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. 2020 Oct 23;25(21):4908. doi: 10.3390/molecules25214908

Table 6.

Experimental (Exp.) and B3LYP/6-311++G(d,p) calculated (Calc.) infrared spectra of monomeric 2-chloro-6-fluorobenzoic acid, and band assignments a.

Exp. Exp. (This Work; Also [58]) Calc. Approximate
Description b
Sym-
metry
Gas Phase Xe Matrix, 20 K B3LYP.
ν ν ν I IR
3566 3542/3522/3519/3512/3507 3662 87.5 ν(O–H) A
n.obs. n.obs. 3141 0.5 ν(CH) +++ A
n.obs. n.obs. 3137 0.4 ν(CH) +0– A
3083 2976 3116 3.6 ν(CH) +–+ A
1779 1770 1776 356.3 ν(C=O) A
1602 1611 1607 67.0 ν(CC) +–++–+ A
1580 1581/1579 1575 72.6 ν(CC) +0–+0– A
1455 1464 1450 35.2 ν(CC) +0– –0+, δ(CH) +– – A
1455 1457/1454 1446 88.1 ν(CC) ++0– –0, δ(CH) ++0 A
1362/1331 c 1376/1371/1364/1356/1332/1327 1324 96.3 ν(C–O), δ(COH) A
1300 1301/1291 1291 1.5 ν(CC) +–+–+– A
1258 1258/1255 1239 64.7 ν(CF), δ(CH) +++ A
1195 1203/1198/1194 1192 70.9 δ(COH), δ(CH) +00 A
1175 1178/1173/1172/1169 1167 117.9 ν(C–O), δ(COH), δ(CH) +–+ A
1151 1149 1142 26.9 ν(CCl), δ(CH) 0+0 A
1093 1101/1098/1096/1094 1093 90.3 ν(C–O), δ(ring)1, δ(CH) +0+ A
1052 1055/1054/1052 1049 27.7 δ(ring)2 A
964 n.obs. 956 0.9 γ(CH) +–+ A
909 912/910/908/907 887 103.8 ν(CCl), ν(CF) A
n.obs. n.obs. 880 0.4 γ(CH) +0– A
786 792/791/788/785 778 46.1 γ(CH) +++, γ(C=O) A
779 777 768 11.2 ν(C–C), δ(OCO) A
779 767 760 26.0 γ(C=O), γ(CH) +++ A
737 735 715 32.5 τ(ring)1 A
662 661/659 653 34.0 δ(OCO) A
582 583/580/575/572 591 82.9 τ(C-O) A
n.obs. n.obs. 565 0.6 τ(ring)2 A
n.i. 569/567 554 5.2 τ(ring)3 A
n.i. 545/543/542 538 23.7 δ(ring)3 A
n.i. 469 463 4.8 δ(ring)4, τ(C–O) A
n.i. n.i. 418 4.4 δ(CFCl) asym A
n.i. n.i. 388 0.3 γ(C-[CCC]) A
n.i. n.i. 343 1.2 δ(ring)4 A
n.i. n.i. 230 0.5 δ(CFCl) sym A
n.i. n.i. 225 0.3 γ(CF) A
n.i. n.i. 174 2.0 γ(CCl) A
n.i. n.i. 141 0.4 w(COOH) A
n.i. n.i. 85 1.6 γ(COOH) A
n.i. n.i. 24 2.3 τ(C–C) A

a Wavenumbers (ν) in cm−1, calculated infrared intensities (IIR) in km·mol−1; n.obs., not observed; n.i., not investigated; ?, uncertain. b Approximate description was obtained using the vibrations animation module of Chemcraft [63]; ν, stretching; δ, bending; w, wagging; γ, rocking; τ, torsion; the symbols +, – and 0 placed in front of the ν(CC), ν(CH), δ(CH) and γ(CH) ring coordinates indicate the movement (distending, compressing, staying, respectively) of the related bonds, starting from that located ortho to the C=O bond of the carboxylic group and proceeding anti-clockwise through the ring. c Fermi interaction with 2 × δ(OCO).