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Cocrystallization of pyrene with Hg(CN)2 gives a new clathrate, namely bis­[dicyanidomercury(II)] pyrene solvate, [Hg(CN)2]2·C16H10, with mol­ecules of pyrene embedded in cavities of the slightly deformed structure of the mercuric salt; the weak inter­molecular N...Hg inter­actions present in pure Hg(CN)2 are maintained in the cocrystal. The X-ray analysis of the resulting compound reveals unusual organic–inorganic inter­actions. One mol­ecule of Hg(CN)2 lies on a crystallographic mirror plane, while in the other, only the Hg atom is on the mirror plane. The mol­ecule of pyrene is cut by a mirror plane perpendicular to the plane of the mol­ecule.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107023463/fa3083sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107023463/fa3083Isup2.hkl
Contains datablock I

CCDC reference: 609776

Comment top

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.

Related literature top

For related literature, see: Aschero et al. (2004); Frey & Ledésert (1971); Hanavolt et al. (1938); Hassel (1926); Hazell et al. (1972); Hvoslef (1958); Jones (1957); Ledesert et al. (1969); Lipkowski (1996); Reckeweg & Simon (2002); Seccombe & Kennard (1969); Zhdanov & Shugan (1944).

Experimental top

Hg(CN)2 was dissolved in acetone and pyrene was added (Aschero et al., 2004).

Refinement top

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.

Computing details top

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).

Figures top
[Figure 1] Fig. 1. The structure of Hg(CN)2, projected along (a) the a axis and (b) the c axis.
[Figure 2] Fig. 2. A view of the 2Hg(CN)2·C16H10 unit, with the atom labelling and with displacement ellipsoids shown at the 50% probability level; atoms labelled with the suffix A are related by the symmetry operation (-x + 1, y, z).
[Figure 3] Fig. 3. The crystal packing of 2Hg(CN)2·C16H10, viewed approximately along the a axis. The shortest weak bonds, between mutually perpendicular Hg(CN)2 molecules, are shown as dashed lines.
[Figure 4] Fig. 4. The coordination around atom Hg1. [Symmetry codes: Hg1A, C11A and N11A: x, -y + 1, z + 1/2; Hg2A, C21A and N21A: -x + 1/2, -y + 1/2, z - 1/2; Hg2B, C21B and N21B: x + 1/2, -y + 1/2, z - 1/2; C7A: x, y, z - 1; C7AA: -x + 1, y, z - 1.]
[Figure 5] Fig. 5. The coordination around atom Hg2. Pyrene molecules I, II and III are at (x, y, z), (x, -y, z - 1/2) and (x, y, z - 1), respectively. The suffix A indicates the symmetry relations (1 - x, y, z) for I, (1 - x, -y, z - 1/2) for II and (1 - x, y, z - 1) for III.
bis[dicyanidomercury(II)] pyrene solvate top
Crystal data top
[Hg(CN)2]2·C16H10Dx = 2.619 Mg m3
Mr = 707.50Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmc21Cell parameters from 30 reflections
a = 11.9893 (3) Åθ = 4.0–25.0°
b = 17.3480 (4) ŵ = 17.10 mm1
c = 8.6266 (2) ÅT = 293 K
V = 1794.25 (7) Å3Lamina, pink
Z = 40.24 × 0.12 × 0.10 mm
F(000) = 1272
Data collection top
Bruker P4 APEX
diffractometer
2251 independent reflections
Radiation source: fine-focus sealed tube2105 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.036
ϕ scansθmax = 28.3°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 1515
Tmin = 0.072, Tmax = 0.181k = 2323
10971 measured reflectionsl = 1110
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-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 = 1.01Δρmax = 0.69 e Å3
2251 reflectionsΔρmin = 1.07 e Å3
128 parametersExtinction correction: refined, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.00131 (4)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983)
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.030 (14)
Crystal data top
[Hg(CN)2]2·C16H10V = 1794.25 (7) Å3
Mr = 707.50Z = 4
Orthorhombic, Cmc21Mo Kα radiation
a = 11.9893 (3) ŵ = 17.10 mm1
b = 17.3480 (4) ÅT = 293 K
c = 8.6266 (2) Å0.24 × 0.12 × 0.10 mm
Data collection top
Bruker P4 APEX
diffractometer
2251 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
2105 reflections with I > 2σ(I)
Tmin = 0.072, Tmax = 0.181Rint = 0.036
10971 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.021H-atom parameters constrained
wR(F2) = 0.044Δρmax = 0.69 e Å3
S = 1.01Δρmin = 1.07 e Å3
2251 reflectionsAbsolute structure: Flack (1983)
128 parametersAbsolute structure parameter: 0.030 (14)
1 restraint
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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Hg10.50000.38506 (3)0.37350 (4)0.02913 (13)
Hg20.50000.13641 (2)0.07906 (4)0.02965 (12)
C110.50000.4584 (5)0.5572 (9)0.0309 (19)
N110.50000.4995 (7)0.6578 (10)0.050 (2)
C120.50000.3046 (5)0.2022 (10)0.031 (2)
N120.50000.2600 (6)0.1063 (11)0.047 (3)
C210.3303 (4)0.1319 (3)0.0887 (7)0.0322 (12)
N210.2373 (4)0.1276 (5)0.093 (3)0.052 (2)
C10.3816 (4)0.1771 (3)0.4988 (7)0.0318 (13)
C20.4400 (4)0.1257 (3)0.5983 (6)0.0279 (11)
C30.3805 (5)0.0734 (3)0.6925 (7)0.0338 (14)
C40.2636 (5)0.0742 (7)0.6895 (12)0.048 (2)
H40.22370.04150.75440.058*
C50.2080 (6)0.1228 (5)0.5920 (10)0.0514 (18)
H50.13050.12090.58780.062*
C60.2642 (5)0.1744 (6)0.4998 (12)0.049 (2)
H60.22410.20800.43700.058*
C70.4444 (5)0.2304 (4)0.4030 (7)0.0391 (16)
H70.40640.26520.34030.047*
C80.4438 (5)0.0223 (4)0.7928 (8)0.0410 (17)
H80.40590.01110.85850.049*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg10.03033 (15)0.0294 (2)0.0276 (3)0.0000.0000.00481 (19)
Hg20.02216 (14)0.0327 (2)0.0341 (3)0.0000.0000.0019 (2)
C110.026 (4)0.041 (5)0.025 (4)0.0000.0000.008 (4)
N110.055 (5)0.049 (5)0.047 (6)0.0000.0000.021 (5)
C120.020 (4)0.035 (5)0.039 (5)0.0000.0000.004 (4)
N120.040 (5)0.050 (6)0.051 (6)0.0000.0000.018 (5)
C210.028 (3)0.033 (3)0.036 (3)0.001 (2)0.000 (3)0.002 (2)
N210.031 (3)0.059 (4)0.065 (6)0.000 (3)0.000 (5)0.008 (3)
C10.036 (3)0.027 (3)0.033 (3)0.004 (2)0.010 (3)0.011 (3)
C20.035 (3)0.025 (2)0.023 (3)0.001 (2)0.002 (2)0.0093 (16)
C30.044 (3)0.033 (4)0.025 (3)0.009 (3)0.001 (3)0.010 (3)
C40.040 (4)0.056 (6)0.048 (5)0.013 (4)0.008 (4)0.010 (4)
C50.037 (3)0.057 (4)0.060 (5)0.002 (3)0.005 (4)0.015 (3)
C60.042 (4)0.047 (6)0.057 (5)0.008 (4)0.013 (4)0.011 (5)
C70.059 (4)0.026 (3)0.032 (3)0.008 (3)0.006 (3)0.005 (3)
C80.057 (4)0.038 (4)0.028 (3)0.008 (3)0.012 (3)0.002 (3)
Geometric parameters (Å, º) top
Hg1—C112.032 (9)C3—C41.402 (7)
Hg1—C122.033 (10)C3—C81.453 (8)
Hg2—C212.038 (5)C4—C51.364 (12)
Hg2—N122.675 (10)C4—H40.9300
C11—N111.123 (14)C5—C61.374 (11)
C12—N121.132 (13)C5—H50.9300
C21—N211.119 (6)C6—H60.9300
C1—C61.407 (7)C7—C7i1.332 (13)
C1—C21.424 (7)C7—H70.9300
C1—C71.450 (8)C8—C8i1.347 (12)
C2—C31.411 (7)C8—H80.9300
C2—C2i1.438 (10)
C11—Hg1—C12175.4 (4)C5—C4—C3120.4 (8)
C21—Hg2—C21i173.6 (3)C5—C4—H4119.8
C21—Hg2—N1293.15 (14)C3—C4—H4119.8
N11—C11—Hg1179.4 (10)C4—C5—C6121.3 (6)
N12—C12—Hg1179.7 (8)C4—C5—H5119.3
C12—N12—Hg2169.7 (8)C6—C5—H5119.3
N21—C21—Hg2178.3 (7)C5—C6—C1121.1 (8)
C6—C1—C2117.8 (6)C5—C6—H6119.5
C6—C1—C7123.0 (7)C1—C6—H6119.5
C2—C1—C7119.1 (5)C7i—C7—C1121.3 (3)
C3—C2—C1120.1 (4)C7i—C7—H7119.3
C3—C2—C2i120.4 (3)C1—C7—H7119.3
C1—C2—C2i119.5 (3)C8i—C8—C3121.5 (3)
C4—C3—C2119.3 (7)C8i—C8—H8119.2
C4—C3—C8122.7 (7)C3—C8—H8119.2
C2—C3—C8118.0 (5)
Symmetry code: (i) x+1, y, z.

Experimental details

Crystal data
Chemical formula[Hg(CN)2]2·C16H10
Mr707.50
Crystal system, space groupOrthorhombic, Cmc21
Temperature (K)293
a, b, c (Å)11.9893 (3), 17.3480 (4), 8.6266 (2)
V3)1794.25 (7)
Z4
Radiation typeMo Kα
µ (mm1)17.10
Crystal size (mm)0.24 × 0.12 × 0.10
Data collection
DiffractometerBruker P4 APEX
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.072, 0.181
No. of measured, independent and
observed [I > 2σ(I)] reflections
10971, 2251, 2105
Rint0.036
(sin θ/λ)max1)0.666
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.044, 1.01
No. of reflections2251
No. of parameters128
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.69, 1.07
Absolute structureFlack (1983)
Absolute structure parameter0.030 (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).

Selected geometric parameters (Å, º) top
Hg1—C112.032 (9)C11—N111.123 (14)
Hg1—C122.033 (10)C12—N121.132 (13)
Hg2—C212.038 (5)C21—N211.119 (6)
C11—Hg1—C12175.4 (4)N12—C12—Hg1179.7 (8)
C21—Hg2—C21i173.6 (3)N21—C21—Hg2178.3 (7)
N11—C11—Hg1179.4 (10)
Symmetry code: (i) x+1, y, z.
Intermolecular contact distances (Å); Mol. I and Mol. I correspond to the molecules defined in Fig. 5 top
Hg1···N11A2.73 (1)
Hg1···N21B2.87 (1)
Hg1···C7B,C3.37 (1)
Hg2···C73.30 (1)
Hg2···C8(mol II)3.38 (1)
Hg2···C8(mol III)3.24 (1)
Hg2···N122.67 (1)
 

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