N21 | 0.2373 (4) | 0.1276 (5) | 0.093 (3) | 0.052 (2) | |
C1 | 0.3816 (4) | 0.1771 (3) | 0.4988 (7) | 0.0318 (13) | |
C2 | 0.4400 (4) | 0.1257 (3) | 0.5983 (6) | 0.0279 (11) | |
C3 | 0.3805 (5) | 0.0734 (3) | 0.6925 (7) | 0.0338 (14) | |
C4 | 0.2636 (5) | 0.0742 (7) | 0.6895 (12) | 0.048 (2) | |
H4 | 0.2237 | 0.0415 | 0.7544 | 0.058* | |
C5 | 0.2080 (6) | 0.1228 (5) | 0.5920 (10) | 0.0514 (18) | |
H5 | 0.1305 | 0.1209 | 0.5878 | 0.062* | |
C6 | 0.2642 (5) | 0.1744 (6) | 0.4998 (12) | 0.049 (2) | |
H6 | 0.2241 | 0.2080 | 0.4370 | 0.058* | |
C7 | 0.4444 (5) | 0.2304 (4) | 0.4030 (7) | 0.0391 (16) | |
H7 | 0.4064 | 0.2652 | 0.3403 | 0.047* | |
C8 | 0.4438 (5) | 0.0223 (4) | 0.7928 (8) | 0.0410 (17) | |
H8 | 0.4059 | −0.0111 | 0.8585 | 0.049* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Hg1 | 0.03033 (15) | 0.0294 (2) | 0.0276 (3) | 0.000 | 0.000 | −0.00481 (19) |
Hg2 | 0.02216 (14) | 0.0327 (2) | 0.0341 (3) | 0.000 | 0.000 | 0.0019 (2) |
C11 | 0.026 (4) | 0.041 (5) | 0.025 (4) | 0.000 | 0.000 | −0.008 (4) |
N11 | 0.055 (5) | 0.049 (5) | 0.047 (6) | 0.000 | 0.000 | −0.021 (5) |
C12 | 0.020 (4) | 0.035 (5) | 0.039 (5) | 0.000 | 0.000 | 0.004 (4) |
N12 | 0.040 (5) | 0.050 (6) | 0.051 (6) | 0.000 | 0.000 | −0.018 (5) |
C21 | 0.028 (3) | 0.033 (3) | 0.036 (3) | −0.001 (2) | 0.000 (3) | −0.002 (2) |
N21 | 0.031 (3) | 0.059 (4) | 0.065 (6) | 0.000 (3) | 0.000 (5) | −0.008 (3) |
C1 | 0.036 (3) | 0.027 (3) | 0.033 (3) | 0.004 (2) | −0.010 (3) | −0.011 (3) |
C2 | 0.035 (3) | 0.025 (2) | 0.023 (3) | −0.001 (2) | 0.002 (2) | −0.0093 (16) |
C3 | 0.044 (3) | 0.033 (4) | 0.025 (3) | −0.009 (3) | 0.001 (3) | −0.010 (3) |
C4 | 0.040 (4) | 0.056 (6) | 0.048 (5) | −0.013 (4) | 0.008 (4) | −0.010 (4) |
C5 | 0.037 (3) | 0.057 (4) | 0.060 (5) | 0.002 (3) | −0.005 (4) | −0.015 (3) |
C6 | 0.042 (4) | 0.047 (6) | 0.057 (5) | 0.008 (4) | −0.013 (4) | −0.011 (5) |
C7 | 0.059 (4) | 0.026 (3) | 0.032 (3) | 0.008 (3) | −0.006 (3) | −0.005 (3) |
C8 | 0.057 (4) | 0.038 (4) | 0.028 (3) | −0.008 (3) | 0.012 (3) | −0.002 (3) |
Hg1—C11 | 2.032 (9) | C3—C4 | 1.402 (7) |
Hg1—C12 | 2.033 (10) | C3—C8 | 1.453 (8) |
Hg2—C21 | 2.038 (5) | C4—C5 | 1.364 (12) |
Hg2—N12 | 2.675 (10) | C4—H4 | 0.9300 |
C11—N11 | 1.123 (14) | C5—C6 | 1.374 (11) |
C12—N12 | 1.132 (13) | C5—H5 | 0.9300 |
C21—N21 | 1.119 (6) | C6—H6 | 0.9300 |
C1—C6 | 1.407 (7) | C7—C7i | 1.332 (13) |
C1—C2 | 1.424 (7) | C7—H7 | 0.9300 |
C1—C7 | 1.450 (8) | C8—C8i | 1.347 (12) |
C2—C3 | 1.411 (7) | C8—H8 | 0.9300 |
C2—C2i | 1.438 (10) | ||
C11—Hg1—C12 | 175.4 (4) | C5—C4—C3 | 120.4 (8) |
C21—Hg2—C21i | 173.6 (3) | C5—C4—H4 | 119.8 |
C21—Hg2—N12 | 93.15 (14) | C3—C4—H4 | 119.8 |
N11—C11—Hg1 | 179.4 (10) | C4—C5—C6 | 121.3 (6) |
N12—C12—Hg1 | 179.7 (8) | C4—C5—H5 | 119.3 |
C12—N12—Hg2 | 169.7 (8) | C6—C5—H5 | 119.3 |
N21—C21—Hg2 | 178.3 (7) | C5—C6—C1 | 121.1 (8) |
C6—C1—C2 | 117.8 (6) | C5—C6—H6 | 119.5 |
C6—C1—C7 | 123.0 (7) | C1—C6—H6 | 119.5 |
C2—C1—C7 | 119.1 (5) | C7i—C7—C1 | 121.3 (3) |
C3—C2—C1 | 120.1 (4) | C7i—C7—H7 | 119.3 |
C3—C2—C2i | 120.4 (3) | C1—C7—H7 | 119.3 |
C1—C2—C2i | 119.5 (3) | C8i—C8—C3 | 121.5 (3) |
C4—C3—C2 | 119.3 (7) | C8i—C8—H8 | 119.2 |
C4—C3—C8 | 122.7 (7) | C3—C8—H8 | 119.2 |
C2—C3—C8 | 118.0 (5) |
Symmetry code: (i) −x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | [Hg(CN)2]2·C16H10 |
Mr | 707.50 |
Crystal system, space group | Orthorhombic, Cmc21 |
Temperature (K) | 293 |
a, b, c (Å) | 11.9893 (3), 17.3480 (4), 8.6266 (2) |
V (Å3) | 1794.25 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 17.10 |
Crystal size (mm) | 0.24 × 0.12 × 0.10 |
Data collection | |
Diffractometer | Bruker P4 APEX diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.072, 0.181 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10971, 2251, 2105 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.666 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.021, 0.044, 1.01 |
No. of reflections | 2251 |
No. of parameters | 128 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.69, −1.07 |
Absolute structure | Flack (1983) |
Absolute structure parameter | 0.030 (14) |
Computer programs: SMART (Bruker, 1997), SMART, SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXP in SHELXTL/PC (Sheldrick, 1990) and SCHAKAL (Keller, 1999), SCHAKAL and publCIF (Westrip, 2007).
Hg1—C11 | 2.032 (9) | C11—N11 | 1.123 (14) |
Hg1—C12 | 2.033 (10) | C12—N12 | 1.132 (13) |
Hg2—C21 | 2.038 (5) | C21—N21 | 1.119 (6) |
C11—Hg1—C12 | 175.4 (4) | N12—C12—Hg1 | 179.7 (8) |
C21—Hg2—C21i | 173.6 (3) | N21—C21—Hg2 | 178.3 (7) |
N11—C11—Hg1 | 179.4 (10) |
Symmetry code: (i) −x+1, y, z. |
Hg1···N11A | 2.73 (1) |
Hg1···N21B | 2.87 (1) |
Hg1···C7B,C | 3.37 (1) |
Hg2···C7 | 3.30 (1) |
Hg2···C8(mol II) | 3.38 (1) |
Hg2···C8(mol III) | 3.24 (1) |
Hg2···N12 | 2.67 (1) |
The ambidentate cyano group is known as a good connecting unit because it can act as bridging ligand; it participates in the formation of structures with cavities and channels. These cavities/channels can contain, for example, organic molecules, and Hg(CN)2 is a good candidate to form compounds similar to the so-called Werner clathrate (Lipkowski, 1996).
The crystal structure of molecular Hg(CN)2, known for a long time (Hassel, 1926; Hanavolt et al., 1938; Zhdanov & Shugan, 1944; Jones, 1957; Hvoslef, 1958; Seccombe & Kennard, 1969; Reckeweg & Simon, 2002), has interactions between N atoms of one molecule and the Hg atoms of others. These interactions involve Hg···N distances ranging from 2.742 (3) to 3.060 (3) Å (Seccombe & Kennard, 1969), and give rise to a distorted octahedral coordination around Hg. Hg(CN)2 crystallizes in the noncentrosymmetric tetragonal space group I42d (No. 122), and the crystal framework contains cavities and channels propagated along the z axis and formed by the Hg···N interactions. In order to enable the Hg···N interactions, the molecules of mercuric cyanide are perpendicular to each other (Fig. 1).
Figs. 1(a) and 1(b) show the structure of Hg(CN)2 projected along the a and c axes, respectively. The channels have a nearly square section with a diagonal of nearly 6 Å; the cavities/channels are flexible and can be modified in order to contain molecules with suitable dimensions.
In the literature, very few examples exist of cocrystals between Hg(CN)2 and an organic molecule. One with tetrahydrofuran has the formula 5Hg(CN)2·4C4H8O (Frey & Ledésert, 1971) and another with methanol is Hg(CN)2·CH3OH (Ledesert et al., 1969). In both structures, an aggregate of Hg(CN)2 molecules, more or less a modification of pure Hg(CN)2 and always connected via Hg···N interactions, hosts organic molecules of tetrahydrofuran or of methanol.
A cocrystallization was performed between Hg(CN)2 and pyrene and the X-ray analysis of the resulting pink crystals reveals the formula 2Hg(CN)2·C16H10 (Fig. 2; Aschero et al., 2004). Tables 1 and 2 list the more significant interactions in the structure. Label A refers to atoms related by the crystallographic mirror plane at x = 0.5.
A noncentrosymmetric nonpolar crystal [Hg(CN)2] and a centrosymmetric nonpolar one (pyrene, P21/a) (Hazell et al., 1972) give rise to a noncentrosymmetric polar ([001] axis) cocrystal; the insertion of the organic molecule does not modify the noncentrosymmetric nature of the mercuric cyanide, but polarity is introduced along one axis. The modification of the Hg(CN)2 packing in the cocrystal gives rise to Hg···N interactions [2.67 (1) and 2.73 (1) Å] shorter than those in pure Hg(CN)2. The cavities inside the Hg(CN)2 framework (with a diagonal size of 8.6 Å), however, become larger than those in pure Hg(CN)2. The molecules of pyrene occupy the cavities aligning their planes parallel to one side of the nearly square cavity and not along the diagonal with the consequence of an interaction between the pyrene molecule and the Hg atoms. The perspective of the unit cell nearly along [100] shows that the planes of pyrene molecules are mutually perpendicular (Fig. 3), as in pure pyrene crystals.
Figs. 4 and 5 show the bonding and weak intermolecular interactions (Tables 1 and 2). Two types of Hg atoms exist in the unit cell with different surroundings. Atom Hg1, bonded to C11 and C12, lies with its two CN groups on the crystallographic mirror plane and coordinates three N atoms of other molecules and one pyrene molecule, assuming an octahedral coordination (Fig. 4). Atom Hg2, bonded to C21 and with only the Hg atom lying on the mirror plane, coordinates atom N12 of another molecule and also three pyrene molecules via C7—C7A and C8—C8A bonds (Fig. 5); the pyrene molecule is cut perpendicularly by the crystallographic mirror plane. Atom Hg2 also has a distorted octahedral coordination. The Hg(CN)2 molecules are not linear (Table 1). With respect to the coordination of pyrene to the Hg atoms, the H atoms of C7 and C8, owing to the short Hg···H distances of nearly 3.4 Å and to the orientation of the C—H bond with respect to Hg, seem have a weak interaction with the metal atom. Therefore, the planar H—C—C—H atom chains seem to interact with Hg atoms.