Tetra­methyl­guanidinium chloride

In the title compound, C₅H₁₄N₃⁺·Cl⁻, the central C atom displays almost ideal trigonal planar geometry. Classical hydrogen bonds of the form N⁺—H...Cl⁻ link the formula units into discrete centrosymmetric dimers.

Key indicators

• Single-crystal X-ray study
• T = 143 K
• Mean [sigma](N-C) = 0.002 Å
• R factor = 0.025
• wR factor = 0.064
• Data-to-parameter ratio = 20.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

The title compound was formed as an unexpected hydrolysis product during a study of guanidinophosphine derivatives (Münchenberg, 1996). Its structure is nevertheless of interest because few salts of this cation have been structurally investigated (CCDC refcodes: BEQQOD, KOYWEA, MATKAT and XERHEH; Version Oct. 2002; Allen & Kennard, 1993), and because of its hydrogen-bonding pattern.

The formula unit displays no imposed crystallographic symmetry. The geometry at the central atom C1 is almost ideal trigonal planar; the r.m.s. deviation from the least-squares plane of C1, N1, N2 and N3 is 0.006 Å. The methyl groups are rotated out of this plane (torsion angles are in Table 1).

The classical hydrogen bonds of the form N⁺—H···Cl^- (Table 2) link the formula units into discrete centrosymmetric dimers (Fig. 1). Further contacts of the form C—H···Cl^-, the shortest of which (C4—H4C···Cl) has a normalized (Steiner, 1998) H···Cl distance of only 2.70 Å, may also be interpreted as hydrogen bonds.

S2. Experimental

prep here!

S3. Refinement

Hydrogen atom positions were obtained from difference syntheses. Methyl groups were refined as idealized rigid groups allowed to rotate about the C—N bonds. H atoms of the NH₂ group were refined freely.

Computing details

Data collection: DIF4 (Stoe & Cie, 1992); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. Dimeric unit of the title compound. Hydrogen bonds (Table 2) are indicated as thick dashed lines. Ellipsoids are at the 50% probability level.

Tetramethylguanidinium chloride

Crystal data

C5H14N3^+·Cl^−	F(000) = 328
Mr = 151.64	Dx = 1.222 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.979 (4) Å	Cell parameters from 50 reflections
b = 13.153 (7) Å	θ = 10–11.5°
c = 9.283 (4) Å	µ = 0.39 mm^−1
β = 104.73 (4)°	T = 143 K
V = 824.1 (7) Å^3	Block, colourless
Z = 4	0.7 × 0.6 × 0.6 mm

Data collection

Stoe STADI-4 diffractometer	Rint = 0.026
Radiation source: fine-focus sealed tube	θmax = 27.6°, θmin = 3.1°
Graphite monochromator	h = −9→9
ω/θ scans	k = −17→0
3151 measured reflections	l = −12→6
1900 independent reflections	3 standard reflections every 60 min
1763 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.065	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0265P)^2 + 0.1898P] where P = (Fo^2 + 2Fc^2)/3
1900 reflections	(Δ/σ)max = 0.001
94 parameters	Δρmax = 0.16 e Å^−3
0 restraints	Δρmin = −0.19 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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

2.6752 (0.0044) x + 9.9297 (0.0086) y + 3.8724 (0.0057) z = 7.0366 (0.0055)

* -0.0098 (0.0009) C1 * 0.0033 (0.0003) N1 * 0.0032 (0.0003) N2 * 0.0033 (0.0003) N3 0.4890 (0.0020) C2 - 0.7075 (0.0019) C3 - 0.4678 (0.0020) C4 0.5822 (0.0019) C5

Rms deviation of fitted atoms = 0.0056

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
Cl	0.65600 (3)	0.417296 (18)	0.23930 (3)	0.02438 (9)
N1	0.31065 (15)	0.58587 (8)	0.10105 (11)	0.0305 (2)
H1A	0.406 (2)	0.5470 (12)	0.1638 (18)	0.044 (4)*
H1B	0.315 (2)	0.5940 (12)	0.0094 (19)	0.043 (4)*
N2	0.02054 (14)	0.67813 (7)	0.06487 (10)	0.0283 (2)
N3	0.11677 (14)	0.57239 (7)	0.26955 (10)	0.0264 (2)
C1	0.14947 (16)	0.61096 (8)	0.14469 (11)	0.0239 (2)
C2	0.0792 (2)	0.75015 (9)	−0.03487 (14)	0.0388 (3)
H2A	0.0067	0.8140	−0.0354	0.047*
H2B	0.0486	0.7219	−0.1358	0.047*
H2C	0.2219	0.7631	−0.0006	0.047*
C3	−0.19258 (17)	0.66968 (9)	0.05025 (14)	0.0341 (3)
H3A	−0.2633	0.6705	−0.0555	0.041*
H3B	−0.2367	0.7270	0.1011	0.041*
H3C	−0.2205	0.6058	0.0953	0.041*
C4	0.20325 (17)	0.47658 (9)	0.33385 (13)	0.0323 (2)
H4A	0.0980	0.4315	0.3485	0.039*
H4B	0.2975	0.4897	0.4300	0.039*
H4C	0.2723	0.4442	0.2663	0.039*
C5	0.00402 (17)	0.62631 (9)	0.35867 (12)	0.0300 (2)
H5A	0.0782	0.6256	0.4636	0.036*
H5B	−0.1241	0.5927	0.3481	0.036*
H5C	−0.0176	0.6968	0.3240	0.036*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl	0.02306 (14)	0.02722 (14)	0.02306 (13)	0.00115 (9)	0.00625 (9)	0.00238 (9)
N1	0.0312 (5)	0.0370 (5)	0.0265 (5)	0.0069 (4)	0.0131 (4)	0.0079 (4)
N2	0.0315 (5)	0.0251 (4)	0.0286 (5)	0.0034 (4)	0.0083 (4)	0.0022 (4)
N3	0.0276 (5)	0.0286 (5)	0.0255 (4)	0.0023 (3)	0.0116 (4)	0.0020 (3)
C1	0.0263 (5)	0.0227 (5)	0.0231 (5)	−0.0019 (4)	0.0068 (4)	−0.0013 (4)
C2	0.0541 (8)	0.0278 (6)	0.0367 (6)	0.0054 (5)	0.0154 (5)	0.0078 (5)
C3	0.0293 (6)	0.0324 (6)	0.0364 (6)	0.0054 (4)	0.0005 (5)	−0.0034 (5)
C4	0.0345 (6)	0.0344 (6)	0.0309 (5)	0.0055 (5)	0.0139 (5)	0.0097 (5)
C5	0.0316 (6)	0.0330 (6)	0.0287 (5)	−0.0033 (4)	0.0136 (4)	−0.0065 (4)

Geometric parameters (Å, º)

N1—C1	1.3304 (15)	C2—H2C	0.980
N1—H1A	0.918 (17)	C3—H3A	0.980
N1—H1B	0.866 (17)	C3—H3B	0.980
N2—C1	1.3417 (15)	C3—H3C	0.980
N2—C2	1.4543 (15)	C4—H4A	0.980
N2—C3	1.4630 (17)	C4—H4B	0.980
N3—C1	1.3370 (14)	C4—H4C	0.980
N3—C4	1.4580 (15)	C5—H5A	0.980
N3—C5	1.4621 (14)	C5—H5B	0.980
C2—H2A	0.980	C5—H5C	0.980
C2—H2B	0.980
C1—N1—H1A	118.3 (9)	N2—C3—H3A	109.5
C1—N1—H1B	120.8 (11)	N2—C3—H3B	109.5
H1A—N1—H1B	119.5 (14)	H3A—C3—H3B	109.5
C1—N2—C2	121.51 (10)	N2—C3—H3C	109.5
C1—N2—C3	121.63 (10)	H3A—C3—H3C	109.5
C2—N2—C3	115.76 (10)	H3B—C3—H3C	109.5
C1—N3—C4	122.60 (9)	N3—C4—H4A	109.5
C1—N3—C5	122.79 (10)	N3—C4—H4B	109.5
C4—N3—C5	114.45 (9)	H4A—C4—H4B	109.5
N1—C1—N3	120.91 (10)	N3—C4—H4C	109.5
N1—C1—N2	119.70 (10)	H4A—C4—H4C	109.5
N3—C1—N2	119.36 (10)	H4B—C4—H4C	109.5
N2—C2—H2A	109.5	N3—C5—H5A	109.5
N2—C2—H2B	109.5	N3—C5—H5B	109.5
H2A—C2—H2B	109.5	H5A—C5—H5B	109.5
N2—C2—H2C	109.5	N3—C5—H5C	109.5
H2A—C2—H2C	109.5	H5A—C5—H5C	109.5
H2B—C2—H2C	109.5	H5B—C5—H5C	109.5
C4—N3—C1—N1	−23.93 (16)	C2—N2—C1—N1	−21.74 (16)
C5—N3—C1—N1	151.32 (11)	C3—N2—C1—N1	145.76 (11)
C4—N3—C1—N2	158.01 (10)	C2—N2—C1—N3	156.35 (10)
C5—N3—C1—N2	−26.74 (16)	C3—N2—C1—N3	−36.16 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl	0.918 (17)	2.415 (17)	3.2863 (17)	158.4 (13)
N1—H1B···Cl^i	0.866 (17)	2.373 (17)	3.2268 (17)	168.9 (14)
C3—H3B···Cl^ii	0.98	2.89	3.773 (2)	150
C4—H4A···Cl^iii	0.98	3.00	3.776 (2)	137
C4—H4C···Cl	0.98	2.77	3.574 (2)	139
C5—H5A···Cl^iv	0.98	2.96	3.922 (2)	167
C5—H5B···Cl^iii	0.98	2.81	3.6492 (19)	144

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+1/2, y+1/2, −z+1/2; (iii) x−1, y, z; (iv) −x+1, −y+1, −z+1.