136
6 Equilibrium Structures from Spectroscopy
Fig. 6.1 Plot of the variation of ε as a function of I 0 with isotopic substitution ( 79 Br → 81 Br)
for seventeen diatomic molecules going from the light DBr (I 0 = 3.9 uÅ 2 ) to the heavy CsBr
(I 0 = 476.4 uÅ 2 ), all values in uÅ 2 . Reproduced from Journal of Molecular Spectroscopy, 215.
Demaison J, Rudolph HD. When is the substitution structure not reliable? 78–84. Copyright 2002,
with permission from Elsevier
et al. 2017). The Cartesian and internal coordinates of equatorial fluorocyclohexane
are also compared in Table 6.3 whose inspection confirms the poor accuracy of the
r s structure.
Table 6.3 Comparison of the r s structure and the semiexperimental equilibrium structure for
equatorial fluorocyclohexane a
Cartesian coordinates b (Å)
a s
a e
b s
b e
c s
c e
C1
−0.9270(16) −0.92971(27) i c
0
0.3308(45)
0.32898(37)
C2
−0.2839(63) −0.25583(69) 1.2579(12) 1.25371(13) −0.1784(84) −0.18171(66)
C3
1.2239(12)
1.22310(19) 1.2615(12) 1.25710(11)
0.2124(71)
0.21498(41)
C4
1.9336(8)
1.92679(14) i c
0
−0.2885(52) −0.28680(51)
Internal coordinates (distances in pm and angles in degree)
r s
r e
r s
r e
C1C2 152.16(44)
151.22(4)
C1C2C3
110.64(36)
110.17(3)
C2C3 151.42(68)
153.12(7)
C2C3C4
111.18(29)
111.01(2)
C3C4 153.17(31)
152.55(3)
C1C2C3C4
55.89(70)
55.99(5)
Reproduced from Physical Chemistry, Chemical Physics; Juanes M, Vogt N, Demaison J, León I,
Lesarri A, Rudolph HD; Axial–equatorial isomerism and semiexperimental equilibrium structures
of fluorocyclohexane (2017) 19: 29162–29169, with permission from the PCCP Owner Societies
a Juanes et al. (2017)
b The uncertainty is calculated with Costain’s rule, δz = 0.0015/|z|
c Imaginary coordinate
6 Equilibrium Structures from Spectroscopy
Fig. 6.1 Plot of the variation of ε as a function of I 0 with isotopic substitution ( 79 Br → 81 Br)
for seventeen diatomic molecules going from the light DBr (I 0 = 3.9 uÅ 2 ) to the heavy CsBr
(I 0 = 476.4 uÅ 2 ), all values in uÅ 2 . Reproduced from Journal of Molecular Spectroscopy, 215.
Demaison J, Rudolph HD. When is the substitution structure not reliable? 78–84. Copyright 2002,
with permission from Elsevier
et al. 2017). The Cartesian and internal coordinates of equatorial fluorocyclohexane
are also compared in Table 6.3 whose inspection confirms the poor accuracy of the
r s structure.
Table 6.3 Comparison of the r s structure and the semiexperimental equilibrium structure for
equatorial fluorocyclohexane a
Cartesian coordinates b (Å)
a s
a e
b s
b e
c s
c e
C1
−0.9270(16) −0.92971(27) i c
0
0.3308(45)
0.32898(37)
C2
−0.2839(63) −0.25583(69) 1.2579(12) 1.25371(13) −0.1784(84) −0.18171(66)
C3
1.2239(12)
1.22310(19) 1.2615(12) 1.25710(11)
0.2124(71)
0.21498(41)
C4
1.9336(8)
1.92679(14) i c
0
−0.2885(52) −0.28680(51)
Internal coordinates (distances in pm and angles in degree)
r s
r e
r s
r e
C1C2 152.16(44)
151.22(4)
C1C2C3
110.64(36)
110.17(3)
C2C3 151.42(68)
153.12(7)
C2C3C4
111.18(29)
111.01(2)
C3C4 153.17(31)
152.55(3)
C1C2C3C4
55.89(70)
55.99(5)
Reproduced from Physical Chemistry, Chemical Physics; Juanes M, Vogt N, Demaison J, León I,
Lesarri A, Rudolph HD; Axial–equatorial isomerism and semiexperimental equilibrium structures
of fluorocyclohexane (2017) 19: 29162–29169, with permission from the PCCP Owner Societies
a Juanes et al. (2017)
b The uncertainty is calculated with Costain’s rule, δz = 0.0015/|z|
c Imaginary coordinate