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

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.