N,N,N',N'-Tetra­methyl­ethyl­enedi­ammonium dichloride

The structure of the title compound, C₆H₁₈N₂²⁺.2Cl^-, has been determined and has a centre of symmetry. The mol­ecule has strong intermolecular hydrogen bonding between each Cl^- and an N-H bond [Cl...N = 3.012 (3) Å].

S1. Comment

The title compound, (I), was formed as an unexpected by-product of the reaction of L-ascorbic acid (vitamin C) with tmed (tmed = N,N,N',N'-tetramethylethanediamine) in CH₂Cl₂ and also from the reaction of ascorbic acid with tmed and copper(II) methoxide in CH₂Cl₂. The reaction of SnCl₂with tmen and tetrachloro-o-quinone to form Cl₄C₆O₂SnCl₂.tmen complexes in methanol has been reported to give N,N,N',N'-tetramethylethylenediamonium dichloride as a by-product (Annan et al., 1987). However the structure of this compound has not been determined by X-ray crystallography. A related compound of N,N,N',N'-tetamethylenediamonium dibromide was formed as a by-product during the crystallization of the compound Ph₃SnInBr₂.tmen in a mixture of CHCl₃/CH₃OH and has been determined crystallograplically (Annan et al., 1991; Annan & Tuck, 1987).

The geometry around each N atom is essentially tetrahedral and the average C—N—C bond angle of 111.3 (9)° is nearly the same as in the previous work of Annan et al. (1991) [111.7 (4)°]. The C—C and average C—N bond distances of 1.526 (5) and 1.491 (7) Å, respectively, compare favourably with those in the compound of Annan et al. (1991), where corresponding values are 1.57 (1) and 1.467 (7) Å. The N1—C1 bond length [1.501 (3) Å] is longer than in the previous work of Annan et al. (1991) [1.442 (7) Å].

A strong intermolecular hydrogen bond occurs between the Cl1(2 − x, 2 − y, 2 − z) and N1 atoms, the H atom being essentially bonded to the N1 atom. The Cl1···N1, Cl1···H1 and N1—H1 distances are 3.012 (3), 2.00 (4) and 1.02 (3) Å, respectively. The sum of the van der Waals radii of Cl and N (3.30 Å) is significantly longer than the intramolecular Cl···N hydrogen-bond length (Bondi, 1964).

S2. Experimental

The title compound was prepared by magnetic stirring of L-ascorbic acid (1 g, 5.68 mmol) and tmed (0.667 g, 5.68 mmol) in 50 ml CH₂Cl₂ for 48 h under N₂ to give a yellow solution and a gummy solid. The precipitate was separated by filtration. The filtrate was evaporated to dryness at room temperature giving a mixture of white and yellow powder. Crystallization of this powder from a mixture of methanol/acetone (50:50, v/v) gave colourless single crystals of the title compound.

S3. Refinement

All the H atoms (except the H1 atom which was fixed from the difference Fourier to the N atom) were fixed at ideal positions with isotropic displacement parameters 1.5U_eq of the related C and N atoms.

Computing details

Data collection: MSC/AFC Diffractomer Control Software (MSC, 1994); cell refinement: MSC/AFC Diffractomer Control Software; data reduction: TEXSAN (MSC, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

(I)

Crystal data

C6H18N2^2+·2Cl^−	Z = 1
Mr = 189.12	F(000) = 102
Triclinic, P1	Dx = 1.200 Mg m^−3
a = 6.1467 (12) Å	Mo Kα radiation, λ = 0.71069 Å
b = 8.075 (3) Å	Cell parameters from 25 reflections
c = 5.770 (2) Å	θ = 10.0–14.4°
α = 101.93 (3)°	µ = 0.56 mm^−1
β = 108.27 (2)°	T = 293 K
γ = 76.65 (2)°	Prismatic, colorless
V = 261.77 (14) Å^3	0.50 × 0.30 × 0.10 mm

Data collection

Rigaku AFC-7S diffractometer	1001 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.061
Graphite monochromator	θmax = 27.5°, θmin = 2.6°
ω–2θ scans	h = 0→7
Absorption correction: ψ scan (North et al., 1968)	k = −10→10
Tmin = 0.927, Tmax = 0.992	l = −7→7
1257 measured reflections	3 standard reflections every 150 reflections
1149 independent reflections	intensity decay: 4.7%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.127	H atoms treated by a mixture of independent and constrained refinement
S = 1.36	Calculated w = 1/[σ^2(Fo^2) + (0.0393P)^2 + 0.1206P] where P = (Fo^2 + 2Fc^2)/3
1149 reflections	(Δ/σ)max < 0.001
49 parameters	Δρmax = 0.48 e Å^−3
0 restraints	Δρmin = −0.33 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	1.27032 (11)	1.23232 (9)	1.60873 (11)	0.0459 (2)
N1	1.1431 (4)	0.7927 (3)	0.8388 (4)	0.0341 (4)
H1	1.010 (6)	0.785 (4)	0.681 (6)	0.051*
C3	1.3483 (5)	0.7534 (4)	0.7396 (5)	0.0477 (6)
H3A	1.3368	0.8397	0.6420	0.072*
H3B	1.3524	0.6427	0.6388	0.072*
H3C	1.4882	0.7526	0.8739	0.072*
C2	1.1553 (6)	0.6607 (3)	0.9900 (6)	0.0492 (7)
H2A	1.0216	0.6883	1.0523	0.074*
H2B	1.2943	0.6588	1.1256	0.074*
H2C	1.1580	0.5498	0.8899	0.074*
C1	1.1201 (4)	0.9718 (3)	0.9780 (5)	0.0363 (5)
H1A	1.1426	1.0505	0.8847	0.054*
H1B	1.2392	0.9752	1.1351	0.054*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0413 (4)	0.0555 (4)	0.0371 (3)	−0.0113 (3)	0.0070 (2)	0.0017 (3)
N1	0.0356 (10)	0.0339 (10)	0.0318 (9)	−0.0068 (8)	0.0107 (8)	0.0001 (8)
C3	0.0438 (14)	0.0555 (16)	0.0456 (14)	−0.0050 (12)	0.0214 (12)	0.0017 (12)
C2	0.0608 (17)	0.0341 (13)	0.0587 (17)	−0.0087 (12)	0.0246 (14)	0.0073 (12)
C1	0.0387 (13)	0.0312 (11)	0.0415 (12)	−0.0108 (9)	0.0148 (10)	0.0002 (9)

Geometric parameters (Å, º)

N1—C2	1.486 (3)	C2—H2A	0.9600
N1—C3	1.487 (3)	C2—H2B	0.9600
N1—C1	1.501 (3)	C2—H2C	0.9600
N1—H1	1.02 (3)	C1—C1^i	1.526 (5)
C3—H3A	0.9600	C1—H1A	0.9700
C3—H3B	0.9600	C1—H1B	0.9700
C3—H3C	0.9600
C1—N1—C2	112.52 (19)	H3B—C3—H3C	109.5
C1—N1—C3	110.6 (2)	N1—C2—H2A	109.5
C2—N1—C3	110.7 (2)	N1—C2—H2B	109.5
N1—C1—C1^i	110.3 (2)	H2A—C2—H2B	109.5
C2—N1—H1	110.7 (18)	N1—C2—H2C	109.5
C3—N1—H1	101.7 (18)	H2A—C2—H2C	109.5
C1—N1—H1	110.0 (18)	H2B—C2—H2C	109.5
N1—C3—H3A	109.5	N1—C1—H1A	109.6
N1—C3—H3B	109.5	C1^i—C1—H1A	109.6
H3A—C3—H3B	109.5	N1—C1—H1B	109.6
N1—C3—H3C	109.5	C1^i—C1—H1B	109.6
H3A—C3—H3C	109.5	H1A—C1—H1B	108.1
C2—N1—C1—C1^i	−70.1 (3)	C3—N1—C1—C1^i	165.5 (3)

Symmetry code: (i) −x+2, −y+2, −z+2.