A structural hierarchy in the hydrogen-bonded adduct N,N'-di­methyl­piperazine-tartaric acid-water (1/2/2): an N-component N-dimensional structure (N = 3) with substructures having N = 1 and 2

In the hydrated adduct N,N'-di­methyl­piperazine-1,4-diium bis(3-carboxy-2,3-di­hydroxy­propanoate) dihydrate, [MeNH(CH₂CH₂)₂NHMe]²⁺·2(C₄H₅O₆)^-·2H₂O or C₆H₁₆N₂²⁺·2C₄H₅O₆^-·2H₂O, formed between racemic tartaric acid and N,N'-di­methyl­piperazine (triclinic P, Z' = 0.5), the cations lie across centres of inversion. The anions alone form chains, and anions and water mol­ecules together form sheets; the sheets are linked by the cations to form a pillared-layer framework. The supramolecular architecture thus takes the form of a family of N-dimensional N-component structures having N = 1, 2 or 3.

S1. Comment

We have recently investigated the salt-like adducts formed by functionalized aromatic carboxylic acids with organic diamines (Burchell, Ferguson et al., 2001; Burchell, Glidewell et al., 2001) and we have now turned our attention to the highly functionalized acyclic acid tartaric acid (2,3-dihydroxy-1,4-butanedioic acid, C₄H₆O₆). Racemic tartaric acid and N,N'-dimethylpiperazine, MeN(CH₂CH₂)₂NMe, form a hydrated salt, i.e. [MeNH(CH₂CH₂)₂NHMe]²⁺.[(C₄H₅O₆)^-]₂·2H₂O, (I) (Fig. 1). This salt crystallizes in space group P1 with Z' = 0.5. The cation adopts a chair conformation, with equatorial N-methyl groups, and it lies across a centre of inversion, chosen for convenience as that at (1/2, 1/2, 1/2). All of the OH units in the anion act as donors in O—H···O hydrogen bonds (Table 1), and the water molecule acts as a double donor and as a single acceptor in O—H···O hydrogen bonds. The overall three-component supramolecular structure is three-dimensional, in the form of a pillared-layer framework, and it is possible to identify a one-dimensional one component substructure built from anions only, and a two-dimensional two-component substructure built from anions and water molecules. There is thus a family of N-dimensional N-component structures for N = 1, 2, 3, precisely as observed in the adduct ethane-1,2-diphosphonic acid–4,4'-bipyridyl–water (1/1/2) (Glidewell et al., 2000).

The carboxyl O3 atom in the anion at (x, y, z) acts as hydrogen-bond donor to the carboxylate O1 atom in the anion at (1 + x, y, z), so generating by translation a C(7) chain running parallel to the [100] direction. In the same anion at (x, y, z), the hydroxyl O6 atom acts as donor to O1 in the anion at (-x, -y, 1 - z). Propagation of these two hydrogen bonds generates a chain of fused rings (Fig. 2), with R²₂(12) rings centred at (n, 0, 1/2) (n = zero or integer) and R²₄(14) rings centred at (n + 1/2, 0, 1/2) (n = zero or integer).

The water O7 atom at (x, y, z) acts as hydrogen-bond donor, via H71 and H72, respectively, to O5 at (x, y, z) and O2 at (1 + x, y, z), so generating a third type of ring, of R³₃(12) type (Fig. 2). The hydroxyl O5 atom at (x, y, z) is a component of the chain of fused rings along (x, 0, 1/2); this O5 atom acts as hydrogen-bond donor to the water O7 atom at (1 - x, 1 - y, 2 - z), which is a component of the chain of fused rings along (x, 1, 1.5). Thus, this final O—H···O hydrogen bond not only gives rise to a second chain of fused rings along the line (x, 1/2, 1) containing two further types of ring, viz. R⁴₄(14) rings centred at (n, 1/2, 1) (n = zero or integer) and R⁴₄(8) rings centred at (n + 1/2, 1/2, 1) (n = zero or integer), but it also serves to link all the [100] chains of fused rings into (011) sheets (Fig. 2). Within these sheets, there are no fewer than five different ring motifs, four of which are centrosymmetric; only the R³₃(12)rings are non-centrosymmetric.

The (011) sheets are almost planar and are linked into a continuous framework by the cations. The two N atoms in the cation centred at (1/2, 1/2, 1/2) are at (x, y, z) and (1 - x, 1 - y, 1 - z), and they act as hydrogen-bond donors to O4 atoms at (x, y, z) and (1 - x, 1 - y, 1 - z), respectively, which lie in adjacent sheets. In this manner, each sheet is linked to its two neighbouring sheets by the cation acting as pillars between the anion–water layers (Fig. 3).

S2. Experimental

Equimolar quantities of racemic tartaric acid and N,N'-dimethylpiperazine were separately dissolved in methanol. The solutions were mixed and set aside to crystallize, giving analytically pure (I). Analysis: found C 37.4, H 7.0, N 6.2%; C₁₄H₃₀N₂O₁₄ requires C 37.3, H 6.7, N 6.2%. Crystals suitable for single-crystal X-ray diffraction were selected directly from the analytical samples.

S3. Refinement

Compound (I) crystallized in the triclinic system; space group P1 was assumed and confirmed by the analysis. The coordinates of the H atoms of the O7 water molecule were determined from a difference map and were then allowed to refine isotropically subject to a DFIX restraint. All other H atoms were treated as riding, with distances C—H = 0.98–1.00 Å, N—H = 0.93 Å and O—H = 0.84 Å.

Computing details

Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).

Figures

	Fig. 1. The molecular components of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. The atom marked `a' is at the symmetry position (1 - x, 1 - y, 1 - z).
	Fig. 2. Part of the crystal structure of (I) showing the [100] chains of fused rings, formed by the anions, linked into a (011) sheet by the water molecules. For the sake of clarity, H atoms bonded to C atoms have been omitted. Atoms marked with an asterisk (*) or hash (#) are at the symmetry positions (1 + x, y, z) and (1 - x, 1 - y, 2 - z), respectively.
	Fig. 3. Part of the crystal structure of (I) showing the linking of the (011) sheets by the cations. For the sake of clarity, H atoms bonded to C atoms have been omitted. Atoms marked with an asterisk (*) are at the symmetry position (1 - x, 1 - y, 1 - z).

N,N'-Dimethylpiperazine–tartaric acid–water (1/2/2)

Crystal data

C6H16N2^2+·2C4H5O6^−·2H2O	Z = 1
Mr = 450.40	F(000) = 240
Triclinic, P1	Dx = 1.531 Mg m^−3
a = 7.2907 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.3423 (4) Å	Cell parameters from 2102 reflections
c = 8.4324 (4) Å	θ = 2.9–27.5°
α = 96.406 (2)°	µ = 0.14 mm^−1
β = 106.359 (2)°	T = 150 K
γ = 90.430 (3)°	Plate, colourless
V = 488.63 (4) Å^3	0.35 × 0.35 × 0.15 mm

Data collection

KappaCCD diffractometer	2237 independent reflections
Radiation source: fine-focus sealed X-ray tube	1691 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.049
ϕ scans, and ω scans with κ offsets	θmax = 27.5°, θmin = 2.9°
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997)	h = 0→9
Tmin = 0.953, Tmax = 0.980	k = −10→10
6667 measured reflections	l = −10→10

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)] = 0.040	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.109	w = 1/[σ^2(Fo^2) + (0.0484P)^2 + 0.0973P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
2237 reflections	Δρmax = 0.29 e Å^−3
149 parameters	Δρmin = −0.24 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.035 (9)

Special details

Experimental. The program DENZO-SMN (Otwinowski & Minor, 1997) uses a scaling algorithm [Fox, G·C. & Holmes, K·C. (1966). Acta Cryst. 20, 886–891] which effectively corrects for absorption effects. High redundancy data were used in the scaling program hence the 'multi-scan' code word was used. No transmission coefficients are available from the program (only scale factors for each frame). The scale factors in the experimental table are calculated from the 'size' command in the SHELXL97 input file.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.32857 (18)	0.40117 (16)	0.41205 (17)	0.0199 (3)
C11	0.3260 (2)	0.5339 (2)	0.5462 (2)	0.0229 (4)
C12	0.5211 (2)	0.5634 (2)	0.6709 (2)	0.0231 (4)
C13	0.1367 (2)	0.3777 (2)	0.2865 (2)	0.0313 (4)
O1	−0.06654 (15)	0.01311 (13)	0.77621 (14)	0.0204 (3)
O2	−0.02032 (16)	0.27533 (14)	0.87855 (15)	0.0250 (3)
O3	0.59478 (15)	−0.00246 (14)	0.78062 (14)	0.0207 (3)
O4	0.53434 (15)	0.17035 (13)	0.58960 (14)	0.0200 (3)
O5	0.34509 (15)	0.28538 (14)	0.88812 (15)	0.0259 (3)
O6	0.15410 (15)	0.14631 (13)	0.54491 (13)	0.0207 (3)
C1	0.0353 (2)	0.14454 (19)	0.83062 (19)	0.0178 (3)
C2	0.2476 (2)	0.13263 (19)	0.83847 (19)	0.0183 (3)
C3	0.2709 (2)	0.06235 (19)	0.67021 (19)	0.0171 (3)
C4	0.4815 (2)	0.08143 (18)	0.67629 (19)	0.0172 (3)
O7	0.72788 (18)	0.38219 (16)	1.06172 (17)	0.0308 (3)
H1	0.3574	0.3061	0.4602	0.024*
H11A	0.2318	0.5047	0.6040	0.027*
H11B	0.2856	0.6342	0.4958	0.027*
H12A	0.5169	0.6557	0.7544	0.028*
H12B	0.5552	0.4670	0.7301	0.028*
H13A	0.1038	0.4772	0.2349	0.047*
H13B	0.0404	0.3514	0.3415	0.047*
H13C	0.1400	0.2892	0.2007	0.047*
H3	0.7076	0.0115	0.7768	0.031*
H5	0.2662	0.3567	0.8955	0.039*
H6	0.1245	0.0864	0.4538	0.031*
H2	0.3072	0.0588	0.9227	0.022*
H3A	0.2305	−0.0548	0.6480	0.021*
H71	0.618 (3)	0.338 (3)	1.011 (3)	0.042 (6)*
H72	0.803 (4)	0.337 (3)	1.004 (3)	0.059 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0183 (6)	0.0208 (7)	0.0194 (7)	−0.0022 (5)	0.0023 (5)	0.0049 (5)
C11	0.0217 (8)	0.0240 (8)	0.0253 (9)	0.0008 (7)	0.0105 (7)	0.0031 (7)
C12	0.0290 (9)	0.0230 (8)	0.0186 (8)	−0.0015 (7)	0.0091 (7)	0.0025 (7)
C13	0.0253 (9)	0.0295 (9)	0.0314 (10)	−0.0039 (7)	−0.0070 (8)	0.0103 (8)
O1	0.0152 (5)	0.0226 (6)	0.0241 (6)	0.0000 (4)	0.0071 (5)	0.0025 (5)
O2	0.0210 (6)	0.0243 (6)	0.0309 (7)	0.0022 (5)	0.0107 (5)	−0.0002 (5)
O3	0.0129 (5)	0.0286 (6)	0.0233 (6)	0.0026 (4)	0.0069 (5)	0.0093 (5)
O4	0.0184 (5)	0.0205 (6)	0.0234 (6)	0.0000 (4)	0.0085 (5)	0.0055 (5)
O5	0.0154 (5)	0.0255 (6)	0.0335 (7)	−0.0026 (5)	0.0065 (5)	−0.0091 (5)
O6	0.0179 (5)	0.0257 (6)	0.0166 (6)	0.0009 (5)	0.0021 (5)	0.0023 (5)
C1	0.0149 (7)	0.0241 (8)	0.0151 (8)	0.0019 (6)	0.0046 (6)	0.0040 (6)
C2	0.0143 (7)	0.0224 (8)	0.0176 (8)	−0.0002 (6)	0.0041 (6)	0.0009 (6)
C3	0.0151 (7)	0.0191 (7)	0.0178 (8)	0.0004 (6)	0.0050 (6)	0.0038 (6)
C4	0.0174 (8)	0.0175 (7)	0.0168 (8)	0.0008 (6)	0.0056 (6)	−0.0003 (6)
O7	0.0181 (6)	0.0394 (8)	0.0310 (7)	−0.0009 (6)	0.0055 (6)	−0.0084 (6)

Geometric parameters (Å, º)

N1—C13	1.494 (2)	O3—C4	1.2972 (19)
N1—C11	1.496 (2)	O3—H3	0.84
N1—C12^i	1.500 (2)	O4—C4	1.2281 (18)
N1—H1	0.93	O5—C2	1.4155 (18)
C11—C12	1.511 (2)	O5—H5	0.84
C11—H11A	0.99	O6—C3	1.4139 (19)
C11—H11B	0.99	O6—H6	0.84
C12—N1^i	1.500 (2)	C1—C2	1.535 (2)
C12—H12A	0.99	C2—C3	1.529 (2)
C12—H12B	0.99	C2—H2	1.00
C13—H13A	0.98	C3—C4	1.528 (2)
C13—H13B	0.98	C3—H3A	1.00
C13—H13C	0.98	O7—H71	0.86 (2)
O1—C1	1.2836 (19)	O7—H72	0.89 (3)
O2—C1	1.2325 (19)
C13—N1—C11	110.46 (13)	H13B—C13—H13C	109.5
C13—N1—C12^i	110.22 (13)	C4—O3—H3	109.5
C11—N1—C12^i	110.83 (12)	C2—O5—H5	109.5
C13—N1—H1	108.4	C3—O6—H6	109.5
C11—N1—H1	108.4	O2—C1—O1	126.46 (14)
C12^i—N1—H1	108.4	O2—C1—C2	118.23 (14)
N1—C11—C12	111.15 (13)	O1—C1—C2	115.30 (13)
N1—C11—H11A	109.4	O5—C2—C3	109.60 (12)
C12—C11—H11A	109.4	O5—C2—C1	111.22 (12)
N1—C11—H11B	109.4	C3—C2—C1	110.92 (12)
C12—C11—H11B	109.4	O5—C2—H2	108.3
H11A—C11—H11B	108.0	C3—C2—H2	108.3
N1^i—C12—C11	111.50 (13)	C1—C2—H2	108.3
N1^i—C12—H12A	109.3	O6—C3—C2	108.65 (12)
C11—C12—H12A	109.3	O6—C3—C4	110.96 (12)
N1^i—C12—H12B	109.3	C2—C3—C4	108.48 (12)
C11—C12—H12B	109.3	O6—C3—H3A	109.6
H12A—C12—H12B	108.0	C2—C3—H3A	109.6
N1—C13—H13A	109.5	C4—C3—H3A	109.6
N1—C13—H13B	109.5	O4—C4—O3	124.49 (13)
H13A—C13—H13B	109.5	O4—C4—C3	121.56 (14)
N1—C13—H13C	109.5	O3—C4—C3	113.95 (13)
H13A—C13—H13C	109.5	H71—O7—H72	103 (2)
C13—N1—C11—C12	−177.87 (13)	C1—C2—C3—O6	49.23 (16)
C12^i—N1—C11—C12	−55.42 (19)	O5—C2—C3—C4	46.77 (17)
N1—C11—C12—N1^i	55.80 (19)	C1—C2—C3—C4	169.96 (12)
O2—C1—C2—O5	−5.5 (2)	O6—C3—C4—O4	5.4 (2)
O1—C1—C2—O5	175.70 (13)	C2—C3—C4—O4	−113.93 (16)
O2—C1—C2—C3	−127.74 (15)	O6—C3—C4—O3	−175.25 (12)
O1—C1—C2—C3	53.45 (18)	C2—C3—C4—O3	65.47 (17)
O5—C2—C3—O6	−73.96 (15)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4	0.93	1.91	2.761 (2)	151
N1—H1···O6	0.93	2.29	2.947 (2)	127
O3—H3···O1^ii	0.84	1.65	2.483 (2)	172
O5—H5···O2	0.84	2.15	2.643 (2)	117
O5—H5···O7^iii	0.84	2.17	2.836 (2)	137
O6—H6···O1^iv	0.84	1.95	2.778 (2)	168
O7—H71···O5	0.86 (2)	1.99 (2)	2.826 (2)	167 (2)
O7—H72···O2^ii	0.89 (3)	1.92 (3)	2.805 (2)	171 (2)

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