NEETChemistryCoordination Compounds
An aqueous solution of a nickel(II) salt reacts with excess potassium cyanide to form a stable coordination complex. Which of the following correctly represents the formula, hybridization of the central metal ion, and magnetic behaviour of the resulting complex?
Options
- A[ Ni ( CN )₄]²⁻, sp ^3, paramagnetic
- B[ Ni ( CN )₄]²⁻, dsp ^2, diamagnetic
- C[ Ni ( CN )₆]⁴⁻, d ^2 sp ^3, diamagnetic
- D[ Ni ( CN )₄]²⁻, sp ^3, diamagnetic
Correct answer
B. [ Ni ( CN )₄]²⁻, dsp ^2, diamagnetic
Step-by-step solution
When a nickel(II) salt reacts with excess CN ^- , the complex formed is the tetracyanidonickelate(II) ion, [ Ni ( CN )₄]²⁻ . The central metal ion is Ni ²⁺ , which has a 3 d ^8 electronic configuration. Since CN ^- is a strong field ligand, it forces the pairing of the two unpaired 3 d electrons against Hund's rule. This vacates one 3 d orbital. The hybridization involves one 3 d , one 4 s , and two 4 p orbitals, resulting in dsp ^2 hybridization (square planar geometry). Because all electrons are paired, the compl