Answer Happy

1.
a) A metal complex, [ML6]3+, was found to be kinetically inert,
with the ligands being quite
resistant to substitution. The UV-vis absorption spectrum was found
to exhibit three d-d
absorptions. The lowest energy of these absorptions was very weak,
the other two were of
significantly higher intensity. The complex was reduced to give
[ML6]2+, This octahedral
complex was found to have a magnetic moment of 3.95 BM at 293 K and
3.85 BM at 77K.

(b)With explanation, how does the UV-vis absorption data of [ML]3+,
in combinations
with the magnetic data for the [ML]2+ allow you to assign the
identity of M? Assign
the d-d transitions for [ML6]3+ , and give the identity of M (4
marks)

c) Addition of a neutral bidentate bridging ligand, L', to two
equivalents of [CrL6]2+ gives
[(CrL5)(μ-L')(CrL5)]4+ which can be oxidised to
[(CrL5)(μ-L')(CrL5)]6+ . Comment on why the
preparation of [(CrL5)(μ-L')(CrL5)]6+ is carried
out via [CrL6]2+, [2]

d) What measurements could be made to investigate the magnetic
coupling within the two
metal centres in the bimetallic complex
[(CrL5)(μ-L')(CrL5)]6+?