Problems: Transition Metal Ions and Complexes
These were Homework Problems from Chapter 23 Klotz & Treichel. This is a link to the answers.
A periodic table and other properties of the elements may be found on this
link.
15. Give the electron
configuration for each ion listed here assuming strong
ligand fields, and tell whether it is paramagnetic or diamagnetic.
(a) Y3+ (b) Pt2+ (c) Rh3+ (d) V2+ (e) Ce4+ (f) U4+
25. Only one of the following nitrogen compounds or ions, NH4+,
NH3, or
NH2-, is incapable of serving as a ligand. Identify this species
and explain
your answer.
37. Which of the following complexes can have geometrical isomers? (If isomers
are possible, draw the structures of the isomers and label them as cis or trans.
(a) [Co(H2O)4Cl2]+ (b) Co(H2O)3F3
(c) [Pt(NH3)Br3]- (d) [Co(en)2(NH3)Cl]2+
39. Decide whether each of the following molecules has an enantiomer: ( An
enantiomer is a sterioisomeric pair consisting
of a ``chiral" compound and its mirror image isomer.)
(a)
(b) 
(c) 
41. Draw all possible isomers (geometric and optical) for the ion
[Cr(C2O4)2(H2O)2]-.
46. From experiment we know that [CoF6]3- is paramagnetic
and
[Co(NH3)6]3+ is diamagnetic. Using the crystal field model,
depict the
electron configuration for each ion. What can you conclude about the effect of
the ligand on the magnitude of Do?
49. In water, the titanium (III) ion, [Ti(H2O)6]3+,
is violet. (Its broad
absorption band occurs at about 500 nm.) What color light is absorbed by the ion?
61. In this equation, we wish to explore the differences between metal
coordination by monodentate and bidentate ligands. Formation constants, Kf,
for [Ni(NH3)3]2+(aq) and [Ni(en)3]2+(aq)
follow.
Ni2+(aq) + 6 NH3(aq) 
[Ni(NH3)6]2+(aq)
Kf = 108
Ni2+(aq) + 3 en(aq) [Ni(en)3]2+(aq) Kf = 1018
The difference in Kf between these complexes, reflecting a large increase
in
stability of the chelated complex, is caused by the chelate effect. Recall that
K is related to the standard free energy of the reaction by 
and 
. Here we know from
experiment that 
for the NH3 reaction is - 109 kJ/mol, and
for the en reaction is -117 kJ/mol. Is the difference in sufficient to account for the 1010
difference in Kf? Comment on the
role of entropy in the second reaction compared with that in NH3 reaction.