Question

Which statement regarding $\left[Cr\right(N{H}_3{)}_6{]}^{3+}$ is incorrect?

• A. It has octahedral geometry
• B. It has $d^{2}s{p}^3$ hybridisation
• C. It is diamagnetic
• D. It is low spin complex

Answer 1

The correct option is C It is diamagnetic

$C{r}^{3+}$ has electronic configuration of $[Ar{]}_{18}{d}^3.C{r}^{3+}$hybridizes six empty orbitals, two $3d$, one $4s$ and three $4p$ orbitals, to form six $d^{2}s{p}^3$hybridised orbitals, which are occupied by six elelctrons pair friom six $N{H}_3$ molecules the three unpaired $3d$ electrons making it occupy the three $d$-orbitals hence are paramagnetic and $N{H}_3$ act as weak field ligand.
Since the three elelctron will occupy the available $3d$-orbitals as per Pauli's exclusion principle they will be unpaired and high spin complex. Thus option (c) is correct.