Question

(a) What type of isomerism is shown by the complex $\left[Co\right(N{H}_3{)}_5\left(SCN\right){]}^{2+}$?
(b) Why is $[NiC{l}_4{]}^{2+}$ paramagnetic while $\left[Ni\right(CN{)}_4{]}^{2-}$ is diamagnetic?
(Atomic number of $Ni=28$)
(c) Why are low spin tetrahedral complexes rarely observed?

Answer 1

(a) Linkage isomerism is shown by the complex.

(b) $C{l}^{-}$ is a weak field ligand so it cannot pair up the electron while $C{N}^{-}$ is a strong field ligand that can pair up the electrons.

(c) The strong field ligands cause pairing of electrons and in most cases make the last d-orbital empty and thus tetrahedral complex is not formed.