Chemistry Reference
In-Depth Information
Table 21 Symmetry analysis of the twisted to
syn
-folded conformational isomerization
Permutation-inversion operators
E
, (18)(1
0
8
0
), (11
0
)(88
0
)(99
0
), (18
0
)(81
0
)(99
0
)
Symmetry operators of t-
D
2
E
, (18
0
)(81
0
)(99
0
), (18)(1
0
8
0
)*, (11
0
)(88
0
)(99
0
)*
Symmetry operators of s-
C
2v
(x)
E
, (18
0
)(81
0
)(99
0
)
Largest common subgroup
Table 22 Possible point groups and conformations of the transition state for interconversion of
the t-
D
2
twisted and the s-
C
2v
(
x
)
syn
-folded conformations
Group of permutation-inversion operators
a
b
TS
h
TS
n
TS
{
E
, (18
0
)(81
0
)(99
0
)}
st-
C
2
(
x
)
2
8
C
2
(
x
) A
{
E
}
ft-
C
1
1
16
C
1
A
a
Point group symmetry along pathway from transition state to reactant or product, i.e., maximum
common subgroup of transition state and reactant or product
b
Symmetry species of the mode of the transition vector (using the conventional setting of the
transition state point group [
279
])
Fig. 37 Schematic
mechanism for the
interconversion of the t-
D
2
twisted and s-
C
2v
(
x
)
syn
-
folded conformations via a
transition state st-
C
2
(
x
)
1
1'
1
1'
1'
st
Z-RPS'
st
Z-RMS'
1
s
Z-RS'
1'
1
1'
1
t
Z-P
t
Z-M
1
1'
1'
1
1
1'
st
st
s
Z-SR'
Z-SPR'
Z-SMR'
1
1'
1'
1
1'
st
st
E-RMR'
E-RPR'
1
s
E-RR'
1
1'
1
1'
t
t
E-P
E-M
1
1
1'
1'
1
1'
st
s
st
E-SMS'
E-SPS'
E-SS'
conformations or as a two-step conformational inversion mechanism of the
syn
-
folded conformations. In Figs.
37
and
38
, enantiomeric versions of the conforma-
tions and transition states are found on opposite sides.
E
- and
Z
-configurations are
not interconverted.
