Powder study of (R)-1-phenyl­ethyl­ammonium (R)-2-phenyl­butyrate form 3

Fernandes, P.; Florence, A.J.; Shankland, K.; Karamertzanis, P.G.; Hulme, A.T.; Anandamanoharan, R.P.

doi:10.1107/S1600536806052093

organic compounds

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ISSN: 2056-9890

Volume 63| Part 1| January 2007| Pages o202-o204

https://doi.org/10.1107/S1600536806052093

Powder study of (R)-1-phenylethylammonium (R)-2-phenylbutyrate form 3

Philippe Fernandes,^a Alastair J. Florence,^a ^* Kenneth Shankland,^b Panagiotis G. Karamertzanis,^c Ashley T. Hulme ^c and R. Parathy Anandamanoharan ^d

^aStrathclyde Institute of Pharmacy and Biomedical Sciences, John Arbuthnott Building, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, Scotland, ^bISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, England, ^cChristopher Ingold Laboratory, Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, England, and ^dDepartment of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, England
^*Correspondence e-mail: alastair.florence@strath.ac.uk

(Received 17 November 2006; accepted 1 December 2006; online 8 December 2006)

The crystal structure of a new polymorph of the title compound, C₈H₁₂N⁺·C₁₀H₁₁O₂⁻, was solved by simulated annealing from laboratory X-ray powder diffraction data, collected at 295 K. Subsequent Rietveld refinement using data collected to 1.54 Å resolution, yielded an R_wp of 0.030. The compound crystallizes with one (R)-1-phenylethylammonium cation and one (R)-2-phenylbutyrate anion in the asymmetric unit.

Comment

The title compound is known to crystallize in at least two polymorphic forms, form 1 (Brianso, 1978 ) and form 2 (Fernandes et al., 2006 ). A third polymorph, form 3, (I), was produced in situ by heating a polycrystalline sample of form 2 to 393 K. The sample remained stable upon cooling to 295 K and the powder data were collected at this temperature.

The compound crystallizes in the monoclinic space group P2₁ with one (R)-1-phenylethylammonium cation and one (R)-2-phenylbutyrate anion in the asymmetric unit (Fig. 1). The structure contains four N—H⋯O hydrogen bonds between the NH₃⁺ and COO⁻ groups on adjacent ions. The ions pack to form a hydrogen-bonded ladder motif, similar to that observed in form 2 (Table 1, Fig. 2).

Figure 1
The asymmetric unit of (I)

with the atom-numbering scheme. Displacement spheres are shown at the 50% probability level. The dashed line indicates a hydrogen bond.

Figure 2
The hydrogen-bonded (dashed lines) ladder motif running parallel to the b axis in (I)

. Atoms not directly involved in hydrogen-bond contacts are omitted for clarity.

Figure 3
Final observed (points), calculated (line) and difference [(y_obs − y_calc)/σ(y_obs)] profiles for the Rietveld refinement of the title compound.

Experimental

A polycrystalline sample of (I) was prepared in situ by heating form 2 from 295 to 393 K until all the sample transformed. The sample was then cooled to 295 K and held at that temperature for the duration of the data collection. The sample was held in a rotating 0.7 mm borosilicate glass capillary and the temperature controlled using an Oxford Cryosystems Cryostream 700 series device. Data were collected using a variable count time (VCT) scheme in which the step time is increased with 2θ (Shankland et al., 1997 ; Hill & Madsen, 2002 $[Hill, R. J. & Madsen, I. C. (2002). Structure Determination from Powder Diffraction Data, edited by W. I. F. David, K. Shankland, L. B. McCusker & Ch. Baerlocher, pp. 114-116. Oxford University Press.]$ ).

Crystal data

C₈H₁₂N⁺·C₁₀H₁₁O₂⁻
M_r = 285.37
Monoclinic, P 2₁
a = 11.88215 (15) Å
b = 5.97647 (8) Å
c = 13.07499 (15) Å
β = 113.510 (1)°
V = 851.43 (2) Å³
Z = 2
D_x = 1.113 Mg m⁻³
Cu Kα₁ radiation
μ = 0.57 mm⁻¹
T = 298 K
Specimen shape: cylinder
12 × 0.7 × 0.7 mm
Specimen prepared at 393 K
Particle morphology: needle, white

Data collection

Bruker AXS D8 Advance diffractometer
Specimen mounting: 0.7 mm borosilicate capillary
Specimen mounted in transmission mode
Scan method: step
Wavelength of incident radiation: 1.54056 Å
Absorption correction: none
2θ_min = 3.0, 2θ_max = 60.0°
Increment in 2θ = 0.017°

Refinement

R_p = 0.026
R_wp = 0.031
R_exp = 0.016
R_B = 0.0223%
S = 1.96
Profile function: Fundamental parameters with axial divergence correction.
145 parameters
Only H-atom coordinates refined
w = 1/σ(Y_obs)²
(Δ/σ)_max = 0.001
Preferred orientation correction: A spherical harmonics-based preferred orientation correction (Järvinen, 1993 ) was applied with TOPAS during the Rietveld refinement

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1NA⋯O1ⁱ	0.963 (7)	2.585 (8)	3.457 (3)	150.7 (5)
N1—H1NA⋯O2ⁱ	0.963 (7)	1.827 (7)	2.683 (3)	146.6 (6)
N1—H1NB⋯O1	0.978 (7)	1.927 (8)	2.754 (3)	140.7 (5)
N1—H1NC⋯O1ⁱⁱ	0.976 (7)	1.958 (9)	2.840 (5)	149.1 (9)
Symmetry codes: (i) x, y+1, z; (ii) $[-x+1, y+{\script{1\over 2}}, -z+2]$ .

The diffraction pattern indexed to a monoclinic cell [M(20) = 95.7 F(20) = 253.2; DICVOL-91; Boultif & Louër, 1991 ] and space group P2₁ was assigned from volume considerations and a statistical consideration of the systematic absences (Markvardsen et al., 2001 ). The data set was background subtracted and truncated to 59.8° 2θ for Pawley (1981 ) fitting (χ²_Pawley = 5.10) and the structure solved using the simulated annealing (SA) global optimization procedure, described previously (David et al., 1998 ), that is now implemented in the DASH computer program (David et al., 2001 ). The SA structure solution used 290 reflections and involved the optimization of two fragments totaling 14 degrees of freedom (six positional and orientational for each fragment present in the asymmetric unit plus a torsion angle for each fragment). All degrees of freedom were assigned random values at the start of the simulated annealing. The best SA solution had a favourable χ_SA²/χ_Pawley² ratio of 1.83 and a chemically reasonable packing arrangement, with no significant misfit to the diffraction data.

The solved structure was then refined against the data in the range 3–59.7° 2θ using a restrained Rietveld (1969 ) method as implemented in Topas (Coelho, 2003 ), with the R_wp falling to 0.030 during the refinement. All atomic positions (including H atoms) for the structure of (I) were refined, subject to a series of restraints on bond lengths, bond angles and planarity. U_iso values for H atoms were constrained to equal 0.1013 Å²

The restraints were set such that bond lengths and angles did not deviate more than 0.01 Å and 0.8°, respectively, from their initial values during the refinement. Atoms C13–C18 and H14–H18 (phenylethylammonium) and atoms C5–C10 and H6–H10 (phenylbutyrate) were restrained to be planar. A spherical harmonics (fourth order) correction of intensities for preferred orientation was applied in the final refinement (Järvinen, 1993). The observed and calculated diffraction patterns for the refined crystal structure are shown in Fig. 3.

Data collection: DIFFRAC plus XRD Commander (Kienle & Jacob, 2003 ); cell refinement: TOPAS (Coelho, 2003); data reduction: DASH (David et al., 2001); program(s) used to solve structure: DASH; program(s) used to refine structure: TOPAS; molecular graphics: ORTEP-3 (Farrugia, 1997 ) and PLATON (Version 011105; Spek, 2003 ); software used to prepare material for publication: enCIFer (Allen et al., 2004 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536806052093/lh2256sup1.cif

Rietveld powder data: contains datablock I. DOI: https://doi.org/10.1107/S1600536806052093/lh2256Isup2.rtv

Computing details top

Data collection: DIFFRAC plus XRD Commander (Kienle & Jacob, 2003); cell refinement: TOPAS; data reduction: DASH (David et al., 2001); program(s) used to solve structure: DASH; program(s) used to refine structure: TOPAS (Coelho, 2003); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Version 011105; Spek, 2003); software used to prepare material for publication: enCIFer (Allen et al., 2004).

(R)-1-phenylethylammonium (R)-2-phenylbutyrate top

Crystal data top

C₈H₁₂N⁺·C₁₀H₁₁O₂⁻	F(000) = 308
M_r = 285.37	D_x = 1.113 Mg m⁻³
Monoclinic, P2₁	Cu Kα₁ radiation, λ = 1.54056 Å
Hall symbol: P 2yb	µ = 0.57 mm⁻¹
a = 11.88215 (15) Å	T = 298 K
b = 5.97647 (8) Å	Particle morphology: needles
c = 13.07499 (15) Å	white
β = 113.510 (1)°	cylinder, 12 × 0.7 mm
V = 851.43 (2) Å³	Specimen preparation: Prepared at 393 K
Z = 2

Data collection top

Bruker AXS D8 Advance diffractometer	Data collection mode: transmission
Radiation source: sealed X-ray tube, Bruker-AXS D8	Scan method: step
Primary focussing, Ge 111 monochromator	2θ_min = 3.0°, 2θ_max = 60.0°, 2θ_step = 0.017°
Specimen mounting: 0.7 mm borosilicate capillary

Refinement top

Least-squares matrix: selected elements only	101 restraints
R_p = 0.026	1 constraint
R_wp = 0.031	Only H-atom coordinates refined
R_exp = 0.016	Weighting scheme based on measured s.u.'s w = 1/σ(Y_obs)²
R_Bragg = 2.23	(Δ/σ)_max = 0.001
4177 data points	Background function: Chebyshev polynomial
Profile function: Fundamental parameters with axial divergence correction.	Preferred orientation correction: A spherical harmonics-based preferred orientation correction (Järvinen, 1993) was applied with Topas during the Rietveld refinement.
145 parameters

Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.3747 (5)	0.1291 (5)	0.8818 (3)	0.0718 (5)*
O2	0.3433 (6)	−0.1669 (7)	0.7721 (2)	0.0718 (5)*
C1	0.3477 (2)	0.0377 (2)	0.78746 (12)	0.0718 (5)*
C2	0.32515 (16)	0.1930 (2)	0.69002 (11)	0.0718 (5)*
C3	0.21939 (14)	0.1089 (3)	0.58677 (13)	0.0718 (5)*
C4	0.09580 (11)	0.1186 (2)	0.60089 (8)	0.0718 (5)*
C5	0.44009 (15)	0.2225 (3)	0.66949 (16)	0.0718 (5)*
C6	0.48329 (13)	0.0467 (3)	0.6259 (3)	0.0718 (5)*
C7	0.58868 (18)	0.0694 (3)	0.60649 (17)	0.0718 (5)*
C8	0.6603 (2)	0.2620 (3)	0.6402 (3)	0.0718 (5)*
C9	0.62251 (17)	0.4285 (3)	0.6930 (3)	0.0718 (5)*
C10	0.51293 (13)	0.4127 (3)	0.70507 (18)	0.0718 (5)*
N1	0.38635 (9)	0.5680 (2)	0.94939 (8)	0.0718 (5)*
C11	0.31720 (10)	0.41721 (19)	1.09033 (9)	0.0718 (5)*
C12	0.30926 (12)	0.6131 (3)	1.01329 (11)	0.0718 (5)*
C13	0.17962 (18)	0.6657 (3)	0.93490 (16)	0.0718 (5)*
C14	0.12161 (15)	0.8606 (3)	0.94873 (16)	0.0718 (5)*
C15	0.00363 (15)	0.9118 (3)	0.87154 (16)	0.0718 (5)*
C16	−0.05983 (16)	0.7575 (3)	0.78734 (16)	0.0718 (5)*
C17	−0.00054 (15)	0.5681 (3)	0.77208 (15)	0.0718 (5)*
C18	0.11465 (16)	0.5141 (3)	0.84997 (16)	0.0718 (5)*
H2	0.3072 (9)	0.3380 (11)	0.7092 (4)	0.1013*
H3A	0.2158 (5)	0.2052 (13)	0.5273 (4)	0.1013*
H3B	0.2387 (5)	−0.0409 (13)	0.5746 (4)	0.1013*
H4A	0.0792 (6)	0.2733 (13)	0.6111 (4)	0.1013*
H4B	0.1002 (5)	0.0244 (13)	0.6644 (4)	0.1013*
H4C	0.0291 (6)	0.075 (2)	0.5316 (5)	0.1013*
H6	0.4350 (5)	−0.0846 (12)	0.5972 (4)	0.1013*
H7	0.6181 (5)	−0.0517 (12)	0.5756 (5)	0.1013*
H8	0.7391 (5)	0.2670 (12)	0.6375 (7)	0.1013*
H9	0.6642 (5)	0.5714 (15)	0.7086 (4)	0.1013*
H10	0.4794 (5)	0.5441 (15)	0.7215 (18)	0.1013*
H1NA	0.3899 (5)	0.7000 (13)	0.9086 (5)	0.1013*
H1NB	0.3565 (5)	0.4469 (13)	0.8949 (4)	0.1013*
H1NC	0.4694 (6)	0.5316 (18)	1.0020 (5)	0.1013*
H11A	0.2726 (5)	0.4561 (13)	1.1364 (4)	0.1013*
H11B	0.2836 (4)	0.2838 (13)	1.0457 (4)	0.1013*
H11C	0.4033 (4)	0.3907 (11)	1.1390 (4)	0.1013*
H12	0.3428 (5)	0.7420 (13)	1.0575 (4)	0.1013*
H14	0.1682 (5)	0.9672 (13)	1.0051 (5)	0.1013*
H15	−0.0339 (5)	1.0449 (15)	0.8853 (4)	0.1013*
H16	−0.1395 (5)	0.7935 (11)	0.7330 (4)	0.1013*
H17	−0.0464 (5)	0.4590 (12)	0.7169 (5)	0.1013*
H18	0.1545 (5)	0.3781 (12)	0.8442 (4)	0.1013*

Geometric parameters (Å, º) top

O1—C1	1.268 (4)	C6—H6	0.956 (7)
O2—C1	1.237 (4)	C7—H7	0.960 (7)
N1—C12	1.4901 (19)	C8—H8	0.951 (8)
N1—H1NC	0.976 (7)	C9—H9	0.967 (9)
N1—H1NA	0.963 (7)	C10—H10	0.943 (11)
N1—H1NB	0.978 (7)	C11—C12	1.523 (2)
C1—C2	1.5113 (19)	C12—C13	1.504 (3)
C2—C3	1.517 (2)	C13—C18	1.402 (3)
C2—C5	1.504 (3)	C13—C14	1.401 (3)
C3—C4	1.553 (2)	C14—C15	1.396 (3)
C5—C6	1.388 (3)	C15—C16	1.403 (3)
C5—C10	1.392 (3)	C16—C17	1.389 (3)
C6—C7	1.380 (3)	C17—C18	1.379 (3)
C7—C8	1.394 (3)	C11—H11A	0.976 (6)
C8—C9	1.384 (4)	C11—H11B	0.975 (7)
C9—C10	1.376 (3)	C11—H11C	0.978 (5)
C2—H2	0.950 (7)	C12—H12	0.950 (7)
C3—H3B	0.953 (8)	C14—H14	0.964 (7)
C3—H3A	0.955 (6)	C15—H15	0.963 (8)
C4—H4A	0.966 (8)	C16—H16	0.954 (6)
C4—H4B	0.987 (6)	C17—H17	0.964 (7)
C4—H4C	0.972 (7)	C18—H18	0.959 (7)

H1NA—N1—H1NB	106.6 (5)	C8—C7—H7	118.5 (5)
H1NA—N1—H1NC	108.5 (7)	C9—C8—H8	121.1 (5)
H1NB—N1—H1NC	108.6 (7)	C7—C8—H8	120.0 (5)
C12—N1—H1NC	108.7 (4)	C10—C9—H9	117.7 (4)
C12—N1—H1NA	109.6 (4)	C8—C9—H9	119.9 (5)
C12—N1—H1NB	114.7 (4)	C5—C10—H10	119.6 (7)
O2—C1—C2	119.24 (17)	C9—C10—H10	118.3 (7)
O1—C1—O2	124.2 (2)	C11—C12—C13	112.82 (13)
O1—C1—C2	116.52 (17)	N1—C12—C13	110.32 (12)
C1—C2—C3	110.62 (13)	N1—C12—C11	110.01 (12)
C3—C2—C5	111.65 (13)	C12—C13—C14	120.56 (16)
C1—C2—C5	110.75 (16)	C12—C13—C18	119.69 (17)
C2—C3—C4	111.65 (13)	C14—C13—C18	119.70 (19)
C6—C5—C10	118.24 (18)	C13—C14—C15	119.52 (17)
C2—C5—C6	119.72 (16)	C14—C15—C16	119.58 (17)
C2—C5—C10	121.61 (16)	C15—C16—C17	120.24 (18)
C5—C6—C7	120.83 (18)	C16—C17—C18	119.69 (17)
C6—C7—C8	120.5 (2)	C13—C18—C17	120.28 (17)
C7—C8—C9	118.2 (2)	C12—C11—H11A	108.6 (4)
C8—C9—C10	121.2 (2)	C12—C11—H11B	109.3 (4)
C5—C10—C9	120.57 (18)	C12—C11—H11C	109.1 (4)
C5—C2—H2	104.8 (6)	H11A—C11—H11B	111.8 (5)
C1—C2—H2	108.7 (4)	H11A—C11—H11C	108.8 (4)
C3—C2—H2	110.1 (5)	H11B—C11—H11C	109.2 (5)
C2—C3—H3A	106.1 (4)	N1—C12—H12	106.6 (4)
C2—C3—H3B	106.9 (4)	C11—C12—H12	108.7 (4)
C4—C3—H3A	109.7 (4)	C13—C12—H12	108.2 (4)
C4—C3—H3B	110.9 (4)	C13—C14—H14	119.1 (5)
H3A—C3—H3B	111.5 (6)	C15—C14—H14	120.8 (5)
H4A—C4—H4B	112.0 (5)	C14—C15—H15	116.9 (4)
H4A—C4—H4C	104.5 (8)	C16—C15—H15	123.1 (4)
C3—C4—H4C	109.7 (5)	C15—C16—H16	119.9 (4)
C3—C4—H4A	107.9 (5)	C17—C16—H16	119.1 (4)
C3—C4—H4B	110.1 (4)	C16—C17—H17	119.4 (4)
H4B—C4—H4C	112.4 (7)	C18—C17—H17	119.5 (4)
C7—C6—H6	117.1 (4)	C13—C18—H18	118.5 (4)
C5—C6—H6	121.4 (4)	C17—C18—H18	121.1 (4)
C6—C7—H7	120.8 (4)

O1—C1—C2—C3	−140.9 (4)	C6—C7—C8—C9	−0.2 (4)
O1—C1—C2—C5	94.8 (4)	C7—C8—C9—C10	−4.6 (5)
O2—C1—C2—C3	41.6 (5)	C8—C9—C10—C5	3.4 (4)
O2—C1—C2—C5	−82.7 (4)	N1—C12—C13—C14	−127.37 (18)
C1—C2—C3—C4	66.34 (18)	N1—C12—C13—C18	55.2 (2)
C5—C2—C3—C4	−169.84 (12)	C11—C12—C13—C14	109.15 (19)
C1—C2—C5—C6	71.0 (2)	C11—C12—C13—C18	−68.3 (2)
C1—C2—C5—C10	−101.35 (19)	C12—C13—C14—C15	176.66 (17)
C3—C2—C5—C6	−52.8 (2)	C18—C13—C14—C15	−5.9 (3)
C3—C2—C5—C10	134.91 (18)	C12—C13—C18—C17	−174.78 (17)
C2—C5—C6—C7	−179.9 (2)	C14—C13—C18—C17	7.7 (3)
C10—C5—C6—C7	−7.3 (4)	C13—C14—C15—C16	6.0 (3)
C2—C5—C10—C9	175.0 (2)	C14—C15—C16—C17	−8.0 (3)
C6—C5—C10—C9	2.6 (3)	C15—C16—C17—C18	9.8 (3)
C5—C6—C7—C8	6.2 (4)	C16—C17—C18—C13	−9.7 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1NA···O1ⁱ	0.963 (7)	2.585 (8)	3.457 (3)	150.7 (5)
N1—H1NA···O2ⁱ	0.963 (7)	1.827 (7)	2.683 (3)	146.6 (6)
N1—H1NB···O1	0.978 (7)	1.927 (8)	2.754 (3)	140.7 (5)
N1—H1NC···O1ⁱⁱ	0.976 (7)	1.958 (9)	2.840 (5)	149.1 (9)

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

Acknowledgements

We thank the Basic Technology programme of the UK Research Councils for funding under the project Control and Prediction of the Organic Solid State (https://www.cposs.org.uk).

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