Diethyl­methyl­eniminium chloride

The title compound, C₅H₁₂N⁺·Cl^-, contains [Et₂N=CH₂]⁺ and Cl^- ions. The C=N double-bond distance is 1.2729 (13) Å and the sum of the angles around the central N atom is 359.92°. There are short contacts [2.973 (1) Å] between the iminium C atom and the Cl^- ion and between five of the C-H H atoms and the Cl^- ion, of which the shortest is 2.623 (11) Å.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.021
• wR factor = 0.058
• Data-to-parameter ratio = 15.3

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT432_ALERT_2_B Short Inter X...Y Contact  Cl1    ..  C6      ..       2.97 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         12

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

There is considerable interest in the structural chemistry of iminium ions, in large part because they can be the cationic components of ionic liquids. The structure presented here may be compared to that of the [Me₂N=CH₂]Cl (Burg, 1989) and [Me₂N=CH₂]Br (Clark et al., 1994) structures which are reported in the literature (Refcodes VAPREJ and LILLOH, respectively; Allen, 2002). There is a short contact between the iminium carbon atom and the Cl^- anion of 2.973 (1) Å. Interestingly, a similar interaction is seen in the dimethylmethyleniminium bromide, but not in the dimethyleneiminium chloride salt. Mayr, et al. have shown that specific cation-anion interactions in iminium halides (C—H···Hal^- hydrogen bonds) may be responsible for the different products that iminium ions with different counterions give in reactions with alkynes and allylsilanes (Mayr et al., 1997). C—H···Hal^- bonds rather than equilibria between ionic and covalent moieties are responsible for the anion dependence of the NMR chemical shifts of iminium ions (Mayr et al., 1997).

Related literature

Structures of [Me₂N═CH₂]⁺ ions with Cl^- (Burg, 1989), Br^- and I^- (Clark et al., 1994), and [NiBr₄]^- (Hitchcock et al., 2003) counter-ions have been published. Strong evidence has been obtained for intermolecular C—H···Cl^- interactions in the title compound from a detailed NMR investigation (Mayr et al., 1997).

For related literature, see: Allen (2002); Ramakrishna et al. (1999).

S2. Experimental

The title compound was obtained from the reaction of Me₂NH with 1,3,5-trichloro-1-thia-2,4,6-triazine, a reaction which was previously reported to be very susceptible to hydrolysis (Ramakrishna et al., 1999), as the only tractable product. Colourless blocks were obtained and a crystal was mounted on a glass fibre in Paratone oil and diffraction data was collected at 173 (2) K. Refinement proceeded normally, but in view of the interest in intermolecular C—H···Cl^- contacts, it was decided to freely refine all the H atom positions, after they were located using the HFIX command in SHELXTL, with the temperature factors set at 1.5 × the attached methyl and 1.2 × CH₂ carbons. A similar approach was taken by (Clark et al., 1994).

Computing details

Data collection: SMART (Bruker, 2006); cell refinement: SMART; data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXSTL (Sheldrick, 2003); program(s) used to refine structure: SHELXTL (Sheldrick, 2003); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures

	Fig. 1. Ellipsoid plot.
	Fig. 2. Packing diagram.

diethylmethyleniminium chloride

Crystal data

C5H12N^+·Cl^−	F(000) = 264
Mr = 121.61	Dx = 1.154 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P2yn	Cell parameters from 7168 reflections
a = 6.6023 (4) Å	θ = 2.6–28.6°
b = 15.7426 (10) Å	µ = 0.44 mm^−1
c = 7.0057 (4) Å	T = 173 K
β = 106.021 (1)°	Block, colourless
V = 699.87 (7) Å^3	0.46 × 0.28 × 0.25 mm
Z = 4

Data collection

Bruker APEX II CCD area-detector diffractometer	1500 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.013
Graphite monochromator	θmax = 27.1°, θmin = 2.6°
φ and ω scans	h = −8→8
7666 measured reflections	k = −20→20
1544 independent reflections	l = −8→8

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.021	Only H-atom coordinates refined
wR(F^2) = 0.058	w = 1/[σ^2(Fo^2) + (0.0289P)^2 + 0.1779P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
1544 reflections	Δρmax = 0.29 e Å^−3
101 parameters	Δρmin = −0.16 e Å^−3
12 restraints	Extinction correction: SHELXTL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.036 (3)

Special details

Geometry. All e.s.d.'s 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.

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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.22927 (3)	0.601617 (15)	0.36447 (3)	0.02793 (10)
C1	1.12954 (18)	0.72306 (8)	0.8063 (2)	0.0445 (3)
H1A	1.041 (2)	0.7606 (10)	0.846 (3)	0.067*
H1B	1.123 (3)	0.7328 (11)	0.661 (2)	0.067*
H1C	1.274 (2)	0.7299 (10)	0.890 (2)	0.067*
C5	0.67421 (19)	0.59059 (8)	0.98303 (18)	0.0368 (3)
H5A	0.806 (2)	0.5944 (9)	1.090 (2)	0.055*
H5B	0.649 (2)	0.5315 (9)	0.937 (2)	0.055*
H5C	0.555 (2)	0.6072 (9)	1.038 (2)	0.055*
C4	0.67811 (15)	0.64901 (6)	0.81260 (15)	0.0272 (2)
H4A	0.5433 (18)	0.6488 (8)	0.7100 (17)	0.033*
H4B	0.7143 (19)	0.7068 (7)	0.8580 (18)	0.033*
C2	1.06293 (14)	0.63213 (7)	0.82196 (15)	0.0270 (2)
H2A	1.142 (2)	0.5943 (7)	0.7609 (19)	0.032*
H2B	1.080 (2)	0.6142 (8)	0.9549 (17)	0.032*
C6	0.78309 (16)	0.58266 (6)	0.54673 (15)	0.0262 (2)
H6A	0.8909 (18)	0.5658 (8)	0.4865 (18)	0.031*
H6B	0.6375 (18)	0.5758 (8)	0.4823 (18)	0.031*
N1	0.83797 (12)	0.62006 (5)	0.71424 (12)	0.02214 (17)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.02520 (14)	0.03059 (15)	0.02709 (15)	−0.00273 (8)	0.00568 (9)	−0.00059 (8)
C1	0.0278 (5)	0.0331 (6)	0.0677 (8)	−0.0042 (4)	0.0050 (5)	−0.0157 (6)
C5	0.0366 (6)	0.0413 (6)	0.0376 (6)	−0.0005 (5)	0.0184 (5)	0.0048 (5)
C4	0.0254 (5)	0.0267 (5)	0.0308 (5)	0.0027 (4)	0.0101 (4)	−0.0018 (4)
C2	0.0210 (4)	0.0325 (5)	0.0252 (5)	0.0032 (4)	0.0027 (3)	0.0013 (4)
C6	0.0271 (5)	0.0243 (4)	0.0267 (5)	0.0001 (4)	0.0068 (4)	0.0016 (4)
N1	0.0216 (4)	0.0194 (3)	0.0251 (4)	0.0017 (3)	0.0058 (3)	0.0027 (3)

Geometric parameters (Å, º)

C1—C2	1.5105 (16)	C4—H4A	0.978 (11)
C1—H1A	0.930 (14)	C4—H4B	0.971 (11)
C1—H1B	1.016 (14)	C2—N1	1.4808 (12)
C1—H1C	0.976 (14)	C2—H2A	0.968 (11)
C5—C4	1.5130 (15)	C2—H2B	0.949 (11)
C5—H5A	0.981 (13)	C6—N1	1.2729 (13)
C5—H5B	0.983 (13)	C6—H6A	0.960 (11)
C5—H5C	1.000 (13)	C6—H6B	0.949 (11)
C4—N1	1.4826 (12)
C6···Cl1^i	2.973 (1)	H2B···Cl1^iii	2.772 (12)
H6B···Cl1	2.623 (11)	H4A···Cl1	2.817 (11)
H6A···Cl1^ii	2.664 (11)	H5A···Cl1^iii	2.925 (14)
C2—C1—H1A	111.1 (11)	N1—C4—H4B	107.3 (7)
C2—C1—H1B	106.4 (10)	C5—C4—H4B	111.5 (7)
H1A—C1—H1B	110.4 (14)	H4A—C4—H4B	109.6 (10)
C2—C1—H1C	108.5 (10)	N1—C2—C1	110.84 (8)
H1A—C1—H1C	110.1 (14)	N1—C2—H2A	106.6 (8)
H1B—C1—H1C	110.3 (14)	C1—C2—H2A	110.3 (7)
C4—C5—H5A	111.3 (9)	N1—C2—H2B	107.2 (8)
C4—C5—H5B	110.8 (9)	C1—C2—H2B	113.2 (8)
H5A—C5—H5B	110.0 (13)	H2A—C2—H2B	108.5 (11)
C4—C5—H5C	109.4 (9)	N1—C6—H6A	118.4 (8)
H5A—C5—H5C	108.2 (13)	N1—C6—H6B	119.0 (8)
H5B—C5—H5C	107.1 (13)	H6A—C6—H6B	122.4 (11)
N1—C4—C5	110.45 (8)	C6—N1—C2	121.29 (8)
N1—C4—H4A	106.1 (7)	C6—N1—C4	120.84 (8)
C5—C4—H4A	111.6 (8)	C2—N1—C4	117.79 (8)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y, z; (iii) x−1, y, z−1.