Question

Give formulas for the following complex ions.

a. tetrachloroferrate(III) ion

b. pentaammineaquaruthenium(III) ion

c. tetracarbonyldihydroxochromium(III) ion

d. amminetrichloroplatinate(II) ion

Short answer

$$\begin{gathered} a.tetrachloroferrate\left(III\right)ion-\left[Fe{\left(Cl\right)}_4\right] \\ b.pentaammineaquaruthenium\left(III\right)ion-Ru{\left(N{H}_3\right)}_5{H}_2{O}^{3+} \\ c.tetracarbonyldihydroxochromium\left(III\right)ion-{\left[Cr{\left(CO\right)}_4{\left(OH\right)}_2\right]}^{+} \\ d.amminetrichloroplatinate\left(II\right)ion-{\left[PtN{H}_3{\left(Cl\right)}_3\right]}^{-} \end{gathered}$$

Step-by-step solution

Coordination sphere

If the coordination sphere is an anion or bears a negative charge, then the name of the central metal atom ends in “ate”. The following are examples:

$$\begin{gathered} tetrachloroferrate\left(III\right)ion-{\left[Fe{\left(Cl\right)}_4\right]}^{-} \\ amminetrichloroplatinate\left(II\right)ion-{\left[PtN{H}_3{\left(Cl\right)}_3\right]}^{-} \end{gathered}$$

Coordination Sphere

If the coordination sphere is cation or bears a positive charge then name of the central metal atom remains as is it. In following compounds metal atom is in coordination sphere which is cation.

$$\begin{gathered} pentaammineaquaruthenium\left(III\right)ion-Ru{\left(N{H}_3\right)}_5{H}_2{O}^{3+} \\ tetracarbonyldihydroxochromium\left(III\right)ion-{\left[Cr{\left(CO\right)}_4{\left(OH\right)}_2\right]}^{+} \end{gathered}$$