Synchrotron and neutron diffraction study of 4-methylpyridine-N-oxide at low temperature

Damay, F.; Carretero-Genevrier, A.; Cousson, A.; Van Beek, W.; Rodriguez-Carvajal, J.; Fillaux, F.

doi:10.1107/S0108768106011608

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Synchrotron and neutron diffraction study of 4-methylpyridine-N-oxide at low temperature

F. Damay, A. Carretero-Genevrier, A. Cousson, W. Van Beek, J. Rodriguez-Carvajal and F. Fillaux

The structure of 4-methylpyridine-N-oxide has been determined at 250, 100 and 10 K by combined synchrotron (C₆H₇NO) and neutron (C₆D₇NO) powder diffraction experiments. At 250 K the space group is I4₁/amd and the tetragonal unit cell [a = b = 7.941 (2), c = 19.600 (5) Å] contains eight equivalent molecules. At 100 K the structure is orthorhombic, with space group Fddd, a = 12.138 (2), b = 10.237 (2) and c = 19.568 (3) Å. The 16 equivalent molecules are rotated by about 8° around the c axis with respect to positions at high temperature. At 10 K the best structural model corresponds to a tetragonal unit cell with the space group P4₁, a = b = 15.410 (2) Å and c = 19.680 (3) Å. The 32 molecules (eight molecules in the asymmetric unit) show complex reorientations around the three cell axes. Whereas at 250 and 100 K the deuterated methyl groups are largely disordered, at 10 K they are ordered in-phase along infinite chains parallel to a and b. Face-to-face methyl groups along c are in an eclipsed configuration. The structure at 10 K suggests that the manifold of rotational tunnelling transitions could be due to inequivalent lattice sites for crystallographically independent methyl groups.

Keywords: 4-methylpyridine-N-oxide molecular systems; neutron powder diffraction; synchrotron powder diffraction; methyl rotational dynamics.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768106011608/av5052sup1.cif Contains datablocks global, 250K, 100K, 10K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768106011608/av5052250Ksup2.rtv Contains datablock 250K
	Structure factor file (CIF format) https://doi.org/10.1107/S0108768106011608/av5052250Ksup3.hkl Contains datablock 250K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768106011608/av5052100Ksup4.rtv Contains datablock 100K
	Structure factor file (CIF format) https://doi.org/10.1107/S0108768106011608/av5052100Ksup5.hkl Contains datablock 100K
	Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768106011608/av505210Ksup6.rtv Contains datablock 10K
	Structure factor file (CIF format) https://doi.org/10.1107/S0108768106011608/av505210Ksup7.hkl Contains datablock 10K

CCDC references: 618454; 618455; 618456

Experimental top

Fully deuterated sample was prepared by repeated exchanges with heavy water

Computing details top

For all compounds, program(s) used to refine structure: FULLPROF; molecular graphics: DIAMOND.

Figures top

Figure 1 Neutron diffraction patterns of powdered 4-methylpyridine-N-oxide at 250 K, 100 K and 10 K. Inset: schematic view of the orientational disordering of the methyl group at 250 K, modelled with anisotropic ellipsoids. Figure 2 [001] projection and unit cell of the structure of 4-methylpyridine-N-oxide at 250 K and 100 K. For the sake of clarity, the D atoms are omitted. Figure 3 Isodensity contours (Fourier method) in the rotational plane (001) of the methyl group at 250, 100, and 10 K. Superscripts (s) and (r) refer to standard and rigid-body group refinements, respectively. Figure 4 Rietveld refinement of the neutron diffraction pattern of fully deuterated 4-methylpyridine-N-oxide at 10 K. Experimental data (open circles). Calculated (continuous line). Allowed Bragg reflections (vertical marks). The difference between the observed and calculated profiles is displayed at the bottom. Inset: schematic view of the molecule and thermal ellipsoids at 10 K. Figure 5 [001] projection of the unit cell for fully deuterated 4-methylpyridine-N-oxide at 10 K. The D atoms are omitted. M1 to M8 refer to the 8 molecules of the asymmetric unit defined in Table 5. Figure 6 Top: view along a of the infinite chains of CD3 rotors parallel to b (zigzag lines) or parallel to a (circles). The unit cell is outlined. Bottom: view along c of two chains. Numbers in parentheses refer to the distances between methyl groups in Table 5. Thick and thin dots correspond to short and long distances, respectively. Dotted circles emphasize possible coupling with rotors in the next layer (z = 0.7) above, while dotted squares indicate possible coupling with rotors in the next layer (z = 0.3) below.

(250K) 4-methylpyridine-N-oxide top

Crystal data top

C₅D₄NO·(CD₃)	V = 1236.03 (6) Å³
M_r = 116	Z = 8
Tetragonal, I4₁/amd	Melting point: 463 K
Hall symbol: -I 4bd 2	Constant Wavelength neutron radiation, λ = 1.225300 Å
a = 7.9411 (2) Å	T = 250 K
c = 19.6002 (5) Å	cylinder, ? × ? × ? mm

Data collection top

Home made powder diffractometer	Specimen mounting: vanadium
Radiation source: nuclear reactor, 3T2	2θ_min = −0.026°, 2θ_max = 125.424°, 2θ_step = 0.050°

Refinement top

R_p = 2.045	Profile function: pseudo-voigt
R_wp = 2.506	49 parameters
R_exp = 1.501	0 restraints
R_Bragg = 4.610
χ² = 2.789	Background function: FullProf Background function number
2279 data points

Crystal data top

C₅D₄NO·(CD₃)	V = 1236.03 (6) Å³
M_r = 116	Z = 8
Tetragonal, I4₁/amd	Constant Wavelength neutron radiation, λ = 1.225300 Å
a = 7.9411 (2) Å	T = 250 K
c = 19.6002 (5) Å	cylinder, ? × ? × ? mm

Data collection top

Home made powder diffractometer	2θ_min = −0.026°, 2θ_max = 125.424°, 2θ_step = 0.050°
Specimen mounting: vanadium

Refinement top

R_p = 2.045	χ² = 2.789
R_wp = 2.506	2279 data points
R_exp = 1.501	49 parameters
R_Bragg = 4.610	0 restraints

Special details top

Geometry. Rigid body group non refined

Refinement. Two rigid-body groups (C5D7NO and CD3 methyl group) with TLS

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
PI1	0.00000	0.25000	0.56339	0.00000
PI2	0.00000	0.25000	0.49468	0.00000
PI3	0.00000	0.10254	0.59687	0.00000	0.50000
PI4	0.00000	0.39746	0.59687	0.00000	0.50000
PI5	0.00000	0.10206	0.66836	0.00000	0.50000
PI6	0.00000	0.39794	0.66836	0.00000	0.50000
PI7	0.00000	0.25000	0.70584	0.00000
PI8	0.00000	0.25000	0.78130	0.00000
PI9	0.00000	−0.00944	0.56656	0.00000	0.50000
PI10	0.00000	0.50944	0.56656	0.00000	0.50000
PI11	0.00000	−0.02099	0.69313	0.00000	0.50000
PI12	0.00000	0.52099	0.69313	0.00000	0.50000
MI2	0.00000	0.14048	0.79950	0.00000	0.50000
MI3	0.09485	0.30476	0.79950	0.00000	0.25000
MI4	−0.09485	0.30476	0.79950	0.00000	0.25000

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
PI1	0.01725	0.02145	0.00194	0.00000	0.00000	0.00000
PI2	0.02551	0.02663	0.00194	0.00000	0.00000	0.00000
PI3	0.02703	0.02007	0.00214	0.00000	0.00000	−0.00036
PI4	0.02703	0.02007	0.00214	0.00000	0.00000	0.00036
PI5	0.02647	0.01967	0.00214	0.00000	0.00000	0.00022
PI6	0.02647	0.01967	0.00214	0.00000	0.00000	−0.00022
PI7	0.01628	0.02084	0.00194	0.00000	0.00000	0.00000
PI8	0.02460	0.02607	0.00194	0.00000	0.00000	0.00000
PI9	0.05404	0.02128	0.00255	0.00000	0.00000	−0.00107
PI10	0.05404	0.02128	0.00255	0.00000	0.00000	0.00107
PI11	0.05591	0.02034	0.00261	0.00000	0.00000	0.00078
PI12	0.05591	0.02034	0.00261	0.00000	0.00000	−0.00078
MI2	0.19500	0.01947	0.00205	0.00000	0.00000	0.00008
MI3	0.05933	0.15515	0.00210	−0.07833	−0.00011	−0.00004
MI4	0.05933	0.15515	0.00210	0.07833	0.00011	−0.00004

Geometric parameters (Å, º) top

PI1—PI2	1.347	PI5—PI6	1.479
PI1—PI3	1.342	PI3—PI7	1.070
PI3—PI4	1.401	PI4—PI8	1.090
PI4—PI5	1.386	PI6—MI2	0.940

PI3—PI1—PI3	121.5	PI4—PI5—PI4	116.0
PI1—PI3—PI4	119.4	PI1—PI3—PI7	117.0
PI3—PI4—PI5	122.9	PI3—PI4—PI8	116.6
PI4—PI5—PI6	122.2	PI5—PI6—MI2	112.3

(100K) 4-methylpyridine-N-oxide top

Crystal data top

C₅D₄NO·(CD₃)	V = 2431.36 (8) Å³
M_r = 116	Z = 16
Orthorhombic, FDDD	Melting point: 463 K
Hall symbol: -F 2uv 2vw	Constant Wavelength Neutron radiation, λ = 1.225300 Å
a = 12.1382 (3) Å	T = 100 K
b = 10.2367 (2) Å	cylinder, ? × ? × ? mm
c = 19.5676 (3) Å

Data collection top

Home made powder diffractometer	Specimen mounting: vanadium
Radiation source: nuclear reactor, 3T2	2θ_min = −0.043°, 2θ_max = 125.407°, 2θ_step = 0.050°

Refinement top

R_p = 2.246	Profile function: pseudo-voigt
R_wp = 2.750	63 parameters
R_exp = 1.419	0 restraints
R_Bragg = 4.201
χ² = 3.725	Background function: FullProf Background function number
2079 data points

Crystal data top

C₅D₄NO·(CD₃)	V = 2431.36 (8) Å³
M_r = 116	Z = 16
Orthorhombic, FDDD	Constant Wavelength Neutron radiation, λ = 1.225300 Å
a = 12.1382 (3) Å	T = 100 K
b = 10.2367 (2) Å	cylinder, ? × ? × ? mm
c = 19.5676 (3) Å

Data collection top

Home made powder diffractometer	2θ_min = −0.043°, 2θ_max = 125.407°, 2θ_step = 0.050°
Specimen mounting: vanadium

Refinement top

R_p = 2.246	χ² = 3.725
R_wp = 2.750	2079 data points
R_exp = 1.419	63 parameters
R_Bragg = 4.201	0 restraints

Special details top

Geometry. Rigid body group non refined

Refinement. Two rigid-body groups (C5D7NO and CD3 methyl group) with TLS

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
PN1	0.62500	0.12500	0.31363	0.00000
PN2	0.62500	0.12500	0.24481	0.00000
PN3	0.54847	0.19307	0.34637	0.00000	0.50000
PN4	0.70153	0.05693	0.34638	0.00000	0.50000
PN5	0.54711	0.19428	0.41813	0.00000	0.50000
PN6	0.70289	0.05572	0.41813	0.00000	0.50000
PN7	0.62500	0.12500	0.45632	0.00000
PN8	0.62500	0.12500	0.53190	0.00000
PN9	0.48973	0.24531	0.31619	0.00000	0.50000
PN10	0.76027	0.00469	0.31620	0.00000	0.50000
PN11	0.48314	0.25118	0.44354	0.00000	0.50000
PN12	0.76686	−0.00118	0.44354	0.00000	0.50000
MN2	0.61868	0.21289	0.55022	0.00000	0.50000
MN3	0.56398	0.07456	0.55022	0.00000	0.50000
MN4	0.69235	0.08754	0.55022	0.00000	0.50000

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
PN1	0.00408	0.00513	0.00074	0.00011	0.00000	0.00000
PN2	0.00450	0.00785	0.00074	−0.00081	0.00000	0.00000
PN3	0.00493	0.00680	0.00092	0.00176	0.00009	0.00039
PN4	0.00493	0.00680	0.00092	0.00176	−0.00009	−0.00039
PN5	0.00493	0.00665	0.00093	0.00144	0.00028	−0.00004
PN6	0.00493	0.00665	0.00093	0.00144	−0.00028	0.00004
PN7	0.00403	0.00479	0.00074	−0.00070	0.00000	0.00000
PN8	0.00445	0.00752	0.00074	−0.00262	0.00000	0.00000
PN9	0.00706	0.01251	0.00131	0.00485	0.00003	0.00101
PN10	0.00706	0.01251	0.00131	0.00485	−0.00003	−0.00101
PN11	0.00727	0.01273	0.00137	0.00471	0.00062	−0.00034
PN12	0.00727	0.01273	0.00137	0.00471	−0.00062	0.00034
MN2	0.06011	0.00467	0.00085	0.00578	0.00003	−0.00007
MN3	0.02244	0.05765	0.00073	−0.03138	−0.00001	0.00000
MN4	0.01414	0.06932	0.00082	0.02591	−0.00002	0.00006

Geometric parameters (Å, º) top

PI1—PI2	1.347	PI5—PI6	1.479
PI1—PI3	1.342	PI3—PI7	1.070
PI3—PI4	1.401	PI4—PI8	1.090
PI4—PI5	1.386	PI6—MI2	0.980

PI3—PI1—PI3	121.5	PI4—PI5—PI4	116.0
PI1—PI3—PI4	119.4	PI1—PI3—PI7	117.0
PI3—PI4—PI5	122.9	PI3—PI4—PI8	116.6
PI4—PI5—PI6	122.2	PI5—PI6—MI2	112.9

(10K) 4-methylpyridine-N-oxide top

Crystal data top

C₅D₄NO·(CD₃)	V = 4673.61 (10) Å³
M_r = 116	Z = 32
Tetragonal, P4₁	Melting point: 463 K
Hall symbol: P 4w	Constant Wavelength Neutron Diffraction radiation, λ = 1.225300 Å
a = 15.41038 (19) Å	T = 10 K
c = 19.6800 (3) Å	cylinder, ? × ? × ? mm

Data collection top

Laboratoire Leon Brillouin diffractometer	Specimen mounting: vanadium
Radiation source: nuclear reactor, 3T2	2θ_min = −0.062°, 2θ_max = 125.388°, 2θ_step = 0.050°

Refinement top

R_p = 2.797	Profile function: pseudo-voigt
R_wp = 3.365	36 parameters
R_exp = 1.428	0 restraints
R_Bragg = 4.047
χ² = 5.523	Background function: FullProf Background function number
2079 data points

Crystal data top

C₅D₄NO·(CD₃)	V = 4673.61 (10) Å³
M_r = 116	Z = 32
Tetragonal, P4₁	Constant Wavelength Neutron Diffraction radiation, λ = 1.225300 Å
a = 15.41038 (19) Å	T = 10 K
c = 19.6800 (3) Å	cylinder, ? × ? × ? mm

Data collection top

Laboratoire Leon Brillouin diffractometer	2θ_min = −0.062°, 2θ_max = 125.388°, 2θ_step = 0.050°
Specimen mounting: vanadium

Refinement top

R_p = 2.797	χ² = 5.523
R_wp = 3.365	2079 data points
R_exp = 1.428	36 parameters
R_Bragg = 4.047	0 restraints

Special details top

Geometry. Rigid body group non refined

Refinement. 16 rigid-body groups (C5D7NO and CD3) with isotropic Bs & TLS

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

	x	y	z	U_iso*/U_eq
PI1	0.65709	0.84503	0.56893	0.00441*
PI2	0.66059	0.85044	0.50069	0.00588*
PI3	0.68840	0.77401	0.59990	0.00224*
PI4	0.62237	0.91077	0.60447	0.00224*
PI5	0.68487	0.76816	0.67090	0.00224*
PI6	0.61863	0.90537	0.67549	0.00224*
PI7	0.64984	0.83381	0.71042	0.00224*
PI8	0.64600	0.82787	0.78536	0.01103*
PI9	0.71501	0.72447	0.56805	0.01445*
PI10	0.59885	0.96508	0.57610	0.01445*
PI11	0.71116	0.70915	0.69359	0.01445*
PI12	0.58982	0.96047	0.70200	0.01445*
MI2	0.61945	0.88463	0.80743	0.00000
MI3	0.60720	0.77515	0.80172	0.00000
MI4	0.70827	0.81906	0.80703	0.00000
PJ1	0.91012	0.59303	0.06510	0.00441*
PJ2	0.91653	0.58600	−0.00292	0.00588*
PJ3	0.88430	0.52406	0.10153	0.00224*
PJ4	0.92969	0.66886	0.09497	0.00224*
PJ5	0.87756	0.53115	0.17232	0.00224*
PJ6	0.92310	0.67642	0.16574	0.00224*
PJ7	0.89683	0.60762	0.20614	0.00224*
PJ8	0.88979	0.61535	0.28084	0.01103*
PJ9	0.86990	0.46598	0.07401	0.01445*
PJ10	0.94975	0.72074	0.06247	0.01445*
PJ11	0.85631	0.47327	0.19958	0.01445*
PJ12	0.93972	0.73937	0.18753	0.01445*
MJ2	0.86939	0.55653	0.30360	0.00000
MJ3	0.94984	0.63213	0.30345	0.00000
MJ4	0.84451	0.66357	0.29537	0.00000
PK1	0.91210	0.84290	0.32425	0.00441*
PK2	0.91424	0.83679	0.25601	0.00588*
PK3	0.83520	0.84164	0.35628	0.00224*
PK4	0.98691	0.85011	0.35873	0.00224*
PK5	0.83273	0.84799	0.42728	0.00224*
PK6	0.98493	0.85648	0.42974	0.00224*
PK7	0.90766	0.85557	0.46574	0.00224*
PK8	0.90531	0.86228	0.54068	0.01103*
PK9	0.77855	0.83573	0.32524	0.01445*
PK10	1.04546	0.85063	0.32955	0.01445*
PK11	0.76866	0.84666	0.45086	0.01445*
PK12	1.04745	0.86222	0.45537	0.01445*
MK2	0.89872	0.80076	0.56407	0.00000
MK3	0.96261	0.89067	0.56036	0.00000
MK4	0.85273	0.90079	0.55769	0.00000
PL1	0.90415	0.84708	0.93959	0.00441*
PL2	0.90530	0.84062	1.00782	0.00588*
PL3	0.91160	0.77488	0.90188	0.00224*
PL4	0.89557	0.92558	0.91079	0.00224*
PL5	0.91042	0.78135	0.83086	0.00224*
PL6	0.89434	0.93255	0.83980	0.00224*
PL7	0.90174	0.86047	0.79811	0.00224*
PL8	0.90047	0.86756	0.72317	0.01103*
PL9	0.91819	0.71481	0.92860	0.01445*
PL10	0.88999	0.97995	0.94428	0.01445*
PL11	0.91669	0.72081	0.80254	0.01445*
PL12	0.88723	0.99775	0.81892	0.01445*
ML2	0.89789	0.80594	0.69948	0.00000
ML3	0.84609	0.90311	0.70566	0.00000
ML4	0.95641	0.89934	0.70429	0.00000
PM1	0.65259	0.58745	0.44163	0.00441*
PM2	0.65923	0.58914	0.50984	0.00588*
PM3	0.64893	0.51065	0.40957	0.00224*
PM4	0.64977	0.66260	0.40720	0.00224*
PM5	0.64202	0.50864	0.33858	0.00224*
PM6	0.64286	0.66108	0.33622	0.00224*
PM7	0.63882	0.58394	0.30019	0.00224*
PM8	0.63152	0.58208	0.22527	0.01103*
PM9	0.65154	0.45371	0.44056	0.01445*
PM10	0.65302	0.72103	0.43640	0.01445*
PM11	0.63927	0.44464	0.31498	0.01445*
PM12	0.64082	0.72387	0.31064	0.01445*
MM2	0.59136	0.53072	0.20831	0.00000
MM3	0.60469	0.64026	0.20584	0.00000
MM4	0.69266	0.57378	0.20160	0.00000
PN1	0.66532	0.84687	0.19799	0.00441*
PN2	0.66450	0.85046	0.26636	0.00588*
PN3	0.73555	0.81521	0.16615	0.00224*
PN4	0.59589	0.87503	0.16320	0.00224*
PN5	0.73664	0.81138	0.09502	0.00224*
PN6	0.59652	0.87139	0.09205	0.00224*
PN7	0.66702	0.83942	0.05624	0.00224*
PN8	0.66793	0.83548	−0.01884	0.01103*
PN9	0.78822	0.79409	0.19744	0.01445*
PN10	0.54250	0.89932	0.19224	0.01445*
PN11	0.79520	0.78513	0.07161	0.01445*
PN12	0.53855	0.89504	0.06617	0.01445*
MN2	0.71334	0.87937	−0.04002	0.00000
MN3	0.68452	0.77288	−0.03680	0.00000
MN4	0.60664	0.85103	−0.03989	0.00000
PO1	0.59572	0.09011	0.45173	0.00441*
PO2	0.58956	0.08190	0.51968	0.00588*
PO3	0.63162	0.02574	0.41537	0.00224*
PO4	0.56583	0.16249	0.42185	0.00224*
PO5	0.63815	0.03407	0.34465	0.00224*
PO6	0.57214	0.17127	0.35115	0.00224*
PO7	0.60851	0.10715	0.31083	0.00224*
PO8	0.61528	0.11618	0.23620	0.01103*
PO9	0.65388	−0.02980	0.44289	0.01445*
PO10	0.53813	0.21079	0.45429	0.01445*
PO11	0.66782	−0.02002	0.31745	0.01445*
PO12	0.54692	0.23128	0.32936	0.01445*
MO2	0.55502	0.13274	0.21386	0.00000
MO3	0.66005	0.16508	0.22210	0.00000
MO4	0.63620	0.05794	0.21283	0.00000
PP1	0.65503	0.59892	0.82756	0.00441*
PP2	0.66032	0.59750	0.75927	0.00588*
PP3	0.57676	0.60449	0.85719	0.00224*
PP4	0.72814	0.59472	0.86450	0.00224*
PP5	0.57100	0.60598	0.92824	0.00224*
PP6	0.72288	0.59618	0.93558	0.00224*
PP7	0.64405	0.60185	0.96916	0.00224*
PP8	0.63824	0.60341	1.04416	0.01103*
PP9	0.52162	0.60758	0.82428	0.01445*
PP10	0.78794	0.59039	0.83715	0.01445*
PP11	0.50594	0.61057	0.94980	0.01445*
PP12	0.78412	0.59261	0.96325	0.01445*
MP2	0.70022	0.60778	1.06718	0.00000
MP3	0.60160	0.65694	1.06187	0.00000
MP4	0.60833	0.54677	1.06359	0.00000

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
MI2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MI3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MI4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
MJ2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MJ3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MJ4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
MK2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MK3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MK4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
ML2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
ML3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
ML4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
MM2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MM3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MM4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
MN2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MN3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MN4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
MO2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MO3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MO4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000
MP2	0.01211	0.00142	0.00005	0.00323	−0.00001	0.00002
MP3	0.01003	0.00257	0.00005	−0.00369	−0.00001	−0.00002
MP4	0.00472	0.00884	0.00005	0.00047	0.00002	0.00000

Geometric parameters (Å, º) top

PI1—PI2	1.347	PI5—PI6	1.479
PI1—PI3	1.342	PI3—PI7	1.070
PI3—PI4	1.401	PI4—PI8	1.090
PI4—PI5	1.386	PI6—MI2	1.070

PI3—PI1—PI3	121.5	PI4—PI5—PI4	116.0
PI1—PI3—PI4	119.4	PI1—PI3—PI7	117.0
PI3—PI4—PI5	122.9	PI3—PI4—PI8	116.6
PI4—PI5—PI6	122.2	PI5—PI6—MI2	113.0

Experimental details

	(250K)	(100K)	(10K)
Crystal data
Chemical formula	C₅D₄NO·(CD₃)	C₅D₄NO·(CD₃)	C₅D₄NO·(CD₃)
M_r	116	116	116
Crystal system, space group	Tetragonal, I4₁/amd	Orthorhombic, FDDD	Tetragonal, P4₁
Temperature (K)	250	100	10
a, b, c (Å)	7.9411 (2), 7.9411 (2), 19.6002 (5)	12.1382 (3), 10.2367 (2), 19.5676 (3)	15.41038 (19), 15.41038 (19), 19.6800 (3)
α, β, γ (°)	90, 90, 90	90, 90, 90	90, 90, 90
V (Å³)	1236.03 (6)	2431.36 (8)	4673.61 (10)
Z	8	16	32
Radiation type	Constant Wavelength neutron, λ = 1.225300 Å	Constant Wavelength Neutron, λ = 1.225300 Å	Constant Wavelength Neutron Diffraction, λ = 1.225300 Å
Specimen shape, size (mm)	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?	Cylinder, ? × ? × ?

Data collection
Diffractometer	Home made powder diffractometer	Home made powder diffractometer	Laboratoire Leon Brillouin
Specimen mounting	Vanadium	Vanadium	Vanadium
Data collection mode	?	?	?
Scan method	?	?	?
2θ values (°)	2θ_min = −0.026 2θ_max = 125.424 2θ_step = 0.050	2θ_min = −0.043 2θ_max = 125.407 2θ_step = 0.050	2θ_min = −0.062 2θ_max = 125.388 2θ_step = 0.050

Refinement
R factors and goodness of fit	R_p = 2.045, R_wp = 2.506, R_exp = 1.501, R_Bragg = 4.610, χ² = 2.789	R_p = 2.246, R_wp = 2.750, R_exp = 1.419, R_Bragg = 4.201, χ² = 3.725	R_p = 2.797, R_wp = 3.365, R_exp = 1.428, R_Bragg = 4.047, χ² = 5.523
No. of data points	2279	2079	2079
No. of parameters	49	63	36

Computer programs: FULLPROF, DIAMOND.

Selected geometric parameters (Å, º) for (250K) top

PI1—PI2	1.347	PI5—PI6	1.479
PI1—PI3	1.342	PI3—PI7	1.070
PI3—PI4	1.401	PI4—PI8	1.090
PI4—PI5	1.386	PI6—MI2	0.940

PI3—PI1—PI3	121.5	PI4—PI5—PI4	116.0
PI1—PI3—PI4	119.4	PI1—PI3—PI7	117.0
PI3—PI4—PI5	122.9	PI3—PI4—PI8	116.6
PI4—PI5—PI6	122.2	PI5—PI6—MI2	112.3

Selected geometric parameters (Å, º) for (100K) top

PI1—PI2	1.347	PI5—PI6	1.479
PI1—PI3	1.342	PI3—PI7	1.070
PI3—PI4	1.401	PI4—PI8	1.090
PI4—PI5	1.386	PI6—MI2	0.980

PI3—PI1—PI3	121.5	PI4—PI5—PI4	116.0
PI1—PI3—PI4	119.4	PI1—PI3—PI7	117.0
PI3—PI4—PI5	122.9	PI3—PI4—PI8	116.6
PI4—PI5—PI6	122.2	PI5—PI6—MI2	112.9

Selected geometric parameters (Å, º) for (10K) top

PI1—PI2	1.347	PI5—PI6	1.479
PI1—PI3	1.342	PI3—PI7	1.070
PI3—PI4	1.401	PI4—PI8	1.090
PI4—PI5	1.386	PI6—MI2	1.070

PI3—PI1—PI3	121.5	PI4—PI5—PI4	116.0
PI1—PI3—PI4	119.4	PI1—PI3—PI7	117.0
PI3—PI4—PI5	122.9	PI3—PI4—PI8	116.6
PI4—PI5—PI6	122.2	PI5—PI6—MI2	113.0

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