(2-Hydroxy­ethyl)­hydrazinium(2+) dichloride

The crystal structure of the title compound, C₂H₁₀N₂O²⁺·2Cl⁻, is built up from one 2-hydroxy­ethyl­hydrazinium(2+) cation and two Cl⁻ anions. The mol­ecular structure is stabilized by O—H...Cl and N—H...Cl hydrogen bonds. The crystal structure is stabilized by one N—H...O and three N—H...Cl inter­actions, and the three-dimensional network of hydrogen bonds stabilizes the crystal packing. All five hydrazinium H atoms are involved in hydrogen bonds to Cl⁻ anions. The Cl...H contact distances range from 2.122 (15) to 2.809 (14) Å.

S1. Comment

Hydrogen bonding plays a key role in molecular recognition and the engineering of organic solids (Desiraju, 1989; Melendez & Hamilton, 1998). The design of highly specific solid-state compounds is of considerable significance in organic chemistry, due to their important applications in the development of new optical, magnetic and electronic systems (Lehn, 1992).

The structure of the title compound, (I), is presented in Fig. 1, and selected bond distances and angles are given in Table 1. The asymmetric unit contains one protonated 2-hydroxyethylhydrazinium cation and two Cl⁻ counter-anions. Atoms N1 and N2 exhibit approximately ideal tetrahedral geometry, with average angles of 109.45 (13) and 109.48 (13)°, respectively.

Hydrogen bonds are abundant in this structure, as might be expected from the structural formula and the liability of amino groups to act as donor. In fact, five different N—H···Cl bonds are found, with H···Cl distances ranging from 2.122 (15) to 2.809 (14) Å. The shortest, N2—H42···Cl2 [2.122 (15) Å], has a nearly linear contact angle [171.1 (13)°]. According to Balmer et al. (2001), this bond is the strongest among those found for N—H···Cl contacts. Table 2 gives the details of the hydrogen-bond geometry of (I). The H atoms on N1 and N2, with the exception of H31, have only one hydrogen bond, while atom H31 forms a three-centre interaction with two Cl atoms. Our investigation shows that the 2-hydroxyethylhydrazinium cation is linked to the two Cl⁻ anions through O1—H1···Cl1 [O1···Cl1 3.0874 (7) Å] and N1—H31···Cl1 [N1···Cl1 3.4104 (8) Å] hydrogen bonds, resulting in the formation of cyclic seven-membered hydrogen-bonded rings, and an N2—H41···Cl2 [N2···Cl2 3.0701 (8) Å] hydrogen bond (Fig. 1).

The 2-hydroxyethylhydrazinium dichloride units are arranged in such a way as to form a two-dimensional network via O—H···Cl and N—H···Cl interactions, which develop parallel to the bc plane. There is also another N—H···Cl interaction, which connects two symmetry-related planar networks (Fig. 2). The N1—H31···O1 interaction builds an approximately zigzag chain, which develops parallel to the c axis (Fig. 3). Importantly, the N1—H32···Cl1 and N2—H43···Cl1 interactions link symmetry-related such zigzag chains to build up a two-dimensional network as a layer, which includes R₆⁶(20) rings (Bernstein et al., 1995) and develops parallel to the bc plane (Fig. 4).

Four independent halogen–halogen contacts in each structure provide the more striking examples of secondary interactions (Table 3). The halogen–halogen interactions form zigzag-like roofs interconnected by Cl···Cl contacts (Fig. 5). In the doubly protonated 2-hydroxyethylhydrazine moiety, the average C2—N1 [1.502 (2) Å], C1—O1 [1.429 (2) Å] and N1—N2 [1.449 (2) Å] distances (Table 1) are in good agreement with the normal values (Orpen et al., 1992; Demir et al., 2002; Parkins et al., 2001).

S2. Experimental

HCl [aqueous, 37% (w/w), 0.93 ml, 30 mmol] was added dropwise to 2-hydroxyethylhydrazine (1.01 ml, 15 mmol) in ether (20 ml) and the resulting solution was stirred for 15 min at 293 K. Colourless single crystals of (I) were obtained by slow evaporation of the solvent, and these crystals were dried in air (m.p. 406–408 K).

S3. Refinement

H atoms were located in a difference map and refined isotropically, with N—H = 0.86 (2)–0.94 (2), O—H = 0.83 (2) and C—H = 0.94 (2)–0.98 (2) Å, and with U_iso(H) values in the range 0.015 (3)–0.030 (4) Ų.

Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997), CAMERON (Watkin et al., 1993) and PLUTON (Spek, 1998); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. A view of the structure of (I), with the atom-numbering scheme. Displacement ellipsoids are darwn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. A packing diagram for (I).
	Fig. 3. The zigzag chain parallel to the c axis built up by N—H···O interactions. Cl atoms have been omitted for clarity. [Symmetry codes: (i) x, −y + 3/2, z + 1/2; (vi) x, 3/2 − y, 1/2 − z.]
	Fig. 4. The two-dimensional network, including the R6^6(20) rings built up by N—H···Cl interactions. [Symmetry codes: (i) x, 3/2 − y, z − 1/2; (ii) 1 − x, y − 1/2, −z + 1/2; (iii) 1 − x, 1 − y, −z; (iv) 2 − x, y + 1/2, −z + 1/2; (v) x, 3/2 − y, 1/2 + z; (vi) x, 1/2 − y, 1/2 + z]
	Fig. 5. The halogen–halogen interactions forming zigzag-like roofs interconnected by Cl···Cl contacts.

2-Hydroxyethylhydrazinium dichloride

Crystal data

C2H10N2O^2+·2Cl^−	F(000) = 312
Mr = 149.02	Dx = 1.571 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 11440 reflections
a = 10.2367 (9) Å	θ = 2.8–29.4°
b = 8.4158 (6) Å	µ = 0.93 mm^−1
c = 7.5111 (7) Å	T = 150 K
β = 103.208 (7)°	Shapeless, colourless
V = 629.96 (9) Å^3	0.54 × 0.50 × 0.43 mm
Z = 4

Data collection

Stoe IPDS-II diffractometer	1678 independent reflections
Radiation source: fine-focus sealed tube	1625 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.077
Detector resolution: 6.67 pixels mm^-1	θmax = 29.1°, θmin = 3.2°
rotation method scans	h = −13→13
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −11→11
Tmin = 0.680, Tmax = 0.735	l = −10→10
11440 measured reflections

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)] = 0.019	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.050	All H-atom parameters refined
S = 1.17	w = 1/[σ^2(Fo^2) + (0.0248P)^2 + 0.1595P] where P = (Fo^2 + 2Fc^2)/3
1678 reflections	(Δ/σ)max = 0.001
104 parameters	Δρmax = 0.31 e Å^−3
0 restraints	Δρmin = −0.24 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
C1	0.71821 (9)	0.61221 (11)	0.54054 (12)	0.01471 (17)
C2	0.80446 (9)	0.53938 (11)	0.42411 (12)	0.01263 (17)
N1	0.72172 (7)	0.49533 (9)	0.23861 (10)	0.01046 (14)
N2	0.80584 (7)	0.43367 (9)	0.12342 (10)	0.01086 (14)
O1	0.67849 (7)	0.76998 (8)	0.48174 (9)	0.01514 (14)
Cl1	0.42289 (2)	0.68909 (3)	0.18828 (3)	0.01514 (7)
Cl2	1.03755 (2)	0.67097 (2)	0.15246 (3)	0.01381 (7)
H1	0.6031 (17)	0.764 (2)	0.411 (2)	0.030 (4)*
H11	0.7758 (13)	0.6167 (17)	0.6645 (18)	0.019 (3)*
H12	0.6416 (14)	0.5456 (17)	0.5414 (19)	0.022 (3)*
H21	0.8750 (13)	0.6121 (16)	0.4098 (18)	0.015 (3)*
H22	0.8457 (13)	0.4459 (17)	0.4768 (18)	0.019 (3)*
H31	0.6791 (14)	0.5740 (17)	0.1803 (19)	0.021 (3)*
H32	0.6598 (14)	0.4161 (17)	0.2489 (19)	0.023 (3)*
H41	0.8646 (14)	0.5063 (18)	0.1082 (19)	0.025 (3)*
H42	0.8514 (14)	0.3496 (17)	0.179 (2)	0.021 (3)*
H43	0.7533 (14)	0.4053 (17)	0.0204 (19)	0.019 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0189 (4)	0.0132 (4)	0.0131 (4)	0.0002 (3)	0.0060 (3)	−0.0013 (3)
C2	0.0135 (4)	0.0133 (4)	0.0098 (4)	0.0015 (3)	−0.0001 (3)	−0.0020 (3)
N1	0.0103 (3)	0.0105 (3)	0.0106 (3)	0.0009 (3)	0.0022 (3)	−0.0007 (3)
N2	0.0117 (3)	0.0107 (3)	0.0103 (3)	0.0003 (3)	0.0028 (3)	−0.0015 (3)
O1	0.0127 (3)	0.0126 (3)	0.0182 (3)	0.0015 (2)	−0.0005 (2)	−0.0043 (2)
Cl1	0.01252 (11)	0.01620 (11)	0.01517 (11)	0.00083 (7)	0.00001 (8)	−0.00335 (7)
Cl2	0.01437 (11)	0.01321 (11)	0.01439 (11)	−0.00396 (7)	0.00437 (8)	−0.00269 (7)

Geometric parameters (Å, º)

C1—O1	1.429 (2)	N1—N2	1.449 (2)
C1—C2	1.5076 (12)	N1—H31	0.86 (2)
C1—H11	0.98 (2)	N1—H32	0.94 (2)
C1—H12	0.966 (14)	N2—H41	0.883 (15)
C2—N1	1.502 (2)	N2—H42	0.895 (15)
C2—H21	0.971 (13)	N2—H43	0.869 (14)
C2—H22	0.94 (2)	O1—H1	0.83 (2)
O1—C1—C2	111.20 (7)	N2—N1—H31	105.9 (9)
O1—C1—H11	108.9 (8)	C2—N1—H31	113.4 (9)
C2—C1—H11	105.2 (8)	N2—N1—H32	107.5 (9)
O1—C1—H12	111.6 (8)	C2—N1—H32	110.4 (9)
C2—C1—H12	110.6 (8)	H31—N1—H32	108.5 (12)
H11—C1—H12	109.1 (12)	N1—N2—H41	110.2 (9)
N1—C2—C1	110.94 (7)	N1—N2—H42	108.9 (9)
N1—C2—H21	109.2 (8)	H41—N2—H42	107.9 (12)
C1—C2—H21	110.9 (8)	N1—N2—H43	107.4 (9)
N1—C2—H22	106.8 (8)	H41—N2—H43	112.2 (13)
C1—C2—H22	111.4 (8)	H42—N2—H43	110.3 (13)
H21—C2—H22	107.5 (11)	C1—O1—H1	107.6 (12)
N2—N1—C2	110.86 (6)
O1—C1—C2—N1	−73.52 (9)	C1—C2—N1—N2	176.77 (7)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···Cl1	0.833 (17)	2.278 (17)	3.0874 (7)	164.1 (15)
N1—H31···O1^i	0.856 (15)	1.986 (14)	2.7257 (10)	144.0 (13)
N1—H31···Cl1	0.856 (15)	2.809 (14)	3.4104 (8)	128.7 (11)
N1—H32···Cl1^ii	0.935 (15)	2.185 (15)	3.0832 (8)	160.9 (12)
N2—H43···Cl1^iii	0.869 (14)	2.246 (15)	3.0864 (8)	162.4 (12)
N2—H41···Cl2	0.883 (15)	2.213 (15)	3.0701 (8)	163.6 (13)
N2—H42···Cl2^iv	0.895 (15)	2.122 (15)	3.0098 (8)	171.1 (13)

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x+1, y−1/2, −z+1/2; (iii) −x+1, −y+1, −z; (iv) −x+2, y−1/2, −z+1/2.