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Question
How would you account for the following:
The d1 configuration is very unstable in ions.
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Solution
In ions, the d1 configuration is unstable, but after losing one electron, it becomes more stable due to the vacant d-orbitals. All elements with d1 configuration are oxidised or undergo disproportionation. e.g.,
\[\ce{3\overset{+6}{\underset{3d^1}{Mn}}O^2-_4 + 4H+ -> 2\overset{+7}{\underset{3d^0}{Mn}}O^-_4 + \overset{+4}{Mn}O2 + 2H2O}\]
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