metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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1,3-Bis(2,4,6-tri­methyl­phen­yl)-3H-imidazol-1-ium tetra­oxidorhenate(VII)

aDepartment of Chemistry, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
*Correspondence e-mail: dave.liles@up.ac.za

(Received 10 November 2011; accepted 25 November 2011; online 30 November 2011)

The title compound, (C21H25N2)[ReO4], was formed as the unexpected product in an attempted synthesis of a rhenium(I)–N-heterocyclic carbene (NHC) complex. The compound has crystallographic mirror symmetry with both the cation and the tetrahedral anion located across a mirror plane. The cation and anion are linked by a C—H⋯O hydrogen bond.

Related literature

For related structures of some halide salts, see: Arduengo et al. (1995[Arduengo, A. J. III, Gamper, S. F., Tamm, M., Calabrese, J. C., Davidson, F. & Craig, H. A. (1995). J. Am. Chem. Soc. 117, 572-573.]); Cole et al. (2002[Cole, M. L., Jones, C. & Junk, P. C. (2002). New J. Chem. 26, 1296-1303.]); Cole & Junk (2004[Cole, M. L. & Junk, P. C. (2004). CrystEngComm, 6, 173-176.]); Lorber & Vendier (2009[Lorber, C. & Vendier, L. (2009). Dalton Trans. pp. 6972-6984.]).

[Scheme 1]

Experimental

Crystal data
  • (C21H25N2)[ReO4]

  • Mr = 555.63

  • Monoclinic, P 21 /m

  • a = 8.2989 (12) Å

  • b = 16.373 (2) Å

  • c = 8.3168 (12) Å

  • β = 111.948 (2)°

  • V = 1048.2 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 5.83 mm−1

  • T = 293 K

  • 0.39 × 0.10 × 0.09 mm

Data collection
  • Bruker (Siemens) P4 diffractometer with a Bruker SMART 1000 CCD detector

  • Absorption correction: multi-scan (SADABS; Bruker, 2001[Bruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.489, Tmax = 0.592

  • 5688 measured reflections

  • 2056 independent reflections

  • 1895 reflections with I > 2σ(I)

  • Rint = 0.029

Refinement
  • R[F2 > 2σ(F2)] = 0.033

  • wR(F2) = 0.083

  • S = 1.13

  • 2056 reflections

  • 136 parameters

  • H-atom parameters constrained

  • Δρmax = 1.32 e Å−3

  • Δρmin = −0.86 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C1—H1⋯O2i 0.93 2.21 3.12 (1) 167 (1)
Symmetry code: (i) x-1, y, z.

Data collection: SMART (Bruker, 2001[Bruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2001[Bruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and POV-RAY (Cason, 2004[Cason, C. J. (2004). POV-RAY for Windows. Persistence of Vision, Raytracer Pty Ltd, Victoria, Australia. URL: http://www.povray.org.]); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

1,3-Bis(2,4,6-trimethylphenyl)-3H-imidazolium tetraoxorhenate(VII) (IMesH[ReO4], 1) was formed as the unexpected product in an attempted synthesis of a rhenium(I)-N-heterocyclic carbene (NHC) complex. The reaction pathway is unexplained. The main feature in the formation of this complex is the oxidation of the rhenium metal from the +1 to the +7 state resulting in a [ReO4]- anion. This anion replaces the Cl- anion in the IMesHCl salt since it is larger and the co-crystallization of more similar sized ions is favoured..

The compound has crystallographic mirror symmetry with the Re1, O1, O2 and the imidazolium C1 and H1 atoms all lying in a mirror plane. The geometry of the imidazolium cation is similar to those observed for previously reported structures of 1,3-Bis(2,4,6-trimethylphenyl)-3H-imidazolium salts, for example halide (Cl-, Br-) salts (Arduengo et al., 1995; Cole et al., 2002; Cole & Junk, 2004; Lorber &Vendier, 2009). The imidazolium C1—H1 is hydrogen bonded to O2 of the [ReO4]- anion (at x - 1, y, z) with H1···O2 = 2.21 (1) Å and C1—H1···O2 = 167 (1)°. Similar hydrogen bonds were observed between the cation and the anion in the halide salts (Cole & Junk, 2004). The Re—O2 bond is somewhat longer (1.714 (5) Å) than the other (nominally double) Re—O bonds (mean 1.690 (6) Å) and may indicate some localization of the anion negative charge on O2.

Related literature top

For related structures of some halide salts see: Arduengo et al. (1995); Cole et al. (2002); Cole & Junk (2004); Lorber & Vendier (2009).

Experimental top

N,N'-Dimesitylimidazolium chloride (IMesHCl, 2 mmol, 0.66 g) was deprotonated with KOtBu in tetrahydrofuran (thf) solution. This mixture was added to a thf solution of [Re2(CO)10] (1.06 mmol, 0.68 g) and stirred. Thin layer chromatography (TLC) was used to monitor the reaction and, due to the initial lack of product formation, the reaction mixture was heated in an oilbath at 70°C for an hour. The thf solvent was removed leaving a brown residue. The product was extracted with hexane and the hexane was then removed under reduced pressure. The residue was purified by column chromatography. A dark yellow fraction was eluted with dichloromethane (dcm). Crystallization from a 1:1 dcm:hexane solution gave light brown crystals of IMesH[ReO4] (1). 1H NMR (δ, p.p.m.), C6D6: 1.91 (br,12H), 2.19 (br, 6H), 6.70 (br, 4H), 7.14 (s, 2H); 13 C NMR (δ, p.p.m.), C6D6: 17.8, 20.9, 121.8, 126.9, 128.9, 129.6, 141.2

Refinement top

All hydrogen atoms were added in calculated positions. Each was allowed to ride on the atom to which it is bonded with an isotropic adp set to 1.2 x (1.5 x for methyl H atoms) the equivalent isotropic adp of that atom.

Structure description top

1,3-Bis(2,4,6-trimethylphenyl)-3H-imidazolium tetraoxorhenate(VII) (IMesH[ReO4], 1) was formed as the unexpected product in an attempted synthesis of a rhenium(I)-N-heterocyclic carbene (NHC) complex. The reaction pathway is unexplained. The main feature in the formation of this complex is the oxidation of the rhenium metal from the +1 to the +7 state resulting in a [ReO4]- anion. This anion replaces the Cl- anion in the IMesHCl salt since it is larger and the co-crystallization of more similar sized ions is favoured..

The compound has crystallographic mirror symmetry with the Re1, O1, O2 and the imidazolium C1 and H1 atoms all lying in a mirror plane. The geometry of the imidazolium cation is similar to those observed for previously reported structures of 1,3-Bis(2,4,6-trimethylphenyl)-3H-imidazolium salts, for example halide (Cl-, Br-) salts (Arduengo et al., 1995; Cole et al., 2002; Cole & Junk, 2004; Lorber &Vendier, 2009). The imidazolium C1—H1 is hydrogen bonded to O2 of the [ReO4]- anion (at x - 1, y, z) with H1···O2 = 2.21 (1) Å and C1—H1···O2 = 167 (1)°. Similar hydrogen bonds were observed between the cation and the anion in the halide salts (Cole & Junk, 2004). The Re—O2 bond is somewhat longer (1.714 (5) Å) than the other (nominally double) Re—O bonds (mean 1.690 (6) Å) and may indicate some localization of the anion negative charge on O2.

For related structures of some halide salts see: Arduengo et al. (1995); Cole et al. (2002); Cole & Junk (2004); Lorber & Vendier (2009).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL and SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and POV-RAY (Cason, 2004); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of 1 showing the atomic numbering scheme. Displacement elipsoids are shown at the 50% probability level and H atoms are shown as small spheres of arbitary radii.
1,3-Bis(2,4,6-trimethylphenyl)-3H-imidazol-1-ium tetraoxidorhenate(VII) top
Crystal data top
(C21H25N2)[ReO4]F(000) = 544
Mr = 555.63Dx = 1.760 Mg m3
Monoclinic, P21/mMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybCell parameters from 4658 reflections
a = 8.2989 (12) Åθ = 2.6–26.5°
b = 16.373 (2) ŵ = 5.83 mm1
c = 8.3168 (12) ÅT = 293 K
β = 111.948 (2)°Needle, light brown
V = 1048.2 (3) Å30.39 × 0.10 × 0.09 mm
Z = 2
Data collection top
Bruker (Siemens) P4
diffractometer
2056 independent reflections
Radiation source: fine-focus sealed tube1895 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
Detector resolution: 8.3 pixels mm-1θmax = 26.5°, θmin = 2.5°
φ and ω scansh = 109
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
k = 1920
Tmin = 0.489, Tmax = 0.592l = 310
5688 measured reflections
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)] = 0.033Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.083H-atom parameters constrained
S = 1.13 w = 1/[σ2(Fo2) + (0.0381P)2 + 1.6122P]
where P = (Fo2 + 2Fc2)/3
2056 reflections(Δ/σ)max < 0.001
136 parametersΔρmax = 1.32 e Å3
0 restraintsΔρmin = 0.86 e Å3
Crystal data top
(C21H25N2)[ReO4]V = 1048.2 (3) Å3
Mr = 555.63Z = 2
Monoclinic, P21/mMo Kα radiation
a = 8.2989 (12) ŵ = 5.83 mm1
b = 16.373 (2) ÅT = 293 K
c = 8.3168 (12) Å0.39 × 0.10 × 0.09 mm
β = 111.948 (2)°
Data collection top
Bruker (Siemens) P4
diffractometer
2056 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
1895 reflections with I > 2σ(I)
Tmin = 0.489, Tmax = 0.592Rint = 0.029
5688 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0330 restraints
wR(F2) = 0.083H-atom parameters constrained
S = 1.13Δρmax = 1.32 e Å3
2056 reflectionsΔρmin = 0.86 e Å3
136 parameters
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.

All hydrogen atoms were added in calculated positions. Each was allowed to ride on the atom to which it is bonded with an isotropic adp set to 1.2 x (1.5 x for methyl H atoms) the equivalent isotropic adp of that atom.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.3511 (4)0.3161 (2)0.0558 (4)0.0350 (7)
C10.2687 (8)0.25000.0779 (7)0.0332 (11)
H10.16940.25000.10460.040*
C20.4899 (6)0.2909 (3)0.0166 (6)0.0441 (10)
H20.56940.32450.00580.053*
C30.3080 (5)0.3994 (2)0.0842 (5)0.0340 (8)
C40.2575 (6)0.4545 (2)0.0539 (5)0.0392 (9)
C50.2133 (6)0.5328 (3)0.0207 (6)0.0425 (9)
H50.17790.57050.11090.051*
C60.2198 (6)0.5569 (2)0.1404 (6)0.0402 (9)
C70.2735 (6)0.5004 (2)0.2743 (6)0.0408 (9)
H70.27830.51600.38350.049*
C80.3202 (6)0.4215 (2)0.2506 (5)0.0370 (9)
C90.3843 (7)0.3635 (3)0.4026 (6)0.0476 (11)
H9A0.48060.33260.39760.071*
H9B0.29230.32700.39820.071*
H9C0.42090.39410.50880.071*
C100.2518 (9)0.4325 (3)0.2318 (6)0.0603 (14)
H10A0.17370.46870.31590.091*
H10B0.21190.37720.25840.091*
H10C0.36600.43750.23450.091*
C110.1718 (8)0.6422 (3)0.1711 (8)0.0561 (13)
H11A0.07860.64040.21310.084*
H11B0.13520.67240.06440.084*
H11C0.27070.66860.25550.084*
Re10.91490 (4)0.25000.40489 (3)0.05388 (13)
O11.0911 (8)0.25000.5917 (7)0.0756 (18)
O20.9768 (8)0.25000.2300 (8)0.0769 (17)
O30.7942 (8)0.3344 (5)0.3947 (7)0.127 (2)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0437 (19)0.0286 (16)0.0382 (17)0.0031 (14)0.0216 (15)0.0005 (13)
C10.038 (3)0.026 (3)0.041 (3)0.0000.021 (2)0.000
C20.050 (2)0.039 (2)0.056 (3)0.009 (2)0.034 (2)0.002 (2)
C30.043 (2)0.0231 (17)0.042 (2)0.0053 (16)0.0221 (18)0.0030 (15)
C40.047 (2)0.032 (2)0.041 (2)0.0073 (18)0.0204 (19)0.0007 (17)
C50.051 (3)0.031 (2)0.045 (2)0.0054 (18)0.017 (2)0.0048 (17)
C60.043 (2)0.029 (2)0.051 (2)0.0043 (17)0.0203 (19)0.0030 (17)
C70.051 (3)0.035 (2)0.042 (2)0.0067 (18)0.024 (2)0.0105 (17)
C80.042 (2)0.033 (2)0.040 (2)0.0068 (17)0.0191 (18)0.0027 (16)
C90.062 (3)0.044 (2)0.039 (2)0.003 (2)0.021 (2)0.0002 (18)
C100.096 (4)0.049 (3)0.043 (2)0.006 (3)0.035 (3)0.002 (2)
C110.071 (3)0.035 (2)0.068 (3)0.003 (2)0.032 (3)0.005 (2)
Re10.04629 (19)0.0774 (2)0.04186 (17)0.0000.02096 (13)0.000
O10.077 (4)0.060 (3)0.072 (4)0.0000.008 (3)0.000
O20.077 (4)0.107 (5)0.060 (3)0.0000.041 (3)0.000
O30.116 (5)0.179 (6)0.081 (3)0.073 (5)0.032 (3)0.004 (4)
Geometric parameters (Å, º) top
N1—C11.330 (5)C7—H70.9300
N1—C21.372 (5)C8—C91.510 (6)
N1—C31.452 (5)C9—H9A0.9600
C1—N1i1.330 (5)C9—H9B0.9600
C1—H10.9300C9—H9C0.9600
C2—C2i1.341 (9)C10—H10A0.9600
C2—H20.9300C10—H10B0.9600
C3—C41.395 (6)C10—H10C0.9600
C3—C81.397 (6)C11—H11A0.9600
C4—C51.390 (6)C11—H11B0.9600
C4—C101.506 (6)C11—H11C0.9600
C5—C61.379 (6)Re1—O11.689 (5)
C5—H50.9300Re1—O31.691 (6)
C6—C71.388 (6)Re1—O3i1.691 (6)
C6—C111.500 (6)Re1—O21.714 (5)
C7—C81.385 (6)
C1—N1—C2108.0 (4)C3—C8—C9122.7 (4)
C1—N1—C3124.8 (3)C8—C9—H9A109.5
C2—N1—C3126.9 (3)C8—C9—H9B109.5
N1—C1—N1i109.0 (5)H9A—C9—H9B109.5
N1—C1—H1125.5C8—C9—H9C109.5
N1i—C1—H1125.5H9A—C9—H9C109.5
C2i—C2—N1107.5 (2)H9B—C9—H9C109.5
C2i—C2—H2126.3C4—C10—H10A109.5
N1—C2—H2126.3C4—C10—H10B109.5
C4—C3—C8122.4 (4)H10A—C10—H10B109.5
C4—C3—N1119.3 (3)C4—C10—H10C109.5
C8—C3—N1118.2 (3)H10A—C10—H10C109.5
C5—C4—C3117.0 (4)H10B—C10—H10C109.5
C5—C4—C10120.1 (4)C6—C11—H11A109.5
C3—C4—C10122.9 (4)C6—C11—H11B109.5
C6—C5—C4122.7 (4)H11A—C11—H11B109.5
C6—C5—H5118.7C6—C11—H11C109.5
C4—C5—H5118.7H11A—C11—H11C109.5
C5—C6—C7118.2 (4)H11B—C11—H11C109.5
C5—C6—C11121.1 (4)O1—Re1—O3109.8 (2)
C7—C6—C11120.7 (4)O1—Re1—O3i109.8 (2)
C8—C7—C6122.1 (4)O3—Re1—O3i109.7 (6)
C8—C7—H7118.9O1—Re1—O2110.5 (3)
C6—C7—H7118.9O3—Re1—O2108.5 (2)
C7—C8—C3117.5 (4)O3i—Re1—O2108.5 (2)
C7—C8—C9119.8 (4)
C2—N1—C1—N1i0.6 (6)C3—C4—C5—C60.7 (7)
C3—N1—C1—N1i174.5 (3)C10—C4—C5—C6178.5 (5)
C1—N1—C2—C2i0.3 (4)C4—C5—C6—C70.3 (7)
C3—N1—C2—C2i174.6 (3)C4—C5—C6—C11179.7 (4)
C1—N1—C3—C4119.1 (5)C5—C6—C7—C80.0 (7)
C2—N1—C3—C466.8 (6)C11—C6—C7—C8179.4 (4)
C1—N1—C3—C861.3 (6)C6—C7—C8—C31.4 (6)
C2—N1—C3—C8112.7 (5)C6—C7—C8—C9177.6 (4)
C8—C3—C4—C52.1 (6)C4—C3—C8—C72.4 (6)
N1—C3—C4—C5178.3 (4)N1—C3—C8—C7178.0 (4)
C8—C3—C4—C10177.1 (5)C4—C3—C8—C9176.5 (4)
N1—C3—C4—C102.4 (6)N1—C3—C8—C93.0 (6)
Symmetry code: (i) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···O2ii0.932.213.12 (1)167 (1)
Symmetry code: (ii) x1, y, z.

Experimental details

Crystal data
Chemical formula(C21H25N2)[ReO4]
Mr555.63
Crystal system, space groupMonoclinic, P21/m
Temperature (K)293
a, b, c (Å)8.2989 (12), 16.373 (2), 8.3168 (12)
β (°) 111.948 (2)
V3)1048.2 (3)
Z2
Radiation typeMo Kα
µ (mm1)5.83
Crystal size (mm)0.39 × 0.10 × 0.09
Data collection
DiffractometerBruker (Siemens) P4
Absorption correctionMulti-scan
(SADABS; Bruker, 2001)
Tmin, Tmax0.489, 0.592
No. of measured, independent and
observed [I > 2σ(I)] reflections
5688, 2056, 1895
Rint0.029
(sin θ/λ)max1)0.629
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.083, 1.13
No. of reflections2056
No. of parameters136
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.32, 0.86

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2008), SHELXTL and SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and POV-RAY (Cason, 2004), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···O2i0.932.213.12 (1)166.8 (4)
Symmetry code: (i) x1, y, z.
 

Acknowledgements

Funding received for this work from the University of Pretoria and the National Research Foundation is acknowledged.

References

First citationArduengo, A. J. III, Gamper, S. F., Tamm, M., Calabrese, J. C., Davidson, F. & Craig, H. A. (1995). J. Am. Chem. Soc. 117, 572–573.  CSD CrossRef CAS Web of Science Google Scholar
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First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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