I get these transitions from my NBO analysis and how these transitions are possible. In some publications itself these transitions are listed and i am very much confused. In UV only four transitions are possible and how these type of transitions shown by NBO analysis. Please help me to clear about this.......
It seems you have understood the NBO results in a wrong way. They are not electronic transitions or excitations. They are second order perturbation energies which gives stabilization energies due to the interactions between those orbitals.
Another major point is ..NBO works on valence bond theory and not on molecular orbital theory basis.
It seems you have understood the NBO results in a wrong way. They are not electronic transitions or excitations. They are second order perturbation energies which gives stabilization energies due to the interactions between those orbitals.
Another major point is ..NBO works on valence bond theory and not on molecular orbital theory basis.
Thank you Krishna sir. I hesitated, when ask this question whether it is correct or not.
Now I realized the fact sir thank you once.....
Mr. Dhandapani,
Can you provide your NBO data or fragments from them?
Dear Bojidarka B. Ivanova Madam,
I attached my NBO text file for your kind perusal...... Waiting for your reply......
Mr. Dhandapani,
You could recognize about the possible electronic transitions within the frame of the UV-VIS region, experimentally onserved from the following discussion and the attachments to it:
https://www.researchgate.net/post/What_is_the_interpretation_if_we_get_a_step_like_absorption_in_UV-Visible_Spectroscopy
From the five (5) observed transitions only two have high probability, the other 3 have low-probability, but they are not 'impossible', they have low intensity due to the series of so-called forbidden rules.
In this respect your data reflect exactly the usually observed UV-VIS bands and their intensity reations as far as the E(2) in your table, given by the equation (attachment) expressing stabilization energy due to i-j delocalization. It depends from the energies of the ith and jth orbitals of the donor and acceptor. Higher values of E(2) mean high stabilization such as for example your p-p* transition having E(2) = 1221.94 kJ.mol-1. The Intensity of the so-called 'forbidden' transition can be influenced by structural factors and/or solute-solvent interactions causing an increasing in the stabilization corresponding n/sigma orbitals such as most probably you have in your molecule. Thus causing for a n-pi* E(2) of 137.28 kJ.mol-1 for example.
Dear Ivanova madam,
First of all thanks for your reply. Just one more clarification, whether this type of forbidden transitions leads to the stabilization of the molecule or not. because this type of enhanced interactions shows abnormal E(2) values when compared with the normal interactions.
Mr. Dhandapani,
Yes the orbital delocalization, has been associated with the stabilization of the geometry (structure).
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