Which of the following does not represent a correct application of the coordination compound?

The correct option is: desferrioxime B is used in treatment of lead poisoning

Let us analyze the applications of the coordination compounds mentioned in the options to understand why this statement is incorrect:

1. Cis-platin:
Cis-platin, $\mathrm{cis}-\left[{\mathrm{PtCl}}_2\right({\mathrm{NH}}_3{)}_2]$, is a well-known coordination compound of platinum. It binds to DNA in cancer cells, cross-linking the DNA strands and preventing replication. This effectively inhibits the growth of tumors, making it a widely used chemotherapy drug. Therefore, this is a correct application.

2. Chlorophyll:
Chlorophyll is a green pigment found in plants and is a coordination complex of magnesium (${\mathrm{Mg}}^{2+}$). It plays a crucial role in capturing light energy during photosynthesis. Therefore, this is a correct application.

3. Cyanocobalamin:
Cyanocobalamin is vitamin B₁₂, which serves as an antipernicious anemia factor. It is a coordination compound of cobalt ($\mathrm{Co}$). Therefore, this is also a correct application.

4. Desferrioxime B:
Desferrioxime B is a chelating agent used to treat acute iron poisoning or iron overload (hemochromatosis) by forming a stable coordination complex with iron (${\mathrm{Fe}}^{3+}$), which is then excreted from the body. On the other hand, lead poisoning is typically treated with chelating agents like EDTA (Ethylene Diamine Tetraacetic Acid). Thus, the statement that desferrioxime B is used for lead poisoning is incorrect.