DFT Study for the Spectroscopic and Structural Analysis of p-Dimethylaminoazobenzene

Table 2

Comparison of experimental FTIR/FT-Raman and calculated (scaled) IR/Raman (gas) & IR vibrational frequencies (cm⁻¹) of DMAB in different solvents employing DFT/B3LYP/6-311G++ with Raman activity and probable assignment (characterized by PED).

Sr. number	Experimental IR/Raman wavenumber (cm^−1)	Calculated wavenumbers (cm^−1)
		DFT/6-311G++ in
		SRaman	Gas phase IR/Raman	Water	DMSO	Acetonitrile	Ethanol	Vibrational assignment
1	3256	6.50	3194.1					υCH (68)
2	3248	10.73	3160.2					υCH (45)
3	3146	3.11	3139.9					υCH (68)
4	3093	1.21	3112.8	3111.8	3119.5	3119.5	3119.5	υCH (33)
5	3085	9.98	3099.2					υCH sym (14)
6	3063	0.23	3065.3	3073.0	3073.0	3073.0	3073.0	υCH ar (14)
7	3000	5.76	2997.5					υCH (42), υCC (18)
8	2932	3.64	2970.3	2980.0	2980.0	2980.0	2980.0	υCCanti sym (88)
9	1899	9.79	2963.6					υCC (26)
10	1872	0.12	2922.9	2925.8	2925.8	2925.8	2925.8	υCH ar (17)
11	1738	148.42	1695.4					υCC (23)
12	1717	8.98	1620.8					υCC sym (19)
13	1689	4.80	1607.2	1592.7	1592.7	1592.7	1592.7	υCC (12), υCH (11)
14	1647	12.03	1600.5					υCC ar (19)
15	1564	11.31	1566.5					υCC ar (11), δCCH (17)
16		3.58	1553.0					υCC (10), δCCH (11)
17	1529	17.79	1539.4					υCC (13), υCH (11)
18	1514	4.92	1525.9	1515.2	1515.2	1515.2	1515.2	βCH (22)
19	1497	197.51	1485.2	1461.0	1461.0	1461.0	1461.0	βCH (26), δHCC (29)
20	1458	256.08	1478.4					βCH (21), υCC (33)
21	1440	97.58	1437.7					υCC (13), δHCC (11), δCCC (37)
22		246.89	1430.9					βCH (18)
23		4.45	1397.0					υCH (22), δHCC (10), δCCC (18)
24	1377	4.58	1363.1					υCC (55)
25		2.47	1356.3	1344.7	1344.7	1352.4	1344.7	υCC (26)
26	1336	4.88	1336.0					βCH (22), υCC (13)
27		2.27	1329.2	1321.4	1321.4	1321.4	1321.4	υCC (16)
28	1314	3.30	1315.6					δHCC (21), υCC (13)
29	1309	19.69	1274.9					υCC (40)
30	1223	169.30	1241.0	1251.7	1251.7	1251.7	1251.7	βCH (24), υCC (12), δCCC (10)
31		7.95	1200.3	1228.4	1228.4	1228.4	1228.4	βCH (22), υCC ar (28)
32		19.53	1193.6					υCCanti sym (21), βCH (11)
33	1160	1.38	1166.4	1189.7	1189.7	1189.7	1189.7	βHCCH (11), γHCC (48), υCC (13)
34		1.23	1146.1	1158.7	1158.7	1158.7	1158.7	υCN (22), υNN (41), δNCH (10)
35	1132	0.69		1135.4	1135.4	1135.4	1135.4	υCN (24), υNN (31), δNCH (16)
36	1090	3.11	1085.1					υCN (19), γCCC (21)
37	1072	1.02	1078.3	1073.4	1073.4	1073.4	1073.4	υCN (16), δNCH (12), δHCC (10)
38	1033	4.36	1057.9	1050.2	1050.2	1050.2	1050.2	υCN (16), γHCC (20)
39		13.73	1051.1					γCCC (23)
40		0.23	1017.2	1011.4	1011.4	1011.4	1011.4	τHCCC (68), τCCCC (13)
41		3.16	963.0					τCCCC (18), υCC (12)
42	917	0.11	935.9	926.2	926.2	926.2	926.2	ΩHCC (51)
43		1.15	861.3					γCCC (48), δHCC (11)
44	839	0.08	834.1	833.2	833.2	833.2	833.2	γCCC (26), ωHCC (12), τHCCC (48)
45	782	2.35	773.1	771.2	771.2	771.2	771.2	τHCCC (28), γCCC (33)
46	734	0.06	739.2	732.4	732.4	732.4	732.4	γCCC (47), υCC (17)
47		0.79	691.7	685.9	685.9	685.9	685.9	δCCC (10), γCCC (11)
48		1.21	671.4					γCCC (19), τCCCC (17)
49		0.03	630.7	623.9	623.9	623.9	623.9	γCCC (11), τCCCC (12)
50		1.24	562.9					γCCC (36)
51	552	0.10	549.3	546.4	546.4	546.4	546.4	δNCC (22), γHCC (14)
52	515	0.03	522.2	523.2	523.2	523.2	523.2	δCN (56), δNCC (16), ωHCC (10)
53		0.09	461.1	468.9	461.1	461.1	461.1	δCN (33), τCCCC (21)
54		0.01	271.3	275.1	275.1	282.9	282.9	τCCCC (26)
55		0.00	176.3	174.4	174.4	174.4	174.4	ωCCCC (33), τCCCC (34)
56		0.02	122.1	120.1	120.1	120.1	120.1	ωCCCC (29)
57		0.00	61.0	73.6	65.9	65.9	73.6	γCCC (46)
58		4.93	40.7	42.6	42.6	42.6	42.6	ωCCCC (27)

Abbreviations: υ: stretching; γ: bending; δ: rocking; τ: torsion; β: scissoring; ω: waging; sym: symmetric; anti sym: anti-symmetric; ar: aromatic.