## O=COO-2, carbon dioxide peroxide dianion

 O4 - C3 \ O1 - O2
The ion charge is -2.

## Atomic Charges and Dipole Moment

O1 charge= 0.045
O2 charge=-0.920
C3 charge=-0.531
O4 charge=-0.593
with a dipole moment of 2.09746 Debye

## Bond Lengths:

between O1 and O2: distance=1.531 ang___ between O1 and C3: distance=1.424 ang___
between O1 and O4: distance=2.186 ang___ between C3 and O4: distance=1.302 ang___

## Bond Angles:

for C3-O1-O2: angle=117.6 deg___ for O4-O1-O2: angle=152.4 deg___

## Bond Orders (Mulliken):

between O1 and O2: order=0.564___ between O1 and C3: order=0.636___
between O1 and O4: order=-0.104___ between C3 and O4: order=0.828___

## 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 O1-O2 with 1.9882 electrons
__has 63.16% O 1 character in a s0.60 p3 hybrid
__has 36.84% O 2 character in a s0.22 p3 hybrid

2. A bonding orbital for O1-C3 with 1.9930 electrons
__has 72.33% O 1 character in a sp2.27 hybrid
__has 27.67% C 3 character in a s0.71 p3 hybrid

3. A bonding orbital for C3-O4 with 1.9987 electrons
__has 16.27% C 3 character in a p-pi orbital ( 99.10% p 0.90% d)
__has 83.73% O 4 character in a p-pi orbital ( 99.91% p 0.09% d)

4. A bonding orbital for C3-O4 with 1.9929 electrons
__has 31.32% C 3 character in a sp2.59 hybrid
__has 68.68% O 4 character in a sp1.72 hybrid

9. A lone pair orbital for O1 with 1.9834 electrons

10. A lone pair orbital for O1 with 1.8725 electrons
__made from a p-pi orbital ( 99.97% p)

11. A lone pair orbital for O2 with 1.9979 electrons

12. A lone pair orbital for O2 with 1.9938 electrons
__made from a p-pi orbital (100.00% p)

13. A lone pair orbital for O2 with 1.9897 electrons
__made from a s0.77 p3 hybrid

14. A lone pair orbital for C3 with 1.9927 electrons

15. A lone pair orbital for O4 with 1.9858 electrons

16. A lone pair orbital for O4 with 1.9264 electrons

95. A antibonding orbital for C3-O4 with 0.1242 electrons
__has 83.73% C 3 character in a p-pi orbital ( 99.10% p 0.90% d)
__has 16.27% O 4 character in a p-pi orbital ( 99.91% p 0.09% d)

-With core pairs on: O 1 O 2 C 3 O 4 -

#### 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 the second lone pair donor orbital, 10, for O1 with the antibonding acceptor orbital, 95, for C3-O4 is 221. kJ/mol.

The interaction of the third lone pair donor orbital, 13, for O2 with the antibonding acceptor orbital, 94, for O1-C3 is 21.5 kJ/mol.

The interaction of the second lone pair donor orbital, 16, for O4 with the antibonding acceptor orbital, 94, for O1-C3 is 109. 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 ----- 13.97
19 ----- 13.60

18 ----- 10.97
17 ----- 10.62

16 -^-v- 7.507
15 -^-v- 7.374
14 -^-v- 6.869

13 -^-v- 4.415
12 -^-v- 4.241

11 -^-v- 2.056
10 -^-v- 1.971

9 -^-v- 1.317

8 -^-v- -0.898

7 -^-v- -7.475

6 -^-v- -12.06

5 -^-v- -14.05

4 -^-v- -256.0

3 -^-v- -493.2

2 -^-v- -493.9

1 -^-v- -495.6

## 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 = -263.6048263703 Hartrees