Download citation
Download citation
link to html
The title compound, C12H21NO3, crystallizes in two polymorphic forms, viz. the tetra­gonal form described here and the monoclinic form described previously [Foces-Foces, López-Rodríguez, Pérez, Martín & Pérez-Hernández (2007). Cryst. Growth Des. 7, 905-911]. The differences in the conformations of the hydroxy­methyl and methylaminocarbonyl substituents have important consequences in the hydrogen-bond inter­action motifs and, therefore, in the packing arrangements. These forms are concomitant polymorphs with melting points differing by 3 K.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010706862X/tr3030sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010706862X/tr3030Isup2.hkl
Contains datablock I

CCDC reference: 681567

Comment top

The structures of ten 7,7-dialkyl-5-hydroxymethyl-6-oxabicyclo[3.2.1] octane-1-carboxylic acid amide derivatives, including the monoclinic polymorph (I), have been recently determined (Foces-Foces et al., 2007). All the reported compounds crystallized as racemates, and the conformations of the hydroxymethyl and N-alkylamide groups were found to be closely related to the type of hydrogen interactions in which they were involved. As part of our structural studies on the inclusion of water molecules into the hydrogen-bond pattern of condensed organic materials, new crystallization attempts of N-alkylamide derivatives in saturated aqueous solution of tetrachloride/n-hexane were undertaken. In the case of 7,7-dimethyl-5-hydroxymethyl-6-oxabicyclo [3.2.1]-1-carboxylic acid methylamide, crystals with different habits (plates and needles in a small quantity) were observed in the same batch suggesting the presence of concomitant polymorphs (Bernstein, 2002).

The plates of (I) belong to the centrosymmetric monoclinic P21/c group, while the needles crystallize in the noncentrosymmetric tetragonal P41 or the enantiomeric P43 space group. However, these crystals, which were separated manually, did not show optical activity, suggesting spontaneous resolution (50:50 mixture of pure enantiomers) of the racemic sample. Several new crystallization attempts were performed under similar conditions and only the monoclinic phase was obtained. This behaviour seems to be not uncommon and has been previously (Dunitz & Bernstein, 1995) and recently reported (Lennartsson et al., 2007). In the methylamide derivatives with ethyl as the alkyl group and with propyl instead of methyl substituents, crystals slightly different in shape appear in the same batch, but all of them were confirmed to belong to the form previously described.

Of the two possible enantiomeric space groups P41 or P43 for the tetragonal form (II), the former, consistent with the 1R,5R enantiomer (negative value for the C1—C2—C3—C4 torsion angle), was selected (Fig. 1) since the absolute structure cannot be determined reliably. In both polymorphic forms, the bicyclic core is rather rigid, and the features distinguishing the forms concern the conformations of the hydroxymethyl and methylamide substituents, which results in a different hydrogen-bonding patterns. In the monoclinic form, having Z' = 2, the hydroxyl group is disordered over two positions (A and B with occupancies of 2:1) adopting, for the same enantiomer (1R,5R), the -gauche/gauche conformations with respect to ether bridge [O1—C1—C2—O2A/B= -61.4 (3)/49.0 (4) and 63.3 (3)/-48.4 (4)° for the two independent molecules]. In the tetragonal form (Table 1 and Fig. 1) the +gauche/-gauche conformation is observed (1R,5R enantiomer), although with significant differences in the amide disposition [C4—C5—C7—O3= -53.2 (2) and 53.2 (2)° versus -68.6 (4)° in (I) and in (II), respectively].

The presence of the two concomitant polymorphs, with a donor/acceptor ratio of less than 1 for OH, –O– and –CONHCH3 groups, can be attributed to the different hydrogen-bonding possibilities. In the reported N-alkylamide derivatives (Foces-Foces et al., 2007), the following three types of paired hydrogen interactions were related to the conformations of the hydroxy and methylamide substituents: (1) OH···OC and NH···Oether; (2) OH···Oether and NH···OC; and (3) OH···OC and NH···OH. In the tetragonal form (II), the N—H···OH bond connects molecules along the fourfold screw axis into one-dimensional frameworks [C(8) graph-set notation (Bernstein et al., 1995); Fig. 2a and Table 2]. The hydroxy group acts as both donor to the carbonyl group and as acceptor of a hydrogen bond from the amide as in type 3, while the ether atom O1 is only involved in a C—H···O interaction (Table 2). These homochiral chains are then assembled along the a and b axes through OH···OC and C—H···Oether bonds into a three-dimensional network (Fig. 2b). However, in the monoclinic form (I), type 1 is observed and the amide group is hydrogen bonded to the ether bridge O1, forming heterochiral chains with a C(6) graph-set motif. Despite the disorder of the hydroxy group, the hydrogen-bonding pattern is not affected, since in each conformation the hydroxy group is hydrogen-bonded to the same carbonyl group. The combination of these interactions results in a two-dimensional network (Fig. 3). The differences in the crystal structures of the two polymorphs are reflected in the simulated powder diffraction spectra (Spek, 2003) shown in Fig. 4.

The proposed rule correlating the molecular conformation of the substituents and the pattern of strong hydrogen interactions in the racemic derivatives (Foces-Foces et al., 2007) is fulfilled by this polymorph. However, the presence of only one enantiomer in the structure drastically affects the crystal packing, since the dimer or synthon formed by centrosymmetrically related molecules, common to the most populated type 3, is absent.

Related literature top

For related literature, see: Bernstein (2002); Bernstein et al. (1995); Dunitz & Bernstein (1995); Foces-Foces, López-Rodríguez, Pérez, Martín & Pérez-Hernández (2007); Lennartsson et al. (2007); Spek (2003).

Experimental top

The synthesis of the title compound has been recently reported (Foces-Foces et al., 2007) and crystals were obtained upon crystallization from a saturated aqueous solution of tetrachloride/n-hexane (50%). Crystals of the two morphologies were obtained in the same batch, viz. plates (monoclinic form with m.p. 451 K, previously reported) and needles in a small quantity (m.p. 454 K) corresponding to the present tetragonal form (II). The needles were separated manually and did no show optical activity in a chloroform solution (Perkin–Elmer 241). No structural phase transition was detected when cooling the sample from room temperature to 170 K.

Refinement top

Friedel pairs were merged during the final cycles of refinements due to the absence of significant anomalous dispersion effects. All H atoms were located in difference Fourier maps and subsequently allowed to refine as riding on their respective C, N and O atoms [C—H = 0.98 (CH3) or 0.99 Å (CH2), N—H = 0.88 Å and O—H = 0.84 Å, with Uiso(H) = 1.2Ueq(C,N) and 1.5Ueq(O) please check change].

Computing details top

Data collection: Collect (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: WinGX (Farrugia, 1999), PLATON (Spek, 2003) and Mercury (Macrae et al., 2006).

Figures top
[Figure 1] Fig. 1. The molecular structure of (II), with 30% probability displacement ellipsoids.
[Figure 2] Fig. 2. (a) The homochiral C(8) chain, along the c axis, resulting from the linkage of the molecules via N—H···OH hydrogen bonds (dotted lines). (b) The three-dimensional hydrogen-bonded framework viewed down c and showing the OH···OC hydrogen bonds responsible for connecting the chains. H atoms not involved in the N—H···OH or O—H···OC hydrogen interactions have been omitted for clarity. [Symmetry codes: (i) x, y, z; (ii) -y + 1, x, z + 1/4; (iii) -x + 1, -y + 1, z + 1/2; (iv) y, -x + 1, z - 1/4; (v) x - 1, y, z; (vi) -y + 1, x - 1, z + 1/4.]
[Figure 3] Fig. 3. The two-dimensional structure in the monoclinic polymorph (I), formed by three heterochiral C(6) chains along the a axis (NH···Oether contacts) connected by OH···OC bonds. Only the major component of the disorder of the hydroxyl group has been maintained. H atoms not involved in the hydrogen interactions have been omitted for clarity.
[Figure 4] Fig. 4. Simulated powder diffraction spectra: (I) monoclinic phase and (II) the present tetragonal phase.
5-Hydroxymethyl-7,7,N-trimethyl-6-oxabicyclo[3.2.1]octane-1-carboxamide top
Crystal data top
C12H21NO3Dx = 1.263 Mg m3
Mr = 227.30Melting point: 454 K
Tetragonal, P41Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 4wCell parameters from 2593 reflections
a = 8.2616 (18) Åθ = 2.5–27.5°
c = 17.517 (4) ŵ = 0.09 mm1
V = 1195.6 (4) Å3T = 170 K
Z = 4Needle, colourless
F(000) = 4960.60 × 0.12 × 0.12 mm
Data collection top
Nonius KappaCCD area-detector
diffractometer
1282 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.032
Horizontally mounted graphite crystal monochromatorθmax = 27.5°, θmin = 2.5°
Detector resolution: 9 pixels mm-1h = 1010
ϕ and ω scansk = 1010
2593 measured reflectionsl = 2222
1412 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.050Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.142H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0887P)2 + 0.4581P]
where P = (Fo2 + 2Fc2)/3
1412 reflections(Δ/σ)max = 0.001
145 parametersΔρmax = 0.38 e Å3
1 restraintΔρmin = 0.33 e Å3
Crystal data top
C12H21NO3Z = 4
Mr = 227.30Mo Kα radiation
Tetragonal, P41µ = 0.09 mm1
a = 8.2616 (18) ÅT = 170 K
c = 17.517 (4) Å0.60 × 0.12 × 0.12 mm
V = 1195.6 (4) Å3
Data collection top
Nonius KappaCCD area-detector
diffractometer
1282 reflections with I > 2σ(I)
2593 measured reflectionsRint = 0.032
1412 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0501 restraint
wR(F2) = 0.142H-atom parameters constrained
S = 1.00Δρmax = 0.38 e Å3
1412 reflectionsΔρmin = 0.33 e Å3
145 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
xyzUiso*/Ueq
O10.7498 (3)0.4425 (3)0.23964 (13)0.0176 (5)
O20.4398 (3)0.3520 (3)0.30670 (14)0.0218 (5)
H20.35440.35250.33270.033*
O31.1590 (3)0.3494 (3)0.39400 (14)0.0261 (6)
N10.9553 (3)0.3761 (4)0.47812 (16)0.0193 (6)
H10.85630.41130.48620.023*
C10.6639 (4)0.5433 (4)0.29450 (18)0.0161 (6)
C20.7056 (4)0.7204 (4)0.2773 (2)0.0254 (8)
H2A0.66310.79070.31840.031*
H2B0.65440.75350.22870.031*
C30.8901 (4)0.7402 (4)0.2715 (2)0.0292 (8)
H3A0.91740.85640.27640.035*
H3B0.92590.70390.22030.035*
C40.9840 (5)0.6441 (4)0.3328 (2)0.0240 (8)
H4A1.09760.63130.31590.029*
H4B0.98480.70730.38080.029*
C50.9122 (4)0.4750 (4)0.34908 (17)0.0159 (6)
C60.7356 (4)0.4968 (4)0.37123 (18)0.0161 (6)
H6A0.68810.39510.39100.019*
H6B0.72170.58390.40950.019*
C71.0197 (4)0.3930 (4)0.40864 (19)0.0168 (6)
C80.4824 (4)0.5144 (4)0.28705 (19)0.0201 (7)
H8A0.42390.59040.32090.024*
H8B0.44850.53660.23390.024*
C90.8925 (4)0.3708 (4)0.27517 (19)0.0173 (6)
C101.0321 (4)0.3769 (6)0.2181 (2)0.0302 (9)
H10A1.12920.33010.24140.036*
H10B1.05340.48960.20390.036*
H10C1.00310.31490.17240.036*
C110.8543 (5)0.1942 (4)0.2934 (2)0.0290 (8)
H11A0.94850.14380.31780.035*
H11B0.82870.13630.24610.035*
H11C0.76140.18900.32810.035*
C121.0435 (4)0.3013 (5)0.5409 (2)0.0254 (8)
H12A0.97530.30040.58670.031*
H12B1.14230.36330.55120.031*
H12C1.07230.19000.52710.031*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0161 (11)0.0202 (12)0.0165 (10)0.0035 (9)0.0008 (9)0.0037 (9)
O20.0149 (11)0.0224 (12)0.0281 (13)0.0019 (9)0.0038 (9)0.0011 (10)
O30.0148 (12)0.0369 (15)0.0265 (13)0.0042 (11)0.0033 (9)0.0023 (11)
N10.0132 (13)0.0241 (15)0.0207 (13)0.0037 (11)0.0009 (11)0.0028 (11)
C10.0159 (14)0.0150 (14)0.0175 (14)0.0022 (12)0.0009 (12)0.0029 (11)
C20.0217 (17)0.0172 (17)0.037 (2)0.0010 (13)0.0034 (15)0.0027 (14)
C30.0245 (18)0.0170 (17)0.046 (2)0.0058 (14)0.0053 (17)0.0104 (16)
C40.0216 (17)0.0157 (16)0.035 (2)0.0034 (14)0.0036 (14)0.0019 (13)
C50.0148 (15)0.0150 (15)0.0178 (14)0.0003 (12)0.0017 (12)0.0008 (11)
C60.0135 (15)0.0171 (15)0.0177 (14)0.0020 (12)0.0005 (11)0.0018 (12)
C70.0126 (14)0.0178 (16)0.0200 (15)0.0005 (12)0.0019 (12)0.0005 (13)
C80.0160 (16)0.0205 (17)0.0238 (16)0.0029 (13)0.0027 (13)0.0019 (13)
C90.0137 (14)0.0208 (16)0.0173 (14)0.0066 (12)0.0024 (12)0.0022 (12)
C100.0197 (18)0.050 (2)0.0212 (17)0.0117 (16)0.0045 (14)0.0047 (16)
C110.0318 (19)0.0172 (17)0.038 (2)0.0059 (14)0.0094 (16)0.0069 (15)
C120.0242 (18)0.0286 (19)0.0235 (17)0.0006 (15)0.0036 (13)0.0075 (14)
Geometric parameters (Å, º) top
O1—C11.456 (4)C4—H4B0.9900
O1—C91.459 (4)C5—C61.520 (4)
O2—C81.429 (4)C5—C71.529 (4)
O2—H20.8400C5—C91.564 (4)
O3—C71.233 (4)C6—H6A0.9900
N1—C71.335 (4)C6—H6B0.9900
N1—C121.457 (4)C8—H8A0.9900
N1—H10.8800C8—H8B0.9900
C1—C61.518 (4)C9—C111.527 (5)
C1—C81.524 (4)C9—C101.527 (5)
C1—C21.533 (5)C10—H10A0.9800
C2—C31.537 (5)C10—H10B0.9800
C2—H2A0.9900C10—H10C0.9800
C2—H2B0.9900C11—H11A0.9800
C3—C41.544 (5)C11—H11B0.9800
C3—H3A0.9900C11—H11C0.9800
C3—H3B0.9900C12—H12A0.9800
C4—C51.544 (5)C12—H12B0.9800
C4—H4A0.9900C12—H12C0.9800
C1—O1—C9110.2 (2)C5—C6—H6A111.7
C8—O2—H2109.5C1—C6—H6B111.7
C7—N1—C12122.2 (3)C5—C6—H6B111.7
C7—N1—H1118.9H6A—C6—H6B109.5
C12—N1—H1118.9O3—C7—N1122.1 (3)
O1—C1—C6104.5 (2)O3—C7—C5122.0 (3)
O1—C1—C8109.5 (2)N1—C7—C5115.9 (3)
C6—C1—C8114.8 (3)O2—C8—C1111.6 (3)
O1—C1—C2107.8 (3)O2—C8—H8A109.3
C6—C1—C2109.1 (3)C1—C8—H8A109.3
C8—C1—C2110.7 (3)O2—C8—H8B109.3
C1—C2—C3109.7 (3)C1—C8—H8B109.3
C1—C2—H2A109.7H8A—C8—H8B108.0
C3—C2—H2A109.7O1—C9—C11108.1 (3)
C1—C2—H2B109.7O1—C9—C10108.5 (3)
C3—C2—H2B109.7C11—C9—C10109.0 (3)
H2A—C2—H2B108.2O1—C9—C5102.3 (2)
C2—C3—C4113.4 (3)C11—C9—C5112.0 (3)
C2—C3—H3A108.9C10—C9—C5116.4 (3)
C4—C3—H3A108.9C9—C10—H10A109.5
C2—C3—H3B108.9C9—C10—H10B109.5
C4—C3—H3B108.9H10A—C10—H10B109.5
H3A—C3—H3B107.7C9—C10—H10C109.5
C5—C4—C3113.7 (3)H10A—C10—H10C109.5
C5—C4—H4A108.8H10B—C10—H10C109.5
C3—C4—H4A108.8C9—C11—H11A109.5
C5—C4—H4B108.8C9—C11—H11B109.5
C3—C4—H4B108.8H11A—C11—H11B109.5
H4A—C4—H4B107.7C9—C11—H11C109.5
C6—C5—C7115.8 (3)H11A—C11—H11C109.5
C6—C5—C4108.0 (3)H11B—C11—H11C109.5
C7—C5—C4107.7 (3)N1—C12—H12A109.5
C6—C5—C9100.2 (2)N1—C12—H12B109.5
C7—C5—C9112.4 (3)H12A—C12—H12B109.5
C4—C5—C9112.7 (3)N1—C12—H12C109.5
C1—C6—C5100.3 (3)H12A—C12—H12C109.5
C1—C6—H6A111.7H12B—C12—H12C109.5
C9—O1—C1—C614.1 (3)C1—C2—C3—C441.3 (4)
C9—O1—C1—C8137.6 (3)O1—C1—C8—O264.3 (3)
C9—O1—C1—C2101.9 (3)C4—C5—C7—O368.6 (4)
O1—C1—C2—C350.5 (4)C4—C5—C7—N1109.3 (3)
C6—C1—C2—C362.4 (4)C12—N1—C7—C5179.5 (3)
C8—C1—C2—C3170.3 (3)C9—C5—C7—O356.1 (4)
C2—C3—C4—C539.5 (5)C6—C1—C8—O252.8 (4)
C3—C4—C5—C655.9 (4)C2—C1—C8—O2177.0 (3)
C3—C4—C5—C7178.4 (3)C1—O1—C9—C11103.0 (3)
C3—C4—C5—C953.8 (4)C1—O1—C9—C10139.0 (3)
O1—C1—C6—C538.3 (3)C1—O1—C9—C515.4 (3)
C8—C1—C6—C5158.2 (3)C6—C5—C9—O138.5 (3)
C2—C1—C6—C576.9 (3)C7—C5—C9—O1162.1 (3)
C7—C5—C6—C1167.7 (3)C4—C5—C9—O176.0 (3)
C4—C5—C6—C171.4 (3)C6—C5—C9—C1177.0 (3)
C9—C5—C6—C146.6 (3)C7—C5—C9—C1146.5 (4)
C12—N1—C7—O31.6 (5)C4—C5—C9—C11168.5 (3)
C6—C5—C7—O3170.4 (3)C6—C5—C9—C10156.7 (3)
C6—C5—C7—N111.7 (4)C7—C5—C9—C1079.8 (4)
C9—C5—C7—N1126.0 (3)C4—C5—C9—C1042.2 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O3i0.841.942.779 (3)179
N1—H1···O2ii0.882.132.936 (4)152
C6—H6B···O1ii0.992.393.292 (4)152
Symmetry codes: (i) x1, y, z; (ii) y+1, x, z+1/4.

Experimental details

Crystal data
Chemical formulaC12H21NO3
Mr227.30
Crystal system, space groupTetragonal, P41
Temperature (K)170
a, c (Å)8.2616 (18), 17.517 (4)
V3)1195.6 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.60 × 0.12 × 0.12
Data collection
DiffractometerNonius KappaCCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2593, 1412, 1282
Rint0.032
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.050, 0.142, 1.00
No. of reflections1412
No. of parameters145
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.38, 0.33

Computer programs: Collect (Nonius, 2000), HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), WinGX (Farrugia, 1999), PLATON (Spek, 2003) and Mercury (Macrae et al., 2006).

Selected torsion angles (º) top
C1—C2—C3—C441.3 (4)C4—C5—C7—N1109.3 (3)
O1—C1—C8—O264.3 (3)C12—N1—C7—C5179.5 (3)
C4—C5—C7—O368.6 (4)C9—C5—C7—O356.1 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O3i0.841.942.779 (3)179
N1—H1···O2ii0.882.132.936 (4)152
C6—H6B···O1ii0.992.393.292 (4)152
Symmetry codes: (i) x1, y, z; (ii) y+1, x, z+1/4.
 

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds