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

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ISSN: 2056-9890
Volume 69| Part 8| August 2013| Pages m441-m442

Tri­chlorido(1,3-di­methyl-2,3-di­hydro-1H-imidazol-2-yl­­idene-κC2)aluminium(III)

aCollege of Chemistry, Leshan Normal University, Binhe Rd 778, Leshan 614000, Sichuan Province, People's Republic of China, and bZhengzhou Research Institute of Comprehensive Utilization of Mineral Resourses of CAGS, Longhai Rd 328, Zhengzhou 450006, Henan Province, People's Republic of China
*Correspondence e-mail: maxborzov@mail.ru

(Received 21 June 2013; accepted 1 July 2013; online 6 July 2013)

The title compound, [Al(C5H8N2)Cl3], was prepared by a thermolytic decomposition under high-vacuum conditions and presents a formal adduct of an Arduengo carbene, 1,3-dimethyl-1H-imidazol-2-yl­idene, and aluminium trichloride. The Al atom adopts a pseudo-tetra­hedral CCl3 coordination environment. All N and C atoms, the Al atom, one of the Cl atoms, and all aromatic H atoms of the mol­ecule lie on a mirror plane. As a result of the mirror symmetry of the mol­ecule, the H atoms of all methyl groups are disordered between symmetry-equivalent positions.

Related literature

For related structurally characterized Arduengo carbene AlX3 (X = Cl, I) adducts, see: Stasch et al. (2004[Stasch, A., Singh, S., Roesky, H. W., Noltemeyer, M. & Schmidt, H.-G. (2004). Eur. J. Inorg. Chem. pp. 4052-4055.]); Ghadwal et al. (2009[Ghadwal, R. S., Roesky, H. W., Herbst-Irmer, R. & Jones, P. G. (2009). Z. Anorg. Allg. Chem. 635, 431-433.]); Bantu et al. (2009[Bantu, B., Pawar, G. M., Wurst, K., Decker, U., Schmidt, A. M. & Buschmeiser, M. R. (2009). Eur. J. Inorg. Chem. pp. 1970-1976.]). For thermolytic inter­conversion of sterically non-hindered 1,3-dialkyl-1H-imidazolium salts with BF4 and PF6 anions into Arduengo carbene adducts with BF3 and PF5, see: Tian et al. (2012[Tian, C., Nie, W., Borzov, M. V. & Su, P. (2012). Organometallics, 31, 1751-1760.]). For the crystal structure of the precursor employed in the synthesis of the title compound, see: Tian et al. (2013[Tian, C., Chen, Q., Hu, W., Nie, W. & Borzov, M. V. (2013). Private communication (CCDC 945892). CCDC, Cambridge, England.]). For a description of the Cambridge Structural Database, see: Allen (2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]).

[Scheme 1]

Experimental

Crystal data
  • [Al(C5H8N2)Cl3]

  • Mr = 229.46

  • Orthorhombic, P n m a

  • a = 8.9075 (7) Å

  • b = 7.3903 (6) Å

  • c = 15.3253 (12) Å

  • V = 1008.85 (14) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.94 mm−1

  • T = 296 K

  • 0.40 × 0.38 × 0.20 mm

Data collection
  • Bruker SMART APEXII diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2007[Bruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.706, Tmax = 0.835

  • 5094 measured reflections

  • 1062 independent reflections

  • 968 reflections with I > 2σ(I)

  • Rint = 0.022

Refinement
  • R[F2 > 2σ(F2)] = 0.033

  • wR(F2) = 0.087

  • S = 1.07

  • 1062 reflections

  • 66 parameters

  • H-atom parameters constrained

  • Δρmax = 0.40 e Å−3

  • Δρmin = −0.43 e Å−3

Table 1
Selected bond lengths (Å)

Cl1—Al1 2.1193 (12)
Cl2—Al1 2.1290 (7)
Al1—C1 2.006 (3)
Al1—Cl2i 2.1291 (7)
Symmetry code: (i) [x, -y+{\script{1\over 2}}, z].

Data collection: APEX2 (Bruker, 2007[Bruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2007[Bruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]); software used to prepare material for publication: SHELXTL and OLEX2.

Supporting information


Comment top

Structurally characterized AlX3 (X = Cl, I) adducts with Arduengo carbenes (ACs) are known since 2004 (Stasch et al., 2004) and are still few (Ghadwal et al., 2009; Bantu et al., 2009). Except of the first described representative, viz. trichlorido(1,3,4,5-dimethyl-2,3-dihydro-1H-imidazol-2-ylidene-κC2)aluminium (Stasch et al., 2004), they all present complexes with sterically hindered ACs which bear either mesityl or 2,6-diisopropylphenyl substituents at the N-atoms. Of interest, in all four structurally characterized X3Al—AC adducts, the Al atoms are in a tetrahedral coordination environment as shown by an analysis of the structures compiled in the Cambridge Structural Database (Allen, 2002) [CSD; Version 5.34, release May 2013; 4 entries, 4 fragments].

Preparation of all Al complexes mentioned above includes, as a step, generation of a free AC by deprotonation of a corresponding imidazolium salt with a strong base under mild conditions. This seriously limits the method due to the known thermal instability of sterically non-hindered ACs even in solution. Recently, we developed a facile route to BF3 and PF5 adducts with sterically non-hindered ACs by a thermolytic decomposition of related imidazolium salts with [BF4-] and/or [PF5-] anions under high-vacuum conditions [573–673 K, 1.3–2.0×10 -1 Pa; Tian et al. (2012)]. Heating of an equimolar mixture of 1,3-dimethyl-1H-imidazolium (hydrogen difluoride), [C5H8N2+][HF2-], (II), and AlCl3 under the same conditions followed by re-crystallization precedures led to formation of the title compound (I), C5H8N2AlCl3, in a moderate yield (see Experimental for the details; for the crystal structure of (II), see: Tian et al., 2013).

Compound (I) presents a formal adduct of an Arduengo carbene, 1,3-dimethyl-1H-imidazol-2-ylidene, and aluminium trichloride. The Al-atom adopts a pseudo-tetrahedral coordination environment, defined by the three Cl atoms and the carbene C atom (Table 1). All N- and C-atoms, the Al-atom, one of the Cl-atoms, and all aromatic H-atoms of the molecule lie on a mirror plane at (x, 1/4, z). The H-atoms of methyl groups are disordered between symmetry equivalent positions (Fig. 1).

Related literature top

For related structurally characterized Arduengo carbene AlX3 (X = Cl, I) adducts, see: Stasch et al. (2004); Ghadwal et al. (2009); Bantu et al. (2009). For thermolytic interconversion of sterically non-hindered 1,3-dialkyl-1H-imidazolium salts with BF4- and PF6- anions into Arduengo carbene adducts with BF3 and PF5, see: Tian et al. (2012). For the crystal structure of the precursor employed in the synthesis of the title compound, see: Tian et al. (2013). For a description of the Cambridge Structural Database, see: Allen (2002).

Experimental top

Acetonitrile and toluene solvents were kept over and distilled from CaH2 and/or Na/K alloy under Ar atmosphere, respectively. AlCl3 was sublimed in high vacuum prior to use. 1H NMR spectra were recorded on a Varian 400 INOVA instrument in CD3CN at 400 MHz and 298 K, with the signal of the residual solvent protons [δ(H) = 1.94 p.p.m.] used as an internal reference.

The imidazolium salt (II) was prepared by a reaction of AgF (1.27 g, 10.0 mmol) and 1,3-dimethyl-1H-imidazolium iodide (2.24 g, 10.0 mmol) in distilled water (25 ml). The precipitate of AgI was filtered off, the filtrate was concentrated till dryness, and dried on the high-vacuum line (1.3–2.0×10 -1 Pa) at 323 K. Recrystallization from an ethanol/acetone mixture (1: 1) followed by double recrystallization from dry acetonitrile gave 0.93 g (6.8 mmol, 68%) of (II) as colorless crystals. 1H NMR δ p.p.m.: 3.85 (s, 6H, CH3), 7.44 (s, 2H, CH=CH), 9.45 (s, 1H, NCHN).

Compound (I): Crystalline (II) (0.93 g, 6.8 mmol) and AlCl3 (0.91 g, 6.8 mmol) were placed into a small apparatus for distillation of high-melting compounds, the system was connected to the high-vacuum line (1.3–2.0×10 -1 Pa) through a liq. N2 cooled trap, evacuated, and heated. At approximately 423 K, the signs of melting were observed and then a strongly exothermic reaction accompanied by a gas evolution started. The temperature of the reaction mixture was then increased up to 573 K and the crude product was collected in the receiver as a reddish oil (reaction vessel temperature 573–673 K). The crude compound of (I) (1.03 g, 4.5 mmol, 66%) was allowed to crystallize in a refrigerator (270 K, 7 days). 1H NMR δ p.p.m.: 3.98 (s, 6H, CH3), 7.24 (s, 2H, CH=CH). Single crystal of (I) suitable for the X-ray diffraction analysis were grown by recrystallization of crude (I) from dry toluene, mounted in a Lindemann glass capillary (Ø 0.5 mm, glove box, N2 atmosphere) and sealed off.

Refinement top

The H atoms were treated as riding atoms with distances C—H = 0.96 (CH3), 0.93 Å (CArH) and Uiso(H) = 1.5 Ueq(C), 1.2 Ueq(C), respectively. The H-atoms of the methyl groups are disordered due to the mirror symmetry of the aromatic ring; hance they were refined with half-occupancy.

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of compound (I). Thermal displacement ellipsoids are shown at the 50% probability level. Bonds to symmetry-equivalent disordered H-atoms are dashed. [Symmetry code: (i) x, -y + 1/2, z.]
Trichlorido(1,3-dimethyl-2,3-dihydro-1H-imidazol-2-ylidene-κC2)aluminium(III) top
Crystal data top
[Al(C5H8N2)Cl3]F(000) = 464
Mr = 229.46Dx = 1.511 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 4672 reflections
a = 8.9075 (7) Åθ = 2.7–28.3°
b = 7.3903 (6) ŵ = 0.94 mm1
c = 15.3253 (12) ÅT = 296 K
V = 1008.85 (14) Å3Block, colourless
Z = 40.40 × 0.38 × 0.20 mm
Data collection top
Bruker SMART APEXII
diffractometer
1062 independent reflections
Radiation source: fine-focus sealed tube968 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.022
Detector resolution: 8.333 pixels mm-1θmax = 26.0°, θmin = 2.6°
phi and ω scansh = 710
Absorption correction: multi-scan
(SADABS; Bruker, 2007)
k = 99
Tmin = 0.706, Tmax = 0.835l = 1817
5094 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) = 0.087H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0365P)2 + 0.7006P]
where P = (Fo2 + 2Fc2)/3
1062 reflections(Δ/σ)max < 0.001
66 parametersΔρmax = 0.40 e Å3
0 restraintsΔρmin = 0.43 e Å3
Crystal data top
[Al(C5H8N2)Cl3]V = 1008.85 (14) Å3
Mr = 229.46Z = 4
Orthorhombic, PnmaMo Kα radiation
a = 8.9075 (7) ŵ = 0.94 mm1
b = 7.3903 (6) ÅT = 296 K
c = 15.3253 (12) Å0.40 × 0.38 × 0.20 mm
Data collection top
Bruker SMART APEXII
diffractometer
1062 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2007)
968 reflections with I > 2σ(I)
Tmin = 0.706, Tmax = 0.835Rint = 0.022
5094 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0330 restraints
wR(F2) = 0.087H-atom parameters constrained
S = 1.07Δρmax = 0.40 e Å3
1062 reflectionsΔρmin = 0.43 e Å3
66 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cl10.07057 (9)0.25000.44325 (6)0.0726 (3)
Cl20.18333 (7)0.01243 (9)0.31551 (4)0.0633 (2)
Al10.15020 (9)0.25000.39170 (5)0.0399 (2)
N10.4590 (3)0.25000.46678 (15)0.0428 (5)
N20.3009 (3)0.25000.57221 (14)0.0405 (5)
C10.3100 (3)0.25000.48390 (17)0.0362 (6)
C20.5401 (3)0.25000.5426 (2)0.0546 (8)
H20.64410.25000.54740.066*
C30.4420 (4)0.25000.6082 (2)0.0537 (8)
H30.46490.25000.66750.064*
C40.5262 (4)0.25000.3794 (2)0.0589 (8)
H4A0.46110.18770.33950.088*0.50
H4B0.62170.18990.38130.088*0.50
H4C0.53990.37250.36000.088*0.50
C50.1634 (4)0.25000.6240 (2)0.0569 (8)
H5A0.08700.31690.59380.085*0.50
H5B0.18250.30540.67960.085*0.50
H5C0.13030.12770.63270.085*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0355 (4)0.1078 (8)0.0747 (6)0.0000.0014 (4)0.000
Cl20.0725 (4)0.0603 (4)0.0570 (4)0.0022 (3)0.0091 (3)0.0172 (3)
Al10.0347 (4)0.0493 (5)0.0356 (4)0.0000.0053 (3)0.000
N10.0334 (12)0.0518 (14)0.0430 (12)0.0000.0001 (10)0.000
N20.0395 (12)0.0463 (13)0.0357 (11)0.0000.0021 (9)0.000
C10.0334 (13)0.0405 (14)0.0348 (12)0.0000.0006 (10)0.000
C20.0343 (15)0.071 (2)0.0590 (18)0.0000.0129 (14)0.000
C30.0503 (17)0.068 (2)0.0431 (15)0.0000.0162 (14)0.000
C40.0402 (16)0.084 (2)0.0524 (17)0.0000.0116 (14)0.000
C50.0509 (18)0.081 (2)0.0387 (15)0.0000.0058 (13)0.000
Geometric parameters (Å, º) top
Cl1—Al12.1193 (12)C2—C31.332 (5)
Cl2—Al12.1290 (7)C2—H20.9300
Al1—C12.006 (3)C3—H30.9300
Al1—Cl2i2.1291 (7)C4—H4A0.9600
N1—C11.352 (3)C4—H4B0.9600
N1—C21.368 (4)C4—H4C0.9600
N1—C41.468 (4)C5—H5A0.9600
N2—C11.356 (3)C5—H5B0.9600
N2—C31.373 (4)C5—H5C0.9600
N2—C51.460 (4)
C1—Al1—Cl1113.32 (9)N2—C1—Al1131.37 (19)
C1—Al1—Cl2106.74 (5)C3—C2—N1107.2 (3)
Cl1—Al1—Cl2109.45 (3)C3—C2—H2126.4
C1—Al1—Cl2i106.74 (5)N1—C2—H2126.4
Cl1—Al1—Cl2i109.45 (3)C2—C3—N2107.3 (3)
Cl2—Al1—Cl2i111.11 (5)C2—C3—H3126.4
C1—N1—C2110.7 (2)N2—C3—H3126.4
C1—N1—C4125.3 (2)N1—C4—H4A109.5
C2—N1—C4124.0 (2)N1—C4—H4B109.5
C1—N2—C3110.3 (2)N1—C4—H4C109.5
C1—N2—C5126.4 (2)N2—C5—H5A109.5
C3—N2—C5123.3 (2)N2—C5—H5B109.5
N1—C1—N2104.6 (2)N2—C5—H5C109.5
N1—C1—Al1124.02 (19)
C2—N1—C1—N20.0Cl2i—Al1—C1—N159.45 (4)
C4—N1—C1—N2180.0Cl1—Al1—C1—N20.0
C2—N1—C1—Al1180.0Cl2—Al1—C1—N2120.55 (4)
C4—N1—C1—Al10.0Cl2i—Al1—C1—N2120.55 (4)
C3—N2—C1—N10.0C1—N1—C2—C30.0
C5—N2—C1—N1180.0C4—N1—C2—C3180.0
C3—N2—C1—Al1180.0N1—C2—C3—N20.0
C5—N2—C1—Al10.0C1—N2—C3—C20.0
Cl1—Al1—C1—N1180.0C5—N2—C3—C2180.0
Cl2—Al1—C1—N159.45 (4)
Symmetry code: (i) x, y+1/2, z.

Experimental details

Crystal data
Chemical formula[Al(C5H8N2)Cl3]
Mr229.46
Crystal system, space groupOrthorhombic, Pnma
Temperature (K)296
a, b, c (Å)8.9075 (7), 7.3903 (6), 15.3253 (12)
V3)1008.85 (14)
Z4
Radiation typeMo Kα
µ (mm1)0.94
Crystal size (mm)0.40 × 0.38 × 0.20
Data collection
DiffractometerBruker SMART APEXII
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2007)
Tmin, Tmax0.706, 0.835
No. of measured, independent and
observed [I > 2σ(I)] reflections
5094, 1062, 968
Rint0.022
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.087, 1.07
No. of reflections1062
No. of parameters66
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.40, 0.43

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009).

Selected bond lengths (Å) top
Cl1—Al12.1193 (12)Al1—C12.006 (3)
Cl2—Al12.1290 (7)Al1—Cl2i2.1291 (7)
Symmetry code: (i) x, y+1/2, z.
 

Footnotes

Previous address: Key Laboratory of Synthetic and Natural Chemistry of the Ministry of Education, College of Chemistry and Material Science, the North-West University of Xi'an, Taibai Bei Avenue 229, Xi'an 710069, Shaanxi Province, People's Republic of China.

Acknowledgements

Financial support from the National Natural Science Foundation of China (project Nos. 20702041 and 21072157) and the Shaanxi Province Administration of Foreign Experts Bureau Foundation (grant No. 20106100079) is gratefully acknowledged. The authors are thankful to Mr Pengfei Su (Xi'an Modern Chemistry Research Institute, East Zhangba Road 168, Xi'an 71065, Shaanxi Province, China) for his help in performing the X-ray experiment.

References

First citationAllen, F. H. (2002). Acta Cryst. B58, 380–388.  Web of Science CrossRef CAS IUCr Journals
First citationBantu, B., Pawar, G. M., Wurst, K., Decker, U., Schmidt, A. M. & Buschmeiser, M. R. (2009). Eur. J. Inorg. Chem. pp. 1970–1976.  Web of Science CSD CrossRef
First citationBruker (2007). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationDolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.  Web of Science CrossRef CAS IUCr Journals
First citationGhadwal, R. S., Roesky, H. W., Herbst-Irmer, R. & Jones, P. G. (2009). Z. Anorg. Allg. Chem. 635, 431–433.  Web of Science CSD CrossRef CAS
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationStasch, A., Singh, S., Roesky, H. W., Noltemeyer, M. & Schmidt, H.-G. (2004). Eur. J. Inorg. Chem. pp. 4052–4055.  Web of Science CSD CrossRef
First citationTian, C., Chen, Q., Hu, W., Nie, W. & Borzov, M. V. (2013). Private communication (CCDC 945892). CCDC, Cambridge, England.
First citationTian, C., Nie, W., Borzov, M. V. & Su, P. (2012). Organometallics, 31, 1751–1760.  Web of Science CSD CrossRef CAS

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Volume 69| Part 8| August 2013| Pages m441-m442
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