Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the di­carb­oxy­lic oxalic and adipic acid homologues

The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C₆H₁₃N₂O⁺·C₂HO₄⁻·2H₂O, (I), and with adipic acid, bis­(4-car­bam­oylpiperidinium) adipate dihydrate, 2C₆H₁₃N₂O⁺·C₆H₈O₄²⁻·2H₂O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carb­oxy­lic acid O—H...O_carboxyl hydrogen-bonding inter­actions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N—H...O hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N—H...O_carboxyl hydrogen bonds, generating cyclic R₄³(10) and R₃²(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water mol­ecule. In the crystal structure, the two inversion-related cations are inter­linked through the two water mol­ecules, which act as acceptors in dual amide N—H...O_water hydrogen bonds, to give a cyclic R₄²(8) association which is conjoined with an R₄⁴(12) motif. Further N—H...O_water, water O—H...O_amide and piperidinium N—H...O_carbox­yl hydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water mol­ecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide–amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

S1. Introduction

The Lewis base piperidine-4-carboxamide (isonipecotamide, INIPA) has provided a considerable number of structures of salts with carb­oxy­lic acids, the majority of which are anhydrous although prepared commonly in an aqueous ethano­lic medium (Smith & Wermuth, 2010a, 2011a). Present in ca 50% of the mostly low-dimensional hydrogen-bonded structures of salts in this series are examples of the head-to-head cyclic dimer association involving the amide group [graph set R₂²(8) (Etter et al., 1990)] (the `amide–amide' motif; Allen et al., 1998). Less common is the lateral head-to-tail cyclic association involving dual piperidinium N—H···O_amide hydrogen bonds [graph set R₂²(14)] (the isonipecotamide motif), such as found in the structure of the 2-nitro­benzoate salt (Smith & Wermuth, 2010b). Hydrated salts are less common in this series, with only six reported among a total of 26 known structures. These are the acetate (a monohydrate; Smith & Wermuth, 2010c), the phenyl­acetate (a hemihydrate; Smith & Wermuth, 2010d), the terephthalate (a dihydrate; Smith & Wermuth, 2011a), the indole-2-carboxyl­ate (a hemihydrate; [Reference?]), the indole-3-carboxyl­ate (a dihydrate; Smith & Wermuth, 2011b) and the picolinate (a 0.25-hydrate; Smith & Wermuth, 2012). Formation of 2:1 INIPA salts with the diprotic organic acids is also unusual, considering the 1:1 reagent stoichiometry employed in the preparations, with only two reported examples, the terephthalate (Smith & Wermuth, 2010a) and the bi­pyridine-4,4'-di­sulfonate (Smith et al., 2010).

However, our 1:1 reaction of INIPA with a series of aliphatic di­carb­oxy­lic acids, employing similar conditions to those used in the preparation of the previous salts, provided two examples of salt hydrates, one of which was a 2:1 salt. These salts are with oxalic acid [4-carbamoylpiperidinium hydrogen oxalate dihydrate, (I)] and adipic acid [bis­(4-carbamoylpiperidinium) adipate dihydrate, (II)]. The double deprotonation in the formation of the 2:1 salt in the case of (II) is consistent with the relative acid dissociation constants pK_a¹ and pK_a² of adipic acid (4.43 and 5.42, respectively) compared with oxalic acid (1.27 and 4.28, respectively). The structures of (I) and (II) are reported herein. In both, hydrogen-bonding associations give three-dimensional structures, with an absence of either the previously described cyclic `amide–amide' hydrogen-bonding motif or the uncommon cyclic `isonipecotamide' motif. However, present in all structures are several different types of enlarged water-bridged cyclic associations.

S2. Experimental

S2.1. Synthesis and crystallization

The title compounds were synthesized by heating together under reflux for 10 min, piperidine-4-carboxamide (isonipecotamide) (0.13 g, 1 mmol) and oxalic acid dihydrate (0.13 g, 1 mmol) [for (I)], or adipic acid (0.15 g, 1 mmol) [for (II)] in ethanol–water (50:50 v/v, 50 ml). After concentration to ca 30 ml, partial room-temperature evaporation of the hot-filtered solutions gave colourless plates of (I) (m.p. 366 K) or prisms of (II) (m.p. 353 K), from which specimens were cleaved for the X-ray analyses.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms involved in hydrogen-bonding inter­actions were located by difference methods and their positional and isotropic displacement parameters were refined. Other H atoms were included in the refinements at calculated positions [C—H = 0.99 (methyl­ene) or 1.00 Å (methine)] using a riding-model approximation, with U_iso(H) = 1.2U_eq(C).

S3. Results and discussion

In the structure of (I) (Fig. 1), the oxalate monoanions give C(5) head-to-tail carb­oxy­lic acid O—H···O_carboxyl hydrogen-bonding inter­actions, forming chains which extend along a (Figs. 3 and 4). This type of chain substructure is common among hydrogen phthalate salt structures, although in those substructures the motif is C(7) (Glidewell et al., 2005; Smith & Wermuth, 2010b). In (I), lying parallel to the hydrogen oxalate chains are INIPA chain substructures generated through N—H···O hydrogen bonds between the amide groups of head-to-head INIPA cations. The links between the chains across b are provided by alternating O—H···O hydrogen-bond bridges involving both water molecules (O1W and O2W) with carboxyl and amide O-atom acceptors, together with amide N—H···O_carboxyl and piperidinium N—H···O_carboxyl hydrogen bonds (Table 2). These inter­actions generate conjoined cyclic ring motifs [graph sets R₄³(10) and R₃²(11)], best seen in Fig. 3. The three-dimensional structure is generated through water–water hydrogen-bonding associations extending down c. There is also an intra­molecular piperidinium–carboxyl inter­action in the structure [N1A—H···O21 = 2.900 (2) Å and N—H···O = 110.8 (14)°] and a water–carboxyl inter­action [O2W—H···O22 = 3.0952 (17) Å and O—H···O = 118.3 (19)°]. The carboxyl groups of the oxalate monoanion are rotated only slightly out of the molecular plane [O12—C1—C2—O22 = -14.1 (2)°].

In the structure of the 2:1 INIPA salt hydrate with adipic acid, (II) (Fig. 2), the asymmetric unit comprises a piperidinium cation, half of an adipate anion, which lies across a crystallographic inversion centre, and a solvent water molecule (O1W). In the crystal structure, the two inversion-related cations are inter­linked through two similarly related water molecules, which act as acceptors in dual amide N—H···O hydrogen bonds, to give a centrosymmetric cyclic association [graph set R₄²(8)] (Table 3). A second conjoined cyclic association [graph set R₄⁴(12)], also involving the amide group and the two water molecules but with both N—H···O_water and water O—H···O_amide hydrogen bonds, links the substructures which extend down b. The piperidinium group gives N—H···O hydrogen-bonding links to O-atom acceptors (O11) of the adipate dianion, giving chain extension along b as well as chain linking across a through atom O12, to give the three-dimensional structure (Fig. 5).

Within the INIPA cations in both salts, the amide side-chain conformations are similar, with comparative values for the minimum C2/C5—C4—C41—O41 ring-to-amide side-chain torsion angle of 47.7 (2)° in (I) and -49.83 (7)° in (II).

The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. Unlike the majority of previous examples, the amide–amide hydogen-bonding motif, which is present in 13 of the 26 known structures of proton-transfer salts of INIPA, is not found in any of the present examples. However, the presence of solvent water molecules in these structures is largely responsible for this non-occurrence, instead promoting enlarged cyclic hydrogen-bonding motifs.

Related literature

For related literature, see: Allen et al. (1998); Etter et al. (1990); Glidewell et al. (2005); Smith & Wermuth (2010a, 2010b, 2010c, 2010d, 2011a, 2011b, 2012); Smith et al. (2010).

Computing details

For both compounds, data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular conformation and atom-numbering scheme for the INIPA cation, the oxalate monoanion and the solvent water molecules in (I). Displacement ellipsoids are drawn at the 40% probability level and inter-species hydrogen bonds are shown as dashed lines.
	Fig. 2. The molecular conformation and atom-numbering scheme for the INIPA cation, the adipate dianion and the solvent water molecule in the asymmetric unit of (II). Displacement ellipsoids are drawn at the 40% probability level and inter-species hydrogen bonds are shown as dashed lines. [Symmetry code: (i) -x + 1, -y - 1, -z.]
	Fig. 3. The cyclic R4^3(10) and R3^2(11) cation–anion–water hydrogen-bonding associations and C(5) anion–anion chain structures in (I), showing hydrogen-bonding associations as dashed lines. Non-associative H atoms have been omitted. For symmetry codes, see Table 2.
	Fig. 4. The three-dimensional hydrogen-bonded network structure of (I), showing hydrogen-bonding associations as dashed lines. Non-interactive H atoms have been omitted. [For symmetry codes, see Table 2?]
	Fig. 5. The three-dimensional hydrogen-bonded structure of (II), showing hydrogen-bonding associations as dashed lines. Non-associative H atoms have been omitted. For symmetry codes, see Table 3.

(I) 4-Carbamoylpiperidinium hydrogen oxalate dihydrate

Crystal data

C6H13N2O^+·C2HO4^−·2H2O	F(000) = 544
Mr = 254.24	Dx = 1.396 Mg m^−3
Monoclinic, P21/n	Melting point: 366 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 5.7265 (5) Å	Cell parameters from 4129 reflections
b = 28.646 (2) Å	θ = 3.5–28.8°
c = 7.4941 (7) Å	µ = 0.12 mm^−1
β = 100.327 (9)°	T = 200 K
V = 1209.44 (18) Å^3	Block, colourless
Z = 4	0.43 × 0.23 × 0.20 mm

Data collection

Oxford Gemini-S CCD area-detector diffractometer	2369 independent reflections
Radiation source: Enhance (Mo) X-ray source	1888 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
Detector resolution: 16.077 pixels mm^-1	θmax = 26.0°, θmin = 3.5°
ω scans	h = −6→7
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −35→35
Tmin = 0.893, Tmax = 0.990	l = −9→5
7562 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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.110	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0648P)^2 + 0.2236P] where P = (Fo^2 + 2Fc^2)/3
2369 reflections	(Δ/σ)max < 0.001
190 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.32 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
O41A	0.7546 (2)	0.26506 (4)	0.28401 (18)	0.0315 (4)
N1A	0.7637 (3)	0.09954 (5)	0.2836 (2)	0.0254 (4)
N41A	1.0119 (3)	0.26870 (5)	0.0906 (2)	0.0301 (5)
C2A	0.6217 (3)	0.11995 (6)	0.1156 (3)	0.0313 (6)
C3A	0.6186 (3)	0.17288 (6)	0.1290 (3)	0.0302 (5)
C4A	0.8702 (3)	0.19264 (5)	0.1614 (2)	0.0236 (5)
C5A	1.0136 (3)	0.17014 (5)	0.3325 (3)	0.0267 (5)
C6A	1.0115 (3)	0.11718 (6)	0.3180 (3)	0.0318 (6)
C41A	0.8724 (3)	0.24535 (6)	0.1826 (2)	0.0232 (5)
O11	0.8036 (2)	0.00182 (4)	0.2462 (2)	0.0354 (4)
O12	0.65900 (19)	−0.07007 (4)	0.26113 (18)	0.0284 (4)
O21	0.3756 (2)	0.03551 (4)	0.2990 (2)	0.0454 (5)
O22	0.2228 (2)	−0.03540 (4)	0.2389 (2)	0.0376 (5)
C1	0.6414 (3)	−0.02690 (5)	0.2568 (2)	0.0220 (5)
C2	0.3964 (3)	−0.00514 (5)	0.2667 (3)	0.0250 (5)
O1W	0.5618 (2)	0.35615 (5)	0.30482 (18)	0.0315 (4)
O2W	0.6185 (2)	0.13264 (4)	0.60447 (19)	0.0289 (4)
H4A	0.94630	0.18440	0.05540	0.0280*
H11A	0.687 (3)	0.1064 (6)	0.381 (3)	0.024 (4)*
H12A	0.764 (3)	0.0683 (8)	0.272 (3)	0.037 (5)*
H21A	0.45720	0.10790	0.09830	0.0380*
H22A	0.69140	0.11060	0.00930	0.0380*
H31A	0.53830	0.18220	0.23000	0.0360*
H32A	0.52740	0.18600	0.01540	0.0360*
H41A	1.019 (3)	0.2994 (8)	0.102 (3)	0.036 (5)*
H42A	1.089 (3)	0.2546 (7)	0.017 (3)	0.029 (5)*
H51A	1.17950	0.18150	0.35020	0.0320*
H52A	0.94550	0.17960	0.43940	0.0320*
H61A	1.09240	0.10750	0.21780	0.0380*
H62A	1.09900	0.10360	0.43200	0.0380*
H22	0.077 (5)	−0.0220 (8)	0.241 (4)	0.055 (7)*
H11W	0.656 (4)	0.3815 (9)	0.281 (4)	0.056 (7)*
H12W	0.639 (4)	0.3318 (9)	0.288 (3)	0.045 (7)*
H21W	0.758 (4)	0.1342 (7)	0.672 (3)	0.040 (6)*
H22W	0.542 (4)	0.1093 (9)	0.649 (4)	0.054 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O41A	0.0434 (7)	0.0230 (6)	0.0323 (7)	−0.0008 (5)	0.0182 (6)	−0.0029 (5)
N1A	0.0316 (8)	0.0168 (7)	0.0283 (8)	−0.0015 (6)	0.0068 (6)	−0.0004 (6)
N41A	0.0396 (9)	0.0195 (8)	0.0352 (9)	−0.0009 (6)	0.0178 (7)	−0.0008 (6)
C2A	0.0364 (10)	0.0279 (9)	0.0261 (10)	−0.0075 (7)	−0.0034 (8)	−0.0019 (7)
C3A	0.0305 (9)	0.0265 (9)	0.0288 (10)	−0.0021 (7)	−0.0073 (7)	0.0036 (7)
C4A	0.0313 (9)	0.0200 (8)	0.0212 (9)	−0.0007 (6)	0.0090 (7)	−0.0015 (6)
C5A	0.0208 (8)	0.0232 (8)	0.0345 (10)	−0.0010 (6)	0.0003 (7)	0.0004 (7)
C6A	0.0253 (9)	0.0260 (9)	0.0434 (12)	0.0039 (7)	0.0043 (8)	0.0018 (8)
C41A	0.0272 (8)	0.0232 (8)	0.0187 (8)	0.0001 (6)	0.0027 (7)	0.0006 (6)
O11	0.0215 (6)	0.0217 (6)	0.0647 (10)	−0.0013 (5)	0.0124 (6)	−0.0004 (6)
O12	0.0232 (6)	0.0203 (6)	0.0428 (8)	0.0015 (4)	0.0088 (5)	0.0003 (5)
O21	0.0275 (7)	0.0229 (7)	0.0885 (13)	0.0012 (5)	0.0181 (7)	−0.0056 (7)
O22	0.0188 (6)	0.0235 (6)	0.0709 (11)	0.0000 (5)	0.0095 (6)	−0.0038 (6)
C1	0.0192 (8)	0.0198 (8)	0.0267 (9)	−0.0006 (6)	0.0032 (6)	−0.0023 (6)
C2	0.0217 (8)	0.0194 (8)	0.0341 (10)	0.0004 (6)	0.0058 (7)	0.0012 (7)
O1W	0.0310 (7)	0.0273 (7)	0.0379 (8)	−0.0009 (6)	0.0108 (6)	0.0050 (6)
O2W	0.0296 (7)	0.0247 (6)	0.0331 (7)	−0.0013 (5)	0.0075 (6)	0.0045 (5)

Geometric parameters (Å, º)

O41A—C41A	1.239 (2)	N41A—H41A	0.88 (2)
O11—C1	1.254 (2)	C2A—C3A	1.520 (2)
O12—C1	1.2407 (18)	C3A—C4A	1.526 (2)
O21—C2	1.1996 (19)	C4A—C41A	1.518 (2)
O22—C2	1.307 (2)	C4A—C5A	1.535 (3)
O22—H22	0.92 (3)	C5A—C6A	1.521 (2)
O1W—H11W	0.94 (3)	C2A—H21A	0.9900
O1W—H12W	0.85 (2)	C2A—H22A	0.9900
O2W—H21W	0.87 (2)	C3A—H32A	0.9900
O2W—H22W	0.90 (3)	C3A—H31A	0.9900
N1A—C2A	1.490 (3)	C4A—H4A	1.0000
N1A—C6A	1.485 (2)	C5A—H52A	0.9900
N41A—C41A	1.326 (2)	C5A—H51A	0.9900
N1A—H12A	0.90 (2)	C6A—H61A	0.9900
N1A—H11A	0.94 (2)	C6A—H62A	0.9900
N41A—H42A	0.87 (2)	C1—C2	1.549 (2)
C2—O22—H22	112.7 (15)	H21A—C2A—H22A	108.00
H11W—O1W—H12W	106 (2)	C2A—C3A—H31A	109.00
H21W—O2W—H22W	106 (2)	C2A—C3A—H32A	109.00
C2A—N1A—C6A	111.90 (14)	H31A—C3A—H32A	108.00
H11A—N1A—H12A	107.0 (17)	C4A—C3A—H31A	109.00
C2A—N1A—H12A	108.6 (14)	C4A—C3A—H32A	109.00
C6A—N1A—H11A	111.1 (12)	C3A—C4A—H4A	109.00
C6A—N1A—H12A	109.7 (11)	C5A—C4A—H4A	109.00
C2A—N1A—H11A	108.3 (12)	C41A—C4A—H4A	109.00
H41A—N41A—H42A	120.4 (18)	C4A—C5A—H51A	109.00
C41A—N41A—H41A	118.2 (13)	H51A—C5A—H52A	108.00
C41A—N41A—H42A	121.3 (13)	C6A—C5A—H52A	109.00
N1A—C2A—C3A	110.28 (16)	C4A—C5A—H52A	109.00
C2A—C3A—C4A	111.01 (14)	C6A—C5A—H51A	109.00
C3A—C4A—C41A	112.05 (14)	N1A—C6A—H61A	110.00
C3A—C4A—C5A	109.00 (14)	N1A—C6A—H62A	110.00
C5A—C4A—C41A	109.70 (12)	C5A—C6A—H61A	110.00
C4A—C5A—C6A	111.28 (16)	C5A—C6A—H62A	110.00
N1A—C6A—C5A	110.30 (14)	H61A—C6A—H62A	108.00
O41A—C41A—N41A	122.28 (16)	O12—C1—C2	118.02 (14)
O41A—C41A—C4A	121.48 (15)	O11—C1—O12	126.73 (16)
N41A—C41A—C4A	116.22 (14)	O11—C1—C2	115.25 (13)
C3A—C2A—H21A	110.00	O21—C2—O22	125.15 (16)
C3A—C2A—H22A	110.00	O21—C2—C1	121.59 (15)
N1A—C2A—H22A	110.00	O22—C2—C1	113.26 (13)
N1A—C2A—H21A	110.00
C6A—N1A—C2A—C3A	−58.24 (19)	C5A—C4A—C41A—O41A	−73.5 (2)
C2A—N1A—C6A—C5A	57.8 (2)	C5A—C4A—C41A—N41A	104.77 (17)
N1A—C2A—C3A—C4A	57.6 (2)	C3A—C4A—C5A—C6A	55.85 (19)
C2A—C3A—C4A—C5A	−56.2 (2)	C4A—C5A—C6A—N1A	−56.7 (2)
C2A—C3A—C4A—C41A	−177.78 (15)	O11—C1—C2—O21	−14.5 (3)
C41A—C4A—C5A—C6A	178.87 (14)	O11—C1—C2—O22	166.30 (16)
C3A—C4A—C41A—O41A	47.7 (2)	O12—C1—C2—O21	165.10 (18)
C3A—C4A—C41A—N41A	−134.03 (17)	O12—C1—C2—O22	−14.1 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H11A···O2W	0.94 (2)	1.94 (2)	2.844 (2)	161.7 (16)
N1A—H12A···O11	0.90 (2)	1.93 (2)	2.8266 (19)	173.3 (17)
N1A—H12A···O21	0.90 (2)	2.456 (19)	2.900 (2)	110.8 (14)
N41A—H41A···O2W^i	0.88 (2)	2.03 (2)	2.8893 (19)	164.6 (17)
N41A—H42A···O41A^i	0.87 (2)	2.20 (2)	3.048 (2)	164.7 (19)
O22—H22···O11^ii	0.92 (3)	1.72 (3)	2.6362 (17)	179 (3)
O1W—H11W···O12^iii	0.94 (3)	1.81 (3)	2.7479 (18)	179 (4)
O1W—H12W···O41A	0.85 (2)	2.03 (3)	2.8485 (18)	164 (2)
O2W—H21W···O1W^iv	0.87 (2)	1.86 (2)	2.7268 (18)	174 (2)
O2W—H22W···O12^v	0.90 (3)	1.82 (3)	2.7067 (17)	169 (2)
O2W—H22W···O22^v	0.90 (3)	2.57 (3)	3.0952 (17)	118.3 (19)
C4A—H4A···O1W^i	1.00	2.40	3.369 (2)	163
C3A—H32A···O41A^vi	0.99	2.54	3.501 (2)	164

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

(II) Bis(4-carbamoylpiperidinium) butane-1,4-dicarboxylate dihydrate

Crystal data

2C6H13N2O^+·C6H8O4^−·2H2O	Z = 1
Mr = 438.52	F(000) = 238
Triclinic, P1	Dx = 1.298 Mg m^−3
Hall symbol: -P 1	Melting point: 353 K
a = 5.8454 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.7696 (5) Å	Cell parameters from 3402 reflections
c = 13.0987 (7) Å	θ = 3.5–28.7°
α = 75.336 (5)°	µ = 0.10 mm^−1
β = 81.763 (5)°	T = 200 K
γ = 78.448 (5)°	Plate, colourless
V = 561.17 (6) Å^3	0.35 × 0.32 × 0.08 mm

Data collection

Oxford Gemini-S CCD area-detector diffractometer	2204 independent reflections
Radiation source: Enhance (Mo) X-ray source	1683 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
Detector resolution: 16.077 pixels mm^-1	θmax = 26.0°, θmin = 3.5°
ω scans	h = −7→7
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −9→9
Tmin = 0.955, Tmax = 0.983	l = −16→16
6679 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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 0.98	w = 1/[σ^2(Fo^2) + (0.0527P)^2] where P = (Fo^2 + 2Fc^2)/3
2204 reflections	(Δ/σ)max = 0.001
160 parameters	Δρmax = 0.20 e Å^−3
0 restraints	Δρmin = −0.16 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
O41A	0.47840 (17)	−0.08622 (13)	0.36125 (8)	0.0349 (3)
N1A	0.8936 (2)	0.38796 (15)	0.21776 (9)	0.0233 (3)
N41A	0.7911 (2)	−0.27558 (15)	0.43346 (9)	0.0280 (4)
C2A	0.9597 (3)	0.24391 (18)	0.15759 (10)	0.0281 (4)
C3A	0.8190 (3)	0.09236 (18)	0.20557 (10)	0.0272 (4)
C4A	0.8500 (2)	0.01611 (16)	0.32290 (10)	0.0211 (4)
C5A	0.7917 (3)	0.16926 (17)	0.38167 (10)	0.0258 (4)
C6A	0.9361 (3)	0.31695 (18)	0.33091 (10)	0.0286 (4)
C41A	0.6907 (2)	−0.12143 (17)	0.37330 (10)	0.0224 (4)
O11	0.12663 (17)	0.65931 (13)	0.11069 (8)	0.0371 (4)
O12	0.42178 (16)	0.50958 (12)	0.20424 (7)	0.0304 (3)
C1	0.3387 (2)	0.62781 (16)	0.12684 (10)	0.0223 (4)
C2	0.5019 (2)	0.73971 (17)	0.04837 (11)	0.0260 (4)
C3	0.4208 (2)	0.94203 (16)	0.03963 (10)	0.0229 (4)
O1W	0.29606 (18)	0.60165 (14)	0.40125 (8)	0.0305 (3)
H4A	1.01680	−0.04350	0.33060	0.0250*
H11A	0.724 (3)	0.441 (2)	0.2130 (13)	0.048 (5)*
H12A	0.981 (3)	0.485 (2)	0.1854 (13)	0.052 (5)*
H21A	1.12940	0.19510	0.15950	0.0340*
H22A	0.92890	0.29530	0.08260	0.0340*
H31A	0.65070	0.13910	0.19690	0.0330*
H32A	0.87070	−0.00540	0.16710	0.0330*
H41A	0.951 (3)	−0.3053 (19)	0.4315 (11)	0.031 (4)*
H42A	0.705 (3)	−0.359 (2)	0.4709 (13)	0.048 (5)*
H51A	0.62270	0.22100	0.38040	0.0310*
H52A	0.82400	0.12030	0.45670	0.0310*
H61A	0.89230	0.41600	0.36870	0.0340*
H62A	1.10490	0.26770	0.33650	0.0340*
H21	0.50840	0.71380	−0.02230	0.0310*
H22	0.66220	0.70430	0.07140	0.0310*
H31	0.25940	0.97640	0.01790	0.0270*
H32	0.41600	0.96750	0.11030	0.0270*
H11W	0.326 (3)	0.561 (2)	0.3382 (16)	0.064 (6)*
H12W	0.349 (3)	0.701 (3)	0.3875 (14)	0.056 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O41A	0.0225 (6)	0.0279 (5)	0.0512 (7)	−0.0103 (4)	−0.0025 (5)	0.0005 (5)
N1A	0.0200 (6)	0.0179 (6)	0.0287 (6)	−0.0068 (5)	−0.0011 (5)	0.0026 (5)
N41A	0.0269 (7)	0.0191 (6)	0.0344 (7)	−0.0080 (5)	0.0003 (5)	0.0018 (5)
C2A	0.0309 (8)	0.0323 (8)	0.0207 (7)	−0.0119 (6)	0.0042 (6)	−0.0041 (6)
C3A	0.0335 (8)	0.0287 (8)	0.0224 (7)	−0.0129 (6)	0.0007 (6)	−0.0075 (6)
C4A	0.0179 (7)	0.0179 (7)	0.0266 (7)	−0.0050 (5)	−0.0016 (5)	−0.0022 (5)
C5A	0.0351 (8)	0.0230 (7)	0.0202 (7)	−0.0119 (6)	−0.0003 (6)	−0.0028 (5)
C6A	0.0383 (9)	0.0247 (7)	0.0258 (7)	−0.0136 (6)	−0.0034 (6)	−0.0049 (6)
C41A	0.0229 (8)	0.0193 (7)	0.0249 (7)	−0.0065 (6)	0.0009 (5)	−0.0047 (5)
O11	0.0238 (6)	0.0345 (6)	0.0462 (7)	−0.0147 (5)	−0.0082 (5)	0.0131 (5)
O12	0.0242 (5)	0.0294 (5)	0.0297 (6)	−0.0043 (4)	−0.0009 (4)	0.0065 (4)
C1	0.0228 (7)	0.0168 (6)	0.0261 (7)	−0.0058 (5)	−0.0004 (6)	−0.0022 (5)
C2	0.0223 (7)	0.0219 (7)	0.0308 (8)	−0.0073 (6)	0.0006 (6)	0.0005 (6)
C3	0.0224 (7)	0.0194 (6)	0.0248 (7)	−0.0076 (5)	0.0007 (5)	−0.0001 (5)
O1W	0.0321 (6)	0.0264 (6)	0.0322 (6)	−0.0140 (5)	−0.0024 (4)	0.0011 (4)

Geometric parameters (Å, º)

O41A—C41A	1.2402 (16)	C2A—H21A	0.9900
O11—C1	1.2525 (16)	C2A—H22A	0.9900
O12—C1	1.2643 (16)	C3A—H32A	0.9900
O1W—H11W	0.939 (19)	C3A—H31A	0.9900
O1W—H12W	0.86 (2)	C4A—H4A	1.0000
N1A—C2A	1.4864 (18)	C5A—H52A	0.9900
N1A—C6A	1.4830 (17)	C5A—H51A	0.9900
N41A—C41A	1.3315 (17)	C6A—H61A	0.9900
N1A—H12A	0.969 (17)	C6A—H62A	0.9900
N1A—H11A	0.999 (18)	C1—C2	1.5236 (18)
N41A—H42A	0.902 (17)	C2—C3	1.5280 (18)
N41A—H41A	0.915 (18)	C3—C3^i	1.5270 (18)
C2A—C3A	1.524 (2)	C2—H21	0.9900
C3A—C4A	1.5237 (18)	C2—H22	0.9900
C4A—C5A	1.5332 (18)	C3—H32	0.9900
C4A—C41A	1.5199 (18)	C3—H31	0.9900
C5A—C6A	1.521 (2)
H11W—O1W—H12W	106.0 (16)	C4A—C3A—H31A	109.00
C2A—N1A—C6A	111.53 (11)	C5A—C4A—H4A	109.00
C2A—N1A—H12A	109.5 (10)	C41A—C4A—H4A	109.00
C6A—N1A—H11A	109.1 (9)	C3A—C4A—H4A	109.00
H11A—N1A—H12A	106.7 (14)	C4A—C5A—H52A	109.00
C2A—N1A—H11A	109.6 (9)	C6A—C5A—H51A	109.00
C6A—N1A—H12A	110.4 (10)	C4A—C5A—H51A	109.00
C41A—N41A—H42A	121.0 (11)	H51A—C5A—H52A	108.00
C41A—N41A—H41A	120.5 (9)	C6A—C5A—H52A	109.00
H41A—N41A—H42A	118.1 (14)	N1A—C6A—H61A	110.00
N1A—C2A—C3A	110.21 (11)	N1A—C6A—H62A	110.00
C2A—C3A—C4A	111.53 (12)	C5A—C6A—H62A	110.00
C3A—C4A—C41A	111.48 (11)	H61A—C6A—H62A	108.00
C5A—C4A—C41A	108.50 (11)	C5A—C6A—H61A	110.00
C3A—C4A—C5A	109.83 (11)	O11—C1—C2	117.40 (11)
C4A—C5A—C6A	111.06 (11)	O12—C1—C2	119.18 (11)
N1A—C6A—C5A	109.86 (12)	O11—C1—O12	123.42 (12)
N41A—C41A—C4A	116.04 (11)	C1—C2—C3	111.94 (10)
O41A—C41A—N41A	123.09 (12)	C2—C3—C3^i	113.17 (10)
O41A—C41A—C4A	120.82 (12)	C1—C2—H22	109.00
N1A—C2A—H22A	110.00	C3—C2—H21	109.00
C3A—C2A—H21A	110.00	C1—C2—H21	109.00
C3A—C2A—H22A	110.00	H21—C2—H22	108.00
H21A—C2A—H22A	108.00	C3—C2—H22	109.00
N1A—C2A—H21A	110.00	C2—C3—H31	109.00
C2A—C3A—H31A	109.00	C2—C3—H32	109.00
C2A—C3A—H32A	109.00	C3^i—C3—H31	109.00
C4A—C3A—H32A	109.00	C3^i—C3—H32	109.00
H31A—C3A—H32A	108.00	H31—C3—H32	108.00
C6A—N1A—C2A—C3A	59.09 (16)	C3A—C4A—C41A—N41A	132.84 (12)
C2A—N1A—C6A—C5A	−59.99 (16)	C5A—C4A—C41A—O41A	71.23 (15)
N1A—C2A—C3A—C4A	−56.04 (16)	C5A—C4A—C41A—N41A	−106.10 (13)
C2A—C3A—C4A—C5A	53.89 (16)	C4A—C5A—C6A—N1A	57.64 (16)
C2A—C3A—C4A—C41A	174.18 (12)	O11—C1—C2—C3	57.12 (15)
C3A—C4A—C5A—C6A	−54.72 (16)	O12—C1—C2—C3	−122.69 (12)
C41A—C4A—C5A—C6A	−176.80 (11)	C1—C2—C3—C3^i	−179.22 (10)
C3A—C4A—C41A—O41A	−49.83 (17)	C2—C3—C3^i—C2^i	−180.00 (10)

Symmetry code: (i) −x+1, −y+2, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1A—H11A···O12	0.999 (18)	1.752 (18)	2.7463 (15)	173.5 (15)
N1A—H12A···O11^ii	0.969 (17)	1.752 (17)	2.7153 (16)	172.3 (16)
N41A—H41A···O1W^iii	0.915 (18)	2.020 (17)	2.9188 (16)	167.0 (14)
N41A—H42A···O1W^iv	0.902 (17)	2.182 (16)	2.9647 (16)	144.8 (15)
O1W—H11W···O12	0.939 (19)	1.88 (2)	2.8092 (14)	169.9 (15)
O1W—H12W···O41A^v	0.86 (2)	1.89 (2)	2.7429 (15)	177.1 (16)
C2A—H22A···O11^vi	0.99	2.53	3.4911 (17)	165

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