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A chair conformation is found for zwitterionic DL-piperidinium-2-carboxylate, C6H11NO2. Hydrogen-bonding interactions involving the carboxylate groups and ammonium H atoms give rise to a two-dimensional structure comprised of interconnected 12-membered rings.
Supporting information
CCDC reference: 155896
Key indicators
- Single-crystal X-ray study
- T = 173 K
- Mean (C-C) = 0.002 Å
- R factor = 0.035
- wR factor = 0.128
- Data-to-parameter ratio = 18.2
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level C:
ABSMU_01 Alert C The ratio of given/expected absorption coefficient lies
outside the range 0.99 <> 1.01
Calculated value of mu = 0.098
Value of mu given = 0.100
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check
Crystals were obtained by the vapour diffusion of diethyl ether into an
ethanol/benzene (5:1 v/v) solution of commercial
dl-piperidine-2-carboxylic acid (Sigma).
Data collection: MSC/AFC Diffractometer Control Software
(Molecular Structure Corporation, 1996); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: TEXSAN.
Crystal data top
C6H11NO2 | F(000) = 280 |
Mr = 129.16 | Dx = 1.304 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71069 Å |
a = 11.148 (3) Å | Cell parameters from 14 reflections |
b = 5.822 (2) Å | θ = 7.4–12.1° |
c = 10.813 (4) Å | µ = 0.10 mm−1 |
β = 110.39 (2)° | T = 173 K |
V = 657.8 (4) Å3 | Block, colourless |
Z = 4 | 0.30 × 0.20 × 0.10 mm |
Data collection top
Rigaku AFC-7R diffractometer | Rint = 0.018 |
Radiation source: rotating anode | θmax = 27.5°, θmin = 3.8° |
Graphite monochromator | h = −14→14 |
ω–2θ scans | k = −7→0 |
3323 measured reflections | l = −14→13 |
1513 independent reflections | 3 standard reflections every 400 reflections |
1191 reflections with I > 2σ(I) | intensity decay: 0.7% |
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)] = 0.035 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.128 | H-atom parameters not refined |
S = 0.98 | w = 1/[σ2(Fo2) + (0.1P)2] where P = (Fo2 + 2Fc2)/3 |
1513 reflections | (Δ/σ)max < 0.001 |
83 parameters | Δρmax = 0.24 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
Crystal data top
C6H11NO2 | V = 657.8 (4) Å3 |
Mr = 129.16 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 11.148 (3) Å | µ = 0.10 mm−1 |
b = 5.822 (2) Å | T = 173 K |
c = 10.813 (4) Å | 0.30 × 0.20 × 0.10 mm |
β = 110.39 (2)° | |
Data collection top
Rigaku AFC-7R diffractometer | Rint = 0.018 |
3323 measured reflections | 3 standard reflections every 400 reflections |
1513 independent reflections | intensity decay: 0.7% |
1191 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
wR(F2) = 0.128 | H-atom parameters not refined |
S = 0.98 | Δρmax = 0.24 e Å−3 |
1513 reflections | Δρmin = −0.19 e Å−3 |
83 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 | |
O21 | 0.09484 (8) | 0.37073 (16) | 0.30718 (9) | 0.0275 (3) | |
O22 | 0.18325 (10) | 0.20556 (18) | 0.50530 (9) | 0.0359 (3) | |
N1 | 0.13411 (9) | −0.00698 (16) | 0.17974 (9) | 0.0175 (3) | |
H1 | 0.1467 | 0.1219 | 0.1366 | 0.0342 (13)* | |
H2 | 0.0481 | −0.0174 | 0.1663 | 0.0342 (13)* | |
C2 | 0.20693 (11) | 0.01657 (19) | 0.32359 (10) | 0.0180 (3) | |
H3 | 0.1955 | −0.1282 | 0.3680 | 0.0342 (13)* | |
C3 | 0.34878 (11) | 0.0429 (2) | 0.34526 (12) | 0.0253 (3) | |
H4 | 0.3978 | 0.0585 | 0.4407 | 0.0342 (13)* | |
H5 | 0.3624 | 0.1835 | 0.3004 | 0.0342 (13)* | |
C4 | 0.39645 (11) | −0.1668 (3) | 0.29050 (13) | 0.0315 (3) | |
H6 | 0.4874 | −0.1445 | 0.3004 | 0.0342 (13)* | |
H7 | 0.3905 | −0.3051 | 0.3413 | 0.0342 (13)* | |
C5 | 0.31718 (12) | −0.2021 (2) | 0.14553 (13) | 0.0283 (3) | |
H8 | 0.3442 | −0.3461 | 0.1141 | 0.0342 (13)* | |
H9 | 0.3331 | −0.0735 | 0.0933 | 0.0342 (13)* | |
C6 | 0.17490 (11) | −0.2146 (2) | 0.12337 (11) | 0.0227 (3) | |
H10 | 0.1256 | −0.2242 | 0.0276 | 0.0342 (13)* | |
H11 | 0.1568 | −0.3544 | 0.1660 | 0.0342 (13)* | |
C21 | 0.15627 (11) | 0.2162 (2) | 0.38344 (11) | 0.0204 (3) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O21 | 0.0283 (4) | 0.0240 (5) | 0.0351 (5) | 0.0079 (4) | 0.0170 (4) | 0.0049 (4) |
O22 | 0.0577 (7) | 0.0307 (6) | 0.0238 (5) | 0.0092 (4) | 0.0196 (4) | −0.0037 (4) |
N1 | 0.0182 (5) | 0.0180 (5) | 0.0171 (5) | −0.0004 (3) | 0.0069 (4) | 0.0001 (3) |
C2 | 0.0199 (5) | 0.0196 (6) | 0.0156 (5) | 0.0022 (4) | 0.0075 (4) | 0.0004 (4) |
C3 | 0.0181 (6) | 0.0320 (7) | 0.0251 (6) | 0.0014 (5) | 0.0067 (4) | −0.0073 (5) |
C4 | 0.0222 (6) | 0.0398 (8) | 0.0320 (7) | 0.0099 (5) | 0.0088 (5) | −0.0073 (6) |
C5 | 0.0279 (6) | 0.0325 (7) | 0.0287 (7) | 0.0041 (5) | 0.0151 (5) | −0.0059 (5) |
C6 | 0.0262 (6) | 0.0214 (6) | 0.0218 (6) | 0.0001 (5) | 0.0100 (5) | −0.0045 (4) |
C21 | 0.0217 (5) | 0.0178 (6) | 0.0254 (6) | −0.0009 (4) | 0.0128 (4) | −0.0021 (4) |
Geometric parameters (Å, º) top
O21—C21 | 1.2508 (15) | C2—C21 | 1.5309 (15) |
O22—C21 | 1.2468 (15) | C3—C4 | 1.5305 (18) |
N1—C2 | 1.4891 (15) | C4—C5 | 1.5216 (18) |
N1—C6 | 1.4943 (15) | C5—C6 | 1.5210 (16) |
C2—C3 | 1.5234 (16) | | |
| | | |
C2—N1—C6 | 111.59 (9) | C6—C5—C4 | 111.61 (10) |
N1—C2—C3 | 109.20 (9) | N1—C6—C5 | 110.22 (9) |
N1—C2—C21 | 111.37 (9) | O22—C21—O21 | 127.42 (11) |
C3—C2—C21 | 112.00 (10) | O22—C21—C2 | 114.85 (10) |
C2—C3—C4 | 110.00 (10) | O21—C21—C2 | 117.72 (10) |
C5—C4—C3 | 110.54 (10) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O22i | 0.92 | 1.90 | 2.7672 (17) | 157 |
N1—H2···O21ii | 0.92 | 1.83 | 2.7005 (17) | 156 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x, y−1/2, −z+1/2. |
Experimental details
Crystal data |
Chemical formula | C6H11NO2 |
Mr | 129.16 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 173 |
a, b, c (Å) | 11.148 (3), 5.822 (2), 10.813 (4) |
β (°) | 110.39 (2) |
V (Å3) | 657.8 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.30 × 0.20 × 0.10 |
|
Data collection |
Diffractometer | Rigaku AFC-7R diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3323, 1513, 1191 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.128, 0.98 |
No. of reflections | 1513 |
No. of parameters | 83 |
H-atom treatment | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.24, −0.19 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O22i | 0.92 | 1.90 | 2.7672 (17) | 157 |
N1—H2···O21ii | 0.92 | 1.83 | 2.7005 (17) | 156 |
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) −x, y−1/2, −z+1/2. |
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The title molecule, (I), exists as a zwitterion [C21—O21 = 1.2508 (15) Å and C21—O22 = 1.2468 (15) Å] and adopts a chair conformation with the carboxylate occupying an equatorial position. The molecular structure is consistent with that found for the tetrahydrate (Bhattacharjee & Chacko, 1979) but features a different packing arrangement.
As shown in Fig. 1, two centrosymmetrically related carboxylate residues are linked by two ammonium cations, leading to the formation of 12-membered rings. As each molecule is involved in two donor and two acceptor hydrogen–bonding interactions that extend in the b and c directions, a two-dimensional network is formed. Layers stack along the a axis via hydrophobic interactions.