research communications
of 1-bromo-2-(phenylselenyl)benzene
aDepartment of Chemistry, The University of Winnipeg, 515 Portage Avenue, Winnipeg, MB, R3B 2E9, Canada, and bDepartment of Chemistry, 360 Parker Building, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
*Correspondence e-mail: j.ritch@uwinnipeg.ca
In the title compound, C12H9BrSe, the Se atom exhibits a bent geometry, with a C—Se—C bond angle of 99.19 (6)°. The ortho Se and Br atoms are slightly displaced from opposite faces of the mean plane of the benzene ring [by 0.129 (2) and 0.052 (2) Å, respectively]. The planes of the benzene and phenyl rings form a dihedral angle of 72.69 (5)°. In the crystal, π-stacking interactions between inversion-related phenyl rings are observed, with a centroid–centroid distance of 3.630 (1) Å.
Keywords: crystal structure; π–π interactions; organoselenium compounds.
CCDC reference: 1050354
1. Chemical context
Organoselenium compounds have been found to have diverse scientific applications. For instance, the antioxidant capabilities of the glutathione peroxidases has inspired the synthesis of selenium-containing enzyme mimetics for therapeutic use (Schewe, 1995), and examples are known of selenium-based conjugated materials exhibiting superconductivity (Jérome et al., 1980). Our research group is interested in organoselenium compounds in the context of designing ligands for coordination to transition metals to generate catalytic complexes. This is an area of growing interest, as examples of selenium-containing catalysts with higher activity than the ubiquitous phosphine analogues are discovered (Kumar et al., 2012). The title compound represents a potentially valuable starting material for the synthesis of ligands containing –SePh donor groups, as the ortho-Br atom provides a site of functionalization via, for example, lithium halogen exchange followed by addition, or a metal-catalyzed cross-coupling reaction. Though previously prepared (Cristau et al., 1985), its structure has remained unreported.
2. Structural commentary
The molecular structure of the title compound, (I), is depicted in Fig. 1. The possesses one complete molecule, which features no disorder. The central Se atom exhibits a bent geometry [C1—Se1—C7 = 99.19 (6)°]. The two planes comprising the benzene and phenyl ring C atoms are twisted by 72.69 (5)° relative to each other. The Br and Se atoms are twisted with respect to the disubstituted benzene ring, as evidenced by displacements in opposite directions from the mean plane of the ring by 0.052 (2) and 0.129 (2) Å, respectively, and the torsion angle Br1—C2—C1—Se1 is 4.2 (1)°.
The Se—C distances of 1.9171 (14) and 1.9198 (14) Å are equal within experimental error. At 1.9044 (14) Å, the C—Br distance is measurably shorter than the Se—C bond lengths.
3. Supramolecular features
The closest intermolecular Se⋯Br distance is 3.8013 (3) Å, which lies outside the sum of the van der Waals radii (3.75 Å) for these two elements (Bondi, 1964). The phenyl group of each molecule is associated with the same group on an adjacent molecule by a slipped π-stacking interaction (Fig. 2). The two molecules in the dimeric units are situated about a crystallographic inversion centre. The centroid-to-centroid separation of the aromatic rings is 3.630 (1) Å, while the nearest centroid-to-plane distance is 3.378 (1) Å. Together, these are indicative of the slipped nature of the π–π interaction. The ring separation is in the normal range (ca 3.3–3.8 Å) for π-stacked interactions (Janiak, 2000). The packing is illustrated in Fig. 3.
4. Database survey
A search of the Cambridge Structural Database (CSD, Version 5.35; Groom & Allen, 2014) reveals 172 structures featuring two-coordinate aryl-substituted selenium centres. The mean bond angle of 98 (4)° and Se—C(aryl) distance of 1.92 (2) Å for these structures match well with the parameters observed for 1-bromo-2-(phenylselenyl)benzene.
Only two structures in the CSD feature the title compound as a ) and 1,4-dibromo-2,3,5,6-tetrakis(phenylseleno)benzene (MUHTOZ; Sato & Kanatomi, 2009). Both of these compounds exhibit similar twisted orientations of the two aromatic rings, but lack π-stacking secondary bonding interactions, presumably due to their highly substituted nature. By contrast, the structure of a less sterically crowded analogue, 1-bromo-8-(phenylselenyl)naphthalene (CIKPUI; Fuller et al., 2007), exhibits slipped π-stacking of the naphthalene rings.
bis(2-bromo-4,5-dimethoxyphenyl) selenide (SAKBIP; Schiffling and Klar, 19895. Synthesis and crystallization
1-Bromo-2-(phenylselenyl)benzene has been prepared in previous reports using several methodologies, including nickel(II)-catalyzed coupling of NaSePh with 1,2-dibromobenzene (Cristau et al., 1985) and the copper-catalyzed coupling of diphenyl diselenide with 1-bromo-2-iodobenzene (Dandapat et al., 2011), which is the procedure followed for this study (Fig. 4). Purification via flash column chromatography with a silica was conducted as reported. Though described by Dandapat et al. (2011) as being a `slightly brown oil', we found that this compound was a nearly colourless liquid which slowly crystallized upon standing at room temperature. NMR spectroscopic analysis matched the reported data.
Though quite soluble in common solvents, including nonpolar solvents such as hexanes, in the highly lipophilic hexamethyldisiloxane we found this substance was only moderately soluble. It crystallized readily as transparent colourless crystals from a solution in this solvent upon storage at 273 K.
6. Refinement
Crystal data, data collection and structure . No special considerations were needed for the H atoms were placed in calculated positions, with C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C), and treated in a riding-model approximation.
details are summarized in Table 1Supporting information
CCDC reference: 1050354
10.1107/S205698901500345X/lh5753sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S205698901500345X/lh5753Isup2.hkl
Supporting information file. DOI: 10.1107/S205698901500345X/lh5753Isup3.cdx
Supporting information file. DOI: 10.1107/S205698901500345X/lh5753Isup4.cml
Organoselenium compounds have been found to have diverse scientific applications. For instance, the antioxidant capabilities of the glutathione peroxidases has inspired the synthesis of selenium-containing enzyme mimetics for therapeutic use (Schewe, 1995), and examples are known of selenium-based conjugated materials exhibiting superconductivity (Jérome et al., 1980). Our research group is interested in organoselenium compounds in the context of designing ligands for coordination to transition metals to generate catalytic complexes. This is an area of growing interest, as examples of selenium-containing catalysts with higher activity than the ubiquitous phosphine analogues are discovered (Kumar et al., 2012). The title compound represents a potentially valuable starting material for the synthesis of ligands containing –SePh donor groups, as the ortho Br atom provides a site of functionalization via, e.g. lithium halogen exchange followed by
addition, or a metal-catalyzed cross-coupling reaction. Though previously prepared (Cristau et al., 1985), its structure has remained unreported.The molecular structure of the title compound, (I), is depicted in Fig. 1. The
possesses one complete molecule, which features no significant disorder. The central Se atom exhibits a bent geometry [C1—Se1—C7 = 99.19 (6)°]. The two planes comprising the benzene and phenyl ring C atoms are twisted by 107.31 (5)° relative to each other. The Br and Se atoms are twisted with respect to the disubstituted benzene ring, as evidenced by displacements in opposite directions from the mean plane of the ring by 0.052 (2) and 0.129 (2) Å, respectively, and the torsion angle Br1—C2—C1—Se1 is 4.2 (1)°.The Se—C distances of 1.9171 (14) and 1.9198 (14) Å are equal within experimental error. At 1.9044 (14) Å, the C—Br distance is measurably shorter than the Se—C bond lengths.
The closest intramolecular Se···Br distance is 3.8013 (3) Å, which lies outside the sum of the van der Waals radii (3.75 Å) for these two elements (Bondi, 1964). The phenyl group of each molecule is associated with the same group on an adjacent molecule by a slipped π-stacking interaction (Fig. 2). The two molecules in the dimeric units are situated about a crystallographic inversion centre. The centroid-to-centroid separation of the aromatic rings is 3.630 (1) Å, while the nearest centroid-to-plane distance is 3.378 (1) Å. Together, these are indicative of the slipped nature of the π–π interaction. The ring separation is in the normal range (ca 3.3–3.8 Å) for π-stacked interactions (Janiak, 2000).
A search of the Cambridge Structural Database (CSD, Version 5.35; Groom & Allen, 2014) reveals 172 structures featuring two-coordinate aryl-substituted selenium centres. The mean bond angle of 98 (4)° and Se—C(aryl) distance of 1.92 (2) Å for these structures match well with the parameters observed for 1-bromo-2-(phenylselenyl)benzene.
Only two structures in the CSD feature the title compound as a π-stacking secondary bonding interactions, presumably due to their highly substituted nature. By contrast, the structure of a less sterically crowded analogue, 1-bromo-8-(phenylselenyl)naphthalene (CIKPUI; Fuller et al., 2007), exhibits slipped π-stacking of the naphthalene rings.
bis(2-bromo-4,5-dimethoxyphenyl) selenide (SAKBIP; Schiffling and Klar, 1989) and 1,4-dibromo-2,3,5,6-tetrakis(phenylseleno)benzene (MUHTOZ; Sato & Kanatomi, 2009). Both of these compounds exhibit similar twisted orientations of the two aromatic rings, but lack1-Bromo-2-(phenylselenyl)benzene has been prepared in previous reports using several methodologies, including nickel(II)-catalyzed coupling of NaSePh with 1,2-dibromobenzene (Cristau et al., 1985) and the copper-catalyzed coupling of diphenyl diselenide with 1-bromo-2-iodobenzene (Dandapat et al., 2011), which is the procedure followed for this study (Figure 4). Purification via flash
with a silica was conducted as reported. Though described by Dandapat et al. as being a `slightly brown oil,' we found that this compound was a nearly colourless liquid which slowly crystallized upon standing at room temperature. NMR spectoscopic analysis matched the reported data.Though quite soluble in common solvents, including nonpolar solvents such as hexanes, in the highly lipophilic hexamethyldisiloxane we found this substance was more moderately soluble. It crystallized readily as transparent colourless crystals from a solution in this solvent upon storage at 273 K.
Data collection: APEX2 (Bruker 2013); cell
SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).Fig. 1. The molecular structure of the title compound, (I), showing 50% probabilty ellipsoids. | |
Fig. 2. Slipped π-stacked dimers of 1-bromo-2-(phenylselenyl)benzene. Each molecule is related to the other by an inversion centre at the centre of the centroid–centroid line. | |
Fig. 3. Packing diagram for (I), veiwed along the crystallographic b axis. | |
Fig. 4. The synthetic route to 1-bromo-2-(phenylselenyl)benzene, (I). |
C12H9BrSe | F(000) = 600 |
Mr = 312.06 | Dx = 1.877 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 8.1171 (4) Å | Cell parameters from 9910 reflections |
b = 7.6028 (4) Å | θ = 2.3–28.2° |
c = 18.1345 (10) Å | µ = 6.97 mm−1 |
β = 99.2668 (6)° | T = 173 K |
V = 1104.52 (10) Å3 | Fragment, colourless |
Z = 4 | 0.35 × 0.32 × 0.26 mm |
Bruker APEXII CCD diffractometer | 2528 reflections with I > 2σ(I) |
ω scans | Rint = 0.016 |
Absorption correction: numerical (SADABS; Bruker, 2013) | θmax = 28.4°, θmin = 2.3° |
Tmin = 0.205, Tmax = 0.361 | h = −10→10 |
21749 measured reflections | k = −10→10 |
2742 independent reflections | l = −24→24 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.017 | H-atom parameters constrained |
wR(F2) = 0.042 | w = 1/[σ2(Fo2) + (0.0194P)2 + 0.5087P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max = 0.001 |
2742 reflections | Δρmax = 0.28 e Å−3 |
127 parameters | Δρmin = −0.45 e Å−3 |
0 restraints |
C12H9BrSe | V = 1104.52 (10) Å3 |
Mr = 312.06 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.1171 (4) Å | µ = 6.97 mm−1 |
b = 7.6028 (4) Å | T = 173 K |
c = 18.1345 (10) Å | 0.35 × 0.32 × 0.26 mm |
β = 99.2668 (6)° |
Bruker APEXII CCD diffractometer | 2742 independent reflections |
Absorption correction: numerical (SADABS; Bruker, 2013) | 2528 reflections with I > 2σ(I) |
Tmin = 0.205, Tmax = 0.361 | Rint = 0.016 |
21749 measured reflections |
R[F2 > 2σ(F2)] = 0.017 | 0 restraints |
wR(F2) = 0.042 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.28 e Å−3 |
2742 reflections | Δρmin = −0.45 e Å−3 |
127 parameters |
Experimental. The following wavelength and cell were deduced by SADABS from the direction cosines etc. They are given here for emergency use only: CELL 0.71074 8.140 7.626 18.183 89.999 99.279 90.004. |
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. |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.37269 (2) | 0.33279 (2) | 0.26417 (2) | 0.03601 (5) | |
Se1 | 0.39491 (2) | 0.65383 (2) | 0.38572 (2) | 0.02860 (5) | |
C1 | 0.19202 (17) | 0.52181 (18) | 0.36221 (7) | 0.0237 (3) | |
C2 | 0.18210 (18) | 0.39017 (19) | 0.30840 (8) | 0.0266 (3) | |
C3 | 0.0361 (2) | 0.2971 (2) | 0.28518 (9) | 0.0349 (3) | |
H3 | 0.0323 | 0.2087 | 0.2479 | 0.042* | |
C4 | −0.1043 (2) | 0.3346 (2) | 0.31696 (10) | 0.0384 (4) | |
H4 | −0.2058 | 0.2735 | 0.3008 | 0.046* | |
C5 | −0.09621 (19) | 0.4610 (2) | 0.37222 (9) | 0.0341 (3) | |
H5 | −0.1918 | 0.4846 | 0.3947 | 0.041* | |
C6 | 0.05039 (18) | 0.55397 (19) | 0.39518 (8) | 0.0283 (3) | |
H6 | 0.0546 | 0.6399 | 0.4335 | 0.034* | |
C7 | 0.32416 (18) | 0.82409 (18) | 0.45228 (8) | 0.0255 (3) | |
C8 | 0.22331 (19) | 0.9649 (2) | 0.42396 (9) | 0.0315 (3) | |
H8 | 0.1849 | 0.9747 | 0.3718 | 0.038* | |
C9 | 0.17967 (19) | 1.0906 (2) | 0.47282 (10) | 0.0350 (3) | |
H9 | 0.1097 | 1.1861 | 0.4541 | 0.042* | |
C10 | 0.23779 (19) | 1.0773 (2) | 0.54880 (10) | 0.0343 (3) | |
H10 | 0.2074 | 1.1636 | 0.5820 | 0.041* | |
C11 | 0.3399 (2) | 0.9387 (2) | 0.57634 (9) | 0.0325 (3) | |
H11 | 0.3809 | 0.9311 | 0.6283 | 0.039* | |
C12 | 0.38282 (18) | 0.81058 (19) | 0.52816 (9) | 0.0283 (3) | |
H12 | 0.4518 | 0.7145 | 0.5471 | 0.034* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.03941 (9) | 0.04133 (10) | 0.02890 (8) | 0.00838 (7) | 0.01038 (6) | −0.00290 (6) |
Se1 | 0.02379 (8) | 0.02797 (8) | 0.03495 (9) | −0.00057 (5) | 0.00750 (6) | −0.00292 (6) |
C1 | 0.0245 (6) | 0.0210 (6) | 0.0253 (6) | 0.0015 (5) | 0.0034 (5) | 0.0045 (5) |
C2 | 0.0294 (7) | 0.0261 (7) | 0.0244 (6) | 0.0041 (6) | 0.0045 (5) | 0.0030 (5) |
C3 | 0.0418 (9) | 0.0299 (8) | 0.0310 (8) | −0.0032 (7) | −0.0002 (6) | −0.0033 (6) |
C4 | 0.0322 (8) | 0.0352 (9) | 0.0460 (9) | −0.0086 (7) | 0.0010 (7) | 0.0016 (7) |
C5 | 0.0274 (7) | 0.0312 (8) | 0.0449 (9) | −0.0010 (6) | 0.0098 (6) | 0.0047 (7) |
C6 | 0.0292 (7) | 0.0230 (7) | 0.0340 (7) | 0.0014 (6) | 0.0089 (6) | 0.0009 (6) |
C7 | 0.0228 (6) | 0.0208 (6) | 0.0332 (7) | −0.0020 (5) | 0.0049 (5) | −0.0010 (5) |
C8 | 0.0296 (7) | 0.0279 (7) | 0.0350 (8) | 0.0009 (6) | −0.0004 (6) | 0.0023 (6) |
C9 | 0.0281 (7) | 0.0251 (7) | 0.0504 (9) | 0.0042 (6) | 0.0023 (7) | 0.0019 (7) |
C10 | 0.0305 (8) | 0.0280 (8) | 0.0457 (9) | −0.0021 (6) | 0.0105 (7) | −0.0069 (7) |
C11 | 0.0338 (8) | 0.0325 (8) | 0.0313 (7) | −0.0031 (6) | 0.0057 (6) | −0.0008 (6) |
C12 | 0.0274 (7) | 0.0233 (7) | 0.0339 (7) | −0.0006 (5) | 0.0038 (6) | 0.0047 (6) |
Br1—C2 | 1.9044 (14) | C6—H6 | 0.9500 |
Se1—C1 | 1.9171 (14) | C7—C8 | 1.395 (2) |
Se1—C7 | 1.9198 (14) | C7—C12 | 1.386 (2) |
C1—C2 | 1.391 (2) | C8—H8 | 0.9500 |
C1—C6 | 1.4001 (19) | C8—C9 | 1.387 (2) |
C2—C3 | 1.386 (2) | C9—H9 | 0.9500 |
C3—H3 | 0.9500 | C9—C10 | 1.386 (2) |
C3—C4 | 1.387 (2) | C10—H10 | 0.9500 |
C4—H4 | 0.9500 | C10—C11 | 1.384 (2) |
C4—C5 | 1.383 (2) | C11—H11 | 0.9500 |
C5—H5 | 0.9500 | C11—C12 | 1.390 (2) |
C5—C6 | 1.389 (2) | C12—H12 | 0.9500 |
C1—Se1—C7 | 99.19 (6) | C8—C7—Se1 | 120.23 (11) |
C2—C1—Se1 | 118.90 (10) | C12—C7—Se1 | 118.99 (11) |
C2—C1—C6 | 117.80 (13) | C12—C7—C8 | 120.67 (14) |
C6—C1—Se1 | 123.27 (11) | C7—C8—H8 | 120.4 |
C1—C2—Br1 | 120.07 (11) | C9—C8—C7 | 119.25 (14) |
C3—C2—Br1 | 117.89 (11) | C9—C8—H8 | 120.4 |
C3—C2—C1 | 122.04 (14) | C8—C9—H9 | 119.9 |
C2—C3—H3 | 120.4 | C10—C9—C8 | 120.25 (15) |
C2—C3—C4 | 119.24 (15) | C10—C9—H9 | 119.9 |
C4—C3—H3 | 120.4 | C9—C10—H10 | 119.9 |
C3—C4—H4 | 120.1 | C11—C10—C9 | 120.16 (15) |
C5—C4—C3 | 119.82 (15) | C11—C10—H10 | 119.9 |
C5—C4—H4 | 120.1 | C10—C11—H11 | 119.9 |
C4—C5—H5 | 119.7 | C10—C11—C12 | 120.22 (15) |
C4—C5—C6 | 120.64 (15) | C12—C11—H11 | 119.9 |
C6—C5—H5 | 119.7 | C7—C12—C11 | 119.45 (14) |
C1—C6—H6 | 119.8 | C7—C12—H12 | 120.3 |
C5—C6—C1 | 120.39 (14) | C11—C12—H12 | 120.3 |
C5—C6—H6 | 119.8 | ||
Br1—C2—C3—C4 | 179.31 (12) | C4—C5—C6—C1 | 0.5 (2) |
Se1—C1—C2—Br1 | 4.17 (16) | C6—C1—C2—Br1 | −177.44 (10) |
Se1—C1—C2—C3 | −175.83 (12) | C6—C1—C2—C3 | 2.6 (2) |
Se1—C1—C6—C5 | 175.87 (11) | C7—C8—C9—C10 | 0.9 (2) |
Se1—C7—C8—C9 | −177.21 (12) | C8—C7—C12—C11 | 0.2 (2) |
Se1—C7—C12—C11 | 176.40 (11) | C8—C9—C10—C11 | 0.1 (2) |
C1—C2—C3—C4 | −0.7 (2) | C9—C10—C11—C12 | −1.0 (2) |
C2—C1—C6—C5 | −2.4 (2) | C10—C11—C12—C7 | 0.8 (2) |
C2—C3—C4—C5 | −1.3 (2) | C12—C7—C8—C9 | −1.1 (2) |
C3—C4—C5—C6 | 1.4 (3) |
Experimental details
Crystal data | |
Chemical formula | C12H9BrSe |
Mr | 312.06 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 173 |
a, b, c (Å) | 8.1171 (4), 7.6028 (4), 18.1345 (10) |
β (°) | 99.2668 (6) |
V (Å3) | 1104.52 (10) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 6.97 |
Crystal size (mm) | 0.35 × 0.32 × 0.26 |
Data collection | |
Diffractometer | Bruker APEXII CCD diffractometer |
Absorption correction | Numerical (SADABS; Bruker, 2013) |
Tmin, Tmax | 0.205, 0.361 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 21749, 2742, 2528 |
Rint | 0.016 |
(sin θ/λ)max (Å−1) | 0.669 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.017, 0.042, 1.06 |
No. of reflections | 2742 |
No. of parameters | 127 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.28, −0.45 |
Computer programs: APEX2 (Bruker 2013), SAINT (Bruker, 2013), SHELXS97 (Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015), OLEX2 (Dolomanov et al., 2009).
Acknowledgements
Funding from The University of Winnipeg is gratefully acknowledged. The authors thank Bob McDonald (X-Ray Crystallography Laboratory, Department of Chemistry, University of Alberta, Edmonton, Canada) for the collection of X-ray diffraction data, and the University of Manitoba, Department of Chemistry, for an adjunct appointment (JSR).
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