Question

The IUPAC name for ${K_2}[OsC{l_5}N]$ is-
1. Potassium pentachloroazidoosmate(VIII)
2. Potassium pentachloroazidoosmate(VI)
3. Potassium pentachloronitridoosmate(VI)
4. Potassium nitroosmate(III)

Answer 1

HintTo get the answer of these types of questions we should firstly learn many rules for the cations and anions for these complex compounds. IUPAC naming of a compound is the unique name for any compound in the world. So, it is prescribed that we should only use the IUPAC name of a compound So, everyone in the world can know the name of that compound.
Step by step process:

Complete step by step answer:
Now to know the IUPAC name of a complex compound we should follow some rules which are given by the IUPAC (International Union for pure and applied chemistry) .
-Some rules are given following:
1.If a coordination compound is ionic, the name of cation is given first whether or not It is the complex ion. It is followed by the name of the ion just like naming a simple salt.the names of cation and anion are separated by space
2.Within a complex Ion, the ligands are named first followed by the metal ion.
- Names of ligands:
I.Anionic ligands ending with -ide are named by replacing -ide with suffix -o or replacing -e by -o.
II.Neutral ligands are given the same names as the neutral molecules
III.Positively charged ligands have suffix -ium
IV. If the number of a particular ligand is more than one in the complex Ion, the number is indicated by using Greek numbers such as di,tri, Penta, Hexa .However, when the name of the ligands includes a number.
V. When more than one type of ligands are present, they are named in alphabetical order without separation by hyphen. This rule has come into force after the 1971 convention.
3. The oxidation state of the central metal is shown by Roman numeral in bracket immediately following its name
4.Complex positive ions and neutral coordination compounds have no special ending with the name of Central metal but Complex negative ions always end in the suffix -ate. In most of the cases, the suffix -ate is fixed to English names of the metals but in some cases -ate is fixed with Latin names of the metals.
The Names of components present in the coordination sphere are written in continuum.
5. The name of the neutral coordination compound is given in the one word only as the name of $[Ni{(CO)_4}]$is tetracarbonylnickel(0).
-Now we have seen many rules so,
We have cation of potassium which have oxidation number +1
Nitrogen atom which have oxidation number -3
Chlorine atom which have oxidation number -1
We have to find the oxidation number of Os:
Let the oxidation number of Os is x.
$
 2 + x + - 5 - 3 = 0 \\
  x - 6 = 0 \\
  x = 6 \\
 $
So the name of above compound will be Potassium pentachloronitridoosmate(VI)
Therefore, correct option will be option number 3.

Note:Complex compound: when a positively charged ion is surrounded by the non-metal and by the ligands of the different types and by the d-block elements. That bulky compound is known as a complex compound or coordination compound.Complex compound is called a coordination compound because many ligands contribute their electrons through the coordinate bonds.