Table 1 The stretching vibrations in cm-1

Table 1 The stretching vibrations in cm^-1

	gas				CHCl₃
conformers	νes(CO)	νcar(CO)	νs(N1H)	νas(N3H)	νes(CO)	νcar(CO)	νs(N1H)	νas(N3H)
2-CF3_cis_anti_anti	1775,5	1835,0	3641,4	3623,8	1773,4	1828,6	3644,4	3623,5
2-CF3_cis_anti_syn	1771,0	1834,3	3631,4^a	3626,1^a	1770,8	1826,1	3633,5^a	3627,6^a
2-CF3_cis_syn_anti	1769,3	1838,3	3640,8	3626,0	1768,6	1828,4	3645,7	3626,7
2-CF3_cis_syn_syn	1771,3	1834,2	3632,7^a	3626,0^a
2-CF3_trans_anti_anti	1754,9	1838,5	3643,5	3628,4
2-CF3_trans_anti_syn	1763,5	1834,6	3632,7^a	3629,3^a
2-CF3_trans_syn_anti	1754,3	1838,7	3643,0	3627,1
2-CF3_trans_syn_syn	1763,0	1834,6	3633,7^a	3631,9^a

3-CF3_cis_anti_anti	1772,0	1835,3	3632,7	3611,2
3-CF3_cis_anti_syn	1772,5	1834,5	3632,6	3615,4
3-CF3_cis_syn_anti	1772,4	1835,2	3631,6	3613,4
3-CF3_cis_syn_syn	1771,9	1834,3	3632,5	3614,5
3-CF3_trans_anti_anti	1750,9	1835,7	3632,2	3614,8
3-CF3_trans_anti_syn	1747,3	1831,9	3627,5	3611,9
3-CF3_trans_syn_anti	1747,6	1834,7	3630,2	3611,6
3-CF3_trans_syn_syn	1747,4	1831,9	3628,8	3611,5
associate^b	1698,9	1763,0	3493,6^c	3568,3^c
dimer	1796,8^d	1784,6^d	3275,6^d	3631,4^d
dimer	1802,0^e	1788,5^e	3315,7^e	3631,4^e

cis or trans refers to the s-cis or s-trans orientation of C=O with respect to C5=C6, syn_anti refers to the syn orientation of CH₃ group and anti orientation of CF₃ group relative to the C4-H4 bond, respectively

^a stronger vibrational coupling of NH stretching vibrations

^b calculation with B3LYP/3-21G

^c significant difference between ν_s(N1H) and ν_as(N3H) is due to the hydrogen bonding

N1H …Cl-CCl₂H

^d A_g symmetry

^eA_u symmetry