Question

When a coordination compound $PdC{l_2}.4N{H_3}$ is mixed with$AgN{O_3}$, $2$ moles of $AgCl$ are precipitated per mole of the compound, find structural formula and IUPAC name of compound.

Answer 1

We need to know what is a coordination compound and predict the coordination compound used in the given condition. Its structural formula and IUPAC name is also to be predicted. A coordination complex is made up of a single atom or ion called the coordination centre, which is normally metallic, and a surrounding series of bound molecules or ions called ligands or complexing agents. The number of ligands that attach to a metal depends on whether the ligand is monodentate or polydentate.

Complete answer:
Let us first understand how a coordination compound is written at the molecular level. The basic formula for writing a coordination compound is [M(Ligand)x]+ ion-. The most important here is the significance of the square bracket. The complex compound is written inside the square bracket and the cation or anion is written outside. The formula of a coordination complex is written in a different order than its name. The chemical symbol of the metal centre is written first. The ligands are written next, with anion ligands coming before neutral ligands. If there is more than one anion or neutral ligand, they are written in alphabetical order according to the first letter in their chemical formula. Ligands are Lewis bases since they can donate electrons to the central metal atom. The metal ions (M) are Lewis bases as they accept the electrons. The overall charge (ion) can be either positive, negative or neutral being cationic, anionic or neutral respectively.
For the given problem, One mole of $AgCl$ necessitates one mole of $C{l^ - }$ ion.
As a result, $2$ mole of $AgCl$ necessitates 2 mol of $C{l^ - }$ ion.
As a result, $2$ moles of Cl must occur outside the coordinate compound's coordination field, i.e. as an ion in the compound.
As a result, $\left[ {Pd{{\left( {N{H_3}} \right)}_4}} \right]C{l_2}$ is the structural formula.
Some rules for naming coordination numbers are:
1. Ligands that act as anions which end in "-ide" are replaced with an ending "-o" (e.g., Chloride → Chloro). Anions ending with "-ite" and "-ate" are replaced with endings "-ito" and "-ato" respectively (e.g., Nitrite → Nitrito, Nitrate → Nitrato).
2. Most neutral molecules that are ligands carry their normal name. The few exceptions are the first four on the chart: ammine, aqua, carbonyl, and nitrosyl.
3. The number of ligands present in the complex is indicated with the prefixes di, tri, etc. The exceptions are polydentates that have a prefix already in their name. When indicating how many of these are present in a coordination complex, put the ligand's name in parentheses and use bis (for two ligands), tris (for three ligands), and tetrakis (for four ligands).
In addition, the first rules to follow are:
1. Ligands are named first in alphabetical order.
2. The name of the metal comes next.
3. The oxidation state of the metal follows, noted by a Roman numeral (II, IV).
Keeping these rules in mind, IUPAC name of $\left[ {Pd{{\left( {N{H_3}} \right)}_4}} \right]Cl{\;_2}$ is tetraamminepalladium(II) Chloride.

Note:
In order to name any coordination compound, the concept of ligands must be clear. Identifying the ligands, naming them and placing them alphabetically is important before proceeding further. In addition to the mentioned rules, identifying the metal atom and calculating its oxidation state must also be known.