91Ó°ÊÓ

We are asked to indicate the coordination number for the central metal atom in each of the following coordination compounds of\(\begin{aligned}{}(a)\left( {Pt{{\left( {{H_2}O} \right)}_2}B{r_2}} \right)\\(b)\left( {Pt\left( {N{H_3}} \right)(py)(Cl)(Br)} \right)\left( {py = } \right.pyridine,\left. {{C_5}{H_5}\;N} \right)\\(c)\left( {Zn{{\left( {N{H_3}} \right)}_2}C{l_2}} \right)\\(d)\left( {Zn\left( {N{H_3}} \right)(py)(Cl)(Br)} \right)\\(e)\left( {Ni{{\left( {{H_2}O} \right)}_4}C{l_2}} \right)\\(f){\left( {Fe{{(en)}_2}{{(CN)}_2}} \right)^ + }\left( {en = } \right.ethylenediamine,\left. {{C_2}{H_8}\;{N_2}} \right)\end{aligned}\)

\((a)\left( {Pt{{\left( {{H_2}O} \right)}_2}B{r_2}} \right)\)

\((b)\left( {Pt\left( {N{H_3}} \right)(py)(Cl)(Br)} \right)\left( {py = } \right.pyridine,\left. {{C_5}{H_5}\;N} \right)\)

\((c)\left( {Zn{{\left( {N{H_3}} \right)}_2}C{l_2}} \right)\)

\((d)\left( {Zn\left( {N{H_3}} \right)(py)(Cl)(Br)} \right)\)

\((e)\left( {Ni{{\left( {{H_2}O} \right)}_4}C{l_2}} \right)\)

\((f){\left( {Fe{{(en)}_2}{{(CN)}_2}} \right)^ + }\left( {en = } \right.ethylenediamine,\left. {{C_2}{H_8}\;{N_2}} \right)\)

• We can see that\({\bf{2}}\)monodentate\(\left( {C{N^ - }} \right)\)ligands and\({\bf{2}}\)bidentate\((en)\)ligands are present inside the coordination sphere, which shows that the coordination number of the central metal ion\({\bf{Fe}}\)is\({\bf{6}}\).
• Since\({\bf{2}}\)monodentate ligans donate\({\bf{2}}\)electrons and each of the bidentate donates\({\bf{2}}\)electrons and since we have\({\bf{2}}\)of them, they donate\({\bf{4}}\)electrons, and their sum is\({\bf{6}}\).

\(\begin{aligned}{}a)Pt &= 4\\b){\rm{Pt}} &= 4\\c)Zn &= 4\\d)Zn &= 4\\e){\rm{Ni}} &= 6\\f){\rm{Fe}} &= 6\end{aligned}\)