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The double mercury salt [Hg(C5H8N2)2][HgClI3]·C2H6OS was prepared and its structure characterized. The [Hg(C5H8N2)2]2+ cation lies about an inversion centre and the [HgClI3]2- anion lies on a mirror plane. Cations and anions are linked to form a one-dimensional polymer by weak Hg...Cl interactions [Hg...Cl 3.3744 (3) Å]. The mercury-carbene bond distance [2.076 (7) Å] is typical of a dicationic mercury-carbene species.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199012640/ta1265sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270199012640/ta1265Isup2.hkl
Contains datablock I

CCDC reference: 140926

Comment top

There has been considerable interest recently in N,N'-dialkylimidazol-2-ylidene ligands as they bind strongly to a number of transition metals, in some cases forming complexes that are unusually robust for carbene ligands (Regitz, 1996; Herrmann et al., 1996 and Herrmann & Köcher, 1997).

Whilst attempting to prepare a bis(N,N'-dimethylimidazol-2-ylidene) mercury salt for possible use as a transmetallation reagent, we produced the mercury double salt, (I), which has the formulation (N,N'-dimethylimidazol-2-ylidene)2Hg·HgClI3 and crystallizes with one disordered molecule of dimethyl sulfoxide. The salt contains two separate mercury-containing moieties. The organometallic part features the two carbene ligands coordinated to the central Hg atom in a strictly linear arrangement which is enforced by crystallographic inversion symmetry. This linear coordination has also been observed in related structures, such as that of (N,N'-diphenyimidazol-2-ylidene)2Hg·(ClO4)2, (II), (Luger & Ruban, 1971), in which the perchlorate anions do not distort the preferred linear coordination of the Hg atom. A different arrangement is found in the case of (N,N'-dimethylimidazol-2-ylidene)2HgCl2, (III), (Arduengo et al., 1996), wherein the two chloride anions are coordinated to mercury, and the metal coordination is distorted toward tetrahedral.

The HgClI32− counterion lies on a crystallographic mirror plane and exhibits dietorted tetrahedral geometry in which the Cl—Hg—I angles are reduced and the I—Hg—I angles increased compared to regular tetrahedral angles to accomodate the larger I atoms. The structure is polymeric through weak interactions between the carbene Hg and the chlorine atoms, which make an approach of 3.3744 (3) Å, with the Cl bridging two Hg centres. The weak interactions show the organometallic moiety to be cloase to square planar, C1—Hg—Cl1 89.5 (2) Å. The Hg1—Cl1—Hg1' (X,0.5+Y, Z) angle is 177.85 (9) Å.

Experimental top

N,N'-Dimethylimidazolium iodide (prepared as described by Sarasin, 1923) (5.3 g) was dissolved in dimethyl sulfoxide (25 ml), to which was added HgCl2 (3.0 g) with stirring. A solution of sodium bicarbonate (1 g) in water (40 ml) was added, followed by ethanol (30 ml). The solution was allowed to stand overnight; during this time a considerable amount of white precipitate formed which was collected by filtration to give the pure title compound (8.7 g, 68% based on organic starting material).

1H NMR: δ 7.62 (s, 4H, H3 + H4), 3.98 (s, 12H, N—CH3). Analysis calculated for [Hg(C5H8N2)2][HgClI3]·C2H6OS: C, 13.27; H, 2.04; N, 5.15; found: C, 13.50; H, 1.71; N, 4.79%.

Crystals were grown by dissolving a small amount of the substrate in dimethyl sulfoxide (70%) and ethanol (30%). Each day a small portion of ethanol (ca 5%) was added, and crystals formed gradually as the overall proportion of ethanol increased.

Refinement top

The dimethyl sulfoxide molecule is disordered with the C and O atoms lying on the mirror plane with the sulfur atom disordered either side of the mirror plane. The maxima and minima in the difference map are 0.79 Å from Hg2 and 0.58 Å from I1, respectively.

Computing details top

Data collection: SMART (Siemens, 1994a); cell refinement: SAINT (Siemens, 1994a); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: SHELXTL (Siemens, 1994b); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The extended structure of (I) showing the linking of cations and anions (50% probability displacement ellipsoids). H atoms and solvent of crystallization removed forclarity.
Bis(N,N'-dimethylimidazol-2-ylidene)mercury(II) Chlorotriiodomercurate(II) Dimethylsulphoxide solvate. top
Crystal data top
[Hg(C5H8N2)2][HgClI3].C2H6OSDx = 3.008 Mg m3
Mr = 1087.73Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, PnmaCell parameters from 7498 reflections
a = 9.6119 (1) Åθ = 1.9–28.3°
b = 13.4954 (1) ŵ = 16.83 mm1
c = 18.514 (3) ÅT = 203 K
V = 2401.57 (5) Å3Needle, colourless
Z = 40.38 × 0.18 × 0.05 mm
F(000) = 1928
Data collection top
Siemens SMART CCD area-detector
diffractometer
2937 independent reflections
Radiation source: fine-focus sealed tube2317 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.051
ω scansθmax = 28.3°, θmin = 1.9°
Absorption correction: multi-scan
(Blessing, 1995)
h = 1112
Tmin = 0.060, Tmax = 0.487k = 1617
14997 measured reflectionsl = 2223
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.110H-atom parameters constrained
S = 1.05Calculated w = 1/[σ2(Fo2) + (0.0576P)2 + 11.9641P]
where P = (Fo2 + 2Fc2)/3
2937 reflections(Δ/σ)max = 0.018
128 parametersΔρmax = 1.33 e Å3
0 restraintsΔρmin = 2.28 e Å3
Crystal data top
[Hg(C5H8N2)2][HgClI3].C2H6OSV = 2401.57 (5) Å3
Mr = 1087.73Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 9.6119 (1) ŵ = 16.83 mm1
b = 13.4954 (1) ÅT = 203 K
c = 18.514 (3) Å0.38 × 0.18 × 0.05 mm
Data collection top
Siemens SMART CCD area-detector
diffractometer
2937 independent reflections
Absorption correction: multi-scan
(Blessing, 1995)
2317 reflections with I > 2σ(I)
Tmin = 0.060, Tmax = 0.487Rint = 0.051
14997 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0380 restraints
wR(F2) = 0.110H-atom parameters constrained
S = 1.05Δρmax = 1.33 e Å3
2937 reflectionsΔρmin = 2.28 e Å3
128 parameters
Special details top

Experimental. The data collection nominally covered over a hemisphere of reciprocal space, by a combination of three sets of exposures; each set had a different ϕ angle for the crystal and each exposure covered 0.3° in ω. Crystal decay was monitored by repeating the initial frames at the end of data collection and analyzing the duplicate reflections.

Refinement. The solution was determined by direct methods. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were placed geometrically and refined with a riding model (including free rotation about C—C bonds for methyl groups), and with Uiso constrained to be 1.2 (1.5 for methyl groups) times Ueq of the carrier atom.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Hg10.50000.00000.50000.03826 (15)
N10.3081 (7)0.0459 (5)0.6294 (4)0.0362 (15)
N20.4717 (7)0.0541 (5)0.6607 (3)0.0332 (15)
C10.4214 (8)0.0030 (6)0.6044 (4)0.0322 (17)
C20.2884 (11)0.0244 (7)0.7009 (5)0.048 (2)
H2A0.21720.04870.73080.058*
C30.3919 (11)0.0390 (7)0.7203 (5)0.048 (2)
H3A0.40560.06710.76620.057*
C40.2185 (10)0.1117 (8)0.5866 (6)0.053 (2)
H4A0.27520.15000.55340.079*
H4B0.15220.07240.55940.079*
H4C0.16880.15630.61860.079*
C50.5940 (10)0.1170 (7)0.6592 (5)0.046 (2)
H5A0.58410.16600.62120.069*
H5B0.67580.07680.65000.069*
H5C0.60390.15020.70540.069*
Hg20.32417 (5)0.25000.38947 (2)0.03989 (15)
I10.17973 (6)0.08099 (5)0.42725 (4)0.05136 (19)
I20.47837 (9)0.25000.26846 (4)0.0458 (2)
Cl10.5064 (3)0.25000.49906 (14)0.0359 (6)
S10.5307 (6)0.2056 (3)0.8693 (3)0.0471 (11)0.50
O10.4624 (12)0.25000.8022 (5)0.068 (3)
C60.6926 (17)0.25000.8765 (11)0.087 (6)
H6A0.74630.23040.83450.130*0.50
H6B0.73580.22360.91980.130*0.50
H6C0.68950.32170.87950.130*0.50
C70.437 (2)0.25000.9406 (8)0.077 (5)
H7A0.34320.22430.93840.116*0.50
H7B0.43490.32180.93860.116*0.50
H7C0.48070.22920.98540.116*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg10.0309 (2)0.0678 (3)0.0161 (2)0.0077 (2)0.00256 (16)0.00307 (19)
N10.040 (4)0.044 (4)0.025 (3)0.003 (3)0.011 (3)0.002 (3)
N20.041 (4)0.041 (4)0.017 (3)0.003 (3)0.000 (3)0.000 (3)
C10.033 (4)0.041 (4)0.023 (4)0.001 (3)0.010 (3)0.003 (3)
C20.059 (6)0.057 (6)0.030 (5)0.004 (5)0.021 (4)0.003 (4)
C30.066 (6)0.055 (5)0.023 (4)0.004 (5)0.009 (4)0.002 (4)
C40.041 (5)0.065 (6)0.052 (6)0.014 (5)0.015 (5)0.011 (5)
C50.050 (5)0.055 (5)0.033 (5)0.006 (4)0.008 (4)0.002 (4)
Hg20.0362 (3)0.0552 (3)0.0282 (3)0.0000.00212 (19)0.000
I10.0395 (3)0.0598 (4)0.0548 (4)0.0027 (3)0.0027 (3)0.0009 (3)
I20.0429 (5)0.0682 (6)0.0262 (4)0.0000.0004 (3)0.000
Cl10.0319 (13)0.0536 (17)0.0222 (14)0.0000.0046 (10)0.000
S10.066 (3)0.041 (2)0.035 (2)0.002 (2)0.001 (2)0.0045 (19)
O10.070 (7)0.110 (9)0.025 (5)0.0000.009 (5)0.000
C60.049 (10)0.15 (2)0.065 (12)0.0000.009 (8)0.000
C70.077 (12)0.124 (16)0.031 (8)0.0000.004 (8)0.000
Geometric parameters (Å, º) top
Hg1—C12.076 (7)C2—C31.360 (15)
Hg1—C1i2.076 (7)Hg2—Cl12.680 (3)
N1—C11.355 (10)Hg2—I22.6863 (9)
N1—C21.367 (11)Hg2—I1ii2.7602 (7)
N1—C41.470 (12)Hg2—I12.7602 (7)
N2—C11.340 (10)S1—O11.528 (11)
N2—C31.359 (11)S1—C61.672 (16)
N2—C51.449 (11)S1—C71.705 (16)
C1—Hg1—C1i180.0N2—C3—C2107.0 (8)
C1—N1—C2109.7 (8)Cl1—Hg2—I2105.72 (6)
C1—N1—C4125.6 (7)Cl1—Hg2—I1ii97.87 (4)
C2—N1—C4124.7 (8)I2—Hg2—I1ii119.262 (18)
C1—N2—C3110.5 (7)Cl1—Hg2—I197.87 (4)
C1—N2—C5125.4 (7)I2—Hg2—I1119.263 (19)
C3—N2—C5124.1 (7)I1ii—Hg2—I1111.44 (3)
N2—C1—N1106.0 (7)O1—S1—C6108.9 (8)
N2—C1—Hg1127.1 (6)O1—S1—C7105.4 (7)
N1—C1—Hg1126.9 (6)C6—S1—C7107.6 (9)
C3—C2—N1106.8 (8)
Symmetry codes: (i) x+1, y, z+1; (ii) x, y+1/2, z.

Experimental details

Crystal data
Chemical formula[Hg(C5H8N2)2][HgClI3].C2H6OS
Mr1087.73
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)203
a, b, c (Å)9.6119 (1), 13.4954 (1), 18.514 (3)
V3)2401.57 (5)
Z4
Radiation typeMo Kα
µ (mm1)16.83
Crystal size (mm)0.38 × 0.18 × 0.05
Data collection
DiffractometerSiemens SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(Blessing, 1995)
Tmin, Tmax0.060, 0.487
No. of measured, independent and
observed [I > 2σ(I)] reflections
14997, 2937, 2317
Rint0.051
(sin θ/λ)max1)0.667
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.110, 1.05
No. of reflections2937
No. of parameters128
H-atom treatmentH-atom parameters constrained
Calculated w = 1/[σ2(Fo2) + (0.0576P)2 + 11.9641P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)1.33, 2.28

Computer programs: SMART (Siemens, 1994a), SAINT (Siemens, 1994a), SAINT, SHELXS97 (Sheldrick, 1997a), SHELXL97 (Sheldrick, 1997b), SHELXTL (Siemens, 1994b), SHELXL97.

Selected geometric parameters (Å, º) top
Hg1—C12.076 (7)N2—C51.449 (11)
N1—C11.355 (10)C2—C31.360 (15)
N1—C21.367 (11)Hg2—Cl12.680 (3)
N1—C41.470 (12)Hg2—I22.6863 (9)
N2—C11.340 (10)Hg2—I12.7602 (7)
N2—C31.359 (11)
Cl1—Hg2—I2105.72 (6)Cl1—Hg2—I197.87 (4)
Cl1—Hg2—I1i97.87 (4)I2—Hg2—I1119.263 (19)
I2—Hg2—I1i119.262 (18)I1i—Hg2—I1111.44 (3)
Symmetry code: (i) x, y+1/2, z.
 

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