Tautomerization, molecular structure, transition state structure, and vibrational spectra of 2-aminopyridines: a combined computational and experimental study

Al-Otaibi, Jamelah S.

doi:10.1186/s40064-015-1363-2

SpringerPlus

Table 3 Calculated fundamental frequencies of 2A3MP at different levels

From: Tautomerization, molecular structure, transition state structure, and vibrational spectra of 2-aminopyridines: a combined computational and experimental study

Mode of vibration	Calculated frequency (cm⁻¹)												Vibrational assignments
	HF/6-311++G(d,p)				B3LYP/6-311++G(d,p)				MP2/6-31G(d)		MP2/6-31G++(d,p)
	Wave number		IR intensity	Raman intensity	Wave number		IR intensity	Raman intensity	Wave number	IR intensity	Wave number	IR intensity
	Unscaled	Scaled	IR intensity	Raman intensity	Unscaled	Scaled	IR intensity	Raman intensity	Unscaled	IR intensity	Unscaled	IR intensity
1	3914	3483	33.46	38.59	3620	3475	33.46	38.59	3681	22.33	3739	28.00	NH₂ asym. stretch
2	3803	3385	38.28	128.04	3478	3339	38.28	128.04	3562	30.68	3612	29.03	NH₂ sym. stretch
3	3359	2990	17.13	158.09	3195	3067	17.13	158.09	3255	13.85	3280	16.47	CH stretch
4	3323	2957	30.04	71.59	3158	3032	30.04	71.59	3218	6.42	3248	1.12	CH stretch
5	3317	2952	8.31	89.51	3148	3022	8.31	89.51	3213	22.11	3240	23.15	CH stretch
6	3243	2886	23.06	57.57	3101	2977	23.06	57.57	3199	10.90	3215	12.60	CH₃ asym. stretch
7	3200	2848	28.38	81	3048	2926	28.38	81.00	3163	12.23	3177	12.32	CH₃ asym. stretch
8	3151	2804	45.23	179.66	2977	2857	45.23	179.66	3087	16.87	3098	23.71	CH₃ sym. stretch
9	1804	1606	23.06	31.04	1692	1624	23.06	31.04	1697	224.58	1680	232.70	NH₂ scissoring + C=C stretch
10	1778	1582	37.92	12.05	1627	1562	37.92	12.05	1666	27.45	1655	42.39	C=C stretch +NH₂ scissoring
11	1775	1580	64.76	16	1615	1550	64.76	16.00	1661	24.71	1648	27.98	C–C stretch
12	1630	1451	28.89	3.63	1509	1449	28.89	3.63	1564	55.80	1547	44.84	CH₃ asym. scissoring
13	1611	1434	53.25	7.83	1489	1429	53.25	7.83	1542	2.25	1514	18.42	C=C stretch
14	1604	1428	7.64	8.99	1485	1426	7.64	8.99	1521	7.14	1510	8.95	CH₃ sym. scissoring
15	1583	1409	162.33	2.14	1466	1407	162.33	2.14	1512	76.96	1497	79.28	C=C stretch + CH₃ sym. scissoring
16	1540	1371	1.55	4.03	1439	1381	1.55	4.03	1466	2.02	1451	1.16	CH₃ sym. scissoring
17	1436	1278	3.3	9.46	1339	1285	3.30	9.46	1439	22.30	1436	29.75	C-NH₂ stretch + CC stretch
18	1414	1258	27.74	12.33	1320	1267	27.74	12.33	1356	1.27	1345	1.36	C = N stretch
19	1341	1193	1.46	9.08	1309	1257	1.46	9.08	1342	8.57	1332	12.77	CH in-plane-bending
20	1267	1128	12.3	2.94	1245	1195	12.30	2.94	1258	7.97	1251	11.77	C–CH3 stretch
21	1240	1104	16.16	13.77	1185	1137	16.16	13.77	1195	0.94	1181	1.02	CH in-plane-bending
22	1162	1034	0.15	0.13	11,024	1079	0.15	0.13	1132	0.88	1122	0.91	CH in-plane-bending
23	1155	1028	20.89	9.88	1077	1033	20.89	9.88	1077	3.27	1064	3.24	CH₃ rocking
24	1129	1005	8.88	11.25	1041	999	8.88	11.25	1075	5.68	1055	4.63	Ring breathing
25	1067	950	0.55	0.91	1006	966	0.55	0.91	1032	3.53	1025	2.90	Trigonal bending
26	1083	964	24.24	8.69	972	933	1.223	0.41	919	7.60	896	9.54	CH out-of-plane
27	1067	950	0.98	0.12	950	912	0.296	0.04	900	3.24	894	3.89	CCC in-plane-bending
28	946	842	2.74	0.99	888	852	2.74	0.99	893	0.79	862	0.16	CH out- of- plane
29	868	773	46.55	1.53	786	755	46.55	1.53	790	45.68	767	10.41	CH out- of- plane
30	860	765	47.18	0.97	779	748	47.18	0.97	770	9.62	764	35.11	CH out- of- plane
31	799	711	4.09	23.58	754	724	4.09	23.58	744	266.64	712	276.48	CCC in-plane-bending
32	658	586	110.56	6.15	606	582	110.56	6.15	648	109.60	601	59.48	CH₂ + twisting in CH₃
33	641	570	31.27	2.13	577	554	31.27	2.13	602	6.33	568	13.57	CNC in-plane-bending
34	586	522	97.34	1.76	560	537	97.34	1.76	539	22.44	535	2.78	CCC in-plane-bending
35	567	505	17.59	4.59	542	520	17.59	4.59	532	4.29	487	15.88	NH₂ wagging
36	489	435	13.89	0.58	449	431	13.89	0.58	447	19.35	445	1.42	C–NH₂ in-plane bending
37	479	426	1.31	0.48	444	426	1.31	0.48	424	1.26	378	15.45	CCC out-of-plane + CNC out-of-plane
38	383	341	56.96	0.58	382	367	56.96	0.58	371	37.72	331	30.52	C–NH₂ out-of-plane
39	325	289	0.24	0.48	300	288	0.24	0.48	301	2.93	301	2.69	C–CH₃ in-plane bending + C-NH₂ in-plane bending
40	294	262	11.34	1.41	266	255	11.34	1.41	269	3.93	232	3.63	C–CH₃ out-of-plane + C-NH₂ in-plane bending
41	195	174	0.81	0.16	178	171	0.81	0.16	184	3.74	177	3.69	CCC out-of-plane
42	174	155	2.52	0.91	156	150	2.52	0.91	158	0.34	146	0.24	CH₃ torsion

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