NEETChemistryCoordination Compounds
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The complex [ PtCl ₄]²⁻ is tetrahedral and paramagnetic, whereas [ NiCl ₄]²⁻ is square planar and diamagnetic. Reason (R): The crystal field splitting energy ( ) for 5d series elements is significantly larger than that for 3d series elements, forcing pairing of electrons in Pt(II) complexes even wi
Options
- ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- CAssertion (A) is true but Reason (R) is false.
- DAssertion (A) is false but Reason (R) is true.
Correct answer
D. Assertion (A) is false but Reason (R) is true.
Step-by-step solution
Assertion (A) is false because [ NiCl ₄]²⁻ contains Ni(II) ( 3d^8 ) with a weak field ligand ( Cl ^- ), resulting in a high-spin tetrahedral and paramagnetic complex. In contrast, [ PtCl ₄]²⁻ contains Pt(II) ( 5d^8 ), which forms a low-spin square planar and diamagnetic complex. Reason (R) is true. The principal quantum number affects the crystal field splitting energy ( ). For 5d series elements like Pt, is about 50% larger than for 3d series elements. This large splitting energy overcomes the pairing energy, caus