Question

What is the coordination number for each of the following complexes or compounds? [Co(NH3)4(H2O)2]3+ [Cr(EDTA)]− [Pt(NH3)4]2+ Na[Au(Cl)2]?

Answer 1

[Co(NH₃)₄(H₂O)₂]³⁺: coordination number = 6.

[Cr(EDTA)]⁻: coordination number = 6.

[Pt(NH₃)₄]²⁺: coordination number = 4.

Na[Au(Cl)₂]: coordination number = 2.

Step-by-step explanation:

• [Co(NH₃)₄(H₂O)₂]³⁺:

In this complex, Co is bonded with 4 molecules of NH₃ (with 4 coordinate bonds, one bond for each molecule) and 2 molecules of H₂O (with 2 coordinate bonds, one bond for each molecule) forming the complex with 6 coordinate bonds.

∴ coordination number = 6.

• [Cr(EDTA)]⁻:

In this complex, Cr is bonded with 1 molecules of EDTA (with 6 coordinate bonds, 4 O atoms and 2 N atoms in EDTA molecule).

∴ coordination number = 6.

• [Pt(NH₃)₄]²⁺:

In this complex, Pt is bonded with 4 molecules of NH₃ (with 4 coordinate bonds, one bond for each molecule).

coordination number = 4.

• Na[Au(Cl)₂]:

In this complex, Au is bonded with 2 atoms of Cl (with 2 coordinate bonds, one bond for each atom).

coordination number = 2.