research papers
The crystal structure of the solid phase of the dipolar aprotic solvent γ-butyrolactone (BL1), C4H6O2, has been solved using the atom–atom potential method and Rietveld-refined against powder diffraction data collected at T = 180 K with a curved position-sensitive detector (INEL CPS120) using Debye–Scherrer diffraction geometry with monochromatic X-rays. It was first deduced from the X-ray experiment that the lattice parameters are a = 10.1282 (4), b = 10.2303 (5), c = 8.3133 (4) Å, β = 93.291 (2)° and that the space group is P21/a, with Z = 8 and two independent molecules in the asymmetric unit. The structure was then solved by global energy minimization of the crystal-lattice atom–atom potentials. The subsequent GSAS-based Rietveld refinement converged to the final crystal-structure model indicator RF2 = 0.0684, profile factors Rp = 0.0517 and Rwp = 0.0694, and a reduced χ2 = 1.671. After further cycles of heating and cooling, a powder diffraction pattern markedly different from the first pattern was obtained, again at T = 180 K, which we tentatively assign to a second polymorph (BL2). All the observed diffraction peaks are well indexed by a triclinic unit cell essentially featuring a doubling of the a axis. An excellent Le Bail fit is obtained, for which Rp = 0.0312 and Rwp = 0.0511.
Keywords: butyrolactone; X-ray powder diffraction; atom–atom potential; low temperature; polymorphism.
Supporting information
CCDC reference: 1159011
4-Hydroxybutyric acid gamma-Lactone top
Crystal data top
C4H6O2 | V = 859.95 (7) Å3 |
Mr = 86.08 | Z = 8 |
Monoclinic, P21/a | Dx = 1.33 Mg m−3 |
Hall symbol: -P 2yab | Cu Kα1 radiation, λ = 1.54056 Å |
a = 10.1282 (4) Å | T = 180 K |
b = 10.2303 (5) Å | white |
c = 8.3133 (4) Å | ?, ? × ? × ? mm |
β = 93.2908 (17)° | Specimen preparation: Prepared at cooled down from 300 to 180 K and 1atm kPa, cooled at 6 K min−1 |
Data collection top
INEL CPS 120 diffractometer | 2θmin = 0.302°, 2θmax = 114.533°, 2θstep = 0.029° |
Radiation source: sealed X-ray tube, INEL CPS 120 |
Refinement top
Least-squares matrix: full | Profile function: CW Profile function number 4 with 21 terms Pseudovoigt profile coefficients as parameterized in P. Thompson, D.E. Cox & J.B. Hastings (1987). J. Appl. Cryst.,20,79-83. Asymmetry correction of L.W. Finger, D.E. Cox & A. P. Jephcoat (1994). J. Appl. Cryst.,27,892-900. Microstrain broadening by P.W. Stephens, (1999). J. Appl. Cryst.,32,281-289. #1(GU) = 220.927 #2(GV) = -88.488 #3(GW) = 20.788 #4(GP) = 0.000 #5(LX) = 1.657 #6(ptec) = 0.00 #7(trns) = 0.00 #8(shft) = 0.0000 #9(sfec) = 0.00 #10(S/L) = 0.0000 #11(H/L) = 0.0000 #12(eta) = 0.0000 #13(S400 ) = 0.0E+00 #14(S040 ) = 0.0E+00 #15(S004 ) = 0.0E+00 #16(S220 ) = 0.0E+00 #17(S202 ) = 0.0E+00 #18(S022 ) = 0.0E+00 #19(S301 ) = 0.0E+00 #20(S103 ) = 0.0E+00 #21(S121 ) = 0.0E+00 Peak tails are ignored where the intensity is below 0.0001 times the peak Aniso. broadening axis 0.0 0.0 1.0 |
Rp = 0.052 | 115 parameters |
Rwp = 0.069 | 58 restraints |
Rexp = 0.060 | (Δ/σ)max = 0.01 |
R(F2) = 0.06663 | Background function: GSAS Background function number 1 with 6 terms. Shifted Chebyshev function of 1st kind 1: -2.45382 2: 1.36696 3: -0.793512 4: 0.878383 5: 2.31191 6: 1.70787 |
χ2 = 1.664 | Preferred orientation correction: Spherical Harmonic ODF Spherical harmonic order= 10 The sample symmetry is: cylindrical (fiber texture) Index = 2 0 -2 Coeff= -0.1928 Index = 2 0 0 Coeff= 0.4183 Index = 2 0 2 Coeff= 0.0753 Index = 4 0 -4 Coeff= 0.1166 Index = 4 0 -2 Coeff= 1.1450 Index = 4 0 0 Coeff= 0.2432 Index = 4 0 2 Coeff= 0.7345 Index = 4 0 4 Coeff= 0.6219 Index = 6 0 -6 Coeff= -1.9053 Index = 6 0 -4 Coeff= 1.2835 Index = 6 0 -2 Coeff= -0.3569 Index = 6 0 0 Coeff= -2.1792 Index = 6 0 2 Coeff= 0.2381 Index = 6 0 4 Coeff= 2.4571 Index = 6 0 6 Coeff= 0.9538 Index = 8 0 -8 Coeff= 0.9905 Index = 8 0 -6 Coeff= -0.0950 Index = 8 0 -4 Coeff= 1.6723 Index = 8 0 -2 Coeff= -1.9020 Index = 8 0 0 Coeff= 3.0183 Index = 8 0 2 Coeff= -0.7880 Index = 8 0 4 Coeff= 1.3471 Index = 8 0 6 Coeff= -1.1220 Index = 8 0 8 Coeff= 1.8006 Index = 10 0-10 Coeff= -0.5927 Index = 10 0 -8 Coeff= 1.0910 Index = 10 0 -6 Coeff= -0.3130 Index = 10 0 -4 Coeff= 1.6547 Index = 10 0 -2 Coeff= -1.0295 Index = 10 0 0 Coeff= 2.0994 Index = 10 0 2 Coeff= 0.2394 Index = 10 0 4 Coeff= -0.3914 Index = 10 0 6 Coeff= 0.3136 Index = 10 0 8 Coeff= 1.0738 Index = 10 0 10 Coeff= -0.8861 Prefered orientation correction range: Min= -0.40080, Max= 3.82007 |
3940 data points |
Crystal data top
C4H6O2 | β = 93.2908 (17)° |
Mr = 86.08 | V = 859.95 (7) Å3 |
Monoclinic, P21/a | Z = 8 |
a = 10.1282 (4) Å | Cu Kα1 radiation, λ = 1.54056 Å |
b = 10.2303 (5) Å | T = 180 K |
c = 8.3133 (4) Å | ?, ? × ? × ? mm |
Refinement top
Rp = 0.052 | χ2 = 1.664 |
Rwp = 0.069 | 3940 data points |
Rexp = 0.060 | 115 parameters |
R(F2) = 0.06663 | 58 restraints |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | ||
O1a | 0.066 (4) | −0.047 (3) | −0.218 (3) | 0.029 (19)* | |
O2a | 0.018 (3) | 0.165 (2) | −0.172 (5) | 0.029 (19)* | |
C1a | 0.042 (3) | 0.274 (4) | −0.064 (5) | 0.029 (19)* | |
C2a | 0.193 (3) | 0.253 (4) | −0.037 (5) | 0.029 (19)* | |
C3a | 0.217 (2) | 0.109 (4) | −0.074 (4) | 0.029 (19)* | |
C4a | 0.084 (2) | 0.052 (3) | −0.139 (2) | 0.029 (19)* | |
O1b | −0.023 (3) | −0.421 (4) | −0.282 (4) | 0.029 (19)* | |
O2b | 0.173 (4) | −0.504 (2) | −0.349 (5) | 0.029 (19)* | |
C1b | 0.283 (6) | −0.486 (2) | −0.450 (6) | 0.029 (19)* | |
C2b | 0.284 (3) | −0.335 (3) | −0.458 (5) | 0.029 (19)* | |
C3b | 0.152 (4) | −0.290 (2) | −0.399 (5) | 0.029 (19)* | |
C4b | 0.075 (4) | −0.413 (2) | −0.359 (3) | 0.029 (19)* | |
H1a | 0.026 (5) | 0.369 (3) | −0.114 (10) | 0.029 (19)* | |
H2a | −0.001 (6) | 0.266 (8) | 0.051 (7) | 0.029 (19)* | |
H3a | 0.222 (8) | 0.273 (7) | 0.086 (8) | 0.029 (19)* | |
H4a | 0.243 (4) | 0.314 (4) | −0.118 (12) | 0.029 (19)* | |
H5a | 0.288 (4) | 0.101 (5) | −0.164 (8) | 0.029 (19)* | |
H6a | 0.250 (4) | 0.058 (5) | 0.034 (7) | 0.029 (19)* | |
H1b | 0.377 (6) | −0.518 (6) | −0.400 (15) | 0.029 (19)* | |
H2b | 0.268 (13) | −0.522 (7) | −0.572 (8) | 0.029 (19)* | |
H3b | 0.294 (9) | −0.305 (7) | −0.580 (8) | 0.029 (19)* | |
H4b | 0.364 (4) | −0.300 (5) | −0.380 (14) | 0.029 (19)* | |
H5b | 0.168 (8) | −0.232 (6) | −0.293 (10) | 0.029 (19)* | |
H6b | 0.098 (4) | −0.236 (7) | −0.492 (11) | 0.029 (19)* |
Geometric parameters (Å, º) top
O1a—C4a | 1.2099 (8) | C3b—C2b | 1.5293 (8) |
O2a—C1a | 1.4398 (8) | C3b—C4b | 1.5298 (8) |
O2a—C3a | 2.20 (4) | C3b—H5b | 1.072 (4) |
O2a—C4a | 1.3600 (8) | C3b—H6b | 1.072 (4) |
C1a—O2a | 1.4398 (8) | C4b—O1b | 1.2099 (8) |
C1a—C2a | 1.5495 (8) | C4b—O2b | 1.3600 (8) |
C1a—H1a | 1.073 (4) | C4b—C3b | 1.5298 (8) |
C1a—H2a | 1.073 (4) | H1a—C1a | 1.073 (4) |
C2a—C1a | 1.5495 (8) | H1a—H2a | 1.764 (8) |
C2a—C3a | 1.5294 (8) | H2a—C1a | 1.073 (4) |
C2a—H3a | 1.068 (4) | H2a—H1a | 1.764 (8) |
C2a—H4a | 1.068 (4) | H3a—C2a | 1.068 (4) |
C3a—O2a | 2.20 (4) | H3a—H4a | 1.774 (8) |
C3a—C2a | 1.5294 (8) | H4a—C2a | 1.068 (4) |
C3a—C4a | 1.5297 (8) | H4a—H3a | 1.774 (8) |
C3a—H5a | 1.072 (4) | H5a—C3a | 1.072 (4) |
C3a—H6a | 1.072 (4) | H5a—H6a | 1.766 (8) |
C4a—O1a | 1.2099 (8) | H6a—C3a | 1.072 (4) |
C4a—O2a | 1.3600 (8) | H6a—H5a | 1.766 (8) |
C4a—C3a | 1.5297 (8) | H1b—C1b | 1.075 (4) |
O1b—C4b | 1.2099 (8) | H1b—H2b | 1.760 (8) |
O2b—C1b | 1.4399 (8) | H2b—C1b | 1.075 (4) |
O2b—C4b | 1.3600 (8) | H2b—H1b | 1.760 (8) |
C1b—O2b | 1.4399 (8) | H3b—C2b | 1.068 (4) |
C1b—C2b | 1.5495 (8) | H3b—H4b | 1.774 (8) |
C1b—H1b | 1.075 (4) | H4b—C2b | 1.068 (4) |
C1b—H2b | 1.075 (4) | H4b—H3b | 1.774 (8) |
C2b—C1b | 1.5495 (8) | H5b—C3b | 1.072 (4) |
C2b—C3b | 1.5293 (8) | H5b—H6b | 1.767 (8) |
C2b—H3b | 1.068 (4) | H6b—C3b | 1.072 (4) |
C2b—H4b | 1.068 (4) | H6b—H5b | 1.767 (8) |
C1a—O2a—C4a | 118 (2) | C1b—O2b—C4b | 118 (3) |
O2a—C1a—C2a | 96.5 (19) | O2b—C1b—C2b | 99.2 (17) |
O2a—C1a—H1a | 116.2 (7) | O2b—C1b—H1b | 115.8 (7) |
O2a—C1a—H2a | 116.2 (7) | O2b—C1b—H2b | 115.7 (7) |
C2a—C1a—H1a | 108.0 (7) | C2b—C1b—H1b | 107.6 (6) |
C2a—C1a—H2a | 107.9 (7) | C2b—C1b—H2b | 107.6 (6) |
H1a—C1a—H2a | 110.6 (8) | H1b—C1b—H2b | 109.8 (8) |
C1a—C2a—C3a | 105.5 (15) | C1b—C2b—C3b | 105.9 (14) |
C1a—C2a—H3a | 109.0 (6) | C1b—C2b—H3b | 108.9 (6) |
C1a—C2a—H4a | 109.0 (7) | C1b—C2b—H4b | 108.9 (6) |
C3a—C2a—H3a | 110.5 (7) | C3b—C2b—H3b | 110.3 (7) |
C3a—C2a—H4a | 110.4 (7) | C3b—C2b—H4b | 110.3 (7) |
H3a—C2a—H4a | 112.3 (8) | H3b—C2b—H4b | 112.2 (8) |
C2a—C3a—C4a | 107.1 (15) | C2b—C3b—C4b | 106.8 (15) |
C2a—C3a—H5a | 109.7 (7) | C2b—C3b—H5b | 109.7 (7) |
C2a—C3a—H6a | 109.7 (7) | C2b—C3b—H6b | 109.7 (7) |
C4a—C3a—H5a | 109.7 (7) | C4b—C3b—H5b | 109.7 (7) |
C4a—C3a—H6a | 109.6 (7) | C4b—C3b—H6b | 109.7 (7) |
H5a—C3a—H6a | 110.9 (8) | H5b—C3b—H6b | 111.1 (8) |
O1a—C4a—O2a | 123.04 (18) | O1b—C4b—O2b | 123.04 (18) |
O1a—C4a—C3a | 127.39 (19) | O1b—C4b—C3b | 127.39 (19) |
O2a—C4a—C3a | 99 (3) | O2b—C4b—C3b | 101 (3) |
Experimental details
Crystal data | |
Chemical formula | C4H6O2 |
Mr | 86.08 |
Crystal system, space group | Monoclinic, P21/a |
Temperature (K) | 180 |
a, b, c (Å) | 10.1282 (4), 10.2303 (5), 8.3133 (4) |
β (°) | 93.2908 (17) |
V (Å3) | 859.95 (7) |
Z | 8 |
Radiation type | Cu Kα1, λ = 1.54056 Å |
Specimen shape, size (mm) | ?, ? × ? × ? |
Data collection | |
Diffractometer | INEL CPS 120 diffractometer |
Specimen mounting | ? |
Data collection mode | ? |
Scan method | ? |
2θ values (°) | 2θmin = 0.302 2θmax = 114.533 2θstep = 0.029 |
Refinement | |
R factors and goodness of fit | Rp = 0.052, Rwp = 0.069, Rexp = 0.060, R(F2) = 0.06663, χ2 = 1.664 |
No. of data points | 3940 |
No. of parameters | 115 |
No. of restraints | 58 |
Computer programs: GSAS.