## Al(OH)4-, Tetrahydroxoaluminate ion

 H4 | H9 O3 \ / O1 - AL2 - O7 - H8 \ O5 - H6
The ion charge is -1.

## Atomic Charges and Dipole Moment

O1 charge=-0.909
AL2 charge= 1.337
O3 charge=-0.908
H4 charge= 0.324
O5 charge=-0.909
H6 charge= 0.324
O7 charge=-0.910
H8 charge= 0.326
H9 charge= 0.325
with a dipole moment of 8.38767 Debye

## Bond Lengths:

between O1 and AL2: distance=1.820 ang___ between O1 and H9: distance=0.972 ang___
between AL2 and O3: distance=1.821 ang___ between AL2 and O5: distance=1.821 ang___
between AL2 and O7: distance=1.817 ang___ between O3 and H4: distance=0.971 ang___
between O5 and H6: distance=0.972 ang___ between O7 and H8: distance=0.972 ang___

## Bond Angles:

for O3-AL2-O1: angle=112.2 deg___ for H4-O3-AL2: angle=110.6 deg___
for O5-AL2-O1: angle=104.1 deg___ for H6-O5-AL2: angle=109.7 deg___
for O7-AL2-O1: angle=112.2 deg___ for H8-O7-AL2: angle=109.8 deg___
for H9-O1-AL2: angle=109.6 deg___

## Bond Orders (Mulliken):

between O1 and AL2: order=0.702___ between O1 and H9: order=0.895___
between AL2 and O3: order=0.698___ between AL2 and O5: order=0.702___
between AL2 and O7: order=0.704___ between O3 and H4: order=0.895___
between O5 and H6: order=0.895___ between O7 and H8: order=0.895___

## 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 O1-Al2 with 1.9892 electrons
__has 91.59% O 1 character in a sp1.33 hybrid
__has 8.41% Al 2 character in a sp2.91 d0.07 hybrid

2. A bonding orbital for O1-H9 with 1.9923 electrons
__has 72.01% O 1 character in a s0.69 p3 hybrid
__has 27.99% H 9 character in a s orbital

3. A bonding orbital for Al2-O3 with 1.9893 electrons
__has 8.42% Al 2 character in a sp2.93 d0.07 hybrid
__has 91.58% O 3 character in a sp1.33 hybrid

4. A bonding orbital for Al2-O5 with 1.9892 electrons
__has 8.42% Al 2 character in a sp2.92 d0.07 hybrid
__has 91.58% O 5 character in a sp1.34 hybrid

5. A bonding orbital for Al2-O7 with 1.9892 electrons
__has 8.40% Al 2 character in a sp2.91 d0.07 hybrid
__has 91.60% O 7 character in a sp1.32 hybrid

6. A bonding orbital for O3-H4 with 1.9925 electrons
__has 72.03% O 3 character in a s0.70 p3 hybrid
__has 27.97% H 4 character in a s orbital

7. A bonding orbital for O5-H6 with 1.9923 electrons
__has 72.01% O 5 character in a s0.69 p3 hybrid
__has 27.99% H 6 character in a s orbital

8. A bonding orbital for O7-H8 with 1.9923 electrons
__has 72.02% O 7 character in a s0.68 p3 hybrid
__has 27.98% H 8 character in a s orbital

18. A lone pair orbital for O1 with 1.9849 electrons

19. A lone pair orbital for O1 with 1.9723 electrons
__made from a p-pi orbital ( 99.97% p)

20. A lone pair orbital for O3 with 1.9848 electrons

21. A lone pair orbital for O3 with 1.9724 electrons
__made from a p-pi orbital ( 99.96% p)

22. A lone pair orbital for O5 with 1.9849 electrons

23. A lone pair orbital for O5 with 1.9723 electrons

24. A lone pair orbital for O7 with 1.9849 electrons

25. A lone pair orbital for O7 with 1.9722 electrons
__made from a p-pi orbital ( 99.97% p)

-With core pairs on: O 1 Al 2 Al 2 Al 2 Al 2 Al 2 O 3 O 5 O 7 -

#### 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, 19, for O1 with the antibonding acceptor orbital, 146, for Al2-O3 is 21.7 kJ/mol.

The interaction of the second lone pair donor orbital, 19, for O1 with the antibonding acceptor orbital, 148, for Al2-O7 is 22.3 kJ/mol.

The interaction of the second lone pair donor orbital, 21, for O3 with the antibonding acceptor orbital, 144, for O1-Al2 is 22.3 kJ/mol.

The interaction of the second lone pair donor orbital, 21, for O3 with the antibonding acceptor orbital, 147, for Al2-O5 is 21.7 kJ/mol.

The interaction of the second lone pair donor orbital, 23, for O5 with the antibonding acceptor orbital, 146, for Al2-O3 is 22.4 kJ/mol.

The interaction of the second lone pair donor orbital, 23, for O5 with the antibonding acceptor orbital, 148, for Al2-O7 is 21.7 kJ/mol.

The interaction of the second lone pair donor orbital, 25, for O7 with the antibonding acceptor orbital, 144, for O1-Al2 is 22.0 kJ/mol.

The interaction of the second lone pair donor orbital, 25, for O7 with the antibonding acceptor orbital, 147, for Al2-O5 is 22.4 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.

29 ----- 5.716

28 ----- 4.593 27 ----- 4.587
26 ----- 4.275

25 -^-v- -1.216

24 -^-v- -1.617
23 -^-v- -1.630

22 -^-v- -2.006

21 -^-v- -2.108

20 -^-v- -2.916 19 -^-v- -2.920

18 -^-v- -3.484

17 -^-v- -5.403
16 -^-v- -5.414

15 -^-v- -6.433

14 -^-v- -6.855

13 -^-v- -18.08
12 -^-v- -18.10 11 -^-v- -18.11

10 -^-v- -18.49

9 -^-v- -62.93 8 -^-v- -62.93
7 -^-v- -62.97

6 -^-v- -100.1

5 -^-v- -500.4 4 -^-v- -500.4
3 -^-v- -500.4 2 -^-v- -500.4

1 -^-v- -1493.

## 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 = -546.1596131523 Hartrees