## BrF4-, bromine tetrafluoride anion

 F3 | F5 - BR1 - F2 | F4
The ion charge is -1.

## Atomic Charges and Dipole Moment

BR1 charge= 0.522
F2 charge=-0.380
F3 charge=-0.380
F4 charge=-0.380
F5 charge=-0.380
with a dipole moment of 0.00187 Debye

## Bond Lengths:

between BR1 and F2: distance=2.017 ang___ between BR1 and F3: distance=2.015 ang___
between BR1 and F4: distance=2.015 ang___ between BR1 and F5: distance=2.017 ang___

## Bond Angles:

for F3-BR1-F2: angle=90.84 deg___ for F4-BR1-F2: angle=89.20 deg___
for F5-BR1-F2: angle=179.9 deg___

## Bond Orders (Mulliken):

between BR1 and F2: order=0.520___ between BR1 and F3: order=0.520___
between BR1 and F4: order=0.521___ between BR1 and F5: order=0.520___

## 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 Br1-F2 with 1.9991 electrons
__has 18.83% Br 1 character in a p3 d0.07 hybrid
__has 81.17% F 2 character in a s0.26 p3 hybrid

2. A bonding orbital for Br1-F4 with 1.9991 electrons
__has 18.83% Br 1 character in a p3 d0.07 hybrid
__has 81.17% F 4 character in a s0.26 p3 hybrid

21. A lone pair orbital for Br1 with 1.9991 electrons
__made from a p-pi orbital (100.00% p)

22. A lone pair orbital for Br1 with 1.9987 electrons

23. A lone pair orbital for F2 with 1.9991 electrons

24. A lone pair orbital for F2 with 1.9987 electrons
__made from a p-pi orbital ( 99.98% p)

25. A lone pair orbital for F2 with 1.9860 electrons

26. A lone pair orbital for F3 with 1.9991 electrons

27. A lone pair orbital for F3 with 1.9987 electrons
__made from a p-pi orbital ( 99.98% p)

28. A lone pair orbital for F3 with 1.9858 electrons

29. A lone pair orbital for F3 with 1.6800 electrons
__made from a s0.26 p3 hybrid

30. A lone pair orbital for F4 with 1.9991 electrons

31. A lone pair orbital for F4 with 1.9987 electrons
__made from a p-pi orbital ( 99.98% p)

32. A lone pair orbital for F4 with 1.9859 electrons

33. A lone pair orbital for F5 with 1.9991 electrons

34. A lone pair orbital for F5 with 1.9987 electrons
__made from a p-pi orbital ( 99.98% p)

35. A lone pair orbital for F5 with 1.9860 electrons

36. A lone pair orbital for F5 with 1.6798 electrons
__made from a s0.26 p3 hybrid

109. A antibonding orbital for Br1-F2 with 0.3039 electrons
__has 81.17% Br 1 character in a p3 d0.07 hybrid
__has 18.83% F 2 character in a s0.26 p3 hybrid

110. A antibonding orbital for Br1-F4 with 0.3033 electrons
__has 81.17% Br 1 character in a p3 d0.07 hybrid
__has 18.83% F 4 character in a s0.26 p3 hybrid

-With core pairs on:Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 Br 1 F 2 F 3 F 4 F 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 the third lone pair donor orbital, 25, for F2 with the antibonding acceptor orbital, 110, for Br1-F4 is 21.2 kJ/mol.

The interaction of the third lone pair donor orbital, 32, for F4 with the antibonding acceptor orbital, 109, for Br1-F2 is 21.3 kJ/mol.

The interaction of lone pair donor orbital, 26, for F3 with the antibonding acceptor orbital, 110, for Br1-F4 is 50.5 kJ/mol.

The interaction of the third lone pair donor orbital, 28, for F3 with the antibonding acceptor orbital, 109, for Br1-F2 is 21.5 kJ/mol.

The interaction of 4th lone pair donor orbital, 29, for F3 with the antibonding acceptor orbital, 110, for Br1-F4 is 607. kJ/mol.

The interaction of lone pair donor orbital, 33, for F5 with the antibonding acceptor orbital, 109, for Br1-F2 is 50.2 kJ/mol.

The interaction of the third lone pair donor orbital, 35, for F5 with the antibonding acceptor orbital, 110, for Br1-F4 is 21.3 kJ/mol.

The interaction of 4th lone pair donor orbital, 36, for F5 with the antibonding acceptor orbital, 109, for Br1-F2 is 606. 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.

40 ----- 10.12 39 ----- 10.11

38 ----- 0.658

37 ----- 0.579

36 -^-v- -2.377

35 -^-v- -3.530

34 -^-v- -3.671

33 -^-v- -3.852
32 -^-v- -3.929
31 -^-v- -3.970

30 -^-v- -4.087
29 -^-v- -4.103

28 -^-v- -4.649

27 -^-v- -5.049

26 -^-v- -5.812

25 -^-v- -7.813
24 -^-v- -7.844

23 -^-v- -16.17

22 -^-v- -22.37

21 -^-v- -22.63
20 -^-v- -22.65

19 -^-v- -23.29

18 -^-v- -67.28

17 -^-v- -67.44 16 -^-v- -67.45

15 -^-v- -67.96
14 -^-v- -67.98

13 -^-v- -170.3

12 -^-v- -171.1
11 -^-v- -171.1

10 -^-v- -228.1

9 -^-v- -649.9 8 -^-v- -649.9 7 -^-v- -649.9 6 -^-v- -649.9

5 -^-v- -1516.
4 -^-v- -1517.
3 -^-v- -1517.

2 -^-v- -1680.

1 -^-v- -13067

## 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 = -2973.5075277932 Hartrees