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Acta Cryst. (2009). E65, m503    [ doi:10.1107/S160053680901280X ]

Bis(guanidinium) tetraiodidomercurate(II)

H. Terao, T. M. Gesing, H. Ishihara, Y. Furukawa and B. T. Gowda

Abstract top

The Hg atom in the crystal structure of the title compound, (CH6N3)2[HgI4], is tetrahedrally coordinated by four I atoms. The [HgI4]2- ions are interconnected to the [C(NH2)3]+ ions by N-H...I hydrogen bonds, forming a three-dimensional network. The four different observed Hg-I distances [2.760 (2), 2.7762 (15), 2.8098 (14) and 2.833 (2) Å] are consistent with four different 127I NQR frequencies observed, showing the existence of four unique I atoms in the tetraiodidomercurate unit.

Comment top

The ability of guanidium ion, [C(NH2)3]+ in making hydrogen bonds and its unique planar shape has been recognized (Terao et al., 2000). Further, the guanidium ions tend to undergo reorientation motions about their (pseudo) C3 axes in the crystals. Due to the soft nature, Hg atoms are amenable to polarization and thus the Hg-halogen bonds are sensitive to the intermolecular interactions such as hydrogen bonding (Ishihara et al., 2002). This was evident in the halogen NQR of the Hg compounds in which the resonance frequencies are widely spread (Furukawa et al., 2005). Thus the study of the structure and bonding of this class of compounds is interesting. As a part of our investigations in this direction (Terao et al., 2009), we report herein the crystal structure of Guanidinium tetraiodomercurate(II) (I). In the structure, the mercury atom is tetrahedrally coordinated by four iodine atoms and the resulting HgI4 tetrahedra are interconnected to the [C(NH2)3]+ ions by iodine-hydrogen bonds forming a three-dimensional network (Fig. 1). Four different Hg—I distances were observed which are consistent with four different I-127 NQR frequencies observed (Furukawa et al., 2005), establishing the existence of four inequivalent I atoms in the tetraiodomercurate unit. The packing diagram of the crystal structure, as viewed in the direction of c axis is shown in Fig. 3.

Related literature top

For synthetic methods, see: Furukawa et al. (2005); For the ability of the guanidinium ion to make hydrogen bonds and its unique planar shape, see: Terao et al. (2000). Hg–halogen bonds are sensitive to intermolecular interactions such as hydrogen bonding (Ishihara et al., 2002), as evidenced by the halogen NQR of Hg compounds in which the resonance frequencies are widely spread (Furukawa et al., 2005). For background to this study, see: Terao et al. (2009)

Experimental top

Guanidinium tetraiodomercurate(II) was prepared by slow concentration of methanolic solution containing mercuric iodide (0.01 mol, 4.54 g) and guanidium iodide (0.024 mol, 4.48 g) in slightly more than 1:2 molar ratio. The purity of the compound was checked by elemental analysis and characterized by its NMR and NQR spectra (Furukawa et al., 2005). The single crystals used in X-ray diffraction studies were grown in methanolic solution by a slow evaporation at room temperature.

Refinement top

The N—H distances were restrained to 0.87–0.88 Å and the coordinates of the H atoms were refined with isotropic displacement parameters set to 1.2 times of the Ueq of the parent atom.

Computing details top

Data collection: EXPOSE (Stoe & Cie, 1999); cell refinement: CELL (Stoe & Cie, 1999); data reduction: XPREP (Bruker, 2003); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL93 (Sheldrick, 2008); molecular graphics: DIAMOND (Crystal Impact, 2008) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL93 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure of (I), showing the atom labeling scheme. The displacement ellipsoids are drawn at the 50% probability level. The H atoms are represented as small spheres of arbitrary radii.
[Figure 2] Fig. 2. Two distinct guanidinium ions in the crystal structure of (I) along with the numbering of the atoms.
[Figure 3] Fig. 3. Packing diagram of (I) as viewed in the direction of c axis.
Bis(guanidinium) tetraiodidomercurate(II) top
Crystal data top
(CH6N3)2[HgI4]Z = 2
Mr = 828.37F(000) = 716
Triclinic, P1Dx = 3.401 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.981 (2) ÅCell parameters from 2000 reflections
b = 8.996 (2) Åθ = 2.7–28.0°
c = 12.302 (3) ŵ = 17.13 mm−1
α = 105.80 (3)°T = 298 K
β = 95.79 (4)°Cylindric, yellow
γ = 118.46 (2)°0.42 × 0.38 × 0.32 mm
V = 808.9 (5) Å3
Data collection top
Stoe IPDS-I
diffractometer		3613 independent reflections
Radiation source: fine-focus sealed tube1846 reflections with I > 2σ(I)
graphiteRint = 0.118
imaging plate dynamic profile intergration scansθmax = 28.0°, θmin = 2.7°
Absorption correction: numerical
(X-SHAPE; Stoe & Cie, 1999)		h = −11→11
Tmin = 0.017, Tmax = 0.057k = −11→11
14500 measured reflectionsl = −16→16
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.059H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.135 w = 1/[σ2(Fo2) + (0.0353P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.81(Δ/σ)max < 0.001
3613 reflectionsΔρmax = 3.08 e Å−3
156 parametersΔρmin = −2.71 e Å−3
32 restraintsExtinction correction: SHELXL93 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.00075 (10)
Crystal data top
(CH6N3)2[HgI4]γ = 118.46 (2)°
Mr = 828.37V = 808.9 (5) Å3
Triclinic, P1Z = 2
a = 8.981 (2) ÅMo Kα radiation
b = 8.996 (2) ŵ = 17.13 mm−1
c = 12.302 (3) ÅT = 298 K
α = 105.80 (3)°0.42 × 0.38 × 0.32 mm
β = 95.79 (4)°
Data collection top
Stoe IPDS-I
diffractometer		3613 independent reflections
Absorption correction: numerical
(X-SHAPE; Stoe & Cie, 1999)		1846 reflections with I > 2σ(I)
Tmin = 0.017, Tmax = 0.057Rint = 0.118
14500 measured reflectionsθmax = 28.0°
Refinement top
R[F2 > 2σ(F2)] = 0.059H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.135Δρmax = 3.08 e Å−3
S = 0.81Δρmin = −2.71 e Å−3
3613 reflectionsAbsolute structure: ?
156 parametersFlack parameter: ?
32 restraintsRogers parameter: ?
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
Hg10.34641 (9)0.61562 (10)0.73508 (6)0.0667 (3)
I10.0809 (2)0.5696 (2)0.84518 (10)0.0650 (3)
I20.53156 (14)0.4740 (2)0.82071 (9)0.0607 (3)
I30.58185 (14)0.9944 (2)0.80058 (10)0.0627 (3)
I40.22651 (14)0.4550 (2)0.49342 (9)0.0673 (3)
C10.0864 (17)0.0540 (15)0.8824 (8)0.051 (3)
N110.2387 (17)0.0661 (18)0.9149 (13)0.072 (4)
H11A0.246 (12)−0.030 (7)0.902 (4)0.12 (3)*
H11B0.333 (7)0.174 (5)0.9499 (19)0.12 (3)*
N120.0824 (14)0.2000 (14)0.9034 (11)0.066 (4)
H12A0.179 (2)0.3056 (13)0.9387 (16)0.12 (3)*
H12B−0.0169 (19)0.193 (2)0.8825 (17)0.12 (3)*
N13−0.0542 (16)−0.1065 (19)0.8300 (14)0.080 (4)
H13A−0.152 (4)−0.111 (8)0.810 (3)0.12 (3)*
H13B−0.054 (9)−0.207 (5)0.815 (3)0.12 (3)*
C20.2590 (18)−0.012 (2)0.5152 (16)0.067 (4)
N210.4067 (18)0.136 (2)0.5198 (14)0.086 (5)
H21A0.453 (8)0.138 (11)0.461 (4)0.12 (3)*
H21B0.457 (8)0.232 (6)0.584 (3)0.12 (3)*
N220.1800 (17)−0.158 (2)0.4211 (13)0.092 (5)
H22A0.085 (3)−0.246 (11)0.427 (11)0.12 (3)*
H22B0.212 (14)−0.173 (18)0.357 (5)0.12 (3)*
N230.193 (2)−0.009 (3)0.6078 (14)0.110 (7)
H23A0.098 (3)−0.100 (11)0.610 (12)0.12 (3)*
H23B0.252 (13)0.093 (8)0.668 (7)0.12 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg10.0686 (4)0.0651 (5)0.0641 (4)0.0319 (4)0.0196 (3)0.0262 (4)
I10.0802 (7)0.0566 (7)0.0743 (7)0.0413 (6)0.0367 (6)0.0307 (6)
I20.0632 (6)0.0535 (7)0.0608 (6)0.0271 (6)0.0115 (5)0.0233 (5)
I30.0605 (6)0.0547 (7)0.0725 (7)0.0284 (6)0.0193 (5)0.0259 (6)
I40.0606 (6)0.0668 (8)0.0540 (6)0.0182 (6)0.0137 (5)0.0237 (6)
C10.060 (9)0.039 (10)0.050 (8)0.023 (8)0.014 (7)0.017 (8)
N110.063 (9)0.069 (11)0.111 (12)0.045 (8)0.032 (9)0.047 (10)
N120.063 (8)0.039 (9)0.077 (9)0.022 (7)−0.004 (7)0.009 (8)
N130.068 (9)0.053 (11)0.113 (13)0.033 (9)0.004 (9)0.027 (10)
C20.053 (9)0.047 (12)0.076 (12)0.014 (9)0.003 (9)0.016 (10)
N210.079 (10)0.048 (11)0.088 (11)0.005 (9)0.033 (9)0.013 (9)
N220.076 (10)0.054 (12)0.060 (9)−0.012 (9)0.006 (8)−0.006 (8)
N230.074 (11)0.096 (15)0.077 (11)−0.007 (10)0.032 (10)0.010 (11)
Geometric parameters (Å, °) top
Hg1—I42.760 (2)N11—H11A0.88 (8)
Hg1—I12.7762 (15)N11—H11B0.87 (5)
Hg1—I22.8098 (14)N12—H12A0.87 (2)
Hg1—I32.833 (2)N12—H12B0.87 (2)
I1—H13Bi2.87 (7)N13—H13A0.87 (5)
I1—H11Ai3.00 (4)N13—H13B0.88 (6)
I2—H21B2.91 (3)C2—N221.30 (2)
I2—H23B2.99 (5)C2—N211.34 (2)
I3—H13Aii2.97 (5)C2—N231.34 (2)
I3—H22Biii3.05 (7)N21—H21B0.87 (4)
I3—H21Aiii3.03 (4)N21—H21A0.87 (7)
I3—H12Bii3.057 (19)N22—H22B0.87 (9)
C1—N131.29 (2)N22—H22A0.87 (9)
C1—N121.29 (2)N23—H23A0.87 (9)
C1—N111.32 (2)N23—H23B0.87 (8)
I4—Hg1—I1113.75 (5)H13A—N13—H13B120 (6)
I4—Hg1—I2109.54 (5)H13A—N13—C1117.4 (42)
I1—Hg1—I2108.81 (4)H13B—N13—C1122.5 (42)
I4—Hg1—I3109.38 (6)N22—C2—N21120.3 (17)
I1—Hg1—I3107.26 (5)N22—C2—N23119.8 (15)
I2—Hg1—I3107.93 (5)N21—C2—N23119.9 (17)
N13—C1—N12121.1 (14)H21B—N21—H21A120 (7)
N13—C1—N11119.7 (14)H21B—N21—C2118.6 (57)
N12—C1—N11119.2 (14)H21A—N21—C2121.3 (58)
H11A—N11—H11B120 (7)H22B—N22—H22A120 (11)
H11A—N11—C1120 (11)H22B—N22—C2126.5 (91)
H11B—N11—C1118.4 (62)H22A—N22—C2113.5 (90)
H12A—N12—H12B120 (2)H23A—N23—H23B120 (11)
H12A—N12—C1119.9 (19)H23A—N23—C2125.3 (100)
H12B—N12—C1120.0 (18)H23B—N23—C2114.6 (100)
N13—C1—N11—H11A0.0 (6)N22—C2—N21—H21B180.0 (5)
N12—C1—N11—H11A−180.0 (5)N23—C2—N21—H21B−0.1 (6)
N13—C1—N11—H11B180.0 (6)N22—C2—N21—H21A0.0 (5)
N12—C1—N11—H11B0.0 (5)N23—C2—N21—H21A179.9 (6)
N13—C1—N12—H12A−180.0 (6)N21—C2—N22—H22B0.1 (6)
N11—C1—N12—H12A0.0 (4)N23—C2—N22—H22B−179.9 (6)
N13—C1—N12—H12B0.1 (9)N21—C2—N22—H22A180.0 (5)
N11—C1—N12—H12B−180.0 (8)N23—C2—N22—H22A0.1 (6)
N12—C1—N13—H13A−0.1 (10)N22—C2—N23—H23A−0.2 (11)
N11—C1—N13—H13A179.9 (7)N21—C2—N23—H23A179.9 (8)
N12—C1—N13—H13B−179.9 (7)N22—C2—N23—H23B−179.9 (7)
N11—C1—N13—H13B0.1 (10)N21—C2—N23—H23B0.1 (9)
Symmetry codes: (i) x, y+1, z; (ii) x+1, y+1, z; (iii) −x+1, −y+1, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N11—H11A···I1iv0.87 (4)3.00 (4)3.78 (2)151 (2)
N12—H12A···I20.87 (4)3.46 (2)3.83 (2)123 (2)
N13—H13A···I3v0.87 (4)2.96 (4)3.80 (2)161 (2)
N13—H13B···I1iv0.87 (4)2.88 (4)3.69 (2)156 (2)
N21—H21A···I3iii0.87 (4)3.03 (4)3.82 (2)151 (2)
N21—H21B···I20.87 (4)2.91 (4)3.74 (2)162 (6)
N22—H22A···I4vi0.87 (9)2.98 (4)3.82 (2)162 (2)
N22—H22B···I3iii0.87 (10)3.05 (4)3.81 (2)147 (2)
N23—H23A···I4vi0.87 (9)2.91 (4)3.71 (2)153 (2)
N23—H23B···I20.87 (4)2.99 (4)3.82 (2)161 (6)
Symmetry codes: (iv) x, y−1, z; (v) x−1, y−1, z; (iii) −x+1, −y+1, −z+1; (vi) −x, −y, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N11—H11A···I1i0.87 (4)3.00 (4)3.78 (2)151 (2)
N12—H12A···I20.87 (4)3.46 (2)3.83 (2)123 (2)
N13—H13A···I3ii0.87 (4)2.96 (4)3.80 (2)161 (2)
N13—H13B···I1i0.87 (4)2.88 (4)3.69 (2)156 (2)
N21—H21A···I3iii0.87 (4)3.03 (4)3.82 (2)151 (2)
N21—H21B···I20.87 (4)2.91 (4)3.74 (2)162 (6)
N22—H22A···I4iv0.87 (9)2.98 (4)3.82 (2)162 (2)
N22—H22B···I3iii0.87 (10)3.05 (4)3.81 (2)147 (2)
N23—H23A···I4iv0.87 (9)2.91 (4)3.71 (2)153 (2)
N23—H23B···I20.87 (4)2.99 (4)3.82 (2)161 (6)
Symmetry codes: (i) x, y−1, z; (ii) x−1, y−1, z; (iii) −x+1, −y+1, −z+1; (iv) −x, −y, −z+1.
Acknowledgements top

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references
References top

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