Research Article
Molecular Structure and Vibrational Analysis of 1-Bromo-2-Chlorobenzene Using ab initio HF and Density Functional Theory (B3LYP) Calculations
Table 2
Observed and HF /6-31+G (d, p), B3LYP/6-31+G (d, p), and B3LYP/6-311++G (d, p) level calculated vibrational frequencies of 1-bromo-2-chlorobenzene.
| S. no. | Symmetry species CS | Observed | Calculated frequency (cm−1) with | Vibrational assignments | frequency | HF/6-31+G (d, p) | B3LYP/6-31+G (d, p) | B3LYP/6-311++G (d, p) | | | FTIR | FTRaman | Unscaled value | Scaled value | Unscaled value | Scaled value | Unscaled value | Scaled value |
| 1 | A′ | — | 3070vs | 3392 | 3069 | 3222 | 3062 | 3206 | 3073 | (C–H) υ | 2 | A′ | 3060vs | — | 3388 | 3066 | 3219 | 3059 | 3202 | 3070 | (C–H) υ | 3 | A′ | — | 3055vs | 3374 | 3053 | 3207 | 3048 | 3190 | 3058 | (C–H) υ | 4 | A′ | — | 3030w | 3358 | 3038 | 3194 | 3035 | 3177 | 3046 | (C–H) υ | 5 | A′ | 1600w | — | 1774 | 1605 | 1621 | 1599 | 1610 | 1603 | (C=C) υ | 6 | A′ | 1570vs | 1570s | 1757 | 1590 | 1614 | 1569 | 1604 | 1579 | (C=C) υ | 7 | A′ | 1460vs | — | 1625 | 1470 | 1490 | 1448 | 1483 | 1460 | (C=C) υ | 8 | A′ | 1440vs | — | 1586 | 1435 | 1462 | 1442 | 1457 | 1434 | (C–C) υ | 9 | A′ | 1260vs | — | 1389 | 1257 | 1326 | 1260 | 1304 | 1250 | (C–C) υ | 10 | A′ | 1170w | — | 1314 | 1189 | 1281 | 1169 | 1276 | 1169 | (C–C) υ | 11 | A′ | 1130vs | 1130 | 1242 | 1124 | 1187 | 1128 | 1185 | 1136 | (C–H) δ | 12 | A′ | 1110vs | — | 1230 | 1113 | 1150 | 1118 | 1147 | 1099 | (C–H) δ | 13 | A′ | 1105w | — | 1198 | 1084 | 1133 | 1101 | 1126 | 1108 | (C–H) δ | 14 | A′ | 1040w | — | 1191 | 1077 | 1098 | 1043 | 1054 | 1037 | (C–H) δ | 15 | A′′ | 1030w | — | 1130 | 1022 | 1058 | 1028 | 1028 | 1024 | (C–H) γ | 16 | A′′ | — | 1010w | 1120 | 1013 | 1030 | 1016 | 988 | 1013 | (C–H) γ | 17 | A′′ | 970w | — | 1093 | 989 | 986 | 973 | 955 | 969 | (C–H) γ | 18 | A′′ | 940vs | — | 1088 | 984 | 967 | 940 | 864 | 936 | (C–H) γ | 19 | A′ | 860 | — | 946 | 856 | 849 | 859 | 761 | 863 | (CCC) δ | 20 | A′ | 760vs | — | 852 | 771 | 767 | 756 | 730 | 759 | (C–Cl) υ | 21 | A′ | 720m | — | 790 | 714 | 731 | 721 | 702 | 719 | (CCC) δ | 22 | A′ | — | 650w | 709 | 642 | 659 | 650 | 659 | 648 | (CCC) δ | 23 | A′ | 560w | — | 608 | 550 | 564 | 556 | 512 | 559 | (C–Br) υ | 24 | A″ | 460m | 460m | 520 | 470 | 477 | 463 | 447 | 458 | (CCC) γ | 25 | A″ | — | 440w | 486 | 440 | 449 | 436 | 443 | 443 | (CCC) γ | 26 | A″ | — | 380w | 426 | 385 | 395 | 384 | 387 | 387 | (CCC) γ | 27 | A′ | — | 280w | 308 | 278 | 286 | 278 | 283 | 283 | (C–Cl) δ | 28 | A′ | — | 240w | 263 | 238 | 242 | 242 | 222 | 240 | (C–Br) δ | 29 | A′′ | — | 170w | 179 | 162 | 163 | 170 | 163 | 169 | (C–Cl) γ | 30 | A′′ | — | 140w | 147 | 133 | 134 | 139 | 123 | 139 | (C–Br) γ |
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vs: very strong; s: strong; m: medium; w: weak; as- asymmetric; s: symmetric; υ: stretching; δ: in-plane bending; γ: out-plane bending; τ: twisting.
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