Coordination Compounds

The cyano and hydroxo complexes are far more stable than those formed by halide ion. This is due to the fact that $C{N^ - }$ and $O{H^ - }$ are strong lewis bases (nucleophiles). Further ${\left[ {Fe{{\left( {OH} \right)}_5}} \right]^{3 - }}$ is not formed. hence most stable ion is ${\left[ {Fe{{\left( {CN} \right)}_6}} \right]^{3 - }}$

Compounds that contain at least one carbon metal bond are known as organometallic compounds. In $C{H_3}$$ - Mg - Br$ (Grignard's reagent) a bond is present between carbon and $Mg$ (Metal) hence it is an organometallic compound.

The chemical formula of nitropentammine chromium $\left( {{\rm I}{\rm I}{\rm I}} \right)$ chloride is

$\left[ {Cr{{\left( {N{H_3}} \right)}_5}\,N{O_2}} \right]C{l_2}$

It can exist in following two structures

$\left[ {Cr{{\left( {N{H_3}} \right)}_5}N{O_2}} \right]C{l_2}\,\,$ and

nitropentammine chromium $\left( {{\rm I}{\rm I}{\rm I}} \right)$ chloride

$\left[ {Cr{{\left( {N{H_3}} \right)}_5}ONO} \right]C{l_2}$

Nitropentammine chromium $\left( {{\rm I}{\rm I}{\rm I}} \right)$ chloride

Therefore the type of isomerism found in this compound is linkage isomerism as nitro group is linked through $N$ as $ - N{O_2}$ or through $O$ as $ - ONO.$