Fe(II) also has a small gap between HOMO and LUMO, because it has 6 electrons in 3d orbitals. CO has a small gap between the HOMO and LUMO. The LUMO is a ПЂ* orbital that is also mostly on carbon, and it is kind of low-energy because the splitting of ПЂ MOs is smaller than Пѓ MOs (because of less overlap). The HOMO is a slightly-bonding orbital that is mostly on carbon. Go back and look at the MO diagram for CO. We can understand how and why CO binds Fe(II) using MO theory. CO binds to the Fe(II) more tightly than O 2, so if you breathe too much CO, your cells won't get any oxygen, because all the Fe(II) in your blood bound CO instead. You use Fe(II) ions in your blood to bind O 2 and carry it to your cells. The reason CO is toxic is because it binds metal ions really tightly. You probably know that CO is toxic (which is why you shouldn't stay in a garage with a car running, because the CO from incomplete combustion can kill you). This is why if you want to store something reactive like K metal, you probably keep it in a bottle of oil. They do burn easily, but you have to get them hot first. Molecules with low HOMO and high LUMO, a big HOMO-LUMO gap, are not very reactive! Hydrocarbons are a good example (like oil, etc). Diagrams of acid/base, redox, and both reactions. You can still predict covalent/ionic bonding based on electronegativity. This depends on the AO energies, which depends on the electronegativity, just like you would expect. Often the energy match is bad, so that no covalent bond forms, just the electron moves. In a redox reaction, the oxidant has a low LUMO, and the reductant has a high HOMO, but this time the oxidant LUMO is lower than the reductant HOMO, so that the electrons in the reductant HOMO move completely to the oxidant LUMO. This creates a bond between the acid and base. A low LUMO usually means an empty valence orbital, like on B or on a cation.) We can make a bonding and anti-bonding combination of the base HOMO and acid LUMO, and that will stabilize the electrons from the base's HOMO, lowering the total energy. (A lone pair in MO theory is an electron pair in a non-bonding MO. What this really means is that the base has a HOMO that is pretty high-energy (a lone pair), and the acid has a LUMO that is pretty low energy. In a Lewis acid/base reaction, an electron pair from the base is shared with the acid. Earlier, we said that most reactions can be called either Lewis acid/base or redox. LUMO is Lowest Unoccupied MO, the lowest-energy MO that doesn't have any electrons in it.ДЇrontier MOs are very important for reactivity. HOMO is Highest Occupied MO, the highest-energy MO that has electrons in it. The frontier MOs are called the HOMO and the LUMO. In this case, we are interested in the MOs at the border between occupied and empty. Distinguish and describe the significance of frontier MOsДЇrontier means a border area, between two things (often, between 2 countries).

Modern Density Functional Theory вЂ“ A Tool for Chemistry / Eds. The NICS results showed that the peripheral 6-membered rings represented the best aromatic properties. Also, the aromaticity of individual rings was evaluated by calculating NICS and HOMHED indices.

In addition, this compound had the lowest hardness (2.912В eV), ionization energy (7.184В eV) and electronegativity (4.272В eV). While the derivative having pyrrole rings had the highest softness (0.172В e/V), chemical potential (вЂ“4.272В eV), and the greatest О» max (403В nm) in the UV spectrum.

In addition, compound 7 had the smallest chemical potential (вЂ“5.837В eV), polarizability (328.560В a.u.) and the lowest energy levels of HOMO (вЂ“8.3672В eV) and LUMO (вЂ“3.3062В eV) orbitals. Among the studied derivatives, the structure containing pyridine and furan rings possessed the highest ionization energy (9.007В eV), electron affinity (2.667В eV), electronegativity (5.837В eV), and was the most polar molecule. The frontier molecular orbitals have been studied based on NBO calculations and the results were used to estimate the HOMOвЂ“LUMO energy gap, ionization potential, electron affinity, electronegativity, electrophilicity index, global hardness, softness, and chemical potential of the compounds. The calculated values of О» max (344В nm to 403В nm) were attributed to HOMO to LUMO electronic transitions of compounds. The UV spectra of compounds were simulated by TD DFT methods. The structures and properties of Circumtrindene derivatives were studied at M062X/6-31+G( d, p) level of theory.

Homo lumo organic chemistry