Substitution reactions at octahedral complexes:

1
Substitution reactions at octahedral
complexes acid and base hydrolysis
2
Acid hydrolysis

• Protonation of a ligand which then dissociates
  from the metal

See Questions 1-3
3
Acid hydrolysis

• Protonation of an inert ligand labilises other
  ligands

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(No Transcript)
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Acid hydrolysis

• Protonation of the metal itself leads to
  labilisation of a ligand

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Base hydrolysis at a transition metal complex is
based on the observation that reactions of the
type are accelerated by increasing OH-
ML4(LH)(X)n OH- ? ML4(LH)(OH)n X-
and the saturation behaviour seen with
acid-catalysed reactions (Chapter 2) does not
occur
Mechanism proposed by Garrick and called the DCB
Mechanism
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(1)
Now
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But
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Substituting into (1)
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Base hydrolysis is usually considerably faster
than acid hydrolysis because of stabilisation of
the transition state by the conjugate base.
Hence a ? donor ligand such as OH- or NH2- is
required for this mechanism