Question

Account for the magnetic property of the tetracyanidonickelate (II) ion.

Answer 1

• The tetracyanicnickelate(II) ion, [Ni(CN)₄]²⁻, is diamagnetic due to the absence of unpaired electrons.
• In this complex, nickel is in the +2 oxidation state with an electronic configuration of 3d⁸.
• The ligand cyanide (CN⁻) is a strong field ligand that causes significant crystal field splitting and promotes pairing of electrons in the lower-energy 3d orbitals.
• This strong field induces pairing of the 3d electrons, leading to the use of one 3d, one 4s, and two 4p orbitals for dsp² hybridisation, forming a square planar geometry.
• As a result, all eight electrons pair up within these orbitals.
• Since all electrons are paired, there are no unpaired electrons, and therefore, the complex exhibits diamagnetic behaviour.