## cis-formic acid, HCOOH (*see note)

 O3 O5 \\ / \ C1 H2 | H4
Tell me about the atomic charges, dipole moment, bond lengths, angles, bond orders,
molecular orbital energies, or total energy.
Tell me about the best Lewis structure.

## Atomic Charges and Dipole Moment

C1 charge= 0.520
H2 charge= 0.389
O3 charge=-0.426
H4 charge= 0.013
O5 charge=-0.496
with a dipole moment of 4.12493 Debye

## Bond Lengths:

between C1 and O3: distance=1.210 ang___ between C1 and H4: distance=1.117 ang___
between C1 and O5: distance=1.372 ang___ between H2 and O5: distance=0.980 ang___
between O3 and O5: distance=2.261 ang___ between H4 and O5: distance=2.086 ang___

## Bond Angles:

for O3-C1-H2: angle=150.7 deg___ for H4-C1-H2: angle=84.95 deg___
for O5-H2-C1: angle=42.11 deg___

## Bond Orders (Mulliken):

between C1 and O3: order=2.016___ between C1 and H4: order=0.968___
between C1 and O5: order=1.014___ between H2 and O5: order=0.841___
between O3 and O5: order=-0.168___ between H4 and O5: order=-0.065___

## 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-O3 with 1.9986 electrons
__has 28.39% C 1 character in a p-pi orbital ( 99.38% p 0.62% d)
__has 71.61% O 3 character in a p-pi orbital ( 99.80% p 0.20% d)

2. A bonding orbital for C1-O3 with 1.9982 electrons
__has 35.50% C 1 character in a sp1.69 hybrid
__has 64.50% O 3 character in a sp1.54 hybrid

3. A bonding orbital for C1-H4 with 1.9898 electrons
__has 56.21% C 1 character in a sp1.95 hybrid
__has 43.79% H 4 character in a s orbital

4. A bonding orbital for C1-O5 with 1.9959 electrons
__has 32.23% C 1 character in a sp2.35 hybrid
__has 67.77% O 5 character in a sp2.31 hybrid

5. A bonding orbital for H2-O5 with 1.9888 electrons
__has 25.84% H 2 character in a s orbital
__has 74.16% O 5 character in a s0.83 p3 hybrid

9. A lone pair orbital for O3 with 1.9833 electrons

10. A lone pair orbital for O3 with 1.8707 electrons

11. A lone pair orbital for O5 with 1.9851 electrons

12. A lone pair orbital for O5 with 1.8812 electrons
__made from a p-pi orbital ( 99.93% p 0.07% d)

80. A antibonding orbital for C1-O3 with 0.1129 electrons
__has 71.61% C 1 character in a p-pi orbital ( 99.38% p 0.62% d)
__has 28.39% O 3 character in a p-pi orbital ( 99.80% p 0.20% d)

-With core pairs on: C 1 O 3 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, 5, for H2-O5 with the second antibonding acceptor orbital, 81, for C1-O3 is 25.4 kJ/mol.

The interaction of the second lone pair donor orbital, 10, for O3 with the antibonding acceptor orbital, 82, for C1-H4 is 121. kJ/mol.

The interaction of the second lone pair donor orbital, 10, for O3 with the antibonding acceptor orbital, 83, for C1-O5 is 177. kJ/mol.

The interaction of the second lone pair donor orbital, 12, for O5 with the antibonding acceptor orbital, 80, for C1-O3 is 224. 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.

16 ----- 3.631

15 ----- 1.647

14 ----- 0.081

13 ----- -1.856

12 -^-v- -6.973

11 -^-v- -8.300

10 -^-v- -9.882

9 -^-v- -11.21
8 -^-v- -11.23

7 -^-v- -14.49

6 -^-v- -16.02

5 -^-v- -25.81

4 -^-v- -27.75

3 -^-v- -270.1

2 -^-v- -506.7

1 -^-v- -508.2

## 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 = -189.8354660635 Hartrees

*Note: The trans-formic acid rotamer is lower in energy.