## SiO42-, silicate dianion

 O3 \\ SI1 - O2 // \ | O4 O5
The ion charge is -2.

## Atomic Charges and Dipole Moment

SI1 charge= 1.440
O2 charge=-0.587
O3 charge=-1.133
O4 charge=-1.134
O5 charge=-0.586
with a dipole moment of 2.12300 Debye

## Bond Lengths:

between SI1 and O2: distance=1.780 ang___ between SI1 and O3: distance=1.617 ang___
between SI1 and O4: distance=1.617 ang___ between SI1 and O5: distance=1.778 ang___
between O2 and O3: distance=2.857 ang___ between O2 and O4: distance=2.870 ang___
between O2 and O5: distance=1.596 ang___ between O3 and O4: distance=2.857 ang___
between O3 and O5: distance=2.859 ang___ between O4 and O5: distance=2.863 ang___

## Bond Angles:

for O3-SI1-O2: angle=114.4 deg___ for O4-SI1-O2: angle=115.1 deg___
for O5-SI1-O2: angle=53.30 deg___

## Bond Orders (Mulliken):

between SI1 and O2: order=0.691___ between SI1 and O3: order=1.522___
between SI1 and O4: order=1.522___ between SI1 and O5: order=0.693___
between O2 and O3: order=-0.075___ between O2 and O4: order=-0.074___
between O2 and O5: order=0.757___ between O3 and O4: order=-0.105___
between O3 and O5: order=-0.075___ between O4 and O5: order=-0.074___

## 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.

### Hybridization in the Best Lewis Structure

1. A bonding orbital for Si1-O2 with 1.9378 electrons
__has 8.87% Si 1 character in a sp2.72 d1.87 hybrid
__has 91.13% O 2 character in a sp2.43 hybrid

2. A bonding orbital for Si1-O3 with 1.9902 electrons
__has 18.08% Si 1 character in a sp2.04 d0.05 hybrid
__has 81.92% O 3 character in a sp1.70 hybrid

3. A bonding orbital for Si1-O3 with 1.9586 electrons
__has 3.70% Si 1 character in a p1.15 d2 hybrid
__has 96.30% O 3 character in a p-pi orbital ( 99.95% p)

4. A bonding orbital for Si1-O4 with 1.9902 electrons
__has 18.11% Si 1 character in a sp2.04 d0.05 hybrid
__has 81.89% O 4 character in a sp1.71 hybrid

5. A bonding orbital for Si1-O4 with 1.9587 electrons
__has 3.70% Si 1 character in a p1.15 d2 hybrid
__has 96.30% O 4 character in a p-pi orbital ( 99.95% p)

6. A bonding orbital for Si1-O5 with 1.9382 electrons
__has 8.89% Si 1 character in a sp2.71 d1.85 hybrid
__has 91.11% O 5 character in a sp2.41 hybrid

7. A bonding orbital for O2-O5 with 1.9871 electrons
__has 49.99% O 2 character in a s0.14 p3 hybrid
__has 50.01% O 5 character in a s0.14 p3 hybrid

17. A lone pair orbital for O2 with 1.9923 electrons

18. A lone pair orbital for O2 with 1.9813 electrons
__made from a p-pi orbital ( 99.98% p)

19. A lone pair orbital for O3 with 1.9821 electrons

20. A lone pair orbital for O3 with 1.9278 electrons

21. A lone pair orbital for O4 with 1.9822 electrons

22. A lone pair orbital for O4 with 1.9276 electrons

23. A lone pair orbital for O5 with 1.9923 electrons

24. A lone pair orbital for O5 with 1.9812 electrons
__made from a p-pi orbital ( 99.98% p)

-With core pairs on:Si 1 Si 1 Si 1 Si 1 Si 1 O 2 O 3 O 4 O 5 -

#### 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 Si1-O2 with the second antibonding acceptor orbital, 123, for Si1-O3 is 56.6 kJ/mol.

The interaction of bonding donor orbital, 1, for Si1-O2 with the second antibonding acceptor orbital, 125, for Si1-O4 is 58.9 kJ/mol.

The interaction of bonding donor orbital, 1, for Si1-O2 with the antibonding acceptor orbital, 126, for Si1-O5 is 106. kJ/mol.

The interaction of the second bonding donor orbital, 3, for Si1-O3 with the antibonding acceptor orbital, 121, for Si1-O2 is 22.0 kJ/mol.

The interaction of the second bonding donor orbital, 3, for Si1-O3 with the second antibonding acceptor orbital, 125, for Si1-O4 is 49.7 kJ/mol.

The interaction of the second bonding donor orbital, 3, for Si1-O3 with the antibonding acceptor orbital, 126, for Si1-O5 is 22.8 kJ/mol.

The interaction of the second bonding donor orbital, 5, for Si1-O4 with the antibonding acceptor orbital, 121, for Si1-O2 is 23.1 kJ/mol.

The interaction of the second bonding donor orbital, 5, for Si1-O4 with the second antibonding acceptor orbital, 123, for Si1-O3 is 49.8 kJ/mol.

The interaction of the second bonding donor orbital, 5, for Si1-O4 with the antibonding acceptor orbital, 126, for Si1-O5 is 22.0 kJ/mol.

The interaction of bonding donor orbital, 6, for Si1-O5 with the antibonding acceptor orbital, 121, for Si1-O2 is 106. kJ/mol.

The interaction of bonding donor orbital, 6, for Si1-O5 with the second antibonding acceptor orbital, 123, for Si1-O3 is 58.6 kJ/mol.

The interaction of bonding donor orbital, 6, for Si1-O5 with the second antibonding acceptor orbital, 125, for Si1-O4 is 56.4 kJ/mol.

The interaction of the second lone pair donor orbital, 20, for O3 with the antibonding acceptor orbital, 121, for Si1-O2 is 27.3 kJ/mol.

The interaction of the second lone pair donor orbital, 20, for O3 with the antibonding acceptor orbital, 124, for Si1-O4 is 57.4 kJ/mol.

The interaction of the second lone pair donor orbital, 20, for O3 with the antibonding acceptor orbital, 126, for Si1-O5 is 26.8 kJ/mol.

The interaction of the second lone pair donor orbital, 22, for O4 with the antibonding acceptor orbital, 121, for Si1-O2 is 26.6 kJ/mol.

The interaction of the second lone pair donor orbital, 22, for O4 with the antibonding acceptor orbital, 122, for Si1-O3 is 57.1 kJ/mol.

The interaction of the second lone pair donor orbital, 22, for O4 with the antibonding acceptor orbital, 126, for Si1-O5 is 27.4 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.

28 ----- 11.99
27 ----- 10.79
26 ----- 10.06

25 ----- 7.584

24 -^-v- 5.123 23 -^-v- 5.117

22 -^-v- 4.307
21 -^-v- 4.257
20 -^-v- 4.146

19 -^-v- 3.189

18 -^-v- 2.451

17 -^-v- 1.993

16 -^-v- 1.318

15 -^-v- -0.091

14 -^-v- -0.941

13 -^-v- -9.657

12 -^-v- -10.38

11 -^-v- -11.00

10 -^-v- -15.35

9 -^-v- -83.55

8 -^-v- -83.69

7 -^-v- -83.86

6 -^-v- -126.0

5 -^-v- -493.8
4 -^-v- -493.8

3 -^-v- -496.6 2 -^-v- -496.6

1 -^-v- -1761.

## 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 = -590.5114340629 Hartrees