Polymorph (I
a) of eldoral [5-ethyl-5-(piperidin-1-yl)barbituric acid or 5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione], C
11H
17N
3O
3, displays a hydrogen-bonded layer structure parallel to (100). The piperidine N atom and the barbiturate carbonyl group in the 2-position are utilized in N-H
N and N-H
O=C hydrogen bonds, respectively. The structure of polymorph (I
b) contains pseudosymmetry elements. The two independent molecules of (I
b) are connected
via N-H
O=C(4/6-position) and N-H
N(piperidine) hydrogen bonds to give a chain structure in the [100] direction. The hydrogen-bonded layers, parallel to (010), formed in the salt diethylammonium 5-ethyl-5-(piperidin-1-yl)barbiturate [or diethylammonium 5-ethyl-2,4,6-trioxo-5-(piperidin-1-yl)-1,3-diazinan-1-ide], C
4H
12N
+·C
11H
16N
3O
3-, (II), closely resemble the corresponding hydrogen-bonded structure in polymorph (I
a). Like many other 5,5-disubstituted derivatives of barbituric acid, polymorphs (I
a) and (I
b) contain the
R22(8) N-H
O=C hydrogen-bond motif. However, the overall hydrogen-bonded chain and layer structures of (I
a) and (I
b) are unique because of the involvement of the hydrogen-bond acceptor function in the piperidine group.
Supporting information
CCDC references: 867018; 867019; 867020
Suitable crystals of (Ia) and (IIa) (Ib)? were obtained from an
ethanol solution of the commercially available product [Source?].
Crystals of (II) were obtained in an NMR tube by evaporation of a dilute
solution of (I) in diethylamine. The FT–IR spectra of (Ia) and
(Ib) are available in the Supplementary materials. All
XPac (Gelbrich & Hursthouse, 2005) calculations cited above were
carried out with a complete set of 17 non-H atomic positions of the
barbiturate molecule.
All H atoms were identified in a difference Fourier map. Methyl H atoms were
idealized (C—H = 0.98 Å) and included as rigid groups allowed to rotate
but not to tip, while methylene H atoms were positioned geometrically (C—H =
0.99 Å) and refined using a riding model. N-bound H atoms were refined with
the N—H distances restrained to 0.88 (2) Å. The Uiso parameters of
all H atoms were refined freely.
Data collection: CrysAlis PRO (Oxford Diffraction, 2003) for (Ia), (II); COLLECT (Nonius, 1998) for (Ib). Cell refinement: CrysAlis PRO (Oxford Diffraction, 2003) for (Ia), (II); SCALEPACK (Otwinowski & Minor, 1997) for (Ib). Data reduction: CrysAlis PRO (Oxford Diffraction, 2003) for (Ia), (II); DENZO and SCALEPACK (Otwinowski & Minor, 1997) for (Ib). For all compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Bruker, 1998) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).
(Ia) 5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione
top
Crystal data top
C11H17N3O3 | F(000) = 512 |
Mr = 239.28 | Dx = 1.343 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2ybc | Cell parameters from 4404 reflections |
a = 7.8761 (2) Å | θ = 3.5–67.2° |
b = 12.7102 (4) Å | µ = 0.82 mm−1 |
c = 11.9438 (3) Å | T = 173 K |
β = 98.189 (3)° | Block, colourless |
V = 1183.46 (6) Å3 | 0.43 × 0.40 × 0.40 mm |
Z = 4 | |
Data collection top
Oxford Xcalibur Ruby Gemini Ultra diffractometer | 2111 independent reflections |
Radiation source: Enhance Ultra (Cu) X-ray Source | 1900 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.030 |
Detector resolution: 10.3575 pixels mm-1 | θmax = 67.3°, θmin = 5.1° |
ω scans | h = −8→9 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2003) | k = −15→14 |
Tmin = 0.719, Tmax = 0.735 | l = −12→14 |
6405 measured reflections | |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.044 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.126 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0823P)2 + 0.3019P] where P = (Fo2 + 2Fc2)/3 |
2117 reflections | (Δ/σ)max < 0.001 |
178 parameters | Δρmax = 0.21 e Å−3 |
2 restraints | Δρmin = −0.21 e Å−3 |
Crystal data top
C11H17N3O3 | V = 1183.46 (6) Å3 |
Mr = 239.28 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 7.8761 (2) Å | µ = 0.82 mm−1 |
b = 12.7102 (4) Å | T = 173 K |
c = 11.9438 (3) Å | 0.43 × 0.40 × 0.40 mm |
β = 98.189 (3)° | |
Data collection top
Oxford Xcalibur Ruby Gemini Ultra diffractometer | 2111 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2003) | 1900 reflections with I > 2σ(I) |
Tmin = 0.719, Tmax = 0.735 | Rint = 0.030 |
6405 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.044 | 2 restraints |
wR(F2) = 0.126 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.09 | Δρmax = 0.21 e Å−3 |
2117 reflections | Δρmin = −0.21 e Å−3 |
178 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
O2 | 0.36517 (13) | 0.45037 (8) | 0.58288 (8) | 0.0228 (3) | |
O4 | 0.44593 (13) | 0.31051 (8) | 0.24714 (8) | 0.0236 (3) | |
O6 | 0.16698 (14) | 0.12057 (8) | 0.51336 (8) | 0.0243 (3) | |
N1 | 0.25601 (15) | 0.28807 (10) | 0.54236 (9) | 0.0186 (3) | |
H1 | 0.226 (2) | 0.2883 (15) | 0.6090 (13) | 0.029 (5)* | |
N3 | 0.41092 (15) | 0.37557 (10) | 0.41746 (10) | 0.0189 (3) | |
H3 | 0.472 (3) | 0.4313 (14) | 0.4043 (17) | 0.040 (5)* | |
N9 | 0.14381 (15) | 0.18896 (9) | 0.26946 (9) | 0.0178 (3) | |
C2 | 0.34506 (17) | 0.37528 (11) | 0.51811 (11) | 0.0182 (3) | |
C4 | 0.38837 (17) | 0.29899 (11) | 0.33517 (11) | 0.0178 (3) | |
C5 | 0.29329 (17) | 0.19810 (11) | 0.36097 (11) | 0.0175 (3) | |
C6 | 0.23423 (18) | 0.19751 (11) | 0.47846 (11) | 0.0188 (3) | |
C7 | 0.42276 (18) | 0.10750 (12) | 0.35950 (12) | 0.0208 (3) | |
H7A | 0.3682 | 0.0409 | 0.3785 | 0.026 (4)* | |
H7B | 0.4530 | 0.1004 | 0.2822 | 0.022 (4)* | |
C8 | 0.58668 (19) | 0.12463 (13) | 0.44271 (13) | 0.0260 (4) | |
H8A | 0.6449 | 0.1883 | 0.4216 | 0.035 (5)* | |
H8B | 0.6627 | 0.0639 | 0.4405 | 0.035 (5)* | |
H8C | 0.5575 | 0.1327 | 0.5193 | 0.033 (5)* | |
C10 | 0.06325 (19) | 0.08342 (12) | 0.25699 (12) | 0.0231 (4) | |
H10A | 0.0107 | 0.0665 | 0.3253 | 0.025 (4)* | |
H10B | 0.1517 | 0.0297 | 0.2490 | 0.029 (5)* | |
C11 | −0.0739 (2) | 0.08171 (13) | 0.15296 (13) | 0.0283 (4) | |
H11A | −0.0192 | 0.0937 | 0.0844 | 0.025 (4)* | |
H11B | −0.1289 | 0.0115 | 0.1462 | 0.034 (5)* | |
C12 | −0.2103 (2) | 0.16542 (14) | 0.15971 (14) | 0.0298 (4) | |
H12A | −0.2906 | 0.1668 | 0.0880 | 0.035 (5)* | |
H12B | −0.2766 | 0.1481 | 0.2217 | 0.037 (5)* | |
C13 | −0.12730 (19) | 0.27285 (13) | 0.18097 (13) | 0.0267 (4) | |
H13A | −0.2155 | 0.3249 | 0.1946 | 0.035 (5)* | |
H13B | −0.0778 | 0.2953 | 0.1131 | 0.026 (4)* | |
C14 | 0.01334 (18) | 0.26990 (12) | 0.28261 (12) | 0.0234 (4) | |
H14A | 0.0694 | 0.3397 | 0.2920 | 0.027 (4)* | |
H14B | −0.0385 | 0.2549 | 0.3517 | 0.028 (4)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O2 | 0.0273 (6) | 0.0227 (6) | 0.0189 (5) | −0.0044 (4) | 0.0051 (4) | −0.0040 (4) |
O4 | 0.0255 (6) | 0.0302 (6) | 0.0161 (5) | −0.0054 (4) | 0.0060 (4) | −0.0005 (4) |
O6 | 0.0305 (6) | 0.0223 (6) | 0.0214 (5) | −0.0061 (4) | 0.0079 (4) | 0.0006 (4) |
N1 | 0.0211 (6) | 0.0209 (6) | 0.0141 (6) | −0.0024 (5) | 0.0036 (5) | −0.0001 (5) |
N3 | 0.0209 (6) | 0.0205 (7) | 0.0158 (6) | −0.0039 (5) | 0.0037 (5) | −0.0005 (5) |
N9 | 0.0160 (6) | 0.0196 (6) | 0.0170 (6) | −0.0009 (5) | −0.0001 (5) | −0.0016 (4) |
C2 | 0.0158 (6) | 0.0217 (8) | 0.0165 (7) | 0.0006 (5) | −0.0003 (5) | 0.0008 (5) |
C5 | 0.0172 (7) | 0.0202 (7) | 0.0148 (7) | −0.0020 (6) | 0.0013 (5) | −0.0011 (5) |
C4 | 0.0147 (6) | 0.0218 (7) | 0.0162 (7) | 0.0001 (5) | −0.0007 (5) | 0.0004 (5) |
C6 | 0.0170 (7) | 0.0217 (7) | 0.0172 (7) | 0.0001 (5) | 0.0006 (5) | 0.0010 (5) |
C7 | 0.0216 (7) | 0.0210 (7) | 0.0199 (7) | 0.0018 (6) | 0.0035 (6) | 0.0001 (6) |
C8 | 0.0232 (8) | 0.0308 (9) | 0.0233 (8) | 0.0046 (6) | 0.0007 (6) | 0.0029 (6) |
C10 | 0.0239 (8) | 0.0211 (8) | 0.0233 (7) | −0.0060 (6) | 0.0001 (6) | 0.0004 (6) |
C11 | 0.0276 (8) | 0.0288 (9) | 0.0269 (8) | −0.0092 (7) | −0.0021 (6) | −0.0016 (6) |
C12 | 0.0199 (7) | 0.0409 (10) | 0.0273 (8) | −0.0057 (7) | −0.0014 (6) | 0.0018 (7) |
C13 | 0.0191 (7) | 0.0333 (9) | 0.0268 (8) | 0.0026 (6) | 0.0000 (6) | 0.0005 (7) |
C14 | 0.0196 (7) | 0.0264 (8) | 0.0238 (7) | 0.0023 (6) | 0.0021 (6) | −0.0032 (6) |
Geometric parameters (Å, º) top
O2—C2 | 1.2246 (17) | C8—H8A | 0.9800 |
O4—C4 | 1.2117 (17) | C8—H8B | 0.9800 |
O6—C6 | 1.2139 (18) | C8—H8C | 0.9800 |
N1—C2 | 1.3647 (18) | C10—C11 | 1.526 (2) |
N1—C6 | 1.3782 (19) | C10—H10A | 0.9900 |
N1—H1 | 0.862 (14) | C10—H10B | 0.9900 |
N3—C2 | 1.3755 (18) | C11—C12 | 1.522 (2) |
N3—C4 | 1.3767 (18) | C11—H11A | 0.9900 |
N3—H3 | 0.881 (16) | C11—H11B | 0.9900 |
N9—C14 | 1.4782 (18) | C12—C13 | 1.520 (2) |
N9—C10 | 1.4824 (18) | C12—H12A | 0.9900 |
N9—C5 | 1.4926 (17) | C12—H12B | 0.9900 |
C5—C4 | 1.5381 (19) | C13—C14 | 1.523 (2) |
C5—C7 | 1.5399 (19) | C13—H13A | 0.9900 |
C5—C6 | 1.5400 (18) | C13—H13B | 0.9900 |
C7—C8 | 1.529 (2) | C14—H14A | 0.9900 |
C7—H7A | 0.9900 | C14—H14B | 0.9900 |
C7—H7B | 0.9900 | | |
| | | |
C2—N1—C6 | 126.01 (12) | C7—C8—H8C | 109.5 |
C2—N1—H1 | 114.2 (13) | H8A—C8—H8C | 109.5 |
C6—N1—H1 | 119.0 (13) | H8B—C8—H8C | 109.5 |
C2—N3—C4 | 126.56 (12) | N9—C10—C11 | 109.75 (12) |
C2—N3—H3 | 116.1 (13) | N9—C10—H10A | 109.7 |
C4—N3—H3 | 117.3 (13) | C11—C10—H10A | 109.7 |
C14—N9—C10 | 110.27 (11) | N9—C10—H10B | 109.7 |
C14—N9—C5 | 110.84 (10) | C11—C10—H10B | 109.7 |
C10—N9—C5 | 115.19 (11) | H10A—C10—H10B | 108.2 |
O2—C2—N1 | 121.54 (12) | C12—C11—C10 | 111.71 (13) |
O2—C2—N3 | 121.27 (13) | C12—C11—H11A | 109.3 |
N1—C2—N3 | 117.19 (12) | C10—C11—H11A | 109.3 |
N9—C5—C4 | 105.90 (10) | C12—C11—H11B | 109.3 |
N9—C5—C7 | 112.83 (11) | C10—C11—H11B | 109.3 |
C4—C5—C7 | 106.21 (11) | H11A—C11—H11B | 107.9 |
N9—C5—C6 | 110.96 (10) | C13—C12—C11 | 110.29 (12) |
C4—C5—C6 | 113.92 (11) | C13—C12—H12A | 109.6 |
C7—C5—C6 | 107.05 (11) | C11—C12—H12A | 109.6 |
O4—C4—N3 | 120.52 (13) | C13—C12—H12B | 109.6 |
O4—C4—C5 | 121.84 (12) | C11—C12—H12B | 109.6 |
N3—C4—C5 | 117.61 (12) | H12A—C12—H12B | 108.1 |
O6—C6—N1 | 120.57 (12) | C12—C13—C14 | 110.97 (13) |
O6—C6—C5 | 121.34 (12) | C12—C13—H13A | 109.4 |
N1—C6—C5 | 118.08 (12) | C14—C13—H13A | 109.4 |
C8—C7—C5 | 112.67 (12) | C12—C13—H13B | 109.4 |
C8—C7—H7A | 109.1 | C14—C13—H13B | 109.4 |
C5—C7—H7A | 109.1 | H13A—C13—H13B | 108.0 |
C8—C7—H7B | 109.1 | N9—C14—C13 | 111.72 (12) |
C5—C7—H7B | 109.1 | N9—C14—H14A | 109.3 |
H7A—C7—H7B | 107.8 | C13—C14—H14A | 109.3 |
C7—C8—H8A | 109.5 | N9—C14—H14B | 109.3 |
C7—C8—H8B | 109.5 | C13—C14—H14B | 109.3 |
H8A—C8—H8B | 109.5 | H14A—C14—H14B | 107.9 |
| | | |
C2—C5—C7—C8 | −4.38 (16) | C8—C7—C5—N9 | 172.30 (11) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N9i | 0.86 (1) | 2.13 (2) | 2.9843 (16) | 172 (2) |
N3—H3···O2ii | 0.88 (2) | 1.97 (2) | 2.8295 (16) | 165 (2) |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, −y+1, −z+1. |
(Ib) 5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione
top
Crystal data top
C11H17N3O3 | F(000) = 1024 |
Mr = 239.28 | Dx = 1.331 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 17714 reflections |
a = 11.9311 (3) Å | θ = 2.9–26.0° |
b = 15.9858 (4) Å | µ = 0.10 mm−1 |
c = 13.0768 (3) Å | T = 120 K |
β = 106.799 (1)° | Needle, colourless |
V = 2387.68 (10) Å3 | 0.25 × 0.04 × 0.04 mm |
Z = 8 | |
Data collection top
Bruker Nonius Roper CCD camera on κ-goniostat diffractometer | 4211 independent reflections |
Radiation source: Bruker Nonius FR591 rotating anode | 3314 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.074 |
Detector resolution: 9.091 pixels mm-1 | θmax = 25.0°, θmin = 3.0° |
ϕ and ω scans | h = −12→14 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2007) | k = −18→19 |
Tmin = 0.976, Tmax = 0.996 | l = −15→15 |
20817 measured reflections | |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.063 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.140 | w = 1/[σ2(Fo2) + (0.0304P)2 + 4.2383P] where P = (Fo2 + 2Fc2)/3 |
S = 1.05 | (Δ/σ)max < 0.001 |
4211 reflections | Δρmax = 0.30 e Å−3 |
356 parameters | Δρmin = −0.25 e Å−3 |
4 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0026 (7) |
Crystal data top
C11H17N3O3 | V = 2387.68 (10) Å3 |
Mr = 239.28 | Z = 8 |
Monoclinic, P21/n | Mo Kα radiation |
a = 11.9311 (3) Å | µ = 0.10 mm−1 |
b = 15.9858 (4) Å | T = 120 K |
c = 13.0768 (3) Å | 0.25 × 0.04 × 0.04 mm |
β = 106.799 (1)° | |
Data collection top
Bruker Nonius Roper CCD camera on κ-goniostat diffractometer | 4211 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2007) | 3314 reflections with I > 2σ(I) |
Tmin = 0.976, Tmax = 0.996 | Rint = 0.074 |
20817 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.063 | 4 restraints |
wR(F2) = 0.140 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.30 e Å−3 |
4211 reflections | Δρmin = −0.25 e Å−3 |
356 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
O2 | 0.58310 (16) | −0.08070 (12) | 0.04977 (15) | 0.0249 (5) | |
O4 | 0.24412 (15) | −0.06590 (11) | 0.13663 (14) | 0.0196 (4) | |
O6 | 0.60661 (16) | 0.01909 (12) | 0.37828 (14) | 0.0240 (5) | |
N1 | 0.59280 (19) | −0.02967 (14) | 0.21411 (17) | 0.0185 (5) | |
H1 | 0.6704 (16) | −0.0258 (17) | 0.229 (2) | 0.020 (7)* | |
N3 | 0.41502 (19) | −0.07521 (14) | 0.09745 (17) | 0.0188 (5) | |
H3 | 0.378 (3) | −0.0905 (18) | 0.0315 (16) | 0.029 (8)* | |
N9 | 0.35583 (18) | 0.07015 (13) | 0.26831 (17) | 0.0174 (5) | |
C2 | 0.5341 (2) | −0.06227 (16) | 0.1158 (2) | 0.0178 (6) | |
C4 | 0.3496 (2) | −0.05345 (15) | 0.1629 (2) | 0.0167 (6) | |
C5 | 0.4111 (2) | −0.01423 (16) | 0.2716 (2) | 0.0170 (6) | |
C6 | 0.5444 (2) | −0.00695 (16) | 0.2936 (2) | 0.0175 (6) | |
C7 | 0.3875 (2) | −0.07105 (16) | 0.3582 (2) | 0.0184 (6) | |
H7A | 0.4230 | −0.0456 | 0.4292 | 0.029 (8)* | |
H7B | 0.3019 | −0.0748 | 0.3471 | 0.012 (6)* | |
C8 | 0.4370 (2) | −0.15919 (17) | 0.3567 (2) | 0.0235 (6) | |
H8A | 0.4023 | −0.1846 | 0.2864 | 0.031 (8)* | |
H8B | 0.4182 | −0.1934 | 0.4118 | 0.028 (8)* | |
H8C | 0.5222 | −0.1560 | 0.3709 | 0.030 (8)* | |
C10 | 0.3797 (2) | 0.11192 (17) | 0.3738 (2) | 0.0215 (6) | |
H10A | 0.4650 | 0.1212 | 0.4037 | 0.012 (6)* | |
H10B | 0.3537 | 0.0754 | 0.4236 | 0.019 (7)* | |
C11 | 0.3158 (2) | 0.19551 (17) | 0.3630 (2) | 0.0249 (6) | |
H11A | 0.2303 | 0.1857 | 0.3391 | 0.019 (7)* | |
H11B | 0.3353 | 0.2234 | 0.4336 | 0.040 (9)* | |
C12 | 0.3496 (3) | 0.25213 (18) | 0.2836 (2) | 0.0288 (7) | |
H12A | 0.4337 | 0.2666 | 0.3105 | 0.029 (8)* | |
H12B | 0.3037 | 0.3046 | 0.2747 | 0.041 (9)* | |
C13 | 0.3257 (3) | 0.20751 (17) | 0.1768 (2) | 0.0255 (6) | |
H13A | 0.3513 | 0.2432 | 0.1259 | 0.019 (7)* | |
H13B | 0.2405 | 0.1975 | 0.1471 | 0.012 (6)* | |
C14 | 0.3906 (2) | 0.12458 (17) | 0.1905 (2) | 0.0234 (6) | |
H14A | 0.3731 | 0.0958 | 0.1206 | 0.023 (8)* | |
H14B | 0.4760 | 0.1350 | 0.2158 | 0.023 (7)* | |
O2' | 1.07255 (17) | 0.09236 (13) | 0.02602 (15) | 0.0290 (5) | |
O4' | 0.73722 (15) | 0.08890 (11) | 0.11944 (14) | 0.0207 (4) | |
O6' | 1.10597 (16) | 0.02770 (12) | 0.36973 (14) | 0.0231 (4) | |
N1' | 1.08721 (19) | 0.06082 (14) | 0.19877 (17) | 0.0191 (5) | |
H1' | 1.1649 (16) | 0.0575 (17) | 0.212 (2) | 0.017 (7)* | |
N3' | 0.90611 (19) | 0.09109 (14) | 0.07617 (17) | 0.0201 (5) | |
H3' | 0.867 (2) | 0.0961 (17) | 0.0095 (15) | 0.018 (7)* | |
N9' | 0.85632 (19) | −0.03070 (13) | 0.27545 (17) | 0.0175 (5) | |
C2' | 1.0258 (2) | 0.08185 (17) | 0.0960 (2) | 0.0201 (6) | |
C4' | 0.8430 (2) | 0.07893 (15) | 0.1466 (2) | 0.0162 (6) | |
C5' | 0.9080 (2) | 0.05192 (16) | 0.2611 (2) | 0.0166 (6) | |
C6' | 1.0416 (2) | 0.04569 (15) | 0.2816 (2) | 0.0179 (6) | |
C7' | 0.8853 (2) | 0.11938 (16) | 0.3364 (2) | 0.0196 (6) | |
H7'1 | 0.7999 | 0.1241 | 0.3254 | 0.023 (7)* | |
H7'2 | 0.9219 | 0.1018 | 0.4112 | 0.021 (7)* | |
C8' | 0.9335 (3) | 0.20529 (17) | 0.3188 (2) | 0.0249 (6) | |
H8'1 | 1.0181 | 0.2011 | 0.3294 | 0.016 (7)* | |
H8'2 | 0.9184 | 0.2454 | 0.3700 | 0.042 (10)* | |
H8'3 | 0.8950 | 0.2243 | 0.2459 | 0.033 (9)* | |
C10' | 0.8829 (2) | −0.05835 (18) | 0.3883 (2) | 0.0237 (6) | |
H10C | 0.8548 | −0.0157 | 0.4299 | 0.038 (9)* | |
H10D | 0.9687 | −0.0638 | 0.4194 | 0.026 (8)* | |
C11' | 0.8244 (3) | −0.14213 (18) | 0.3958 (2) | 0.0276 (7) | |
H11C | 0.8460 | −0.1604 | 0.4713 | 0.034 (9)* | |
H11D | 0.7383 | −0.1352 | 0.3708 | 0.022 (7)* | |
C12' | 0.8611 (3) | −0.20901 (18) | 0.3286 (3) | 0.0313 (7) | |
H12C | 0.9460 | −0.2204 | 0.3577 | 0.035 (9)* | |
H12D | 0.8181 | −0.2616 | 0.3309 | 0.037 (9)* | |
C13' | 0.8343 (3) | −0.17848 (17) | 0.2145 (2) | 0.0270 (7) | |
H13C | 0.7486 | −0.1727 | 0.1834 | 0.011 (6)* | |
H13D | 0.8625 | −0.2201 | 0.1715 | 0.023 (7)* | |
C14' | 0.8929 (2) | −0.09464 (17) | 0.2097 (2) | 0.0235 (6) | |
H14C | 0.9790 | −0.1016 | 0.2355 | 0.022 (7)* | |
H14D | 0.8724 | −0.0753 | 0.1346 | 0.023 (7)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O2 | 0.0222 (10) | 0.0340 (11) | 0.0205 (10) | 0.0023 (9) | 0.0093 (8) | −0.0018 (8) |
O4 | 0.0156 (10) | 0.0253 (10) | 0.0169 (9) | 0.0002 (8) | 0.0032 (7) | 0.0011 (7) |
O6 | 0.0186 (10) | 0.0309 (11) | 0.0203 (10) | −0.0005 (8) | 0.0020 (8) | −0.0064 (8) |
N1 | 0.0136 (12) | 0.0211 (12) | 0.0204 (12) | −0.0009 (9) | 0.0043 (9) | 0.0003 (9) |
N3 | 0.0185 (12) | 0.0224 (12) | 0.0144 (11) | −0.0005 (9) | 0.0031 (9) | −0.0031 (9) |
N9 | 0.0162 (11) | 0.0191 (12) | 0.0174 (11) | 0.0015 (9) | 0.0054 (9) | −0.0015 (9) |
C2 | 0.0189 (14) | 0.0195 (14) | 0.0142 (13) | 0.0029 (11) | 0.0036 (11) | 0.0012 (10) |
C4 | 0.0153 (14) | 0.0151 (13) | 0.0191 (13) | 0.0008 (10) | 0.0043 (11) | 0.0020 (10) |
C5 | 0.0168 (14) | 0.0171 (14) | 0.0171 (13) | 0.0005 (10) | 0.0052 (11) | −0.0011 (10) |
C6 | 0.0202 (14) | 0.0139 (13) | 0.0188 (14) | 0.0006 (11) | 0.0061 (11) | −0.0004 (10) |
C7 | 0.0188 (14) | 0.0185 (14) | 0.0183 (13) | 0.0003 (11) | 0.0059 (11) | 0.0011 (10) |
C8 | 0.0239 (15) | 0.0225 (15) | 0.0217 (14) | −0.0018 (12) | 0.0028 (12) | 0.0026 (12) |
C10 | 0.0210 (14) | 0.0208 (14) | 0.0221 (14) | −0.0018 (11) | 0.0051 (11) | −0.0044 (11) |
C11 | 0.0214 (15) | 0.0230 (15) | 0.0299 (16) | 0.0007 (12) | 0.0068 (12) | −0.0089 (12) |
C12 | 0.0222 (16) | 0.0186 (15) | 0.0443 (18) | 0.0021 (12) | 0.0076 (14) | −0.0021 (13) |
C13 | 0.0220 (15) | 0.0220 (15) | 0.0340 (16) | 0.0015 (12) | 0.0106 (13) | 0.0077 (12) |
C14 | 0.0253 (15) | 0.0218 (15) | 0.0254 (15) | 0.0021 (12) | 0.0110 (12) | 0.0018 (12) |
O2' | 0.0213 (10) | 0.0461 (13) | 0.0209 (10) | −0.0012 (9) | 0.0081 (8) | 0.0033 (9) |
O4' | 0.0170 (10) | 0.0255 (11) | 0.0189 (9) | 0.0008 (8) | 0.0042 (8) | −0.0009 (8) |
O6' | 0.0164 (10) | 0.0322 (11) | 0.0183 (10) | −0.0005 (8) | 0.0011 (8) | 0.0032 (8) |
N1' | 0.0126 (12) | 0.0260 (13) | 0.0177 (12) | 0.0007 (9) | 0.0030 (9) | 0.0001 (9) |
N3' | 0.0168 (12) | 0.0279 (13) | 0.0141 (11) | −0.0018 (10) | 0.0018 (9) | 0.0004 (10) |
N9' | 0.0181 (12) | 0.0184 (12) | 0.0164 (11) | −0.0015 (9) | 0.0057 (9) | −0.0020 (9) |
C2' | 0.0202 (14) | 0.0202 (14) | 0.0212 (14) | −0.0026 (11) | 0.0081 (12) | −0.0016 (11) |
C4' | 0.0172 (14) | 0.0141 (13) | 0.0166 (13) | −0.0013 (10) | 0.0040 (11) | −0.0019 (10) |
C5' | 0.0157 (13) | 0.0191 (14) | 0.0159 (13) | −0.0027 (10) | 0.0058 (10) | −0.0014 (10) |
C6' | 0.0210 (14) | 0.0128 (13) | 0.0202 (14) | −0.0004 (11) | 0.0063 (12) | −0.0022 (10) |
C7' | 0.0170 (14) | 0.0220 (14) | 0.0199 (13) | 0.0017 (11) | 0.0055 (11) | 0.0001 (11) |
C8' | 0.0221 (15) | 0.0217 (15) | 0.0287 (16) | −0.0013 (12) | 0.0038 (12) | −0.0014 (12) |
C10' | 0.0236 (15) | 0.0282 (16) | 0.0174 (14) | −0.0024 (12) | 0.0027 (11) | 0.0038 (11) |
C11' | 0.0228 (15) | 0.0291 (16) | 0.0280 (16) | 0.0001 (12) | 0.0029 (12) | 0.0107 (13) |
C12' | 0.0211 (15) | 0.0225 (16) | 0.0478 (19) | 0.0013 (12) | 0.0060 (14) | 0.0084 (13) |
C13' | 0.0235 (15) | 0.0199 (15) | 0.0382 (17) | −0.0001 (12) | 0.0099 (13) | −0.0030 (12) |
C14' | 0.0215 (15) | 0.0225 (15) | 0.0283 (15) | −0.0016 (11) | 0.0103 (12) | −0.0052 (12) |
Geometric parameters (Å, º) top
O2—C2 | 1.211 (3) | O2'—C2' | 1.213 (3) |
O4—C4 | 1.221 (3) | O4'—C4' | 1.218 (3) |
O6—C6 | 1.214 (3) | O6'—C6' | 1.220 (3) |
N1—C6 | 1.376 (3) | N1'—C6' | 1.368 (3) |
N1—C2 | 1.376 (3) | N1'—C2' | 1.374 (3) |
N1—H1 | 0.892 (17) | N1'—H1' | 0.894 (17) |
N3—C4 | 1.360 (3) | N3'—C4' | 1.361 (3) |
N3—C2 | 1.386 (3) | N3'—C2' | 1.383 (3) |
N3—H3 | 0.883 (18) | N3'—H3' | 0.867 (17) |
N9—C10 | 1.484 (3) | N9'—C14' | 1.480 (3) |
N9—C14 | 1.486 (3) | N9'—C10' | 1.484 (3) |
N9—C5 | 1.497 (3) | N9'—C5' | 1.492 (3) |
C4—C5 | 1.533 (3) | C4'—C5' | 1.537 (3) |
C5—C6 | 1.536 (4) | C5'—C7' | 1.536 (4) |
C5—C7 | 1.540 (3) | C5'—C6' | 1.541 (4) |
C7—C8 | 1.530 (4) | C7'—C8' | 1.532 (4) |
C7—H7A | 0.9900 | C7'—H7'1 | 0.9900 |
C7—H7B | 0.9900 | C7'—H7'2 | 0.9900 |
C8—H8A | 0.9800 | C8'—H8'1 | 0.9800 |
C8—H8B | 0.9800 | C8'—H8'2 | 0.9800 |
C8—H8C | 0.9800 | C8'—H8'3 | 0.9800 |
C10—C11 | 1.525 (4) | C10'—C11' | 1.527 (4) |
C10—H10A | 0.9900 | C10'—H10C | 0.9900 |
C10—H10B | 0.9900 | C10'—H10D | 0.9900 |
C11—C12 | 1.518 (4) | C11'—C12' | 1.527 (4) |
C11—H11A | 0.9900 | C11'—H11C | 0.9900 |
C11—H11B | 0.9900 | C11'—H11D | 0.9900 |
C12—C13 | 1.520 (4) | C12'—C13' | 1.514 (4) |
C12—H12A | 0.9900 | C12'—H12C | 0.9900 |
C12—H12B | 0.9900 | C12'—H12D | 0.9900 |
C13—C14 | 1.520 (4) | C13'—C14' | 1.521 (4) |
C13—H13A | 0.9900 | C13'—H13C | 0.9900 |
C13—H13B | 0.9900 | C13'—H13D | 0.9900 |
C14—H14A | 0.9900 | C14'—H14C | 0.9900 |
C14—H14B | 0.9900 | C14'—H14D | 0.9900 |
| | | |
C6—N1—C2 | 126.5 (2) | C6'—N1'—C2' | 126.6 (2) |
C6—N1—H1 | 117.1 (18) | C6'—N1'—H1' | 117.6 (18) |
C2—N1—H1 | 116.3 (18) | C2'—N1'—H1' | 115.8 (18) |
C4—N3—C2 | 126.8 (2) | C4'—N3'—C2' | 126.9 (2) |
C4—N3—H3 | 118 (2) | C4'—N3'—H3' | 116.5 (19) |
C2—N3—H3 | 114 (2) | C2'—N3'—H3' | 115.5 (19) |
C10—N9—C14 | 110.9 (2) | C14'—N9'—C10' | 111.0 (2) |
C10—N9—C5 | 114.5 (2) | C14'—N9'—C5' | 109.6 (2) |
C14—N9—C5 | 109.84 (19) | C10'—N9'—C5' | 114.3 (2) |
O2—C2—N1 | 122.5 (2) | O2'—C2'—N1' | 122.7 (3) |
O2—C2—N3 | 121.5 (2) | O2'—C2'—N3' | 121.3 (2) |
N1—C2—N3 | 115.9 (2) | N1'—C2'—N3' | 116.1 (2) |
O4—C4—N3 | 120.9 (2) | O4'—C4'—N3' | 120.9 (2) |
O4—C4—C5 | 120.4 (2) | O4'—C4'—C5' | 120.6 (2) |
N3—C4—C5 | 118.7 (2) | N3'—C4'—C5' | 118.5 (2) |
N9—C5—C4 | 104.6 (2) | N9'—C5'—C7' | 112.7 (2) |
N9—C5—C6 | 111.2 (2) | N9'—C5'—C4' | 105.09 (19) |
C4—C5—C6 | 113.4 (2) | C7'—C5'—C4' | 107.1 (2) |
N9—C5—C7 | 112.3 (2) | N9'—C5'—C6' | 111.4 (2) |
C4—C5—C7 | 107.5 (2) | C7'—C5'—C6' | 107.4 (2) |
C6—C5—C7 | 107.9 (2) | C4'—C5'—C6' | 113.2 (2) |
O6—C6—N1 | 120.0 (2) | O6'—C6'—N1' | 120.2 (2) |
O6—C6—C5 | 121.6 (2) | O6'—C6'—C5' | 121.1 (2) |
N1—C6—C5 | 118.4 (2) | N1'—C6'—C5' | 118.6 (2) |
C8—C7—C5 | 112.3 (2) | C8'—C7'—C5' | 113.0 (2) |
C8—C7—H7A | 109.1 | C8'—C7'—H7'1 | 109.0 |
C5—C7—H7A | 109.1 | C5'—C7'—H7'1 | 109.0 |
C8—C7—H7B | 109.1 | C8'—C7'—H7'2 | 109.0 |
C5—C7—H7B | 109.1 | C5'—C7'—H7'2 | 109.0 |
H7A—C7—H7B | 107.9 | H7'1—C7'—H7'2 | 107.8 |
C7—C8—H8A | 109.5 | C7'—C8'—H8'1 | 109.5 |
C7—C8—H8B | 109.5 | C7'—C8'—H8'2 | 109.5 |
H8A—C8—H8B | 109.5 | H8'1—C8'—H8'2 | 109.5 |
C7—C8—H8C | 109.5 | C7'—C8'—H8'3 | 109.5 |
H8A—C8—H8C | 109.5 | H8'1—C8'—H8'3 | 109.5 |
H8B—C8—H8C | 109.5 | H8'2—C8'—H8'3 | 109.5 |
N9—C10—C11 | 110.6 (2) | N9'—C10'—C11' | 110.8 (2) |
N9—C10—H10A | 109.5 | N9'—C10'—H10C | 109.5 |
C11—C10—H10A | 109.5 | C11'—C10'—H10C | 109.5 |
N9—C10—H10B | 109.5 | N9'—C10'—H10D | 109.5 |
C11—C10—H10B | 109.5 | C11'—C10'—H10D | 109.5 |
H10A—C10—H10B | 108.1 | H10C—C10'—H10D | 108.1 |
C12—C11—C10 | 111.2 (2) | C12'—C11'—C10' | 111.4 (2) |
C12—C11—H11A | 109.4 | C12'—C11'—H11C | 109.4 |
C10—C11—H11A | 109.4 | C10'—C11'—H11C | 109.4 |
C12—C11—H11B | 109.4 | C12'—C11'—H11D | 109.4 |
C10—C11—H11B | 109.4 | C10'—C11'—H11D | 109.4 |
H11A—C11—H11B | 108.0 | H11C—C11'—H11D | 108.0 |
C11—C12—C13 | 109.4 (2) | C13'—C12'—C11' | 109.1 (2) |
C11—C12—H12A | 109.8 | C13'—C12'—H12C | 109.9 |
C13—C12—H12A | 109.8 | C11'—C12'—H12C | 109.9 |
C11—C12—H12B | 109.8 | C13'—C12'—H12D | 109.9 |
C13—C12—H12B | 109.8 | C11'—C12'—H12D | 109.9 |
H12A—C12—H12B | 108.2 | H12C—C12'—H12D | 108.3 |
C12—C13—C14 | 110.3 (2) | C12'—C13'—C14' | 110.8 (2) |
C12—C13—H13A | 109.6 | C12'—C13'—H13C | 109.5 |
C14—C13—H13A | 109.6 | C14'—C13'—H13C | 109.5 |
C12—C13—H13B | 109.6 | C12'—C13'—H13D | 109.5 |
C14—C13—H13B | 109.6 | C14'—C13'—H13D | 109.5 |
H13A—C13—H13B | 108.1 | H13C—C13'—H13D | 108.1 |
N9—C14—C13 | 111.0 (2) | N9'—C14'—C13' | 111.6 (2) |
N9—C14—H14A | 109.4 | N9'—C14'—H14C | 109.3 |
C13—C14—H14A | 109.4 | C13'—C14'—H14C | 109.3 |
N9—C14—H14B | 109.4 | N9'—C14'—H14D | 109.3 |
C13—C14—H14B | 109.4 | C13'—C14'—H14D | 109.3 |
H14A—C14—H14B | 108.0 | H14C—C14'—H14D | 108.0 |
| | | |
C2—C5—C7—C8 | 0.5 (3) | C2'—C5'—C7'—C8' | −1.4 (3) |
C8—C7—C5—N9 | 176.2 (2) | C8'—C7'—C5'—N9' | −177.5 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N9′ | 0.89 (2) | 2.13 (2) | 3.012 (3) | 173 (3) |
N3—H3···O4′i | 0.88 (2) | 2.05 (2) | 2.901 (3) | 161 (3) |
N1′—H1′···N9ii | 0.89 (2) | 2.19 (2) | 3.072 (3) | 168 (2) |
N3′—H3′···O4i | 0.87 (2) | 2.04 (2) | 2.870 (3) | 159 (3) |
Symmetry codes: (i) −x+1, −y, −z; (ii) x+1, y, z. |
(II) diethylammonium 5-ethyl-2,4,6-trioxo-5-(piperidin-1-yl)-1,3-diazinan-1-ide
top
Crystal data top
C4H12N+·C11H16N3O3− | F(000) = 1360 |
Mr = 312.41 | Dx = 1.162 Mg m−3 |
Orthorhombic, Pbca | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 13761 reflections |
a = 11.8270 (3) Å | θ = 3.6–67.3° |
b = 16.1719 (4) Å | µ = 0.67 mm−1 |
c = 18.6774 (5) Å | T = 173 K |
V = 3572.35 (16) Å3 | Block, colourless |
Z = 8 | 0.20 × 0.15 × 0.15 mm |
Data collection top
Oxford Xcalibur Ruby Gemini Ultra diffractometer | 3209 independent reflections |
Radiation source: Enhance Ultra (Cu) X-ray Source | 2921 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.034 |
Detector resolution: 10.3575 pixels mm-1 | θmax = 67.4°, θmin = 5.2° |
ω scans | h = −14→13 |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2003) | k = −17→19 |
Tmin = 0.880, Tmax = 1.000 | l = −22→22 |
25972 measured reflections | |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.035 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.097 | w = 1/[σ2(Fo2) + (0.0561P)2 + 0.9238P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
3209 reflections | Δρmax = 0.34 e Å−3 |
240 parameters | Δρmin = −0.21 e Å−3 |
3 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00061 (11) |
Crystal data top
C4H12N+·C11H16N3O3− | V = 3572.35 (16) Å3 |
Mr = 312.41 | Z = 8 |
Orthorhombic, Pbca | Cu Kα radiation |
a = 11.8270 (3) Å | µ = 0.67 mm−1 |
b = 16.1719 (4) Å | T = 173 K |
c = 18.6774 (5) Å | 0.20 × 0.15 × 0.15 mm |
Data collection top
Oxford Xcalibur Ruby Gemini Ultra diffractometer | 3209 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2003) | 2921 reflections with I > 2σ(I) |
Tmin = 0.880, Tmax = 1.000 | Rint = 0.034 |
25972 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.035 | 3 restraints |
wR(F2) = 0.097 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.34 e Å−3 |
3209 reflections | Δρmin = −0.21 e Å−3 |
240 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
O2 | 0.36833 (7) | 0.04134 (6) | 0.10261 (4) | 0.0365 (2) | |
O4 | 0.69794 (7) | −0.01818 (5) | 0.21295 (4) | 0.0298 (2) | |
O6 | 0.39495 (7) | 0.11518 (5) | 0.33359 (4) | 0.0267 (2) | |
N1 | 0.38581 (8) | 0.07638 (6) | 0.21795 (5) | 0.0238 (2) | |
H1 | 0.3141 (11) | 0.0885 (9) | 0.2167 (8) | 0.036 (4)* | |
N3 | 0.53698 (8) | 0.01186 (6) | 0.15455 (5) | 0.0260 (2) | |
N9 | 0.64215 (7) | 0.12923 (5) | 0.29358 (5) | 0.0202 (2) | |
C2 | 0.43096 (10) | 0.04239 (7) | 0.15588 (6) | 0.0246 (3) | |
C4 | 0.60384 (9) | 0.01384 (6) | 0.21349 (6) | 0.0224 (2) | |
C5 | 0.56512 (9) | 0.05679 (6) | 0.28353 (5) | 0.0198 (2) | |
C6 | 0.44116 (9) | 0.08508 (6) | 0.28135 (6) | 0.0208 (2) | |
C7 | 0.57601 (10) | −0.00660 (7) | 0.34462 (6) | 0.0241 (3) | |
H7A | 0.6567 | −0.0209 | 0.3512 | 0.029 (3)* | |
H7B | 0.5484 | 0.0186 | 0.3897 | 0.029 (3)* | |
C8 | 0.50883 (11) | −0.08552 (8) | 0.32946 (8) | 0.0350 (3) | |
H8A | 0.4294 | −0.0714 | 0.3208 | 0.046 (4)* | |
H8B | 0.5140 | −0.1227 | 0.3708 | 0.049 (4)* | |
H8C | 0.5400 | −0.1131 | 0.2871 | 0.044 (4)* | |
C10 | 0.63744 (10) | 0.16675 (7) | 0.36570 (6) | 0.0272 (3) | |
H10A | 0.6535 | 0.1240 | 0.4022 | 0.032 (4)* | |
H10B | 0.5605 | 0.1886 | 0.3746 | 0.029 (3)* | |
C11 | 0.72330 (11) | 0.23676 (8) | 0.37252 (8) | 0.0373 (3) | |
H11A | 0.7171 | 0.2619 | 0.4207 | 0.044 (4)* | |
H11B | 0.8006 | 0.2141 | 0.3674 | 0.041 (4)* | |
C12 | 0.70400 (12) | 0.30274 (8) | 0.31597 (9) | 0.0413 (3) | |
H12A | 0.6296 | 0.3294 | 0.3235 | 0.045 (4)* | |
H12B | 0.7633 | 0.3458 | 0.3195 | 0.053 (5)* | |
C13 | 0.70774 (11) | 0.26256 (7) | 0.24253 (8) | 0.0361 (3) | |
H13A | 0.7846 | 0.2408 | 0.2335 | 0.038 (4)* | |
H13B | 0.6907 | 0.3044 | 0.2054 | 0.045 (4)* | |
C14 | 0.62223 (10) | 0.19230 (7) | 0.23768 (6) | 0.0282 (3) | |
H14A | 0.5449 | 0.2150 | 0.2430 | 0.031 (3)* | |
H14B | 0.6276 | 0.1661 | 0.1899 | 0.031 (3)* | |
N1S | 0.66644 (9) | −0.04274 (6) | 0.04136 (5) | 0.0259 (2) | |
H1SA | 0.6156 (12) | −0.0228 (9) | 0.0751 (8) | 0.039 (4)* | |
H1SB | 0.6371 (12) | −0.0403 (9) | −0.0033 (7) | 0.035 (4)* | |
C1S | 0.69010 (13) | −0.13007 (8) | 0.05976 (8) | 0.0408 (3) | |
H1S3 | 0.7188 | −0.1334 | 0.1095 | 0.067 (6)* | |
H1S4 | 0.7492 | −0.1520 | 0.0274 | 0.044 (4)* | |
C2S | 0.58521 (19) | −0.18141 (11) | 0.05292 (14) | 0.0784 (7) | |
H2S1 | 0.5252 | −0.1575 | 0.0826 | 0.091 (7)* | |
H2S2 | 0.6010 | −0.2380 | 0.0689 | 0.096 (7)* | |
H2S3 | 0.5609 | −0.1823 | 0.0028 | 0.129 (12)* | |
C3S | 0.76908 (11) | 0.01015 (9) | 0.04231 (7) | 0.0364 (3) | |
H3S1 | 0.8270 | −0.0137 | 0.0101 | 0.049 (4)* | |
H3S2 | 0.8007 | 0.0116 | 0.0914 | 0.040 (4)* | |
C4S | 0.74151 (18) | 0.09649 (10) | 0.01856 (9) | 0.0592 (5) | |
H4S1 | 0.7129 | 0.0953 | −0.0307 | 0.069 (6)* | |
H4S2 | 0.8099 | 0.1307 | 0.0207 | 0.090 (7)* | |
H4S3 | 0.6837 | 0.1199 | 0.0502 | 0.066 (6)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O2 | 0.0290 (5) | 0.0592 (6) | 0.0213 (4) | 0.0039 (4) | −0.0060 (3) | −0.0060 (4) |
O4 | 0.0222 (4) | 0.0362 (5) | 0.0308 (5) | 0.0062 (3) | 0.0006 (3) | −0.0078 (3) |
O6 | 0.0224 (4) | 0.0360 (4) | 0.0218 (4) | 0.0013 (3) | 0.0033 (3) | −0.0055 (3) |
N1 | 0.0166 (5) | 0.0337 (5) | 0.0211 (5) | 0.0015 (4) | −0.0010 (4) | −0.0026 (4) |
N3 | 0.0237 (5) | 0.0333 (5) | 0.0212 (5) | 0.0022 (4) | 0.0005 (4) | −0.0059 (4) |
N9 | 0.0191 (4) | 0.0202 (4) | 0.0214 (5) | −0.0010 (3) | −0.0005 (3) | −0.0001 (3) |
C2 | 0.0233 (6) | 0.0309 (6) | 0.0195 (5) | −0.0019 (4) | 0.0002 (4) | −0.0018 (4) |
C4 | 0.0213 (5) | 0.0229 (5) | 0.0230 (6) | −0.0010 (4) | 0.0021 (4) | −0.0025 (4) |
C5 | 0.0178 (5) | 0.0223 (5) | 0.0193 (5) | −0.0011 (4) | −0.0001 (4) | −0.0014 (4) |
C6 | 0.0192 (5) | 0.0230 (5) | 0.0203 (5) | −0.0021 (4) | 0.0011 (4) | 0.0001 (4) |
C7 | 0.0262 (6) | 0.0230 (5) | 0.0232 (5) | −0.0001 (4) | −0.0002 (4) | 0.0021 (4) |
C8 | 0.0361 (7) | 0.0261 (6) | 0.0428 (7) | −0.0056 (5) | 0.0022 (6) | 0.0031 (5) |
C10 | 0.0293 (6) | 0.0259 (6) | 0.0265 (6) | −0.0018 (5) | −0.0009 (5) | −0.0057 (5) |
C11 | 0.0356 (7) | 0.0310 (6) | 0.0454 (8) | −0.0060 (5) | −0.0037 (6) | −0.0114 (6) |
C12 | 0.0377 (7) | 0.0232 (6) | 0.0630 (9) | −0.0075 (5) | 0.0055 (7) | −0.0050 (6) |
C13 | 0.0328 (6) | 0.0252 (6) | 0.0503 (8) | −0.0014 (5) | 0.0095 (6) | 0.0081 (5) |
C14 | 0.0289 (6) | 0.0254 (6) | 0.0302 (6) | 0.0006 (5) | 0.0008 (5) | 0.0062 (5) |
N1S | 0.0285 (5) | 0.0296 (5) | 0.0196 (5) | 0.0025 (4) | 0.0004 (4) | −0.0022 (4) |
C1S | 0.0560 (9) | 0.0314 (7) | 0.0351 (7) | 0.0095 (6) | 0.0108 (6) | 0.0021 (5) |
C2S | 0.0853 (14) | 0.0378 (9) | 0.1121 (19) | −0.0165 (9) | 0.0529 (14) | −0.0110 (10) |
C3S | 0.0343 (7) | 0.0473 (8) | 0.0276 (6) | −0.0096 (6) | −0.0006 (5) | −0.0024 (5) |
C4S | 0.0902 (13) | 0.0427 (8) | 0.0448 (9) | −0.0235 (9) | −0.0093 (9) | 0.0048 (7) |
Geometric parameters (Å, º) top
O2—C2 | 1.2406 (14) | C11—H11B | 0.9900 |
O4—C4 | 1.2275 (14) | C12—C13 | 1.518 (2) |
O6—C6 | 1.2198 (13) | C12—H12A | 0.9900 |
N1—C6 | 1.3603 (14) | C12—H12B | 0.9900 |
N1—C2 | 1.3896 (14) | C13—C14 | 1.5238 (16) |
N1—H1 | 0.871 (13) | C13—H13A | 0.9900 |
N3—C2 | 1.3479 (15) | C13—H13B | 0.9900 |
N3—C4 | 1.3558 (14) | C14—H14A | 0.9900 |
N9—C10 | 1.4784 (14) | C14—H14B | 0.9900 |
N9—C14 | 1.4784 (14) | N1S—C1S | 1.4801 (16) |
N9—C5 | 1.4959 (13) | N1S—C3S | 1.4852 (16) |
C4—C5 | 1.5503 (14) | N1S—H1SA | 0.928 (13) |
C5—C6 | 1.5364 (15) | N1S—H1SB | 0.904 (13) |
C5—C7 | 1.5393 (15) | C1S—C2S | 1.498 (2) |
C7—C8 | 1.5298 (16) | C1S—H1S3 | 0.9900 |
C7—H7A | 0.9900 | C1S—H1S4 | 0.9900 |
C7—H7B | 0.9900 | C2S—H2S1 | 0.9800 |
C8—H8A | 0.9800 | C2S—H2S2 | 0.9800 |
C8—H8B | 0.9800 | C2S—H2S3 | 0.9800 |
C8—H8C | 0.9800 | C3S—C4S | 1.501 (2) |
C10—C11 | 1.5262 (16) | C3S—H3S1 | 0.9900 |
C10—H10A | 0.9900 | C3S—H3S2 | 0.9900 |
C10—H10B | 0.9900 | C4S—H4S1 | 0.9800 |
C11—C12 | 1.519 (2) | C4S—H4S2 | 0.9800 |
C11—H11A | 0.9900 | C4S—H4S3 | 0.9800 |
| | | |
C6—N1—C2 | 125.61 (10) | C13—C12—H12A | 109.9 |
C6—N1—H1 | 118.0 (10) | C11—C12—H12A | 109.9 |
C2—N1—H1 | 116.2 (10) | C13—C12—H12B | 109.9 |
C2—N3—C4 | 121.25 (9) | C11—C12—H12B | 109.9 |
C10—N9—C14 | 110.75 (9) | H12A—C12—H12B | 108.3 |
C10—N9—C5 | 114.38 (8) | C12—C13—C14 | 110.71 (10) |
C14—N9—C5 | 110.77 (8) | C12—C13—H13A | 109.5 |
O2—C2—N3 | 122.39 (10) | C14—C13—H13A | 109.5 |
O2—C2—N1 | 116.43 (10) | C12—C13—H13B | 109.5 |
N3—C2—N1 | 121.19 (10) | C14—C13—H13B | 109.5 |
O4—C4—N3 | 120.80 (10) | H13A—C13—H13B | 108.1 |
O4—C4—C5 | 117.63 (9) | N9—C14—C13 | 111.51 (10) |
N3—C4—C5 | 121.57 (9) | N9—C14—H14A | 109.3 |
N9—C5—C6 | 110.57 (8) | C13—C14—H14A | 109.3 |
N9—C5—C7 | 112.19 (8) | N9—C14—H14B | 109.3 |
C6—C5—C7 | 107.32 (8) | C13—C14—H14B | 109.3 |
N9—C5—C4 | 106.08 (8) | H14A—C14—H14B | 108.0 |
C6—C5—C4 | 113.14 (9) | C1S—N1S—C3S | 113.09 (11) |
C7—C5—C4 | 107.60 (8) | C1S—N1S—H1SA | 107.2 (9) |
O6—C6—N1 | 121.48 (10) | C3S—N1S—H1SA | 108.7 (9) |
O6—C6—C5 | 121.68 (9) | C1S—N1S—H1SB | 109.2 (9) |
N1—C6—C5 | 116.84 (9) | C3S—N1S—H1SB | 107.4 (9) |
C8—C7—C5 | 112.03 (9) | H1SA—N1S—H1SB | 111.3 (13) |
C8—C7—H7A | 109.2 | N1S—C1S—C2S | 110.63 (14) |
C5—C7—H7A | 109.2 | N1S—C1S—H1S3 | 109.5 |
C8—C7—H7B | 109.2 | C2S—C1S—H1S3 | 109.5 |
C5—C7—H7B | 109.2 | N1S—C1S—H1S4 | 109.5 |
H7A—C7—H7B | 107.9 | C2S—C1S—H1S4 | 109.5 |
C7—C8—H8A | 109.5 | H1S3—C1S—H1S4 | 108.1 |
C7—C8—H8B | 109.5 | C1S—C2S—H2S1 | 109.5 |
H8A—C8—H8B | 109.5 | C1S—C2S—H2S2 | 109.5 |
C7—C8—H8C | 109.5 | H2S1—C2S—H2S2 | 109.5 |
H8A—C8—H8C | 109.5 | C1S—C2S—H2S3 | 109.5 |
H8B—C8—H8C | 109.5 | H2S1—C2S—H2S3 | 109.5 |
N9—C10—C11 | 110.82 (10) | H2S2—C2S—H2S3 | 109.5 |
N9—C10—H10A | 109.5 | N1S—C3S—C4S | 110.78 (12) |
C11—C10—H10A | 109.5 | N1S—C3S—H3S1 | 109.5 |
N9—C10—H10B | 109.5 | C4S—C3S—H3S1 | 109.5 |
C11—C10—H10B | 109.5 | N1S—C3S—H3S2 | 109.5 |
H10A—C10—H10B | 108.1 | C4S—C3S—H3S2 | 109.5 |
C12—C11—C10 | 111.29 (11) | H3S1—C3S—H3S2 | 108.1 |
C12—C11—H11A | 109.4 | C3S—C4S—H4S1 | 109.5 |
C10—C11—H11A | 109.4 | C3S—C4S—H4S2 | 109.5 |
C12—C11—H11B | 109.4 | H4S1—C4S—H4S2 | 109.5 |
C10—C11—H11B | 109.4 | C3S—C4S—H4S3 | 109.5 |
H11A—C11—H11B | 108.0 | H4S1—C4S—H4S3 | 109.5 |
C13—C12—C11 | 108.85 (10) | H4S2—C4S—H4S3 | 109.5 |
| | | |
C2—C5—C7—C8 | 2.70 (14) | C8—C7—C5—N9 | −172.63 (9) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N9i | 0.87 (1) | 2.15 (1) | 3.0136 (13) | 174 (1) |
N1S—H1SA···N3 | 0.93 (1) | 1.84 (1) | 2.7555 (13) | 169 (1) |
N1S—H1SB···O2ii | 0.90 (1) | 1.86 (1) | 2.7204 (13) | 159 (1) |
Symmetry codes: (i) x−1/2, y, −z+1/2; (ii) −x+1, −y, −z. |
Experimental details
| (Ia) | (Ib) | (II) |
Crystal data |
Chemical formula | C11H17N3O3 | C11H17N3O3 | C4H12N+·C11H16N3O3− |
Mr | 239.28 | 239.28 | 312.41 |
Crystal system, space group | Monoclinic, P21/c | Monoclinic, P21/n | Orthorhombic, Pbca |
Temperature (K) | 173 | 120 | 173 |
a, b, c (Å) | 7.8761 (2), 12.7102 (4), 11.9438 (3) | 11.9311 (3), 15.9858 (4), 13.0768 (3) | 11.8270 (3), 16.1719 (4), 18.6774 (5) |
α, β, γ (°) | 90, 98.189 (3), 90 | 90, 106.799 (1), 90 | 90, 90, 90 |
V (Å3) | 1183.46 (6) | 2387.68 (10) | 3572.35 (16) |
Z | 4 | 8 | 8 |
Radiation type | Cu Kα | Mo Kα | Cu Kα |
µ (mm−1) | 0.82 | 0.10 | 0.67 |
Crystal size (mm) | 0.43 × 0.40 × 0.40 | 0.25 × 0.04 × 0.04 | 0.20 × 0.15 × 0.15 |
|
Data collection |
Diffractometer | Oxford Xcalibur Ruby Gemini Ultra diffractometer | Bruker Nonius Roper CCD camera on κ-goniostat diffractometer | Oxford Xcalibur Ruby Gemini Ultra diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2003) | Multi-scan (SADABS; Sheldrick, 2007) | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2003) |
Tmin, Tmax | 0.719, 0.735 | 0.976, 0.996 | 0.880, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6405, 2111, 1900 | 20817, 4211, 3314 | 25972, 3209, 2921 |
Rint | 0.030 | 0.074 | 0.034 |
(sin θ/λ)max (Å−1) | 0.598 | 0.596 | 0.599 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.126, 1.09 | 0.063, 0.140, 1.05 | 0.035, 0.097, 1.04 |
No. of reflections | 2117 | 4211 | 3209 |
No. of parameters | 178 | 356 | 240 |
No. of restraints | 2 | 4 | 3 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.21, −0.21 | 0.30, −0.25 | 0.34, −0.21 |
Hydrogen-bond geometry (Å, º) for (Ia) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N9i | 0.862 (14) | 2.128 (15) | 2.9843 (16) | 172.1 (17) |
N3—H3···O2ii | 0.881 (16) | 1.970 (16) | 2.8295 (16) | 164.6 (19) |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) for (Ib) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N9' | 0.892 (17) | 2.125 (18) | 3.012 (3) | 173 (3) |
N3—H3···O4'i | 0.883 (18) | 2.05 (2) | 2.901 (3) | 161 (3) |
N1'—H1'···N9ii | 0.894 (17) | 2.191 (18) | 3.072 (3) | 168 (2) |
N3'—H3'···O4i | 0.867 (17) | 2.042 (19) | 2.870 (3) | 159 (3) |
Symmetry codes: (i) −x+1, −y, −z; (ii) x+1, y, z. |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N9i | 0.871 (13) | 2.146 (13) | 3.0136 (13) | 173.9 (14) |
N1S—H1SA···N3 | 0.928 (13) | 1.839 (13) | 2.7555 (13) | 168.8 (14) |
N1S—H1SB···O2ii | 0.904 (13) | 1.856 (13) | 2.7204 (13) | 159.2 (14) |
Symmetry codes: (i) x−1/2, y, −z+1/2; (ii) −x+1, −y, −z. |
Torsion angles (°) in the barbiturate molecules (Ia), (Ib) and (II) topStructure | C2···C5—C7—C8 | C8—N7—C5—N1 |
(Ia) | -4.38 (16) | 172.20 (11) |
(Ib), mol. A | 0.5 (2) | 176.2 (2) |
(Ib), mol. B* | -1.5 (3) | -177.5 (2) |
(II) | 2.70 (13) | -172.63 (9) |
Note: (*) C2'···C5'—C7'—C8' and C8'—N7'—C5'—N1' |
As part of a larger investigation of derivatives of barbituric acid (Gelbrich et al., 2007; Zencirci et al., 2009, 2010; Gelbrich et al., 2010a,b; Gelbrich, Zencirci et al., 2010; Gelbrich et al., 2011), we have studied two solid forms of 5-ethyl-5-piperidylbarbituric acid (I), CAS No. 509-87-5, and its diethylammonium salt, (II). Compound (I), also known as eldoral, has been marketed as a sedative and hypnotic drug since 1936 (Anders, 1954). According to Brandstätter-Kuhnert & Aepkers (1962), three distinct polymorphs of (I) grow from the melt. Their melting points were given as 490 K (form I), 483 K (form II; also the polymorph of the sublimate investigated by Fischer, 1939) and 477 K (form III). From sublimation experiments at 473 K we obtained polymorph (Ia) as long needles and polymorph (Ib) as blocks. Crystals of (Ia) and (Ib) also formed concomitantly from an ethanol solution. The results of thermomicroscopic and differential scanning calorimetry experiments confirmed (Ia) and (Ib) to be identical with forms I and II, respectively, studied by Brandstätter-Kuhnert & Aepkers (1962). The diethylammonium salt, (II), was obtained by slow evaporation of a solution of (I) in diethylamine.
As expected, the barbiturate entity adopts the same principle geometry (Fig. 1) in all three investigated crystal structures. The barbiturate ring is essentially planar and the piperidyl ring has a chair conformation. The ethyl conformation is such that the torsion angle C2···C5—C7—C8 is close to 0°, and C8—C7—C5—N9 is close to 180° (see Table 4).
The relative geometry of the five potential hydrogen-bond donor or acceptor functions of a barbiturate ring (two NH and three carbonyl groups, respectively) is inflexible. As a result, certain standard N—H···O═C bonded structures are frequently observed in 5,5-substituted derivatives of barbituric acid, usually one of four common chain structures (Gelbrich et al., 2011). In categorizing these structures, it is useful to distinguish between the two topologically equivalent carbonyl groups in the 4- and 6-positions on the one hand and the carbonyl group in the 2-position on the other. In the case of eldoral, (I), the piperidyl N atom can be utilized as an additional hydrogen-bond acceptor, which increases the number of feasible hydrogen-bond motifs.
The crystal structure of (Ia) contains one independent molecule (Fig. 1). Two barbiturate rings are N—H···O═C bonded to one another via a centrosymmetric R22(8) ring (Etter et al., 1990), and this interaction involves the C2 carbonyl group. One N—H···N bond links each barbiturate ring to the piperidyl group of a second molecule that is related to the first by a c-glide operation. Overall, the N—H···O═C and N—H···N interactions result in a corrugated layer structure parallel to (100) with p21/b layer symmetry. It contains larger R66(28) rings connecting four molecules (Fig. 2).
The asymmetric unit of the second polymorph, (Ib), consists of two molecules (denoted A and B, Fig. 3). The barbiturate rings of A- and B-type molecules are doubly N—H···O═C bonded to one another so that an R22(8) ring is formed. In contrast with the situation found in (Ia), one of the two equivalent C4/6 carbonyl groups in each molecule is utilized in this interaction (rather than the C2 group). The resulting `dimeric' N—H···O═C bonded unit is connected to two other units of the same kind via N—H···N(piperidyl) interactions, so that A- and B-type molecules are linked to one another as a consequence. An infinite hydrogen-bonded chain structure parallel to [100] is generated (Fig. 4), which contains centrosymmetric R44(18) rings that link four molecules together.
The nature of single-component crystal structures containing more than one (Z' > 1) independent molecule has been discussed by several authors in recent years (Steiner, 2000; Steed, 2003; Desiraju, 2007; Anderson & Steed, 2007; Bernstein, 2011). In order to gain a better understanding of such a crystal structure, it is useful to establish the geometric differences and commonalities between its Z' independent molecular environments, and thereby the presence (or absence) of local or peudo-symmetry elements in the crystal structure. For example, investigations with the computer program XPac (Gelbrich & Hursthouse, 2005) have revealed that local symmetry elements are present in a Z' = 4 form of carbamazepine (Gelbrich & Hursthouse, 2006), as well as in a Z' = 2 polymorph of sulfathiazole (Gelbrich et al., 2008).
An analogous XPac analysis for the structure of (Ib) reveals that its two complete molecular shells around A and B (each consisting of n = 15 molecules) exhibit roughly the same geometry, i.e. molecules A and B are related to one another by an approximate symmetry transformation. However, a relatively high XPac dissimilarity index x (Fabbiani et al., 2009) of 9.0 (calculated for n = 15) for the two independent molecular shells of A and B is obtained, which indicates that the deviation from proper symmetry relationships is considerable.
More details can be deduced from the diagram in Fig. 5. For each comparison between a pair of molecules in shell A with the matching pair in shell B, the individual dissimilarity parameter xi is plotted against the corresponding distance parameter δd,i. The latter is the absolute difference of the distances between the two respective molecular centroids in the shells of A and B, and some of the differences are as high as 1 Å (data points encircled by a dashed line). However, a subset of data points (encircled by a dotted line) lies much closer to the origin than the rest, and it gives a combined x value of just 1.8 (for n = 5). These data points correspond to a shell fragment of five neighbouring molecules, which in turn represents the hydrogen-bonded chain shown in Fig. 4. Overall, the XPac results are consistent with an approximate C2/c pseudo-symmetry of (Ib), in which the pseudo-glide symmetry (perpendicular to [010]; glide vector parallel to [100]) between hydrogen-bonded A and B molecules is particularly well preserved.
Fig. 6 shows the asymmetric unit of the diethylammonium salt, (II). The NH group of the barbiturate ring is bonded to the piperidyl ring of the next molecule. This interaction alone results in an extended chain parallel to [100] (translation of 11.827 Å), as the two molecules are related by an a-glide plane perpendicular to [001] (Fig. 7). An XPac comparison reveals that it has the same geometry as the corresponding N—H···N bonded chain propagating along [001] (translation of 11.944 Å) in polymorph (Ia). The XPac dissimilarity index x for this one-dimensional supramolecular construct is 5.2 (for n = 2). The NH2 group of the cation of (II) acts as a bridge between two anions, i.e. via an N—H···O═C bond to the C2 carbonyl group of the first anion and via an N—H···N bond to the 1-nitrogen of the second. Neighbouring anions are thereby doubly bridged so that a centrosymmetric R44(12) ring is formed. This interaction, in combination with the (anion)N—H···N(anion) bonds, results in a hydrogen-bonded layer which lies parallel to (001).
In Fig. 8, the hydrogen-bonded structures of (Ia), (Ib) and (II) are compared with those of two analogous 5,5-substituted barbituric acid derivatives with N—H···A bonds (A = hydrogen-bond acceptor), 3-oxocyclobarbital [Cambridge Structural Database (Allen, 2002) refcode BARCOX; Chentli-Benchikha et al., 1977) and bromo-meso-sarcosinuric acid (BMBARA10; Pascard-Billy, 1970). The barbiturate ring is represented as a hexagon, with NH groups drawn as arrows and the utilized hydrogen-bond acceptor sites as either circles (barbiturate carbonyl group), filled squares (5-substituted group, R) or open squares (deprotonated barbiturate N atom) (Figs. 8a and 8b). The close one-dimensional relationship between the hydrogen-bonded structures of (Ia) and (II) discussed above is apparent from Fig. 8(c). Moreover, the N—H···O═C R22(8) linkage between adjacent N—H···N(piperidyl) bonded chains in (Ia) is neatly substituted in (II) for two mutually opposite N···H—N—H···O bridges via a central cation. This similarity between (Ia) and (II) may also indicate a feasible transition mechanism for the removal of diethylamine from (II). Indeed, phase identification on the basis of FT–IR spectra has indicated that, upon solvent loss, the crystals of (II) transform exclusively into form (Ia).
For each structure, the configuration of utilized hydrogen-bond donor and acceptor sites is illustrated in Fig. 8(b). Polymorph (Ia) has the same configuration as BMBARA10, while (Ib) exhibits the same characteristics as BARCOX. However, quite different one- and two-dimensional hydrogen-bonded structures result from this within each of the two pairs. We note that there are only two recurring hydrogen-bonded motifs within this set. One is the C(5) chain motif found in (Ia) and (II), and the other is the R22(8) ring motif involving the A function of the C2 carbonyl group, which is present in (Ia) and in BMBARA10.