S. No. IR Vibrational assignment (%PED)
Theoretical wave number Experimental wave number
Unscaled Scaled*
1 31 31 - δ(O22-C23) [59] + Φ(R) [14] + g(C1-N8) [9] + g(C4-N7) [9]
2 37 36 - τ(O22-C23) [31] - δ(C23-C26) [19] + τ(C1-N8) [8] + β(C3-O22) [8] + Φ(R) [8]
3 56 55 - δ(O22-C23) [70] + τ(C1-N8) [9] + Φ(R) [7]
4 63 62 - Φ(R) [35]+τ(C4-N7) [15]+δ(O22-C23) [17]
5 82 81 - τ(C3-O22) [25] + δ(C23-C26) [22] + γ(C3-O22) [21] + δ(O22-C23) [10] + Φ(R) [9]
6 108 107 - γ(N7-H12) [27] + τ(N7-C18) [17] + Φ(R) [11]
7 129 128 - γ(N8-H13) [32] + Φ(R) [27] + τ(C1-N8) [13] + τ(N8-C14) [10] + Φ(R) [9]
8 147 146 - γ(C4-N7) [38] + Φ(R) [22] + τ(C4-N7) [9] + τ(N7-C18) [8]
9 168 167 - γ(C3-O22) [38] + Φ(R) [17]+g(C4-N7) [17] + δ(O22- C23) [8]
10 173 171 - τ(N8-C14) [60] + Φ(R) [10] + τ(C1-N8) [9] + Φ(R) [9]
11 190 189 - β(C4-N7) [27] + β(C6-Cl9) [20] + δ(N8-H13) [10] + β(C1-N8) [10] + δ(N7-H12) [9]
12 220 218 - γ(C6-Cl9) [44] + Φ(R) [12] + Φ(R) [11]
13 224 222 - β(C6-Cl9) [29] + γ(C6-Cl9) [21] + β(C1-N8) [20]
14 235 233 - τ(C23-C26) [56] + β(C6-Cl9) [9]
15 259 257 - τ(C23-C26) [16] + β(C6-Cl9) [13] + δ(N8-C14) [10]+ ν(C4-C5) [7]
16 271 269 - α(R) [22] – δ(N7-C18) [11] – δ(N8-H13) [11] – β(C6-Cl9) [10]
17 324 321 - γ(C3-O22) [28] – β(C5-O10) [15] – β(C2-O11) [15] +α(R) [14] – δ(N8-H13) [10]
18 335 332 - β(C3-O22) [45] – γ(C3-O22) [13]
19 356 353 - δ(C23-C26) [26] + γ(C3-O22) [17] +δ(O22- C23) [17]– ν(C6-Cl9) [10] – α(R) [7]
20 379 376 - γ(C3-O22) [34] + δ(O22-C23) [24] – γ(C6-Cl9) [7]
21 416 412 - β(C5-O10) [21] – β(C2-O11) [20] + δ(N7-H12) [9]
22 461 457 - α(R) [35] – δ(N7-H12) [10] – δ(N8-H13) [9] – α(R) [8] – β(C2-O11) [7]
23 512 507 - γ(C4-N7) [15] –δ(O22-C23) [12] + δ(N8-H13) [10] +α(R) [9]– γ(C3-O22) [7]
24 538 533 - γ(C4-N7) [20] + γ(C1-N8) [20]+δ(O22- C23) [15]+ γ(C2-O11) [10] + Φ(R) [10]
25 557 551 569 δ(N7-H12) [15] + β(C2-O11) [11] – ν(C2-C3) [11] – ν(C3-C4) [8] – ν(C6-Cl9) [8]
26 613 608 - γ(C3-O22) [29] -Φ(R) [20]- δ(O22- C23) [10]+ δ(C23-C26) [26]+γ(C4-N7) [7] – γ(C1-N8) [7]
27 650 644 641 γ(C3-O22) [21] – α(R) [12] – γ(N7-H12) [10] – γ(C1-N8) [8]
28 677 670 - γ(C3-O22) [36] + τ(C4-N7) [20] + γ(N7-H12) [13] – Φ(R) [8]
29 707 700 - γ(N8-H13) [38] + τ(C1-N8) [36] – ν(C4-C5) [8]
30 753 745 - Φ(R) [32] + γ(C3-O22) [30] – γ(C2-O11) [14] + γ(C5-O10) [7]
31 764 757 752 γ(C5-O10) [27] + Φ(R) [21] + γ(C2-O11) [17] – γ(C4-N7) [14] – Φ(R) [11]
32 791 784 - β(C5-O10) [24] + ν(C6-Cl9) [20] + β(C4-N7) [8] + β(C3-O22) [7] – ν(N7-C18) [7]
33 818 811 - δ(C26-H27) [37] – δ(C23-H25) [37] + δ(C23-H25) [11]
34 834 826 - β(C1-N8) [18] + β(C2-O11) [13] + β(C3-O22) [9] – ν(C6-Cl9) [9]
35 871 863 890 ν(O22-C23) [34] + δ(C26-H27) [22] + γ(C3-O22) [11]
36 983 974 - ν(N8-C14) [14] +ν(C1-C2) [14] + β(C1-N8) [8] – β(C3-O22) [7]
37 1012 1002 - ν(C23-C26) [17] + β(C4-N7) [9] + ν(N8-C14) [9] + ν(C4-C5) [8] – δ(C26-H27) [8] + β(C3-O22) [7] + ν(N7-C18) [7]
38 1032 1022 - ν(C23-C26) [22] – ν(N7-C18) [21] – ν(O22-C23) [12] – ν(N8-C14) [11]
39 1075 1065 965 ν(N7-C18) [18] – ν(O22-C23) [15] – ν(C4-C5) [12] + ν(C23-C26) [9] – α(R) [7]
40 1119 1088 1128 ν(C3-O22) [19] – ν(O22-C23) [17] – ν(C1-C2) [14] + ν(N8-C14) [13] + δ(C26-H27) [7]
41 1134 1103 - δ(C26-H27) [41] – ν(C23-C26) [18]
42 1139 1108 - δ(C14-H15) [67] – δ(C14-H16) [24] + δ(C14-H17) [8]
43 1142 1111 - δ(C18-H19) [77] – δ(C18-H21) [8]
44 1173 1141 - δ(C23-H25) [50] + δ(C26-H27) [29] + δ(C23-H25) [8]
45 1187 1154 - δ(C14-H16) [33] + δ(C14-H15) [11] + δ(C14-H16) [7]
46 1206 1173 - δ(C18-H20) [35] – δ(N7-H12) [9] + δ(C18-H20) [7] – ν(C3-O22) [7]
47 1268 1234 - ν(C1-N8) [13] + β(N8-H13) [10] – β(C1-N8) [9] + ν(C5-C6) [8] – ν(N8-C14) [7] + β(C5-O10) [7]
48 1294 1259 - δ(C23-H25) [33] – ν(C4-N7) [14] – β(N7-H12) [9] + ν(C3-O22) [8]
49 1304 1269 - δ(C23-H25) [39] + ν(C4-N7) [13] + β(N7-H12) [9] –ν(C3-O22) [9]
50 1337 1301 1332 ν(C5-C6) [39] – ν(C4-C5) [13] – ν(C1-N8) [11] – ν(C1-C6) [8] + β(C5-O10) [7]
51 1359 1322 - ν(C2-C3) [39] – ν(C3-O22) [10] – ν(C1-C2) [9] + β(C2-O11) [8]
52 1401 1362 1405 δ(C26-H27) [60] – δ(C23-H24) [31]
53 1423 1384 - δ(C23-H24) [45] + δ(C26-H27) [31] + ν(C23-C26) [11]
54 1463 1423 - δ(C14-H15) [72] - δ(C18-H19) [14]
55 1468 1428 - δ(C18-H19) [70] + δ(C14-H15) [16]
56 1482 1442 - δ(C26-H28) [61] - δ(C26-H29) [28] - δ(C26-H27) [8]
57 1485 1444 - δ(C18-H21) [87] - δ(C18-H19) [8]
58 1489 1449 1470 δ(C14-H17) [91] - δ(C14-H15) [7]
59 1501 1460 - δ(C26-H29) [52] + δ(C28-H28) [23] - δ(C23-H24) [10] - δ(C26-H27) [7]
60 1507 1466 - δ(C18-H20) [66] - δ(C14-H16) [11] - δ(C18-H20) [7]
61 1508 1467 - δ(C14-H16) [72] + δ(C18-H20) [11]- δ(C14-H16) [7]
62 1517 1476 - δ(C23-H24) [86] + δ(C26-H29) [6]
63 1557 1514 1554 β(N8-H13) [39] - β(N7-H12) [13]- ν(C2-O11) [9]
64 1564 1522 - β(N7-H12) [35] + β(N8-H13) [13] + ν(C4-N7) [8]
65 1628 1584 - ν(C1-C6) [23] - ν(C3-C4) [20] - ν(C2-O11) [11] - ν(C1-N8) [10]
66 1639 1595 1602 ν(C1-N8) [15] - ν(C3-C4) [14] - ν(C1-C6) [14] - ν(C5-O10) [8] - ν(C2-O11) [8] + ν(C4-N7) [7]
67 1685 1639 - ν(C2-O11) [32] + ν(C5-O10) [29] - ν(C3-C4) [13] + ν(C4-N7) [7]
68 1707 1661 1692 ν(C5-O10) [36] – ν(C2-O11) [18] + α(R) [9] + ν(C1-N8) [8] – ν(C4-N7) [7]
69 2992 2910 2842 ν(C23-H24) [94]
70 3033 2950 2989 ν(C18-H19) [69] + ν(C18-H21) [14] + ν(C18-H20) [11]
71 3034 2951 3015 ν(C26-H29) [35] + ν(C26-H27) [34] + ν(C26-H28) [26]
72 3049 2966 3042 ν(C14-H16) [40] + ν(C14-H15) [34] + ν(C14-H17) [26]
73 3081 2997 - ν(C23-H25) [71] + ν(C26-H29) [15]
74 3101 3017 - ν(C26-H27) [53] – ν(C26-H29) [23] + ν(C23-H25) [12] – ν(C26-H28) [9]
75 3102 3017 - ν(C18-H21) [39] + ν(C18-H20) [31] - ν(C18-H19) [27]
76 3110 3026 - ν(C26-H28) [59] - ν(C26-H29) [25] + ν(C23-H25) [11]
77 3114 3029 - ν(C14-H16) [52] - ν(C14-H15) [47]
78 3127 3042 - ν(C14-H17) [72] - ν(C14-H15) [19] - ν(C14-H16) [8]
79 3135 3049 - ν(C18-H20) [55] - ν(C18-H21) [44]
80 3479 3385 3356 ν(N8-H13) [99]
81 3515 3419 - ν(N7-H12) [99]

The numbers (in bracket) after the modes are the % potential energy calculated using normal coordinate analysis. The abbreviations are: ν=stretching, ω=wagging, τ=twisting, ρ=rocking, σ=scissoring, γ=out-of-plane deformation, β=in-plane deformation, α=planar ring deformation, φ=non-planar ring deformation, δ=deformation. The modes in bold letters in the last column are the assigned modes.
*With the scale factor of 0.9906 for calculated wave numbers lower than 1100 cm-1 and the scale factor 0.9728 for larger wave numbers.
Table 4: Vibrational assignments of cemb.