Question 22.1: Determine the oxidation state of the central metal atom in e...
Determine the oxidation state of the central metal atom in each of the following compounds:
(a) [Ru(NH3)5(H2O)]Cl2, (b) [Cr(NH3)6](NO3)3, and (c) Fe(CO)5.
Strategy Identify the components of each compound, and use known oxidation states and charges to determine the oxidation state of the metal.
Setup (a) [Ru(NH3)5(H2O)]Cl2 consists of a complex ion (the part of the formula enclosed in square brackets) and two Cl– counter ions. Because the overall charge on the compound is zero, the complex ion is [Ru(NH3)5(H2O)]2+. There are six ligands: five ammonia molecules and one water molecule. Each molecule has a zero charge (i.e., each ligand is neutral), so the charge on the metal is equal to the overall charge on the complex ion.
(b) [Cr(NH3)6](NO3)3 consists of a complex ion and three NO_{3}^{-} ions, making the complex ion [Cr(NH3)6]3+. Each of the six ammonia molecule ligands is neutral (i.e., each has a zero charge), making the charge on the metal equal to the overall charge on the complex ion.
(c) Fe(CO)5 does not contain a complex ion. The ligands are CO molecules, which have a zero charge, so the central metal also has a zero charge.
(a) +2
(b) +3
(c) 0