Coordination Compounds 2 Question 6
####7. The degenerate orbitals of $\left[Cr\left(H _2 O\right) _6\right]^{3+}$ are
(a) $d _{z^{2}}$ and $d _{x z}$
(b) $d _{x z}$ and $d _{y z}$
(c) $d _{x^{2}-y^{2}}$ and $d _{x y}$
(d) $d _{y z}$ and $d _{z^{2}}$
(2019 Main, 9 April I)
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Solution:
- The degenerate orbitals of $\left[Cr\left(H _2 O\right) _6\right]^{3+}$ are $d _{x z}$ and $d _{y z}$. Electronic configuration of $Cr^{3+}$ is $3 d^{5} 4 s^{1}$. The five $d$-orbitals in an isolated gaseous atom or ion have same energy, i.e. they are degenerate. This degeneracy has been removed due to the ligand electron-metal electron repulsions in the octahedral complex to yield three orbitals of lower energy, $t _{2 g}$ set and two orbitals of higher energy, $e _g$ set.
