Question

Assume that the MO diagram of IBr is analogous to that of ICl ( Fig. 2.24 ). (a) What basis set of atomic orbitals would be used to generate the IBr molecular orbitals? (b) Calculate the bond order of IBr. (c) Comment on the relative stabilities and bond orders of IBr and IBr 2.

Answer 1

Start by drawing the electornconfigurations:

a)

Electronic configuration of Bromine : [Ar] 4s2 3d10 4p5

Electronic configuration of Iodine : [Kr] 4d10 5s2 5p5

Therefore:

The atomic orbitals involved in molecular orbitals of IBr are

Bromine: 4s 4p

Iodine: 5s 5p

b) Bond order = (Number of electrons in BO - number of electrons in ABO) / 2

Bond order = (8-6) /2 = 1

Bond order of IBr2 = 2

c)

IBr is much likely to be stable since it has a lower bond order (i.e. simplier mix)

then

IBr2 is most likely to be in resonance form + ionic state, which makes it much more reactive than IBr