




Supporting information
![]() | Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010900780X/gd3278sup1.cif |
![]() | Structure factor file (CIF format) https://doi.org/10.1107/S010827010900780X/gd3278Isup2.hkl |
CCDC reference: 730103
2,6-Dibromo-N-phenylformamide was synthesized following a known procedure (Ugi et al., 1965). Commercially available 2,6-dibromo-N-phenylaniline [Quantity?] (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 reduced pressure 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 (I) were grown from the filtrate. The purity of the compound was confirmed by NMR. It was found to exist in solution (C6D6) as a mixture of cis- and trans-isomers in a ratio of 2:1.
H atoms were located in difference maps and then treated as riding, with C—H = 0.95 Å and N—H = 0.88 Å, and with Uiso(H) = 1.2Ueq(C,N).
Data collection: SMART (Bruker, 2004); cell refinement: Please give details; 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, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).
C7H5Br2NO | F(000) = 528 |
Mr = 278.94 | Dx = 2.181 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 5600 reflections |
a = 4.2946 (5) Å | θ = 2.9–28.2° |
b = 13.8755 (16) Å | µ = 9.48 mm−1 |
c = 14.2541 (19) Å | T = 173 K |
V = 849.40 (18) Å3 | Needle, colourless |
Z = 4 | 0.56 × 0.08 × 0.08 mm |
Bruker SMART CCD area-detector diffractometer | 2100 independent reflections |
Radiation source: fine-focus sealed tube | 1841 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
ω scans | θmax = 28.3°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | h = −5→5 |
Tmin = 0.069, Tmax = 0.466 | k = −17→18 |
5541 measured reflections | l = −13→19 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.027 | H-atom parameters constrained |
wR(F2) = 0.060 | w = 1/[σ2(Fo2) + (0.0246P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.002 |
2100 reflections | Δρmax = 0.63 e Å−3 |
100 parameters | Δρmin = −0.34 e Å−3 |
0 restraints | Absolute structure: Flack (1983), with how many Friedel pairs? |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.055 (18) |
C7H5Br2NO | V = 849.40 (18) Å3 |
Mr = 278.94 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 4.2946 (5) Å | µ = 9.48 mm−1 |
b = 13.8755 (16) Å | T = 173 K |
c = 14.2541 (19) Å | 0.56 × 0.08 × 0.08 mm |
Bruker SMART CCD area-detector diffractometer | 2100 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | 1841 reflections with I > 2σ(I) |
Tmin = 0.069, Tmax = 0.466 | Rint = 0.030 |
5541 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | H-atom parameters constrained |
wR(F2) = 0.060 | Δρmax = 0.63 e Å−3 |
S = 1.03 | Δρmin = −0.34 e Å−3 |
2100 reflections | Absolute structure: Flack (1983), with how many Friedel pairs? |
100 parameters | Absolute structure parameter: 0.055 (18) |
0 restraints |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.6446 (8) | 0.5095 (3) | 1.0260 (2) | 0.0230 (7) | |
C2 | 0.5337 (8) | 0.4185 (3) | 1.0465 (2) | 0.0258 (8) | |
C3 | 0.3629 (9) | 0.3660 (3) | 0.9820 (2) | 0.0307 (8) | |
H3 | 0.2838 | 0.3043 | 0.9981 | 0.037* | |
C4 | 0.3075 (9) | 0.4043 (3) | 0.8930 (2) | 0.0318 (9) | |
H4 | 0.1965 | 0.3678 | 0.8476 | 0.038* | |
C5 | 0.4140 (10) | 0.4951 (3) | 0.8711 (2) | 0.0301 (8) | |
H5 | 0.3733 | 0.5217 | 0.811 | 0.036* | |
C6 | 0.5810 (9) | 0.5478 (3) | 0.9368 (2) | 0.0264 (8) | |
C7 | 0.6710 (8) | 0.6171 (3) | 1.1599 (2) | 0.0267 (8) | |
H7 | 0.7963 | 0.6516 | 1.2034 | 0.032* | |
N1 | 0.8164 (7) | 0.5652 (2) | 1.0936 (2) | 0.0256 (6) | |
H1 | 1.0212 | 0.5652 | 1.0914 | 0.031* | |
O1 | 0.3881 (6) | 0.6230 (2) | 1.16817 (18) | 0.0343 (6) | |
Br1 | 0.60975 (10) | 0.36474 (3) | 1.16701 (3) | 0.03610 (12) | |
Br2 | 0.72105 (9) | 0.67353 (3) | 0.90624 (2) | 0.03202 (11) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0160 (15) | 0.030 (2) | 0.0226 (15) | 0.0025 (14) | 0.0014 (12) | −0.0091 (14) |
C2 | 0.0233 (18) | 0.031 (2) | 0.0233 (17) | 0.0016 (16) | 0.0024 (13) | −0.0012 (15) |
C3 | 0.031 (2) | 0.0286 (19) | 0.0324 (18) | −0.0037 (18) | −0.0042 (16) | −0.0034 (17) |
C4 | 0.028 (2) | 0.035 (2) | 0.0318 (19) | 0.0015 (17) | −0.0033 (15) | −0.0105 (16) |
C5 | 0.036 (2) | 0.032 (2) | 0.0224 (15) | 0.0025 (19) | −0.0050 (16) | −0.0004 (15) |
C6 | 0.0269 (18) | 0.027 (2) | 0.0253 (17) | 0.0011 (17) | 0.0044 (15) | −0.0030 (14) |
C7 | 0.0255 (19) | 0.030 (2) | 0.0244 (16) | −0.0018 (14) | −0.0046 (14) | −0.0009 (15) |
N1 | 0.0192 (14) | 0.0308 (17) | 0.0267 (14) | −0.0007 (12) | −0.0014 (13) | −0.0040 (13) |
O1 | 0.0198 (12) | 0.0472 (18) | 0.0359 (13) | 0.0011 (12) | 0.0028 (12) | −0.0137 (13) |
Br1 | 0.0455 (2) | 0.0347 (2) | 0.02810 (18) | 0.00086 (19) | −0.00546 (17) | 0.00495 (17) |
Br2 | 0.0391 (2) | 0.0292 (2) | 0.02770 (17) | −0.00247 (18) | 0.00208 (17) | −0.00098 (15) |
C1—C2 | 1.382 (5) | C4—H4 | 0.95 |
C1—C6 | 1.404 (5) | C5—C6 | 1.388 (5) |
C1—N1 | 1.439 (4) | C5—H5 | 0.95 |
C2—C3 | 1.384 (5) | C6—Br2 | 1.896 (4) |
C2—Br1 | 1.900 (4) | C7—O1 | 1.223 (4) |
C3—C4 | 1.396 (5) | C7—N1 | 1.343 (4) |
C3—H3 | 0.95 | C7—H7 | 0.95 |
C4—C5 | 1.376 (5) | N1—H1 | 0.88 |
C2—C1—C6 | 118.1 (3) | C4—C5—C6 | 120.1 (3) |
C2—C1—N1 | 121.7 (3) | C4—C5—H5 | 120 |
C6—C1—N1 | 120.2 (3) | C6—C5—H5 | 120 |
C1—C2—C3 | 121.5 (3) | C5—C6—C1 | 120.8 (3) |
C1—C2—Br1 | 119.4 (3) | C5—C6—Br2 | 119.6 (3) |
C3—C2—Br1 | 119.1 (3) | C1—C6—Br2 | 119.6 (3) |
C2—C3—C4 | 119.6 (4) | O1—C7—N1 | 124.4 (3) |
C2—C3—H3 | 120.2 | O1—C7—H7 | 117.8 |
C4—C3—H3 | 120.2 | N1—C7—H7 | 117.8 |
C5—C4—C3 | 119.8 (3) | C7—N1—C1 | 121.4 (3) |
C5—C4—H4 | 120.1 | C7—N1—H1 | 119.3 |
C3—C4—H4 | 120.1 | C1—N1—H1 | 119.3 |
C6—C1—C2—C3 | −0.4 (5) | C4—C5—C6—Br2 | −179.1 (3) |
N1—C1—C2—C3 | 178.6 (3) | C2—C1—C6—C5 | −0.6 (5) |
C6—C1—C2—Br1 | −179.1 (3) | N1—C1—C6—C5 | −179.7 (3) |
N1—C1—C2—Br1 | −0.1 (5) | C2—C1—C6—Br2 | 178.7 (3) |
C1—C2—C3—C4 | 1.8 (6) | N1—C1—C6—Br2 | −0.3 (5) |
Br1—C2—C3—C4 | −179.5 (3) | O1—C7—N1—C1 | −1.1 (6) |
C2—C3—C4—C5 | −2.1 (6) | C2—C1—N1—C7 | −82.6 (5) |
C3—C4—C5—C6 | 1.1 (6) | C6—C1—N1—C7 | 96.3 (4) |
C4—C5—C6—C1 | 0.3 (6) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.88 | 2.08 | 2.793 (4) | 138 |
Symmetry code: (i) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C7H5Br2NO |
Mr | 278.94 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 173 |
a, b, c (Å) | 4.2946 (5), 13.8755 (16), 14.2541 (19) |
V (Å3) | 849.40 (18) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 9.48 |
Crystal size (mm) | 0.56 × 0.08 × 0.08 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2004) |
Tmin, Tmax | 0.069, 0.466 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5541, 2100, 1841 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.060, 1.03 |
No. of reflections | 2100 |
No. of parameters | 100 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.63, −0.34 |
Absolute structure | Flack (1983), with how many Friedel pairs? |
Absolute structure parameter | 0.055 (18) |
Computer programs: SMART (Bruker, 2004), Please give details, SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), PLATON (Spek, 2009) and DIAMOND (Brandenburg, 1999), WinGX (Farrugia, 1999).
C1—N1 | 1.439 (4) | C7—O1 | 1.223 (4) |
C2—Br1 | 1.900 (4) | C7—N1 | 1.343 (4) |
C6—Br2 | 1.896 (4) | ||
O1—C7—N1 | 124.4 (3) | C7—N1—C1 | 121.4 (3) |
C6—C1—N1—C7 | 96.3 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.88 | 2.08 | 2.793 (4) | 138 |
Symmetry code: (i) x+1, y, z. |
The title compound, (I) (Fig. 1), is of interest as part of a study on polymorphism and phase transformations in 2,6-disubstituted N-phenylformamides (Omondi et al. 2005). It is only the second among the 2,6-disubstituted N-phenylformamides that crystallizes in a Sohnke space group. Another example of these chiral N-phenylformamides is 2,6-difluoro-4-bromo-N-phenylformamide [Cambridge Structural Database (Allen, 2002) refcode SEDGAJ; Ferguson et al., 1998]. In the present study, the effect of different interactions (N—H···O hydrogen bonds and C—H···O, Cl···Cl and π–π intermolecular interactions) on the phase transitions of 2,6-dichloro-N-phenylformamide and 2-chloro-6-methyl-N-phenylformamide have been studied.
Molecules of compound (I) are linked through N—H···O hydrogen bonds, forming chains that run along the crystallographic a direction. The molecules in the chains are related by translation, with the aryl rings stacked parallel to each other along the N—H···O hydrogen-bonded chains. Connecting each of these N—H···O hydrogen-bonded chains, in the crystallographic b direction, are Br···O interactions [Kubicki, 2004, and references therein; Br2···O1 = 3.100 (3) Å] between molecules related by a 21 screw axis along the a axis, and in the crystallographic c direction, intermolecular Br···Br interactions [Br1···Br2 = 3.527 (7) Å] (Fig. 2), also between molecules related by a 21 screw axis, along the b axis. Two Br···O intermolecular interactions and the N—H···O hydrogen bond form a ring between adjacent hydrogen-bonded chains described by graph-set motif R23(12) (Etter, 1990; Bernstein et al., 1995).
Atom Br2 is involved in two intermolecular interactions (Fig. 3). It has been reported that Br is frequently involved in such contacts as a result of its non-spherical shape (Lieberman et al., 2000; Lommerse et al., 1996; Beyer et al., 2001). Atom Br2 of (I) interacts with atom O1 head-on and with atom Br1 side-on (O being a nucleophile and Br an electrophile). This leads to a two-dimensional network similar to those in 2,3,6,7-tetrabromonaphthalene (space group P21/c) or the cocrystal of 2,3,6,7-tetrabromonaphthalene and bromobenzene (Navon et al., 1997).
Although compound (I) has the same hydrogen-bonded chains as the high-temperature forms of 2,6-dichloro-N-phenylformamide and 2-chloro-6-methyl-N-phenylformamide, and of 2,6-dimethyl-N-phenylformamide (Omondi et al., 2005), in which they all have one short axes of about 4 Å along which the formamide molecules are stacked along the N—H···O hydrogen-bonded chain (Fig. 2), the packing in (I) is similar only to that in 2,6-dichloro-N-phenylformamide, where the N—H···O hydrogen-bonded chains in the high-temperature form are connected through Cl···Cl contacts forming (010) sheets.
Using the OPIX suite of programs (Gavezzotti, 2003), the lattice energy of (I) was calculated to be -90.5 kJ mol-1. These calculations permitted estimation of the contributions to this energy of the intermolecular N—H···O, Br···O and Br···Br interactions as -40, -9.5 and -8.1 kJ mol-1, respectively. This energy pattern resembles that for the high-temperature forms of 2,6-dichloro-N-phenylformamide and 2-chloro-6-methyl-N-phenylformamide, and that of 2,6-dimethyl-N-phenylformamide (Omondi et al., 2005), in which there is one strong stabilizing interaction (along the N—H···O hydrogen-bonded chain), while the second and third stabilizing interactions are significantly weaker.