D-block Elements and Complex Compounds

Introduction to Complex Compounds

• D-block elements form complex compounds.
• Complex compounds are those in which either the cation or anion is complex and the other is normal.

Ionization of Compounds

• Example: Ionization of Cu(NH3)4 SO4:
  • Ionization of Cu(NH3)4: Cu(NH3)4^(2+) + SO4^(2-)

Properties of D-block Elements

• Small Size
• High Nuclear Charge
• Vacant d-orbitals
• These three characteristics permit the formation of complex compounds.

Structure of Complex Compounds

• In complex compounds, coordinate bonds are formed between the central metal atom/ion and ligands.
• Example: The structure of K4[Fe(CN)6] is octahedral.

Normal vs Complex Ions

• Simple ions: like K+ and MnO4-
• Complex ions: which are difficult to test like K4[Fe(CN)6]

Effective Atomic Number (EAN)

• EAN = Z - x + (number of ligands × denticity)
• EAN indicates stability.
• Example: The EAN of K4[Fe(CN)6] is 36, like krypton, which makes it stable.

Hybridization in Complex Compounds

• Vacant orbitals are needed for hybridization.
• Example: In D2SP3 hybridization, two d, one s, and three p orbitals are involved.

Conclusion

• The ability of D-block elements to form complex compounds is due to their small size, high nuclear charge, and vacant d-orbitals.