77665544

Inorganic Computation lab molecule report

NH₃ analysis

NH₃ details

heading	heading
Molecule name	NH3
Basis set	6-31G(d,p)
RMS gradient	0.00000485
Final energy	-56.55776873 a.u.
Point group	C3v

         Item               Value     Threshold  Converged?
 Maximum Force            0.000004     0.000450     YES
 RMS     Force            0.000004     0.000300     YES
 Maximum Displacement     0.000072     0.001800     YES
 RMS     Displacement     0.000035     0.001200     YES

NH3

Table showing vibrations

Vibrational questions

1) How many modes do you expect from the 3N-6 rule?
6
2)Which modes are degenerate?
2&3,5 & 6
3)Which modes are bending vibrations and which modes are bond stretch vibrations?
1,2 & 3 are bending vibrations whereas 4,5 & 6 are bond stretch vibrations
4) 4
5) one mode is known as the umbrella mode, which mode is this?
Mode 1
6) How many bands would you expect to see in an experimental spectrum of gaseous ammonia There are 6 modes but as 4 of them are degenerate, this gives 4 bands as there are 4 distinct frequencies.

Charge distribution for ammonia

The expectation for the charges on the nitrogen atom and the hydrogen atoms is that nitrogen would have the highest charge density, being more negative. This is because nitrogen is a more electronegative atom. The actual charges were that Nitrogen had a charge of: -1.125 and each hydrogen atom had a charge of: +0.375. 0.375*3 is +1.125. This means that overall ammonia is neutral.

N₂ and H₂ analysis

molecule name: N₂
Calculation method: B3LYP
Basis set: 6-31G(d,p)
RMS gradient: 0.00000060
Final energy: -109.52412868 a.u.
Point group: D_∞h

N₂ information

heading	heading
Molecule name	N2
Calculation method	B3LYP
Basis set	6-31G(d,p)
Final energy	-109.52412868 a.u.
Point group	D∞h

         Item               Value     Threshold  Converged?
 Maximum Force            0.000001     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000000     0.001800     YES
 RMS     Displacement     0.000000     0.001200     YES

test molecule

H₂ information

heading	heading
Molecule name	H2
Calculation method	B3LYP
Basis set	6-31G(d,p)
RMS gradient	0.00000017
Final energy	-1.17853936 a.u.
Point group	D∞h

         Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000450     YES
 RMS     Force            0.000000     0.000300     YES
 Maximum Displacement     0.000000     0.001800     YES
 RMS     Displacement     0.000001     0.001200     YES

test molecule

Energy calculations

In order to calculate the energy of the reaction, the following calculation can be used, using the stoichiometry from the overall equation.

E(NH3)= -56.55776873
2*E(NH3)= -113.1155375
E(N2)= -109.52412868
E(H2)= -1.17853936
3*E(H2)= -3.53561808
ΔE=2*E(NH3)-[E(N2)+3*E(H2)]= -0.05579074
All in atomic units.
In order to convert this answer from a.u. to kJ mol^-1 this value can be multiplied by 2625.5.
This gives a value of -146.48 kJ mol^-1.
As energy is released when this reaction takes place, this means that NH₃ has a lower energy than the two gaseous reactants, meaning that it is more stable.

BH₃ analysis

BH₃ Information

heading	heading
Molecule name	BH3
Calculation method	B3LYP
Basis set	6-31G(d,p)
RMS gradient	0.00305259
Final energy	-26.61511243 a.u.
Point group	D3h

         Item               Value     Threshold  Converged?
 Maximum Force            0.000004     0.000450     YES
 RMS     Force            0.000003     0.000300     YES
 Maximum Displacement     0.000017     0.001800     YES
 RMS     Displacement     0.000011     0.001200     YES

test molecule

Charges

The charges present on the hydrogen are -0.099 a.u. with 3 hydrogens present. This means that the charge on boron is +0.297. This means that hydrogen is more electronegative than boron.

Molecular orbitals of Borane

This is the 1s molecular orbital of borane which is only occupied by boron's electrons as it is too low in energy for there to be an interaction between the Hydrogen electrons. This is because it is embedded deep, close to the nucleus it is a very stable orbital, hence the low energy of -6.77140 .

This is the main bonding orbital in borane. This is the 2s MO. There is a large gap in energy between the 1s orbital. However, it is the lowest energy bonding orbital, meaning it is the lowest in energy. This implied that there is the largest contribution from the hydrogen 1s orbitals. There is an equal contribution from all 3 hydrogen 1s electrons. There is an energy of -0.51254.

This is the borane P x or y orbital. There is some bonding character taking place as there is overlap between the P orbital and the hydrogen 1s orbitals. However, there is more anti-bonding character due to the presence of a node. Potentially due to the orientation of the P orbitals, one of the hydrogen atoms doesn't contribute towards the MO.

This is the Pz orbital as there is lots of bonding character along the plane of the molecule. There is contribution from all of the hydrogen atoms. However, there is less bonding character and more anti-bonding character because of the presence node again. There is an energy of 0.35079 This is the same energy as the other P MO. This is because they both have the same amount of bonding overall, even considering the none bonding character from the H atom in the previous MO, the energy is still the same.

This is an empty P orbital as there is no distortion from the original "P orbital" shape and the node of the P orbital is where the plane of borane is. This means that this is a none bonding orbital and that there is no contribution from the hydrogen 1s electrons. This P orbital is now the LUMO in borane.

Cl₂ analysis

Cl₂ Information

heading	heading
Molecule name	Cl2
Calculation method	B3LYP
Basis set	6-31G(d,p)
RMS gradient	0.00002511
Final energy	-920.34987886
Point group	D∞h

         Item               Value     Threshold  Converged?
 Maximum Force            0.000043     0.000450     YES
 RMS     Force            0.000043     0.000300     YES
 Maximum Displacement     0.000121     0.001800     YES
 RMS     Displacement     0.000172     0.001200     YES