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NH3

Key information

Basic information
Name of the molecule NH3
Calculation method RB3LYP
Basis set 6-31G(d,p)
Final energy E in atomic units (a.u.) -56.55776873
RMS gradient (a.u.) 0.00000485
Point group C3v
Optimised N-H bond distance 1.02 ± 0.01Å
Optimised H-N-H bond angle 106 ± 1°


Item table

         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

The optimisation file is linked to here


Vibrations

Display vibration of NH3















Information of each vibration
Wavenumber /cm-1 symmetry intensity (arbitrary units) image
1090 A1 145
1694 E 14
1694 E 14
3461 A1 1
3590 E 0
3590 E 0


Questions relate to vibrations by their wavenumber

How many modes do you expect from the 3N-6 rule?

6 modes

Which modes are degenerate (ie have the same energy)?

Two modes have 1694cm-1 and the other two have 3590cm-1

Which modes are "bending" vibrations and which are "bond stretch" vibrations?

Bending vibrations: 1090 and 1694 cm-1

Bond stretch: 3461 and 3590 cm-1

Which mode is highly symmetric?

3461cm-1

One mode is known as the "umbrella" mode, which one is this?

1090cm-1

How many bands would you expect to see in an experimental spectrum of gaseous ammonia?

Two bands


Charge analysis

Charge on atoms
N-atom -1.125
H-atom 0.375

Because N is more eletronegative than H, so N is likely to have a negative charge and H is likely to have a positive charge.

N2

Key information

Basic information
Name of the molecule N2
Calculation method RB3LYP
Basis set 6-31G(d,p)
Final energy E in atomic units (a.u.) -109.52412868
RMS gradient (a.u.) 0.00000060
Point group D∞h
Optimised N-N bond distance 1.11 ± 0.01Å

N2 is a diatomic molecule, so no bond angle.

Item table

         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


N2

The optimisation file is linked to here


Vibrations

Display vibration of N2
















Information of each vibration
Wavenumber /cm-1 symmetry intensity (arbitrary units) image
2457 SGG 0

Charge analysis

Charge on atoms
N-atom 0.000
N-atom 0.000

N2 dosen't have dipole moment, so IR intensity is 0. It is a neutral molecule, so the charge on atoms are 0.

H2

Key information

Basic information
Name of the molecule H2
Calculation method RB3LYP
Basis set 6-31G(d,p)
Final energy E in atomic units (a.u.) -1.17853936
RMS gradient (a.u.) 0.00000017
Point group D∞h
Optimised H-H bond distance 0.74 ± 0.01Å

H2 is a diatomic molecule, so no bond angle.

Item table

         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


H2

The optimisation file is linked to here

Vibrations

Display vibration of H2















Information of each vibration
Wavenumber /cm-1 symmetry intensity (arbitrary units) image
4465 SGG 0

Charge analysis

Charge on atoms
H-atom 0.000
H-atom 0.000

H2 dosen't have dipole moment, so the IR intensity is 0. It is a neutral molecule, so the charge on atoms are 0.

Mono-metallic complex

AGISEP


Identifier of this mono-metalic complex: AGISEP (CCDC 704102)

The basic information of this mono-metalic complex is shown on this page:

[[1]]


This mono-metallic complex contains two N-N bonds, which are 1.136(3) Å and 1.139(3) Å. Both of them are slightly longer than the optimised N2 bond length (1.11 ± 0.01Å). That is due to some electrons on N in the mono-metallic complex are delocalised to the nearby bonds, and results in a longer bond length. N-N is likely to have a resonance form and obtains some double bond characters.

Futhermore, the optimised bond length is measured from a single N2 molecule in gas state, which means there is no external influences on the bond. However, the N-N bond length in mono-metallic compelx is measured in solid state.

Haber-Bosch process

N2 + 3H2 -> 2NH3


Energy for this process (in a.u.):

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)]= -113.1155375 - [(-109.52412868) + (-3.53561808)] = -0.05579074 = -146.5 kJ/mol

This reaction is a exothermic reaction, so ammonia product is more stable.


CH4

Key information

Basic information
Name of the molecule CH4
Calculation method RB3LYP
Basis set 6-31G(d,p)
Final energy E in atomic units (a.u.) -40.52401404
RMS gradient (a.u.) 0.00003263
Point group Td
Optimised C-H bond distance 1.09 ± 0.01Å
Optimised H-C-H bond angle 109 ± 1°


Item table

         Item               Value     Threshold  Converged?
 Maximum Force            0.000063     0.000450     YES
 RMS     Force            0.000034     0.000300     YES
 Maximum Displacement     0.000179     0.001800     YES
 RMS     Displacement     0.000095     0.001200     YES
CH4

The optimisation file is linked to here


Vibrations

Display vibration of CH4















Information of each vibration
Wavenumber /cm-1 symmetry intensity (arbitrary units) image
1356 T2 14
1356 T2 14
1356 T2 14
1578 E 0
1578 E 0
3046 A1 0
3162 T2 25
3162 T2 25
3162 T2 25

Charge analysis

Charge on atoms
C-atom -0.930
H-atom 0.233

Because C is more eletronegative than H, so carbon is likely to behave negatively and H is likely to have a positive charge instead.

Molecular orbital

Information of molecular orbitals
relative energy (a.u.) occupied/unoccupied molecular orbital other information image
-10.16707 occupied 1σ

in-phase overlap

non-bonding orbital

formed by 1s orbital in carbon

-0.69041 occupied 2σ

in-phase overlap

bonding orbital

formed by 1s orbital in hydrogen and 2p orbital in carbon

-0.38831 occupied 1π, HOMO

in-phase overlap

3 degenerate states

one node (because there is a change in colour)

bonding orbitals

formed by 1s orbital in hydrogen and 2s orbital in carbon

0.11824 unoccupied 3σ*,LUMO

out-of-phase overlap

two nodes (because there is a change in colour)

anti-bonding orbital

formed by 1s orbital in hydrogen and 2s orbital in carbon

0.17677 unoccupied 2π*

out-of-phase overlap

three degenerate states

one node (because there is a change in colour)

anti-bonding orbital

formed by 1s orbital in hydrogen and 2p orbital in carbon

Independence (HCN)

Key information

Basic information
Name of the molecule HCN
Calculation method RB3LYP
Basis set 6-31G(d,p)
Final energy E in atomic units (a.u.) -93.42458132
RMS gradient (a.u.) 0.00017006
Point group CV
Optimised C-H bond distance 1.07 ± 0.01Å
Optimised C-N bond distance 1.16 ± 0.01Å
Optimised H-C-N bond angle 180°


Item table

         Item               Value     Threshold  Converged?
 Maximum Force            0.000370     0.000450     YES
 RMS     Force            0.000255     0.000300     YES
 Maximum Displacement     0.000676     0.001800     YES
 RMS     Displacement     0.000427     0.001200     YES
HCN

The optimisation file is linked to here

Vibrations

Display vibration of HCN
















Information of each vibration
Wavenumber /cm-1 symmetry intensity (arbitrary units) image
766 PI 35
766 PI 35
2214 SG 2
3479 SG 57

Charge analysis

Charge on atoms
C-atom 0.073
H-atom 0.234
N-atom -0.308

Because N is the most eletronegative atom among the three, so nitrogen is likely to behave negatively. Carbon's electronegativity is slightly higher than hydrogen, so carbon has a greater positive atom charge than hydrogen.

Molecular orbital

Information of molecular orbitals
relative energy (a.u.) occupied/unoccupied molecular orbital other information image
-14.36050 occupied 1σ

in-phase overlap

non-bonding orbital

formed by 1s orbital in nitrogen

-10.24608 occupied 2σ

in-phase overlap

non-bonding orbital

formed by 1s orbital in carbon

-0.91995 occupied 3σ

in-phase overlap

-0.60777 occupied 1π

in-phase overlap

one node (because there is a change in colour)

bonding orbital

-0.38064 occupied 4σ

two nodes (because there is a change in colour)

Marking

Note: All grades and comments are provisional and subject to change until your grades are officially returned via blackboard. Please do not contact anyone about anything to do with the marking of this lab until you have received your grade from blackboard.

Wiki structure and presentation 1/1

Is your wiki page clear and easy to follow, with consistent formatting?

YES

Do you effectively use tables, figures and subheadings to communicate your work?

YES

NH3 1/1

Have you completed the calculation and given a link to the file?

YES

Have you included summary and item tables in your wiki?

YES

Have you included a 3d jmol file or an image of the finished structure?

YES

Have you included the bond lengths and angles asked for?

YES

Have you included the “display vibrations” table?

YES

Have you added a table to your wiki listing the wavenumber and intensity of each vibration?

YES

Did you do the optional extra of adding images of the vibrations?

YES

Have you included answers to the questions about vibrations and charges in the lab script?

YES

N2 and H2 0.5/0.5

Have you completed the calculations and included all relevant information? (summary, item table, structural information, jmol image, vibrations and charges)

YES

Crystal structure comparison 0.5/0.5

Have you included a link to a structure from the CCDC that includes a coordinated N2 or H2 molecule?

YES

Have you compared your optimised bond distance to the crystal structure bond distance?

YES

Haber-Bosch reaction energy calculation 1/1

Have you correctly calculated the energies asked for? ΔE=2*E(NH3)-[E(N2)+3*E(H2)]

YES

Have you reported your answers to the correct number of decimal places?

YES

Do your energies have the correct +/- sign?

YES

Have you answered the question, Identify which is more stable the gaseous reactants or the ammonia product?

YES

Your choice of small molecule 4/5

Have you completed the calculation and included all relevant information?

YES

Have you added information about MOs and charges on atoms?

YES

You could have analysed the calculated vibrations. You could have explained the relative energies of the MOs.

Independence 1/1

If you have finished everything else and have spare time in the lab you could:

Check one of your results against the literature, or

Do an extra calculation on another small molecule, or

YES - you could have analysed the calculated vibrational modes and commented on the MOs in more detail.

Do some deeper analysis on your results so far

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