Q66P - Chemistry: Molecular Nature Of Matter And Change

Question

What is the coordination number of the metal ion and the number of individual ions per formula unit in each of the compounds in Problem 23.64?

Step-by-Step Solution

Answer

$\mathrm{a}){\left(\text{Co}{\left(\text{en}\right)}_2{\text{Br}}_2\right)}_2{\text{SO}}_4$- Coordination number: 6; 6 ions

$\mathrm{b}){\left(\text{Cr}{\left({\text{NH}}_3\right)}_6\right)}_2{\left({\text{CuCl}}_4\right)}_3$- Coordination number: 4; 17 ions

$\mathrm{c}\left){\mathrm{K}}_4\right(\text{Fe}\left(\text{CN}\right)$- Coordination number: 6; 11 ions

Step 1: Definition of Coordination Compound

A coordination complex is made up of a core atom or ion, known as the coordination center, which is typically metallic, and an array of attached molecules or ions that are known as ligands or complexing agents.

Step 2: Solve the given statements

The coordination number is the number of ligands directly attached to the central metal ion in a coordination compound. These ligands can be ions, atoms, or molecules. The most common coordination number is 6, but it is also not rare to see 2 and 4 as coordination numbers.

(Co(en)${\left.{\text{Br}}_2\right)}_2{\text{SO}}_4$ - There are four ligands bonded with the central metal ion (en is bidentate) so the coordination number is 6. This compound consists of 6 ions $\left({\text{Co}}^{3+},4{\text{Br}}^{-}\right.\left.{\text{and SO}}_4^{2-}\right)$.

${\left(\text{Cr}{\left({\text{NH}}_3\right)}_6\right)}_2{\left({\text{CuCl}}_4\right)}_3$- There are six ligands bonded with , so the coordination number is 6; there are 4 ligands bonded with , so the coordination number is 4. This compound consists of 17 ions $\left(2{\text{Cr}}^{3+},3{\text{Cu}}^{2+}\right.$and $\left.12{\text{Cl}}^{-}\right)$.

${\text{K}}_4\left(\text{Fe}{\left(\text{CN}\right)}_6\right)$- There are six ligands bonded with a central metal ion, so the coordination number is 6. This compound consists of 11 ions ( $4 {\text{K}}^{+},6\text{CN}$- and ${\mathrm{Fe}}^{2+})$