Spectroscopic details on the molecular structure of pyrimidine‑2‑thiones heterocyclic compounds: computational and antiviral activity against the main protease enzyme of SARS-CoV-2

Table 1 Calculated frequencies from B3LYP/6–31(d,P), corrected values treated with scale factor (0.962), and experimental IR frequencies

Functional group	Frequency B3LYP/6–31(d,p) (cm⁻¹)	Frequency x scale factor (cm⁻¹)	Experimental Frequency (cm⁻¹)
L1
N–H	3659 and 3634	3519 and 3497	3368 and 3243
= C–H	3265	3140	3050
–C–H	3162	3041	2978
C = C	1623	1561	1612–1602
C = N	1494	1437	1488
L2
N–H	3490	3357	3225
= C–H	3286	3161	3060
–C–H	3116	2997	2989
C = C	1661	1597	1615–1589
C = N	1644	1581	1619
C–O	1491	1434	1491
L3
= C–H	3286	3161	3058
–C–H	3150	3030	2967
C = N	1663	1599	1624 and 1631
C = C	1655	1592	1608–1599
C–N	1489–1382	1432–1329	1490
C–C	1169	1124	1100
L4
N–H	3625	3487	3195
= C–H	3275	3150	3069
–C–H	3168	3047	2988
C = O	1816	1647	1691
C = N	1693	1628	1631, 1625
C = C	1631	1569	1609–1595
C–N	1490–1373	1433–1320	1496
L5
N–H	3705	3564	3275
= C–H	3290	3165	3060–3030
–C–H	3153	3033	2923
C = N	1709	1644	1643, 1632
C = C	1650	1587	1611–1594
C–N	1492–1377	1324–1435	1493

ISSN: 2661-801X