Ruman wiki-page
EX3 section
BH3
Item Value Threshold Converged? Maximum Force 0.000007 0.000450 YES RMS Force 0.000004 0.000300 YES Maximum Displacement 0.000028 0.001800 YES RMS Displacement 0.000014 0.001200 YES
Low frequencies --- -38.8634 -38.8412 -18.7509 -0.0042 0.0451 0.2082 Low frequencies --- 458.9323 1681.0420 1681.0424
| Wavenumber (cm-1 | Intensity (arbitrary units) | symmetry | IR Active? | Type |
|---|---|---|---|---|
| 1163 | 93 | A2 | Yes | out-of-plane bend |
| 1213 | 14 | E' | Very slight | bend |
| 1213 | 14 | E' | Very slight | bend |
| 2582 | 0 | A1' | No | symmetric stretch |
| 2715 | 126 | E' | Yes | asymmetric stretch |
| 2715 | 126 | E' | Yes | asymmetric stretch |
BH3 Molecule |
NH3
Item Value Threshold Converged? Maximum Force 0.000005 0.000450 YES RMS Force 0.000003 0.000300 YES Maximum Displacement 0.000012 0.001800 YES RMS Displacement 0.000006 0.001200 YES
File:RUUMAAAAAN NH3 FREQIII.LOG
Low frequencies --- -11.6527 -11.6490 -0.0048 0.0332 0.1312 25.5724 Low frequencies --- 1089.6616 1694.1736 1694.1736
NH3 Molecule |
NH3BH3
Item Value Threshold Converged? Maximum Force 0.000041 0.000450 YES RMS Force 0.000014 0.000300 YES Maximum Displacement 0.000603 0.001800 YES RMS Displacement 0.000278 0.001200 YES
E(NH3)=-56.55776863
E(BH3)=-26.61532363
E(NH3BH3)=-83.22468929
ΔE=E(NH3BH3)-[E(NH3)+E(BH3)] ΔE=-83.22468929 - (-26.61532363+-56.55776863) ΔE=-0.05159au =-135kJ/mol
This energy is quite weak for a covalent bond.
Smf115 (talk) 08:10, 17 May 2018 (BST)Good consideration of the accuracy of reported energy values and correct calculation.
BH3NH3 Molecule |
BBr3
Item Value Threshold Converged? Maximum Force 0.000008 0.000450 YES RMS Force 0.000005 0.000300 YES Maximum Displacement 0.000036 0.001800 YES RMS Displacement 0.000023 0.001200 YES
Low frequencies --- -0.0137 -0.0064 -0.0046 2.4315 2.4315 4.8421 Low frequencies --- 155.9631 155.9651 267.7052
BBr3 Molecule |
BBr3 DOI:10042/202327
Project section
Benzene
Item Value Threshold Converged? Maximum Force 0.000196 0.000450 YES RMS Force 0.000096 0.000300 YES Maximum Displacement 0.001062 0.001800 YES RMS Displacement 0.000381 0.001200 YES
Low frequencies --- -16.9577 -14.2980 -9.2699 -0.0012 -0.0005 -0.0005 Low frequencies --- 413.7998 414.4799 620.8650
Benzene |
Borazine
Item Value Threshold Converged? Maximum Force 0.000117 0.000450 YES RMS Force 0.000036 0.000300 YES Maximum Displacement 0.000327 0.001800 YES RMS Displacement 0.000104 0.001200 YES
Low frequencies --- -11.3791 0.0008 0.0011 0.0014 9.0995 10.8730 Low frequencies --- 288.5041 290.3971 404.0139
Borazine |
| Benzene----------------------------------------Borazine | Comparison |
|---|---|
 |
MO 22 is similar for both structures and shows out of phase p orbitals. However, borazine’s orbitals are more distrorted than that of bezenes due to different sized p orbitals between atoms. Each atom on borazine has less contribution to the MO than that of benzene. Due to this, the MO of borazine is higher in energy 0.02422 Hartrees (64KJ/mol), whilst benzenes MO has an energy of 0.00267 Hartrees (7KJ/mol). |
 |
MO 17 is very similar for both molecules. This MO features all in phase pi orbitals bonding together, showing the delocalisation present within the structures. The Borazine MO is slightly more contracted at the nitrogen atoms, due to the higher electronegativity of nitrogen compared to borane. As we expect borazine is slightly lower in energy at -0.36130 Hartrees (-947KJ/mol). Whilst benzene has an energy of -0.35998 Hartrees (-945KJ/mol) |
 |
MO 14 for benzene and MO 15 for borazine both show out of phase sigma orbitals with lobes present at the atomic centres. MO 14 has an energy of -0.43854 Hartrees (-1151KJ/mol), whilst MO 15 on borazine is -0.43198 Hartrees (-1134KJ/mol). |
 |
For benzene the charge is symmetrical distributed, showing all the hydrogens having the same positive value of 0.239, and all carbon atoms having the same slightly negative value of +0.239.
Borazine shows an uneven distribution of charge. The nitrogen atoms (red) have the lowest charge of -1.102 with it hydrogens atoms having charges of +0.432. Whilst boron (light green) has a positive charge of 0.747 with it hydrogen molecules having a charge of -0.077. The positive charge on the boron is due to the fact that it is bonded to the highly electronegative nitrogen atom, shifting electron density onto the nitrogen, making the nitrogen more negative and the boron more positive. Furthermore, boron donates electron density towards its hydrogen atoms, thereby allowing the hydrogens to experience a slight negative charge. |
Smf115 (talk) 08:15, 17 May 2018 (BST)Good attempt at the charge analysis with mention of symmetry and electronegativity. Smf115 (talk) 08:15, 17 May 2018 (BST)Nice range of MOs chosen, however, the energies of the MOs can't be compared. Good mention of electronegativity however, the overall character and mention whether they were sigma- or pi- orbitals should have been made for a better comparison.
Aromatic molecules have a ring of resonance bonds that provide more stability than similar geometric arrangements of structures containing the same set of atoms. Compounds can be classed as aromatic if they have 4n+2 pi electrons. This is known as Huckle’s rule and therefore can be used to prove that aromatic molecules do not have to be planar. For example, the aromatic compound cyclooctatetraene conforms to a non-planar ‘tub’ conformation, and has 8 pi electrons. Aromaticity is commonly thought to arise from its 6 Pz orbitals which form a pi bond, leading to the formation of a delocalised ring of electron density above and below the ring. However, sigma orbitals can contribute to this delocalisation ring, and in few cases, only some fragments from p orbitals can be thought to contribute to this system.
Smf115 (talk) 08:15, 17 May 2018 (BST)Nice cover of the basic conceptes of aromatiticty. However, the discussion is a bit brief and mention of more complex ideas, such as sigma-aromaticty, and reference to MOs is needed to develop it further.
Smf115 (talk) 08:15, 17 May 2018 (BST)Overall a good attempt at the report and project section.