Question

(2 pts)  For the octahedral complex ion [FeCl₆]^3-  answer the following questions:

a.  What is the coordination number for iron?   ____________

b.  What is the oxidation number for the iron ion?  ________________

c.   What is the electron configuration for the iron ion?  _________________

d.  Using crystal field theory,

i.  Draw the ground state distribution for the iron cation’s d electrons.  Indicate whether the crystal field splitting is large or small.  

ii.  Determine whether the compound is diamagnetic or paramagnetic (this should be evident from your sketch.)

Diamagnetic or paramagnetic?  _________________

Answer 1

a) For octagedral complex [FeCl6]3- cordination number of Fe is 6

b) x + 6(-1) = -3

Therefore x = +3

Oxidation number of Fe is +3

c) electronic configuration of iron in +3 oxidation state is 1s2 2s2 p6 3s2 3p6 3d5

The compound has one unpaired electron.

d) i) Cl is weak field ligand, It will form high spin complex. Crystal field splitting is large.

ii) fe in gound state has 4s2 3d6 configuration, therefore Fe+3 is 3d5. Upon pairing it has one unpaired electron, which makes it paramagnetic complex.