Level 1 – Case 15
102
E Ex xp pe er ri im me en nt ta al l D Da at ta a
1
Frontier molecular orbitals (FMO), energy levels, and atom coefficients in oxay
zoline N-oxide N N
1:
N
O
Me
Me
Me
E HOMO = -8.58 eV
E LUMO = +0.56 eV
+0.64
-0.31
-0.57
+0.36
+0.37
-0.59
+0.65
-0.18
O
N
O
Me
Me
Me
FMO, energy levels, and atom coefficients in trans-1-nitropropene 4
Me
N
O
O
Me
N
O
O
+0.55
E HOMO = -11.27 eV
+0.69
-0.03
-0.15
-0.19
E LUMO = -0.87 eV
-0.43
+0.63
-0.40
+0.33
+0.33
FMO, energy levels, and atom coefficients in trans-2-methyl butenoate 5:
Me
C
E HOMO = -10.51 eV
+0.67
+0.57
MeO
O
-0.02
-0.27
-0.10
Me
C
E LUMO = -0.01 eV
-0.48
+0.66
MeO
O
-0.40
+0.33
+0.16
D Di is sc cu us ss si io on n
R Re e e ea ac ct ti ti ti t ti ti t tiv vi vi vi v vi vi v vit ity ty ty y
Prior to discussing the reactivity of the dipolarophiles 4 and 5 towards 1,3-dipole
1, we have to determine which are the FMO involved in the [3+2] cycloaddition.
The pair of frontier orbitals to be considered are those that show the smaller
HOMO-LUMO energy gap. The relative disposition of the frontier orbitals for dipole 1 (HOMO = –8.58 eV; LUMO = +0.56 eV) and dipolarophiles 4 (HOMO =
–11.27 eV; LUMO = –0.87 eV) and 5 (HOMO = –10.51 eV; LUMO = –0.01 eV)
1 The calculations of the frontier molecular orbital (FMO), energies, and coefficients of the
reactants were performed at the RHF/AM1 level using the MOPAC program (Version
5.0).