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The structures of two distinct polymorphic forms of N-(2,6-difluoro­phen­yl)formamide, C7H5F2NO, have been studied using single crystals obtained under different crystallizing conditions. The two forms crystallize in different space groups, viz. form (Ia) in the ortho­rhom­bic Pbca and form (Ib) in the monoclinic P21 space group. Each polymorph crystallizes with one complete mol­ecule in the asymmetric unit and they have a similar mol­ecular geometry, showing a trans conformation with the formamide group being out of the plane of the aromatic ring. The packing arrangements of the two polymorphs are quite different, with form (Ia) having mol­ecules that are stacked in an alternating arrangement, linked into chains of N—H...O hydrogen bonds along the crystallographic a direction, while form (Ib) has its N—H...O hydrogen-bonded mol­ecules stacked in a linear fashion. A theoretical study of the two structures allows information to be gained regarding other contributing inter­actions, such as π–π and weak C—H...F, in their crystal structures.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109032004/gz3168sup1.cif
Contains datablocks global, Ia, Ib

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270109032004/gz3168Iasup2.hkl
Contains datablock Ia

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270109032004/gz3168Ibsup3.hkl
Contains datablock Ib

CCDC references: 749727; 749728

Comment top

The use of fluorine atoms or the induction of fluorine-containing moieties into organic compounds has been shown to be useful in modulating physical, chemical and biological properties of target compounds (Thayer, 2006; Zheng et al., 2007; Ravikumar et al., 2003). Formamides have also been used as simple theoretical and experimental models for important chemical and biological compounds as was mentioned in our previous publications (Omondi et al., 2005, 2008; Omondi, Levendis et al., 2009 and references therein); and those with at least a carbon–fluorine bond would probably be just as useful, if not more useful, in the sense that they fall into the category of organic compounds that are commonly found in pharmaceuticals and agrochemicals (Thayer, 2006).

The primary molecular packing of formamides is dominated by N—H···O hydrogen bonds (Ferguson et al., 1998; Boeyens et al., 1988; Godwa et al., 2000). As a part of the study on polymorphism and phase transformations in 2,6-disubstituted N-arylformamides (Omondi et al., 2005) in which the effect of chloromethyl exchange and the role of weak interactions on their structural and thermal properties was investigated, N-(2,6-difluorophenyl)formamide [(I) in the scheme] was also found to exist in two structural phases [forms (Ia) and (Ib)] (Fig. 1) similar to those of 2,6-dichloro-N-phenylformamide [(II) in the scheme] and 2-chloro-6-methyl-N-phenylformamide [(III) in the scheme] (Omondi et al., 2005). The crystals of the two forms of compounds (II) and (III) were obtained at different temperatures, orthorhombic form (IIa) and (IIIa) at room temperature from solution and monoclinic form (IIb) and (IIIb) at high temperature by sublimation. Recently, we have also reported on the crystal structure of 2,6-dibromo-N-phenylformamide (Omondi, Lemmerer et al., 2009) which forms hydrogen-bonded chains similar to forms (IIb) and (IIIb) (Omondi et al., 2005), compound (Ib) in this report and 2,6-dimethyl-N-phenylformamide (Omondi et al., 2005). In a related study, 2,6-disubstituted-N-phenylthioamides (Omondi, Lemmerer et al., 2009) were found to exist in only one known phase, but adopted a cis conformation, different from that of the 2,6-disubstituted-N-phenylformamides.

An overlay of the two structures (Ia) and (Ib) (Fig. 2) reveals similar conformations for the two polymorphic forms. Only one case, that of N-phenylformamide, is known to exist as a cis- and trans-conformer in one crystal (Omondi et al., 2008). Thioacetanilide (Michta et al., 2008) was also found to have four independent molecules, all with a trans conformation, in the asymmetric unit. The angle between the planes defined by the aryl ring C1–C6 and the formamide group C1—N1—C7—O1 is larger in form (Ia) [60.2 (2)°] compared with form (Ib) [56.7 (3)°]. This is different from what has been observed in the previously reported two forms of compounds (II) and (III) (Omondi et al., 2005) and also for the two forms of N-2,6-dichloroacetanilide (Nagarajan et al., 1986), where the structures of crystals of 'form a' have a lower value of this torsion angle compared with those of 'form b'. Bond distances and angles (Tables 1 and 3) for both polymorphs are comparable with those of similar structures from the literature (Omondi et al., 2005 and references therein).

A comparison of the cell parameters of form (Ia) with the room-temperature orthorhombic phases of (II) and (III) [(IIa) and (IIIa)] reveals that the three compounds are isostructural and isomorphous with variations in the cell dimensions. The three structures have similar packing patterns. However, compounds (Ib), (IIb) and (IIIb) are not isostructural. Hydrogen-bonding patterns for the two polymorphic forms are shown in Figs. 3, 4, 6 and 7. The hydrogen-bonding distances and angles are given in Tables 2 and 4.

In the crystal, (Ia) has molecules linked by the N—H···O hydrogen bonds forming chains of molecules related by a glide plane in the crystallographic a direction. This results in the formamide molecules pointing in alternating directions (Fig. 3). Adjacent N—H···O hydrogen-bonded chains are held together through ππ interactions [Cg···Cg(-x + 2, -y + 1, -z + 1) = 3.903 (5) Å]. Joining of molecules by the N—H···O and ππ intermolecular interactions results in (010) sheets. Neighbouring sheets interact with each other through very weak C—H···F [H3···F2(-x + 3/2, y - 1/2, z) = 2.685 (1) Å] interactions (Fig. 4).

The crystals of form (Ib) were found to exist in the batch of crystals of 2,6-diflouro-N-phenylthioamide. Since 2,6-diflouro-N-phenylformamide is a starting material in the synthesis of 2,6-difluoro-N-phenylthioamide, it was assumed that unconverted 2,6-difluoro-N-phenylformamide from the reaction crystallized out under the influence of 2,6-difluoro-N-phenylthioamide, thereby obtaining (Ib). Attempts to grow crystals of (Ib) under controlled conditions were not successful as only the starting crystals of 2,6-difluoro-N-phenylformamide and 2,6-difluoro-N-phenylthioamide were obtained in their original forms. Attempts to convert (Ia) to (Ib) by sublimation of a powder of (Ia) in a similar manner to converting (IIa) and (IIIa) to (IIb) and (IIIb), respectively, were also unsuccessful. Due to limited amounts of (Ib), further studies (thermal and crystallographic) were not possible. Fig. 5 shows crystals of (Ib) in a batch of crystals of 2,6-difluoro-N-phenylthioamide.

Hydrogen-bonded chains in compound (Ib) are very similar to those of (IIb) and (IIIb) (Omondi et al., 2005). In these structures, the molecules are stacked with the aryl rings linearly arranged on top of one another and related by translation along a short crystallographic axis [the a axis for (Ib) and (IIb) and b axis for (IIIb)]. This results in the molecules being parallel to each other, forming chains through N—H···O hydrogen bonding along the crystallographic a direction (Fig. 6). Neighbouring N—H···O hydrogen-bonded chains in (Ib) are further connected through C—H···F intermolecular interactions [F2···H5(-x + 2, y + 1/2, -z + 2) = 2.647 (2) Å, F1···H3(x + 1, y, z) = 2.446 (2) Å] (Fig. 7). The second C—H···F interaction in (Ib) is shorter [2.446 (2) Å] than the lower limits set by Rowland & Taylor (1996) at 2.54 Å for normalized hydrogen positions. This would be an indication that the interaction is only secondary and therefore exists as a result of the close proximity of neighbouring molecules caused by the N—H···O, the longer C—H···F, and possibly a C—H···π, intermolecular interactions [C2—F1···π (-x + 1, y + 1/2, -z + 1), C2···π = 3.825 (2) Å and C2—F1···π = 143°].

The stability of the two polymorphs was assessed on the basis of the different intermolecular interactions involved in their crystal packing. Estimation and description of lattice energies by summation of potential energies between interacting atoms (or atom–atom interaction energies) were carried out using the ZipOpec module of the OPIX program suite (Gavezzotti, 2003) described by the UNI force field (Filippini & Gavezzotti, 1994) in a similar manner as was done for (II) and (III) (Omondi et al., 2005). Values of -91.3 and -89.9 kJ mol-1 were obtained for the lattice energies of forms (Ia) and (Ib), respectively.

In addition to lattice energies, ZipOpec calculates molecule–molecule interaction energies to identify which molecular arrangements contribute most to the overall lattice stabilization. For compound (Ia), the most stabilizing interaction is between molecules involved in the formation of the N—H···O chain (-35.2 kJ mol-1), followed by molecules arranged in a ππ interaction configuration (-21.9 kJ mol-1). The third most stabilizing interaction (-9.1 kJmol-1) brings neighbouring F and H atoms into close proximity to form C—H···F interactions. In (Ib), the most stabilizing interaction is again between molecules involved in the N—H···O chain formation (-36.9 kJ mol-1). The next most stabilizing geometries contribute -12.6 and -12.4 kJ mol-1 and involve molecules interacting via C—H···F and C—F···π interactions, respectively, towards lattice stability. As we mentioned previously (Omondi et al., 2005), it seems like the ππ interaction configuration in (Ia) which is not present in (Ib) contributes to the preferential formation of (Ia) at room temperature.

After standing for several weeks and even after heating (as observed by DSC [differential scanning calorimetry]), compound (Ib) does not seem to revert to (Ia), unlike the analogue of (III) (Omondi et al., 2005). Should a transformation of (Ia) to (Ib) be found, we would speculate that the mechanism for such a transformation is similar to that proposed for the polymorphs of (II) and (III). In this case, C—H···F intermolecular interactions would play a similar role to Cl···Cl interactions in (II) and (III). The phase transformation of (IIa) and (IIIa) involves rotation of the aryl group, leaving the N—H···O hydrogen-bonding chain intact with the aryl rings stacked along the short axis. The transformation of (IIa) was said to be entropically driven as it reverts back to form (IIa) in large part because of the stabilizing ππ interactions, whereas there was no reverse change for compound (III) probably due to inhibition by intermolecular C—H···O interactions present in (IIIb) but not present in (IIb).

Related literature top

For related literature, see: Boeyens et al. (1988); Ferguson et al. (1998); Filippini & Gavezzotti (1994); Gavezzotti (2003); Godwa et al. (2000); Michta et al. (2008); Nagarajan et al. (1986); Omondi et al. (2005, 2008); Ravikumar et al. (2003); Rowland & Taylor (1996); Thayer (2006); Ugi et al. (1965); Zheng et al. (2007).

Experimental top

N-(2,6-difluorophenyl)formamide was synthesized following a known procedure (Ugi et al., 1965). Commercially available 2,6-difluoro-N-phenylaniline (Aldrich, purity > 95%) was heated in a tenfold excess of formic acid for a period of 15 h at 363 K. The excess formic acid was then removed under vacuum to give a white solid, which was treated with dilute hydrochloric acid (0.1 M HCl, 10 ml) and ethyl acetate (60 ml). The organic layer was separated from the aqueous layer, dried over magnesium sulfate and filtered. Colourless needle-shaped crystals of N-(2,6-difluorophenyl)formamide were grown from the filtrate The compound was obtained in good yields (over 80%). The purity of the compound was confirmed by NMR spectroscopy using a Bruker 300 MHz instrument. It was found to exist in solution (C6D6) as a mixture of cis- and trans-isomers in a ratio of 2:1.

The second polymorph of N-(2,6-difluorophenyl)formamide (Ib) could only be found as an impurity during the preparation of 2,6-difluoro-N-phenylthioamide. Efforts to produce (Ib) experimentally by sublimation of (Ia) or by seeding a solution of (Ia) using crystals of 2,6-difluoro-N-phenylthioamide were not successful.

Refinement top

With the exception of the H atoms involved in hydrogen bonding (i.e. H1), all H atoms were positioned geometrically, with C—H = 0.95 Å, and allowed to ride on their parent atoms with Uiso(H) = 1.2Ueq(C). H1 was located in the difference map and refined freely.

Computing details top

For both compounds, data collection: SMART (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997), PLATON (Spek, 2009) and DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. Views of forms (Ia) and (Ib) showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. An overlay of the structures of the polymorphic forms (Ia) and (Ib).
[Figure 3] Fig. 3. A view of (Ia) down the crystallographic b axis showing N—H···O hydrogen-bonded chains (short dashed lines) that are linked by ππ intermolecular interactions (long dashed lines). [Symmetry codes: (i) x - 1/2, y, -z + 3/2; (ii) -x + 2, -y + 1, -z + 1.]
[Figure 4] Fig. 4. A view of (Ia) down the crystallographic a axis showing C—H···F interactions (in short dashed lines). [Symmetry code: (i) -x + 3/2, y - 1/2, z.]
[Figure 5] Fig. 5. Crystals of compound (Ib) (transparent with dimensions of about 0.7 × 0.15 × 0.05 [unit?], indicated by arrows) in a batch of crystals of 2,6-difluorophenylthioamide (dark patches).
[Figure 6] Fig. 6. A view of (1b) down the crystallographic c axis showing N—H···O hydrogen-bonded chains.[Symmetry code: (i) x - 1, y, z.]
[Figure 7] Fig. 7. A view of (1b) down the crystallographic a axis showing C—H···F interactions. [Symmetry codes: (i) -x, y + 1/2, 1 - z; (ii) -x, y - 1/2, 1 - z.].
(Ia) N-(2,6-difluorophenyl)formamide top
Crystal data top
C7H5F2NOF(000) = 640
Mr = 157.12Dx = 1.532 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 9351 reflections
a = 8.5031 (15) Åθ = 2.9–28.0°
b = 11.387 (2) ŵ = 0.14 mm1
c = 14.075 (3) ÅT = 298 K
V = 1362.8 (4) Å3Needle, colourless
Z = 80.5 × 0.16 × 0.1 mm
Data collection top
CCD area-detector
diffractometer
1006 reflections with I > 2σ(I)
ω scansRint = 0.039
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
θmax = 28.0°, θmin = 2.9°
Tmin = 0.933, Tmax = 0.986h = 1011
8426 measured reflectionsk = 1115
1637 independent reflectionsl = 1818
Refinement top
Refinement on F2H atoms treated by a mixture of independent and constrained refinement
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0457P)2 + 0.1294P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.037(Δ/σ)max < 0.001
wR(F2) = 0.100Δρmax = 0.15 e Å3
S = 1.02Δρmin = 0.12 e Å3
1637 reflectionsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
105 parametersExtinction coefficient: 0.017 (2)
1 restraint
Crystal data top
C7H5F2NOV = 1362.8 (4) Å3
Mr = 157.12Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 8.5031 (15) ŵ = 0.14 mm1
b = 11.387 (2) ÅT = 298 K
c = 14.075 (3) Å0.5 × 0.16 × 0.1 mm
Data collection top
CCD area-detector
diffractometer
1637 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
1006 reflections with I > 2σ(I)
Tmin = 0.933, Tmax = 0.986Rint = 0.039
8426 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0371 restraint
wR(F2) = 0.100H atoms treated by a mixture of independent and constrained refinement
S = 1.02Δρmax = 0.15 e Å3
1637 reflectionsΔρmin = 0.12 e Å3
105 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.93365 (16)0.40677 (13)0.65042 (10)0.0403 (4)
C20.84099 (19)0.50268 (15)0.67277 (11)0.0485 (4)
C30.7354 (2)0.55047 (15)0.60991 (13)0.0631 (5)
H30.67260.61370.62760.076*
C40.7244 (2)0.50308 (19)0.52029 (13)0.0671 (6)
H40.65430.53550.47680.081*
C50.8151 (2)0.40870 (18)0.49392 (12)0.0603 (5)
H50.80730.37680.43330.072*
C60.91744 (17)0.36285 (14)0.55948 (11)0.0471 (4)
C70.99516 (18)0.31247 (15)0.79871 (12)0.0509 (4)
H71.0730.28160.83780.061*
N11.04056 (16)0.35676 (13)0.71596 (10)0.0473 (4)
O10.86048 (13)0.30868 (11)0.82797 (8)0.0641 (4)
F10.85624 (14)0.55027 (9)0.76039 (7)0.0722 (4)
F21.00861 (12)0.27001 (9)0.53586 (7)0.0677 (4)
H11.131 (2)0.3511 (15)0.7007 (12)0.052 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0338 (7)0.0430 (8)0.0441 (8)0.0044 (7)0.0018 (6)0.0028 (7)
C20.0496 (9)0.0459 (9)0.0499 (10)0.0017 (8)0.0037 (7)0.0015 (7)
C30.0556 (11)0.0563 (11)0.0773 (12)0.0088 (9)0.0041 (9)0.0188 (9)
C40.0541 (11)0.0812 (13)0.0662 (12)0.0061 (10)0.0088 (9)0.0341 (11)
C50.0575 (10)0.0774 (13)0.0459 (9)0.0174 (10)0.0031 (8)0.0077 (9)
C60.0416 (9)0.0490 (9)0.0508 (9)0.0085 (8)0.0077 (7)0.0008 (8)
C70.0385 (7)0.0614 (10)0.0528 (9)0.0088 (8)0.0062 (7)0.0031 (8)
N10.0302 (7)0.0595 (9)0.0523 (8)0.0027 (7)0.0015 (6)0.0013 (7)
O10.0412 (6)0.0923 (10)0.0587 (7)0.0095 (6)0.0023 (5)0.0214 (6)
F10.0870 (8)0.0617 (7)0.0680 (7)0.0153 (6)0.0011 (5)0.0175 (5)
F20.0703 (7)0.0668 (7)0.0662 (7)0.0036 (5)0.0099 (5)0.0183 (5)
Geometric parameters (Å, º) top
C1—C61.381 (2)C4—H40.93
C1—C21.383 (2)C5—C61.372 (2)
C1—N11.4147 (19)C5—H50.93
C2—F11.3534 (17)C6—F21.3524 (18)
C2—C31.373 (2)C7—O11.2178 (19)
C3—C41.375 (3)C7—N11.327 (2)
C3—H30.93C7—H70.93
C4—C51.374 (3)N1—H10.800 (18)
C6—C1—C2116.10 (14)C6—C5—C4118.18 (16)
C6—C1—N1121.51 (14)C6—C5—H5120.9
C2—C1—N1122.39 (14)C4—C5—H5120.9
F1—C2—C3119.42 (15)F2—C6—C5119.73 (15)
F1—C2—C1117.96 (14)F2—C6—C1116.98 (14)
C3—C2—C1122.62 (16)C5—C6—C1123.29 (16)
C2—C3—C4118.70 (17)O1—C7—N1125.73 (15)
C2—C3—H3120.7O1—C7—H7117.1
C4—C3—H3120.7N1—C7—H7117.1
C5—C4—C3121.09 (16)C7—N1—C1122.58 (14)
C5—C4—H4119.5C7—N1—H1118.9 (12)
C3—C4—H4119.5C1—N1—H1118.3 (12)
C6—C1—C2—F1178.35 (13)C4—C5—C6—C10.0 (2)
N1—C1—C2—F10.9 (2)C2—C1—C6—F2179.14 (12)
C6—C1—C2—C31.7 (2)N1—C1—C6—F20.1 (2)
N1—C1—C2—C3179.02 (15)C2—C1—C6—C50.8 (2)
F1—C2—C3—C4178.27 (15)N1—C1—C6—C5179.91 (14)
C1—C2—C3—C41.8 (2)O1—C7—N1—C10.3 (3)
C2—C3—C4—C50.9 (3)C6—C1—N1—C7120.59 (17)
C3—C4—C5—C60.1 (3)C2—C1—N1—C760.2 (2)
C4—C5—C6—F2179.93 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.801 (17)2.050 (17)2.843 (2)170
Symmetry code: (i) x+1/2, y, z+3/2.
(Ib) N-(2,6-difluorophenyl)formamide top
Crystal data top
C7H5F2NOF(000) = 160
Mr = 157.12Dx = 1.577 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 8124 reflections
a = 4.468 (2) Åθ = 2.3–28°
b = 8.486 (3) ŵ = 0.14 mm1
c = 8.881 (1) ÅT = 123 K
β = 100.698 (5)°Needle, colourless
V = 330.88 (19) Å30.35 × 0.09 × 0.04 mm
Z = 2
Data collection top
CCD area-detector
diffractometer
710 reflections with I > 2σ(I)
ω scansRint = 0.040
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
θmax = 28°, θmin = 2.3°
Tmin = 0.951, Tmax = 0.994h = 55
8100 measured reflectionsk = 1111
843 independent reflectionsl = 1111
Refinement top
Refinement on F2H atoms treated by a mixture of independent and constrained refinement
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0431P)2 + 0.0279P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.031(Δ/σ)max < 0.001
wR(F2) = 0.076Δρmax = 0.19 e Å3
S = 1.08Δρmin = 0.21 e Å3
843 reflectionsAbsolute structure: Flack (1983)
104 parametersAbsolute structure parameter: 10 (10)
2 restraints
Crystal data top
C7H5F2NOV = 330.88 (19) Å3
Mr = 157.12Z = 2
Monoclinic, P21Mo Kα radiation
a = 4.468 (2) ŵ = 0.14 mm1
b = 8.486 (3) ÅT = 123 K
c = 8.881 (1) Å0.35 × 0.09 × 0.04 mm
β = 100.698 (5)°
Data collection top
CCD area-detector
diffractometer
843 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)
710 reflections with I > 2σ(I)
Tmin = 0.951, Tmax = 0.994Rint = 0.040
8100 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.031H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.076Δρmax = 0.19 e Å3
S = 1.08Δρmin = 0.21 e Å3
843 reflectionsAbsolute structure: Flack (1983)
104 parametersAbsolute structure parameter: 10 (10)
2 restraints
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.6039 (5)0.6745 (3)0.7482 (3)0.0243 (5)
C20.3661 (5)0.6227 (3)0.6355 (2)0.0264 (5)
C30.2352 (5)0.4765 (3)0.6376 (3)0.0324 (5)
H30.07040.44590.55940.039*
C40.3490 (6)0.3746 (3)0.7564 (3)0.0352 (6)
H40.26180.27290.75970.042*
C50.5883 (6)0.4198 (3)0.8699 (3)0.0351 (6)
H50.66770.34970.9510.042*
C60.7092 (5)0.5677 (3)0.8635 (3)0.0294 (5)
C70.5730 (5)0.9590 (3)0.7401 (2)0.0270 (5)
H70.68021.05530.73710.032*
N10.7345 (4)0.8263 (2)0.7452 (2)0.0269 (4)
F10.2649 (3)0.72061 (17)0.51670 (14)0.0383 (4)
F20.9449 (3)0.61452 (19)0.97244 (16)0.0425 (4)
O10.2991 (3)0.9680 (2)0.73884 (19)0.0319 (4)
H10.930 (7)0.846 (4)0.751 (3)0.057 (10)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0223 (10)0.0211 (10)0.0299 (11)0.0005 (8)0.0061 (9)0.0020 (9)
C20.0262 (11)0.0245 (11)0.0271 (11)0.0053 (10)0.0017 (9)0.0013 (10)
C30.0299 (12)0.0266 (12)0.0396 (13)0.0037 (11)0.0035 (10)0.0101 (11)
C40.0370 (13)0.0205 (12)0.0503 (17)0.0034 (10)0.0141 (12)0.0066 (11)
C50.0421 (14)0.0255 (13)0.0385 (13)0.0070 (10)0.0091 (11)0.0075 (11)
C60.0265 (12)0.0288 (13)0.0314 (12)0.0037 (10)0.0018 (9)0.0002 (11)
C70.0249 (8)0.0196 (10)0.0350 (12)0.0057 (9)0.0022 (9)0.0002 (10)
N10.0196 (9)0.0239 (10)0.0360 (11)0.0029 (8)0.0021 (8)0.0006 (9)
F10.0433 (8)0.0319 (8)0.0337 (8)0.0020 (6)0.0085 (6)0.0014 (6)
F20.0381 (8)0.0415 (9)0.0402 (8)0.0007 (7)0.0127 (6)0.0058 (7)
O10.0237 (7)0.0212 (8)0.0507 (10)0.0005 (7)0.0066 (7)0.0010 (8)
Geometric parameters (Å, º) top
C1—C61.383 (3)C4—H40.95
C1—C21.389 (3)C5—C61.372 (4)
C1—N11.416 (3)C5—H50.95
C2—F11.353 (2)C6—F21.351 (3)
C2—C31.373 (3)C7—O11.224 (3)
C3—C41.385 (4)C7—N11.334 (3)
C3—H30.95C7—H70.95
C4—C51.381 (4)N1—H10.88 (3)
C6—C1—C2115.8 (2)C6—C5—C4118.8 (2)
C6—C1—N1121.7 (2)C6—C5—H5120.6
C2—C1—N1122.5 (2)C4—C5—H5120.6
F1—C2—C3119.0 (2)F2—C6—C5120.0 (2)
F1—C2—C1117.9 (2)F2—C6—C1116.8 (2)
C3—C2—C1123.1 (2)C5—C6—C1123.2 (2)
C2—C3—C4118.5 (2)O1—C7—N1125.9 (2)
C2—C3—H3120.7O1—C7—H7117
C4—C3—H3120.7N1—C7—H7117
C5—C4—C3120.5 (2)C7—N1—C1123.11 (17)
C5—C4—H4119.8C7—N1—H1111 (2)
C3—C4—H4119.8C1—N1—H1126 (2)
C6—C1—C2—F1177.06 (18)C4—C5—C6—C10.2 (4)
N1—C1—C2—F12.2 (3)C2—C1—C6—F2178.58 (19)
C6—C1—C2—C31.4 (3)N1—C1—C6—F20.7 (3)
N1—C1—C2—C3179.4 (2)C2—C1—C6—C50.7 (3)
F1—C2—C3—C4177.3 (2)N1—C1—C6—C5179.9 (2)
C1—C2—C3—C41.2 (3)O1—C7—N1—C10.8 (4)
C2—C3—C4—C50.1 (4)C6—C1—N1—C7124.1 (2)
C3—C4—C5—C60.5 (4)C2—C1—N1—C756.7 (3)
C4—C5—C6—F2179.5 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.88 (3)1.97 (3)2.807 (3)158
Symmetry code: (i) x+1, y, z.

Experimental details

(Ia)(Ib)
Crystal data
Chemical formulaC7H5F2NOC7H5F2NO
Mr157.12157.12
Crystal system, space groupOrthorhombic, PbcaMonoclinic, P21
Temperature (K)298123
a, b, c (Å)8.5031 (15), 11.387 (2), 14.075 (3)4.468 (2), 8.486 (3), 8.881 (1)
α, β, γ (°)90, 90, 9090, 100.698 (5), 90
V3)1362.8 (4)330.88 (19)
Z82
Radiation typeMo KαMo Kα
µ (mm1)0.140.14
Crystal size (mm)0.5 × 0.16 × 0.10.35 × 0.09 × 0.04
Data collection
DiffractometerCCD area-detector
diffractometer
CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2004)
Multi-scan
(SADABS; Bruker, 2004)
Tmin, Tmax0.933, 0.9860.951, 0.994
No. of measured, independent and
observed [I > 2σ(I)] reflections
8426, 1637, 1006 8100, 843, 710
Rint0.0390.040
(sin θ/λ)max1)0.6600.661
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.100, 1.02 0.031, 0.076, 1.08
No. of reflections1637843
No. of parameters105104
No. of restraints12
H-atom treatmentH atoms treated by a mixture of independent and constrained refinementH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.15, 0.120.19, 0.21
Absolute structure?Flack (1983)
Absolute structure parameter?10 (10)

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), PLATON (Spek, 2009) and DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) for (Ia) top
C1—N11.4147 (19)C7—N11.327 (2)
C7—O11.2178 (19)
C6—C1—N1121.51 (14)O1—C7—N1125.73 (15)
C2—C1—N1122.39 (14)C7—N1—C1122.58 (14)
C2—C1—N1—C760.2 (2)
Hydrogen-bond geometry (Å, º) for (Ia) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.801 (17)2.050 (17)2.843 (2)170
Symmetry code: (i) x+1/2, y, z+3/2.
Selected bond and torsion angles (º) for (Ib) top
C6—C1—N1121.7 (2)O1—C7—N1125.9 (2)
C2—C1—N1122.5 (2)C7—N1—C1123.11 (17)
C2—C1—N1—C756.7 (3)
Hydrogen-bond geometry (Å, º) for (Ib) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O1i0.88 (3)1.97 (3)2.807 (3)158
Symmetry code: (i) x+1, y, z.
 

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