What is the electron configuration for the transition metal ion(s) in each of the following compounds?

a. (NH₄)₂[Fe(H₂O)₂Cl₄]

b. [Co(NH₃)₂(NH₂CH₂CH₂NH₂)₂]I₂

c. Na₂[TaF₇]

d. [Pt(NH₃)₄I₂][PtI₄]

Pt forms +2 and +4 oxidation states in compounds.

Interpretation: The electron configuration of metal ion in each given complex compound is to be stated.

Concept introduction: Valence electrons are filled in four principal orbitals according to the energy levels. The four orbitals are s,p,d and f .

The metals from group 3-12 are known as first row transition metals. The general form of valence electron configuration of these metals is,

[Nobel gas]nfxndynsz

The distribution of electrons among different orbitals is given by electron configuration. When an element loses an electron, a positive charge is accumulated on it, whereas when an element gains an electron, negative charge is accumulated on it.

EXPLANATION

(a)

To write: The electron configuration of metal ion in (NH4)2[Fe(H2O)2Cl4] .

The metals from group 3-12 are known as first row transition metals. The general form of valence electron configuration of these metals is,

[Nobel gas]nfxndynsz

Where,

• n is the shell of principal orbital.
• x is the number of electrons in f orbital.
• y is the number of electrons in d orbital.
• z is the number of electrons in s orbital.

In the complex compound (NH4)2[Fe(H2O)2Cl4] , the metal ion is Fe2+ .

Iron is a group 8 element. The atomic number of iron (Fe) is 26 and its electronic configuration is,

[Ar]3d64s2

It loses two electrons to acquire two positive charges and becomes Fe2+ . The electronic configuration of Fe2+ is,

Fe2+=Fe−2e−

Substitute the electron configuration of Fe in the above equation.

Fe2+=Fe−2e−=[Ar]3d64s2−2e−=[Ar]3d6

(b)

To write: The electron configuration of metal ion in [Co(NH3)2(NH2CH2CH2NH2)]I2 .

In the complex compound [Ag(NH3)2]Cl , metal ion is Co2+ .

Cobalt is a group 9 element. The atomic number of cobalt (Co) is 27 and its electronic configuration is,

[Ar]3d74s2

It loses two electrons to acquire two positive charges and becomes Co2+ . The electronic configuration of Co2+ is,

Co2+=Co−2e−

Substitute the electron configuration of Co in the above equation.

Co2+=Co−2e−=[Ar]3d74s2−2e−=[Ar]3d7

 (c)

To write: The electron configuration of metal ion in Na2[TaF7]