Question

Which of the following statements is incorrect regarding the naming of complex compounds?
A. $N{H^{2 - }}$ , will be named as 'amido'
B. ' $en$ ' will be named as 'ethylenediamine'
C. ${C_2}{O_2}{S_2}^{2 - }$ will be named as 'dithio oxalato'
D. $C{H_3}^ -$ will be named as 'methyl'

Answer 1

Hint : For such types of questions one needs to keep the rules for nomenclature of coordination compounds and the names given to the ligands in mind.

Complete step by step solution :
So, some of the rules for nomenclature of complex/co-ordination Anionic ligands are as follows:
i. Ligands are named first in alphabetical order.
ii. The name of the metal comes next.
iii. The oxidation state of the metal follows, noted by a Roman numeral in parentheses (II, IV).
iv. Anionic ligands in coordination complexes which end in " $- ide$ " are replaced with an ending " $- o$ " (e.g., $Chloride \to chloro$ ). Anions ending with " $- ite$ " and " $- ate$ " are replaced with ending " $- ito$ " and " $- ato$ " respectively.
v. Most neutral molecules that are ligands carry their normal name, but the exceptions are: ammine, aqua, carbonyl, and nitrosyl.
vi. If there are more than one number of ligands in the complex then it is indicated with the prefixes di, tri, etc. The exceptions are poly-dentates, the one with more than one donor sites for example, en and $EDT{A^{^{4 - }}}$ are the most common. When indicating how many of these are present in a coordination complex, we put the ligand's name in brackets and use bis, tris, and tetrakis.
Now, applying the above-mentioned rules we have the solution as follows,
A. $N{H^{2 - }}$ is a ligand whose nomenclature in terms of coordination complexes is given as “imido” rather than of “amido” as the amido is referred to $N{H^{2 - }}$ ion. Hence, the given statement is incorrect.
B. $en$ is a ligand whose naming in terms of coordination complexes is given as “ethylenediamine”. Hence, the given statement is correct.
C. ${C_2}{O_2}{S_2}^{2 - }$ is a ligand whose naming in terms of coordination complexes is given as “dithio oxalato”. Hence, the given statement is correct.
D. $C{H_3}^ -$ is a ligand whose naming in terms of coordination complexes is given as “methyl”. Hence, the given statement is correct.
Therefore, Option A is the incorrect statement.

Note : The student can be confused about the naming as one has to keep in mind that the anion nomenclature is written first followed by the cation.