(S)-2-Methylpiperazinediium dichloride 0.42-hydrate

The cations and anions of the chiral title compound, C₅H₁₄N₂²⁺·2Cl⁻·0.42H₂O, are linked by N—H⋯Cl hydrogen bonds into chains propagating in [100], which contain R₄²(14) loops.

Related literature

For crystal structures containing the same chiral cation, see: Muller et al. (2005); Tuel et al. (2002). For background on graph theory, see: Bernstein et al. (1995).

Experimental

Crystal data

• C₅H₁₄N₂²⁺·2Cl⁻·0.42H₂O

• M_r = 180.65

• Monoclinic, P 2₁

• a = 5.7548 (2) Å

• b = 11.6176 (4) Å

• c = 6.9248 (2) Å

• β = 105.7599 (16)°

• V = 445.57 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 0.66 mm⁻¹

• T = 120 (2) K

• 0.10 × 0.08 × 0.02 mm

Data collection

• Nonius KappaCCD diffractometer

• Absorption correction: none

• 5193 measured reflections

• 1999 independent reflections

• 1952 reflections with I > 2σ(I)

• R_int = 0.071

Refinement

• R[F² > 2σ(F²)] = 0.042

• wR(F²) = 0.110

• S = 1.05

• 1999 reflections

• 93 parameters

• 1 restraint

• H-atom parameters constrained

• Δρ_max = 0.93 e Å⁻³

• Δρ_min = −0.23 e Å⁻³

• Absolute structure: Flack (1983), 929 Friedel pairs

• Flack parameter: 0.04 (9)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H2⋯Cl2	0.92	2.25	3.096 (2)	153
N1—H1⋯Cl2^i	0.92	2.24	3.136 (2)	166
N2—H3⋯Cl1	0.92	2.26	3.149 (2)	163
N2—H4⋯Cl1^i	0.92	2.30	3.137 (2)	152
Symmetry code: (i) x-1, y, z.

Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997), SCALEPACK and SORTAV (Blessing, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

The title compound, (I), is a chiral molecular salt, in which the organic species has accepted two protons from the hydrochloric acid. The geometrical parameters of the C₅H₁₄N₂²⁺ dication (Fig. 1) are similar to those of the same speies in other structures (Muller et al., 2005; Tuel et al., 2002) and its six-membered ring is a typical chair. The C4 stereogenic centre has S configuration and the pendant C5 methyl group occupies an equatorial position with respect to the ring.

In the crystal of (I), the cations and anions are linked by N—H···Cl hydrogen bonds (Table 1) into chains propagating in [100], with two chloride ions bridging each dication, as shown in Fig 2. In terms of graph theory (Bernstein et al., 1995), R₄²(14) loops arise from this connectivity.

The O1 water molecule is partially occupied in the crystal of (I), although there is no obvious crystallographic reason (e.g. symmetry generated close contacts) as to why this should be the case. Based on short O···Cl contacts of less than 3.5 Å, the water molecule probably participates in O—H···Cl hydrogen bonds thereby helping to crosslink the [100] chains, but the water H atoms could not be found or placed unambiguously in the present study.

Related literature

For crystal structures containing the same chiral cation, see: Muller et al. (2005); Tuel et al. (2002). For background on graph theory, see Bernstein et al. (1995).

S2. Experimental

Equimolar quantities of 0.1 M aqueous (S)-2-methylpiperazine and 0.1 M aqueous hydrochloric acid were mixed, leading to a clear solution. Colourless plates of (I) grew as the water slowly evaporated.

S3. Refinement

When refined with full occpancy, atom O1 showed an excessively large U_iso value of 0.15 Ų. Its fractional site occupancy was refined and rapidly converged to 0.420 (11) with a more reasonable U_iso value and improvement in fit. Its U^ij values were subsequently refined and converged without difficulty. Its presumed attached H atoms could not be located from difference maps in the present study. Attempts at geometrical placement were ambiguous, as there are several possible O···Cl contacts that might correspond to O—H···Cl hydrogen bonds.

The other hydrogen atoms were geometrically placed (C—H = 0.95–0.99 Å, N—H = 0.92 Å) and refined as riding with U_iso(H) = 1.2U_eq(C,N) or 1.5U_eq(methyl C). The methyl group was allowed to rotate, but not tip, to best fit the electron density.

The highest difference peak is 0.73Å from H1.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997) and SORTAV (Blessing, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. View of the molecular structure of (I) showing 50% displacement ellipsoids (arbitrary spheres for the H atoms). Hydrogen bonds are indicated by double-dashed lines.
	Fig. 2. Fragement of a [100] hydrogen bonded chain of cations and anions in the crystal of (I). The carbon-bound H atoms are omitted for clarity. Symmetry code suffixes: (*) x - 1, y, z; (#) x + 1, y, z.

(S)-2-Methylpiperazinediium dichloride 0.42-hydrate

Crystal data

C5H14N2^2+·2Cl^−·0.42H2O	F(000) = 192
Mr = 180.65	Dx = 1.346 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 2691 reflections
a = 5.7548 (2) Å	θ = 2.9–27.5°
b = 11.6176 (4) Å	µ = 0.66 mm^−1
c = 6.9248 (2) Å	T = 120 K
β = 105.7599 (16)°	Plate, colourless
V = 445.57 (3) Å^3	0.10 × 0.08 × 0.02 mm
Z = 2

Data collection

Nonius KappaCCD diffractometer	1952 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.071
Graphite monochromator	θmax = 27.5°, θmin = 3.1°
ω and ϕ scans	h = −7→7
5193 measured reflections	k = −14→15
1999 independent reflections	l = −8→9

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)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.110	w = 1/[σ^2(Fo^2) + (0.0558P)^2 + 0.1729P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max < 0.001
1999 reflections	Δρmax = 0.93 e Å^−3
93 parameters	Δρmin = −0.23 e Å^−3
1 restraint	Absolute structure: Flack (1983), 929 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.04 (9)

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	Occ. (<1)
N1	0.7382 (4)	−0.00043 (19)	0.4593 (3)	0.0150 (4)
H1	0.6241	−0.0130	0.5278	0.018*
H2	0.8880	−0.0125	0.5468	0.018*
N2	0.4376 (4)	0.06003 (19)	0.0680 (3)	0.0171 (5)
H3	0.5504	0.0729	−0.0016	0.020*
H4	0.2869	0.0723	−0.0181	0.020*
C1	0.7209 (4)	0.1215 (3)	0.3871 (4)	0.0181 (5)
H5	0.8509	0.1372	0.3220	0.022*
H6	0.7418	0.1745	0.5025	0.022*
C2	0.4781 (5)	0.1420 (2)	0.2391 (4)	0.0190 (5)
H7	0.3490	0.1324	0.3076	0.023*
H8	0.4703	0.2219	0.1881	0.023*
C3	0.4563 (5)	−0.0617 (2)	0.1406 (4)	0.0176 (5)
H9	0.4345	−0.1146	0.0249	0.021*
H10	0.3263	−0.0774	0.2058	0.021*
C4	0.7000 (5)	−0.0841 (2)	0.2891 (4)	0.0164 (5)
H11	0.8297	−0.0729	0.2197	0.020*
C5	0.7142 (6)	−0.2064 (3)	0.3697 (5)	0.0228 (6)
H12	0.8577	−0.2143	0.4839	0.034*
H13	0.7248	−0.2605	0.2639	0.034*
H14	0.5694	−0.2232	0.4133	0.034*
Cl1	0.88946 (10)	0.12630 (6)	−0.08251 (9)	0.02299 (18)
Cl2	1.28588 (11)	−0.04977 (5)	0.61677 (10)	0.02002 (17)
O1	0.1426 (11)	0.3549 (5)	0.1162 (10)	0.039 (2)	0.420 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0128 (10)	0.0182 (10)	0.0123 (11)	0.0011 (7)	0.0003 (8)	0.0017 (8)
N2	0.0175 (10)	0.0190 (11)	0.0128 (11)	0.0002 (8)	0.0010 (9)	0.0012 (8)
C1	0.0173 (12)	0.0148 (12)	0.0210 (13)	−0.0016 (11)	0.0033 (10)	−0.0015 (13)
C2	0.0188 (11)	0.0174 (12)	0.0204 (12)	0.0027 (9)	0.0048 (9)	0.0000 (10)
C3	0.0206 (12)	0.0166 (12)	0.0139 (12)	0.0009 (10)	0.0017 (10)	−0.0010 (10)
C4	0.0180 (11)	0.0165 (11)	0.0146 (12)	0.0031 (9)	0.0042 (9)	−0.0003 (9)
C5	0.0228 (15)	0.0182 (14)	0.0241 (17)	0.0033 (10)	0.0008 (13)	0.0022 (11)
Cl1	0.0175 (3)	0.0339 (4)	0.0176 (3)	0.0027 (3)	0.0048 (2)	0.0015 (3)
Cl2	0.0129 (3)	0.0300 (3)	0.0166 (3)	−0.0009 (2)	0.0031 (2)	−0.0016 (3)
O1	0.042 (4)	0.027 (4)	0.050 (4)	0.004 (2)	0.017 (3)	0.003 (3)

Geometric parameters (Å, º)

N1—C1	1.497 (4)	C2—H7	0.9900
N1—C4	1.497 (3)	C2—H8	0.9900
N1—H1	0.9200	C3—C4	1.519 (4)
N1—H2	0.9200	C3—H9	0.9900
N2—C2	1.488 (3)	C3—H10	0.9900
N2—C3	1.495 (3)	C4—C5	1.521 (4)
N2—H3	0.9200	C4—H11	1.0000
N2—H4	0.9200	C5—H12	0.9800
C1—C2	1.510 (3)	C5—H13	0.9800
C1—H5	0.9900	C5—H14	0.9800
C1—H6	0.9900
C1—N1—C4	111.7 (2)	N2—C2—H8	109.5
C1—N1—H1	109.3	C1—C2—H8	109.5
C4—N1—H1	109.3	H7—C2—H8	108.1
C1—N1—H2	109.3	N2—C3—C4	111.0 (2)
C4—N1—H2	109.3	N2—C3—H9	109.4
H1—N1—H2	107.9	C4—C3—H9	109.4
C2—N2—C3	110.9 (2)	N2—C3—H10	109.4
C2—N2—H3	109.5	C4—C3—H10	109.4
C3—N2—H3	109.5	H9—C3—H10	108.0
C2—N2—H4	109.5	N1—C4—C3	109.5 (2)
C3—N2—H4	109.5	N1—C4—C5	109.6 (2)
H3—N2—H4	108.1	C3—C4—C5	110.8 (2)
N1—C1—C2	110.0 (2)	N1—C4—H11	109.0
N1—C1—H5	109.7	C3—C4—H11	109.0
C2—C1—H5	109.7	C5—C4—H11	109.0
N1—C1—H6	109.7	C4—C5—H12	109.5
C2—C1—H6	109.7	C4—C5—H13	109.5
H5—C1—H6	108.2	H12—C5—H13	109.5
N2—C2—C1	110.8 (2)	C4—C5—H14	109.5
N2—C2—H7	109.5	H12—C5—H14	109.5
C1—C2—H7	109.5	H13—C5—H14	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H2···Cl2	0.92	2.25	3.096 (2)	153
N1—H1···Cl2^i	0.92	2.24	3.136 (2)	166
N2—H3···Cl1	0.92	2.26	3.149 (2)	163
N2—H4···Cl1^i	0.92	2.30	3.137 (2)	152

Symmetry code: (i) x−1, y, z.