Question

The IUPAC name for ${K_3}[Co{(N{O_2})_6}]$
A. Potassium (Ⅰ)hexanitrocobaltate( Ⅱ)
B. Potassium (Ⅰ)hexanitrocobaltate(Ⅳ)
C. Potassium hexanitrocobalt ($0$)
D. Potassium hexanitrocobaltate (Ⅲ)

Answer 1

Coordination compounds are chemical compounds made up of an array of anions or neutral molecules connected together by coordinate covalent bonds to a central atom. Coordination complexes are another name for coordination compounds.

Complete answer:
The IUPAC name for ${K_3}[Co{(N{O_2})_6}]$ is Potassium hexanitrocobaltate (Ⅲ).
In this complex, there are six $NO_2^ -$ , so they are named as hexanitro. The cobalt has $- 3$ charge, therefore the name of the central metal ends with -ate followed by the charge in Roman letters.
The coordination number of the complex is $6$
Some characteristics of coordination complexes are:
Because unpaired electrons absorb light in their electronic transitions, the coordination compounds formed by transition elements are coloured. Iron(Ⅱ) complexes, for example, can be green or pale green in colour, whereas coordination compounds containing iron(III) are brown or yellowish-brown in colour.
Due to the existence of unpaired electrons, the resulting coordination complexes have a magnetic character when the coordination centre is a metal.
The chemical reactivity of coordination molecules varies. They can take part in both inner-sphere and outer-sphere electron transfer reactions.
Hence , the correct option is D. Potassium hexanitrocobaltate (Ⅲ) .

Note:
The total number of sigma bonds through which the ligands are bound to the coordination centre is referred to as the coordination number of the central atom in the coordination complex. The ligands are the molecules or ions that are attached to the central atom (also known as complexing agents).