Question

The correct way of naming Co in [CoCl2(en)2]^+ is ________

(a) cobalt(III)

(b) cobalt(II)

(c) cobaltate(III)

(d) cobaltate(II)

I have been asked this question during an online exam.

Enquiry is from Nomenclature of Coordination Compounds in chapter Coordination Compounds of Chemistry – Class 12

Answer 1

Correct choice is (a) cobalt(III)

Explanation: The complex ion given is cationic and hence the metal is named same as the element. Also, the oxidation number of cobalt is +3 as (en) is a neutral ligand and Cl has -1 charge. Thus, the correct naming for Co is cobalt(III).