Bis(1-benzyl-3-methyl­imidazolium-κC 2)mercury(II) bis­(hexa­fluoridophosphate)

Rosenani A Haque; Abbas Washeel Salman; Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536811032235

. 2011 Aug 17;67(Pt 9):m1242–m1243. doi: 10.1107/S1600536811032235

Bis(1-benzyl-3-methylimidazolium-κC ²)mercury(II) bis(hexafluoridophosphate)

Rosenani A Haque ^a, Abbas Washeel Salman ^a, Madhukar Hemamalini ^b, Hoong-Kun Fun ^b,^*,^‡

PMCID: PMC3200814 PMID: 22064754

Abstract

The asymmetric unit of the title complex, [Hg(C₁₁H₁₂N₂)₂](PF₆)₂, consists of one bis(1-benzyl-3-methylimidazolium)mercury(II) cation, one half of the cation and an additional Hg^II atom, which lies on an inversion centre, and three hexafluoridophosphate anions. The Hg^II atoms exist in a linear coordination geometry [C—Hg—C = 178.9 (2) and 180°] formed by two carbene C atoms from the imidazole rings. In the crystal, the cations and anions are connected via C—H⋯F hydrogen bonds, forming a three-dimensional network.

Related literature

For details of N-heterocyclic carbenes, see: Herrmann (2002 ▶); Arduengo et al. (1991 ▶); Herrmann et al. (1998 ▶); McGuinness et al. (1999 ▶); Wanzlick & Schönherr (1968 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

[Hg(C₁₁H₁₂N₂)₂](PF₆)₂
M _r = 834.98
Monoclinic,
a = 15.1260 (17) Å
b = 10.3044 (11) Å
c = 26.398 (3) Å
β = 102.275 (2)°
V = 4020.5 (8) Å³
Z = 6
Mo Kα radiation
μ = 5.97 mm⁻¹
T = 100 K
0.34 × 0.32 × 0.05 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.233, T _max = 0.751
23876 measured reflections
7062 independent reflections
5985 reflections with I > 2σ(I)
R _int = 0.046

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.087
S = 1.06
7062 reflections
559 parameters
H-atom parameters constrained
Δρ_max = 1.71 e Å⁻³
Δρ_min = −2.05 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811032235/is2765sup1.cif

e-67-m1242-sup1.cif^{(31.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811032235/is2765Isup2.hkl

e-67-m1242-Isup2.hkl^{(338.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C10—H10A⋯F15ⁱ	0.93	2.32	3.240 (7)	171
C11—H11C⋯F6ⁱⁱ	0.96	2.55	3.375 (7)	144
C13—H13A⋯F7ⁱ	0.93	2.43	3.355 (7)	175
C18—H18A⋯F5ⁱⁱ	0.97	2.50	3.282 (6)	138
C18—H18B⋯F13ⁱⁱ	0.97	2.45	3.111 (6)	125
C21—H21A⋯F12ⁱⁱⁱ	0.93	2.51	3.351 (6)	150
C29—H29B⋯F17^iv	0.97	2.48	3.125 (7)	123
C31—H31A⋯F11^iv	0.93	2.43	3.271 (6)	150

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

RAH and AWS thank Universiti Sains Malaysia (USM) for the FRGS fund (203/PKIMIA/671115), short term grant (304/PKIMIA/639001) and RU grants (1001/PKIMIA/813023 and 1001/PKIMIA/811157). AWS thanks Universiti Sains Malaysia (USM) for the RU grant (1001/PKIMIA/843090). HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University Grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

In the last two decades, N-heterocyclic carbene (NHC) ligands have emerged as useful and versatile ligands in organometallic chemistry (Herrmann, 2002). The chemistry of NHCs attracted much attention after the isolation of the first stable, crystalline free carbene (Arduengo et al., 1991) which was [1,3-bis(adamantly)imidazole-2-ylidene]. Carbene ligands have some similarities to phosphine ligands, but metal- carbene complexes are often more stable than similar metal phosphine complexes (Herrmann et al., 1998; McGuinness et al., 1999). The first mercury(II)-NHC complex was prepared by Wanzlick and Schönherr (1968) via direct reaction of an imidazolium salt with mercury(II) acetate. However, in spite of being the earliest example of NHC-metal complexes prepared, NHC-mercury complexes have received little attention compared with other metals. Similarly, their applications have not been widely explored.

The asymmetric unit of title complex (I) consists of one bis(1-benzyl-3- methylimidazolium)mercury(II) cation, a half of the (1-benzyl-3-methyl imidazolium)mercury(II) cation (which lies on an inversion centre) and three hexafluorophosphate anions as shown in Fig. 1. The Hg^II atom exists in a linear coordination geometry formed by two C atoms from the imidazole rings. The bond distances of Hg1–C8 = 2.070 (5) Å; Hg1–C19 = 2.073 (5) Å and Hg2–C30 = 2.070 (5) Å. The distorted octahedral geometry of phosphate ion has typical P–F distances [1.578 (4)–1.610 (3) Å] and F—P—F angles [88.37 (19)–179.4 (2)°]. All bond lengths and bond angles in (I) are in the range of expected values.

In the crystal structure (Fig. 2), ions are connected by C10—H10A···F15; C13—H13A···F7; C18—H18A···F5; C18—H18B···F13; C21—H21A···F12; C29—H29B···F17 and C31—H31A···F11 hydrogen bonds (Table 1), forming a three-dimensional network.

Experimental

Hg(OAc)₂ (0.35 g, 1.09 mmol) was added to a solution of 1-benzyl-3-methylimidazolium hexafluorophosphate (0.6 g, 1.88) in 40 ml of acetonitrile. The mixture was refluxed at 353–363 K for 18 h to give a clear solution. The solvent was removed under reduced pressure to afford a white solid. The white solid was collected, washed with distilled water (3 × 5 ml) and recrystallized from acetonitrile. Yield: 62.4 %, m.p. = 540–543 °C. Crystal suitable for X-ray analysis was obtained by slow diffusion of diethyl ether into solution of the complex in acetonitrile.