Coordination Compounds 1 Question 12
####12. As per IUPAC nomenclature, the name of the complex $\left[Co\left(H _2 O\right) _4\left(NH _3\right) _2\right] Cl _3$ is
(2012)
(a) tetraaquadiaminecobalt (III) chloride
(b) tetraaquadiamminecobalt (III) chloride
(c) diaminetetraaquacobalt (III) chloride
(d) diamminetetraaquacobalt (III) chloride
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Answer:
Correct Answer: 12. (c)
Solution:
- First of all, the compound has complex positive part " $\left[Co\left(H _2 O\right) _4\left(NH _3\right) _2\right]^{3+}$ therefore, according to IUPAC conventions, positive part will be named first. Secondly, in writing name of complex, ligands are named first in alphabetical order, irrespective of its charge, hence “ammine” will be written prior to “aqua”. Therefore, name of the complex is $\left[Co\left(H _2 O\right) _4\left(NH _3\right) _2\right] Cl _3$. Diamminetetraaqua cobalt (III) chloride.
NOTE In alphabetical order, original name of ligands are considered not the initials of prefixes. Also, special precaution should be taken in spelling name of $NH _3$ ligand as it is ammine.
