Milmindani
Contents
Lab1 Marking
It's good that you have a working wiki. However, your reported image and charges of N2F2 do not correspond to an optimised structure. Don't forget to consider the accuracy to which you report your data the next time. If you have any queries, please contact Prof. Hunt.
BH3 Molecule
calculation data
| name of submitted log file | BH3 Optimisation DM.log |
| molecule | BH3 |
| method | B3LYP |
| calculation method | RB3LYP |
| basis set | 6-31G(d,p) |
| final energy | -26.615324 |
| RMS gradient | 0.000002 |
| point group | D3H |
| Confirmed it is Minima | Yes |
Item Table
Item Value Threshold Converged? Maximum Force 0.000004 0.000015 YES RMS Force 0.000003 0.000010 YES Maximum Displacement 0.000017 0.000060 YES RMS Displacement 0.000011 0.000040 YES
NH3 Molecule
calculation data
| name of submitted log file | NH3 Optimisation DM.log |
| molecule | NH3 |
| method | RB3LYP |
| basis set | 6-31G(d,p) |
| final energy | -56.557769 |
| RMS gradient | 0.000000 |
| point group | C3V |
Item Table
Item Value Threshold Converged? Maximum Force 0.000000 0.000015 YES RMS Force 0.000000 0.000010 YES Maximum Displacement 0.000003 0.000060 YES RMS Displacement 0.000001 0.000040 YES
rotateable 3D Jmol image NH |
Important geometric parameters
Optimised bond distance and angle for NH3
Bond Distance: r(N-H)=1.01797Â
Bond Angle: 37.12783°
Low frequencies --- -5.6864 -3.6131 -3.6124 0.0017 0.0048 0.0162
Low frequencies --- 1089.3674 1693.9284 1693.9284
| Mode | 1 | 2 | 3 | 4 | 5 | 6 |
| wavenumber (cm-1) | 1089.3674 | 1693.9284 | 1693.9284 | 3461.3788 | 3589.9285 | 3589.9285 |
| Symmetry | A1 | E | E | A1 | E | E |
| intensity (arbitrary units) | 145.4277 | 13.5571 | 13.5572 | 1.0593 | 0.2699 | 0.2699 |
| Charges | N-Atom | H-Atom | H-Atom | H-Atom |
| Charge | -1.125 | 0.375 | 0.375 | 0.375 |
Project Molecule N2F2
calculation data
| name of submitted log file | N2F2 MOLECULE 1 DM.log |
| molecule | N2F2 |
| method | RB3LYP |
| basis set | 6-31G(d,p) |
| final energy | -309.012413 |
| RMS gradient | 0.000000 |
| point group | C2V |
Item Table
Item Value Threshold Converged? Maximum Force 0.000001 0.000015 YES RMS Force 0.000000 0.000010 YES Maximum Displacement 0.000001 0.000060 YES RMS Displacement 0.000001 0.000040 YES
rotateable 3D Jmol image Nf |
Important geometric parameters
Optimised bond distance and angle for NH3
Bond Distance: r(N-F)=1.28000Â
Bond Distance: r(N=N)=1.23200Â
Bond Angle (N-F): 120°
Low frequencies --- 0.0013 0.0015 0.0017 3.2233 4.3533 5.0998
Low frequencies --- 347.8772 561.2472 771.6105
| Mode | 1 | 2 | 3 | 4 | 5 | 6 |
| wavenumber (cm-1) | 347.8772 | 561.2472 | 771.6105 | 949.4548 | 987.2543 | 1636.6075 |
| Symmetry | A1 | A2 | B2 | A1 | B2 | A1 |
| intensity (arbitrary units) | 0.6108 | 0.0000 | 74.7044 | 75.4125 | 81.1265 | 20.5391 |
| Charges | N-Atom | F-Atom | N-Atom | F-Atom |
| Charge | 0.191 | -0.191 | 0.191 | -0.191 |
Questions:
the molecule from the log file does not have bonds between the F and N atoms, what is going on here?
It does have bonds, you just need to change the number from 8 to 1 or 2 to see where the animation connects the bond together.
IR analysis
how many vibrations are expected from the 3N-6 rule?
The 3N-6 rule, calculates the number of vibrational modes in the molecule where N=the total number of atoms. As N2F2 has 4 atoms, N=4. So 3*(4)-6 = 6 vibrational modes are present in N2F2.
why are there only 4 peaks in the IR spectrum?
The molecule is symmetrical so although there are 6 vibrational modes, only 4 modes are visible because the symmetry of the molecule cancels dipole so they do not show up in an IR spectrum.
which vibration is the asymmetric N-F stretch?
The vibration at 775 cm-1 is the asymmetric N-F stretch.
what is the nature of the highest energy vibration?
This is the N=N stretch located at 1640 cm-1. The peak is small which is due to the tight N=N bond not moving that much.
MO analysis:
which MOs are core orbital MOs?
The 1S orbitals of both F atoms and the 1s orbitals of both N atoms. MO's 1-4.
provide a picture of MO 9 and beside it draw the LCAO diagram
