o-Dibromobenzene

Figure 1. Optimized Geometry from 6-31G Theory

Optimized (lowest energy) bond length using 6-31G theory most closely matched literature values.

Table 1. Calculated o-Dibromobenzene Bond Length and Bond Order Data

Atom Number	Atom Pair Number	Bond Length (Angstroms)	Bond Order
1	3	1.384	1.408
2	10	1.385	1.408
3	12	1.384	1.464
8	11	1.072	.934
1	5	1.921	1.089
2	11	1.384	1.464
4	10	1.921	1.089
1	10	1.379	1.437
2	9	1.071	.927
3	6	1.071	.927
7	12	1.072	.934
11	12	1.387	1.433

Figure 2. Highest Occupied Molecular Orbital	3-Dimensional representation of the highest occupied molecular orbital (HOMO). The HOMO is one of many bonding orbitals for o-bromobenzene.
Figure 3. Lowest Unoccupied Molecular Orbital	3-Dimensional representation of the lowest unoccupied molecular orbital (LUMO). The LUMO is an anti-bonding orbital with three orthogonal nodal planes.

Table 2. UV-Vis Absorbance Wavelength Data

Ground to Excited State Number	Absorbance Wavelength (nanometers)
1	200
2	194
3	189
4	183
5	172
6	160
7	150
8	149
9	148
10	144

Table 3. Major Peaks in Vibrational Spectrum and Corresponding Bond Vibrations.

Frequency (cm-1)	Explanation
898	Hydrogens vibrating perpendicular to the plane of the aromatic ring
1145	Carbons stretching in aromatic ring
1648	Carbons stretching in aromatic ring

Comparison to published IR data: NIST WebBook IR spectrum for o-dichlorobenzene. Note that variations between calculated data presented in Table 3 and NIST WebBook spectrum show variation due to substitution of chlorine for bromine.