## 1-dehydro-butane cation, CH3CH2CH2CH2+ (*see note)

 H5 H4 \ | H13 C3 \ / | H11 C1 - C2 | / | | \ H9 - C8 H12 H7 H6 \ H10
The ion charge is 1.

## Atomic Charges and Dipole Moment

C1 charge=-0.091
C2 charge=-0.131
C3 charge=-0.053
H4 charge= 0.185
H5 charge= 0.197
H6 charge= 0.198
H7 charge= 0.188
C8 charge=-0.396
H9 charge= 0.189
H10 charge= 0.168
H11 charge= 0.160
H12 charge= 0.198
H13 charge= 0.186
with a dipole moment of 4.18068 Debye

## Bond Lengths:

between C1 and C2: distance=1.731 ang___ between C1 and C3: distance=1.827 ang___
between C1 and C8: distance=1.525 ang___ between C1 and H12: distance=1.107 ang___
between C1 and H13: distance=1.120 ang___ between C2 and C3: distance=1.405 ang___
between C2 and H6: distance=1.096 ang___ between C2 and H7: distance=1.096 ang___
between C3 and H4: distance=1.098 ang___ between C3 and H5: distance=1.097 ang___
between C3 and H13: distance=1.931 ang___ between C8 and H9: distance=1.103 ang___
between C8 and H10: distance=1.100 ang___ between C8 and H11: distance=1.103 ang___

## Bond Angles:

for C3-C1-C2: angle=46.42 deg___ for H4-C3-C1: angle=111.7 deg___
for H5-C3-C1: angle=103.7 deg___ for H6-C2-C1: angle=105.4 deg___
for H7-C2-C1: angle=111.6 deg___ for C8-C1-C2: angle=113.2 deg___
for H9-C8-C1: angle=108.6 deg___ for H10-C8-C1: angle=111.9 deg___
for H11-C8-C1: angle=112.4 deg___ for H12-C1-C2: angle=93.65 deg___
for H13-C1-C2: angle=119.9 deg___

## Bond Orders (Mulliken):

between C1 and C2: order=0.389___ between C1 and C3: order=0.324___
between C1 and C8: order=0.915___ between C1 and H12: order=0.895___
between C1 and H13: order=0.837___ between C2 and C3: order=1.020___
between C2 and H6: order=0.962___ between C2 and H7: order=0.966___
between C3 and H4: order=0.961___ between C3 and H5: order=0.940___
between C3 and H13: order=0.090___ between C8 and H9: order=0.965___
between C8 and H10: order=0.963___ between C8 and H11: order=0.945___

## Best Lewis Structure

The Lewis structure that is closest to your structure is determined. The hybridization of the atoms in this idealized Lewis structure is given in the table below. Please note that your structure can't be well described by a single Lewis structure, because of extensive delocalization.

### Hybridization in the Best Lewis Structure

1. A bonding orbital for C1-C2 with 1.6274 electrons
__has 54.19% C 1 character in a s0.75 p3 hybrid
__has 45.81% C 2 character in a s0.51 p3 hybrid

2. A bonding orbital for C1-C8 with 1.9911 electrons
__has 54.65% C 1 character in a sp2.08 hybrid
__has 45.35% C 8 character in a sp2.65 hybrid

3. A bonding orbital for C1-H12 with 1.9174 electrons
__has 63.64% C 1 character in a s0.60 p3 hybrid
__has 36.36% H12 character in a s orbital

4. A bonding orbital for C1-H13 with 1.8626 electrons
__has 63.24% C 1 character in a sp2.22 hybrid
__has 36.76% H13 character in a s orbital

5. A bonding orbital for C2-C3 with 1.9939 electrons
__has 49.79% C 2 character in a sp2.23 hybrid
__has 50.21% C 3 character in a sp2.10 hybrid

6. A bonding orbital for C2-H6 with 1.9744 electrons
__has 63.04% C 2 character in a sp2.77 hybrid
__has 36.96% H 6 character in a s orbital

7. A bonding orbital for C2-H7 with 1.9864 electrons
__has 62.83% C 2 character in a sp2.57 hybrid
__has 37.17% H 7 character in a s orbital

8. A bonding orbital for C3-H4 with 1.9907 electrons
__has 62.70% C 3 character in a sp2.23 hybrid
__has 37.30% H 4 character in a s orbital

9. A bonding orbital for C3-H5 with 1.9866 electrons
__has 62.81% C 3 character in a sp2.21 hybrid
__has 37.19% H 5 character in a s orbital

10. A bonding orbital for C8-H9 with 1.9821 electrons
__has 61.64% C 8 character in a s0.94 p3 hybrid
__has 38.36% H 9 character in a s orbital

11. A bonding orbital for C8-H10 with 1.9914 electrons
__has 60.88% C 8 character in a s0.97 p3 hybrid
__has 39.12% H10 character in a s orbital

12. A bonding orbital for C8-H11 with 1.9900 electrons
__has 60.53% C 8 character in a s0.96 p3 hybrid
__has 39.47% H11 character in a s orbital

17. A lone pair orbital for C3 with 0.5627 electrons
__made from a s0.18 p3 hybrid

-With core pairs on: C 1 C 2 C 3 C 8 -

#### Donor Acceptor Interactions in the Best Lewis Structure

The localized orbitals in your best Lewis structure can interact strongly. A filled bonding or lone pair orbital can act as a donor and an empty or filled bonding, antibonding, or lone pair orbital can act as an acceptor. These interactions can strengthen and weaken bonds. For example, a lone pair donor->antibonding acceptor orbital interaction will weaken the bond associated with the antibonding orbital. Conversly, an interaction with a bonding pair as the acceptor will strengthen the bond. Strong electron delocalization in your best Lewis structure will also show up as donor-acceptor interactions.
Interactions greater than 20 kJ/mol for bonding and lone pair orbitals are listed below.

The interaction of bonding donor orbital, 1, for C1-C2 with the lone pair acceptor orbital, 17, for C3 is 1028 kJ/mol.

The interaction of bonding donor orbital, 3, for C1-H12 with the lone pair acceptor orbital, 17, for C3 is 31.0 kJ/mol.

The interaction of bonding donor orbital, 4, for C1-H13 with the lone pair acceptor orbital, 17, for C3 is 363. kJ/mol.

The interaction of bonding donor orbital, 5, for C2-C3 with the lone pair acceptor orbital, 17, for C3 is 69.2 kJ/mol.

The interaction of bonding donor orbital, 10, for C8-H9 with the antibonding acceptor orbital, 139, for C1-C2 is 22.4 kJ/mol.

The interaction of lone pair donor orbital, 17, for C3 with the antibonding acceptor orbital, 142, for C1-H13 is 20.0 kJ/mol.

The interaction of lone pair donor orbital, 17, for C3 with the antibonding acceptor orbital, 143, for C2-C3 is 25.9 kJ/mol.

## Molecular Orbital Energies

The orbital energies are given in eV, where 1 eV=96.49 kJ/mol. Orbitals with very low energy are core 1s orbitals. More antibonding orbitals than you might expect are sometimes listed, because d orbitals are always included for heavy atoms and p orbitals are included for H atoms. Up spins are shown with a ^ and down spins are shown as v.

20 ----- -3.773

19 ----- -3.894

18 ----- -5.450

17 ----- -7.899

16 -^-v- -13.82

15 -^-v- -14.02

14 -^-v- -15.04

13 -^-v- -15.32

12 -^-v- -15.68

11 -^-v- -16.64

10 -^-v- -17.37

9 -^-v- -18.35

8 -^-v- -20.80

7 -^-v- -21.20

6 -^-v- -23.62

5 -^-v- -27.48

4 -^-v- -271.3

3 -^-v- -273.4

2 -^-v- -273.8

1 -^-v- -274.0

## Total Electronic Energy

The total electronic energy is a very large number, so by convention the units are given in atomic units, that is Hartrees (H). One Hartree is 2625.5 kJ/mol. The energy reference is for totally dissociated atoms. In other words, the reference state is a gas consisting of nuclei and electrons all at infinite distance from each other. The electronic energy includes all electric interactions and the kinetic energy of the electrons. This energy does not include translation, rotation, or vibration of the the molecule.

Total electronic energy = -157.5537861409 Hartrees

* Linear butyl cation rearranges easily to this cyclic cation or the 2-dehydro-butane cation, which is lower in energy. The linear cation cannot be obtained by minimization procedures using LSDA/DFT or ab initio theory. However, the B3LYP energies from Gaussian98 are: linear -156.6265915 H and cyclic -156.6581973 H. Because two of the C-C bond orders in the ring are so small, and the corresponding bond lengths are so long, it is difficult to decide whether this is a very distorted conformer of 1-dehydro-butane cation or a complex of ethyl cation with ethylene.