Question

IUPAC name of $N{a_3}[Co{(N{O_2})_6}]$ is-
(A) Sodium hexanitrocobaltate$(III)$
(B) Sodium cobalt nitrate
(C) Tri Sodium hexanitro cobalt
(D) hexanitro cobalt$(III)$trisodium complex

Answer 1

IUPAC nomenclature is widely used in many forms of chemistry. IUPAC is the International Union of Pure and Applied Chemistry. To answer these kinds of questions we need to know all the rules on how to name a coordinated compound. Detailed explanation is given below.

Complete step-by-step answer: A complex is a substance wherein a metal atom or ion is related to a gathering of neutral atoms or anions called ligands. Coordination mixes are neutral substances (for example uncharged) in which at any rate one particle is available as a complex.
The coordination compounds are named in the following way.
You have to name the ligands first, in alphabetical order, then the metal atom or ion.
For anionic ligands which ends with "$- O$"; for anions that ends with "$- ide$"(e.g. chloride), "$- ate$" (e.g. sulfate), and "$- ite$" (e.g. nirite), we need to change the endings as follows: $- ide$ $- O$ ; - ate$$$$ - ato; $- ite$ $- itov$
For neutral ligands,we need to use the common name of the molecule e.g. ${H_2}NC{H_2}C{H_2}N{H_2}$ (ethylenediamine). Important exceptions: water is called ‘aqua’, ammonia is called ‘ammine’, carbon monoxide is called ‘carbonyl’, and the ${N_2}$and ${O_2}$ are called ‘dinitrogen’ and ‘dioxygen’.
Some common ligands-
$B{r^-} \to$bromo $F{^-} \to$fluoro $C{N^-} \to$cyano $O{H^-} \to$hydroxo ${C_5}{H_5}N \to$pyridine
$C{H_3}CO{O^-} \to$acetato $NH_3 \to$ammine $NO \to$nitrosyl $CO \to$carbonyl
${H_2}NC{H_2}C{H_2}N{H_2} \to$ethylenediamine
Greek prefixes are used to designate the number of each type of ligand in the complex ion, e.g. $di -$, $tri -$ and $tetra -$. If the ligand already contains a Greek prefix (e.g. ethylenediamine) or if it is polydentate ligands (ie. can attach at more than one binding site) the prefixes $bis -$, $tris -$, $tetrakis -$, $pentakis -$, are used instead.
So, the name of the given compound in the question will be:
N{a_3}[Co{(N{O_2})_6}]$$$$ \to Sodium hexanitrocobaltate$(III)$. Here, cobalt is the ligand.

Hence the correct option is (A).

Note: The metal atom or ion should be written before the ligands in the chemical formula. And for a complex molecule named cation before the anion. After naming the ligands, name the central metal. If the complex ion is a cation, the metal is named the same as the element.