Question

The IUPAC name of ${\mathrm{Na}}_2[\mathrm{Ni}(\mathrm{EDTA}\left)\right]$ is

Answer 1

Coordination compounds:

• A coordination complex may be defined as a compound that results from the combination of two or more stable chemical species and retains its identity in the solid as well as the dissolved state.
• The cation to which one or more neutral molecules or ions are coordinated is called the central ion.
• The molecules or ions so attached are called ligands.
• The atom in the ligand which can donate the electron pair is called the donor atom.
• The total number of ligands attached to a central ion is called the coordination number of that ion.
• The central ion together with molecules or ions coordinated to it constitutes what is termed a coordination complex.

IUPAC naming of Coordination compounds:

• In ionic coordination complexes, the cation is named first and then the anion.
• In naming the coordination sphere, the ligands are named first and then the central metal ion.
• The names of negative ligands end in ‘o’ and of positive ligands end in ‘ium’, the neutral ligands are named as such.
• The ligands are named in alphabetical order irrespective of being neutral, negatively charged, or positively charged.
• When more than one simple ligands of a particular kind are present in the complex, the prefixes di, tri, tetra, penta are used to indicate their number
• However, if the ligands have complex names such as ethylenediamine, triphenylphosphine, ethylenediamminetetraacetato, etc which themselves contain the affixes di, tri..etc so their numbers 2, 3, 4 are represented by bis, tris, tetrakis, etc.
• When the complex is anionic, the name of the central atom ends in ‘ate’, with no characteristic ending for cationic and neutral complexes.
• The oxidation state of the central ion is designed by a Roman numeral in parentheses at the end of the name of the complexes without space between the two.

IUPAC name of ${\mathrm{Na}}_2[\mathrm{Ni}(\mathrm{EDTA}\left)\right]$: Disodium ethylenediamminetetraacetatonickelate(II)

Step 1 The oxidation number of Nickel

Charge of ${\mathrm{Na}}_2$ is $+2$

Charge of $\mathrm{EDTA}$ is $-2$

$$\begin{gathered} 2+x+(-4)=0 \\ x-2=0 \\ x=2 \end{gathered}$$

Step 2 IUPAC name of ${\mathrm{Na}}_2[\mathrm{Ni}(\mathrm{EDTA}\left)\right]$

The ligands present in the given compound are two Sodium atoms and one $\mathrm{EDTA}$ molecule.

$\mathrm{EDTA}$ is Ethylenediamminetetraacetate ion and it is a negative ligand and the negative ligands end with ‘o’

The central metal atom is Nickel and the oxidation number is 2.

Therefore, Disodium ethylenediamminetetraacetatonickel(II)

Hence, Disodium ethylenediamminetetraacetatonickel(II) is the IUPAC name of ${\mathrm{Na}}_2[\mathrm{Ni}(\mathrm{EDTA}\left)\right]$.