CUET Preparation Today
Case: Read the passage and answer the following questions The naming of mononuclear coordination compounds follows some rules. Cations are always named before the anions. The ligands are then listed in alphabetical order. In the case of polydentate ligands, ligands are named alphabetically using the prefix di, tri, tetra, Penta etc, to indicate the number of ligands of that type present. |
What is the name the compound [Co(H2NCH2CH2NH2)3]2(SO4)3 ? |
tris(ethane-1,2–diamine)cobalt(III) sulphate di(ethane-1,2–diamine)cobalt(III) sulphate tris(ethane-1,2–diamine)cobalt(III)tri sulphate None of the above |
tris(ethane-1,2–diamine)cobalt(III) sulphate |
[Co(H2NCH2CH2NH2)3]2(SO4)3 → 2[Co(H2NCH2CH2NH2)3]3+ + 3SO42- The sulphate is the counter anion in this molecule. Since it takes 3 sulphates to bond with two complex cations, the charge on each complex cation must be +3. Further, ethane-1,2–diamine is a neutral molecule, so the oxidation number of cobalt in the complex ion must be +3. Remember that you never have to indicate the number of cations and anions in the name of an ionic compound. |
