Question

1.

a) What are the atomic orbitals that make up:

i) Benzene: homo, lumo, homo-2, lumo+2

ii) Butadiene: homo, lumo, homo-1,lumo+1

iii) Formaldehyde: homo and lumo.

- to what number molecular orbitals do these belong?

iii)

b) For the ten molecular orbitals of N2, what are their characteristics? What are the characteristics features of each bonding and antibonding orbital? How do the Pi 2p and the Pi*2p molecular orbitals differ in relative spatial orientation?

Answer 1

Benzene has an atomic orbital p in each carbon atom 6 p orbitals In each orbital there is an electron (electron A) There are 6 electons ----> They form 6 molecular orbitals The a Molecular Orbitals of Benzene ------LUMO Lowest Unoccupied Molecular Orbital) Energy - HOMO HOMO (High (Highest Occupied Molecular Orbital) 1 1 46 + 0 0

to — LUMO - LUMO2+ mt ET HOMO-2 Las HOMO 2 hv Skip an electron from 12 to na Skip an electron from iz to its ft HOMO tz # To m2 + + Ground state Excited state LUMO 2+ HOMO-2

Butadiene has an atomic orbital p in each carbon atom N --> 000 In each orbital there is an electron (electron A) There are 4 electons ----> They form 4 molecular orbitals The i Molecular Orbitals of Butadiene LUMO 8888 088, tua -T3 LUMO -FI, HOMO 000 0 hv Energy Skip an electron from tyto z ool — та номо 000 o 0 00 411, Ground state Excited state HOMO HOMO- 200 HOMO LUMO LUMO 1+

Atomic orbitals of formaldehyde a bond ----> 2 MOT 2 electrons a sp2 fo sp2 Hsp spa spa spa 3 MOO Molecular a orbitals of formaldehyde Y — 12 LUMO T, LUMO Energy - TT, HOMO

Atomic orbitals of N, 2p+ тар 3p+** A+ 3p3 p orbitals give rise to two molecular orbital zo and c2p* T₂P TIP 232 Energy Two 2s orbitals give rise to two molecular orbital 02 and 02* 025 1s2 Joz Two 1s orbitals give rise to two molecular orbital , and , * N

Atomic orbitals of N, Cop* TIP 3p% + 1 + 3p p orbitals give rise to two molecular orbital 02p and cze* Thap TzP 202 2s2 Energy Two 2s orbitals give rise to two molecular orbital 02 and 02* 025 1s2 Two 1s orbitals give rise to two molecular orbital , and o, * N Molecular orbitals of NA op* _ 130* — op — 720 Energy os ++++ 0,5