Which of the following sequences of hybridisation, geometry and magnetic nature are correct for the given coordination compounds ? Choose the correct answer from the options given below :
- A, B, C and D
- B, C and D only
- A, C and D only
- A, B and D only
Answer
(4) A, B and D only
Solution
A. [NiCl4]2-: Ni2+, 3d8; Cl- is weak ⇒ no pairing ⇒ sp3, tetrahedral, 2 unpaired e ⇒ paramagnetic ✓
B. [Ni(NH3)6]2+: Ni2+, 3d8; the two unpaired 3d electrons cannot be paired, so no inner d orbital is free ⇒ outer 4s, 4p, 4d orbitals used ⇒ sp3d2 (outer orbital), octahedral, 2 unpaired e ⇒ paramagnetic ✓
C. [Ni(CO)4]: Ni(0), 3d84s2; CO is strong ⇒ 4s electrons pushed into 3d ⇒ 3d10, sp3, tetrahedral, no unpaired e ⇒ diamagnetic ✗ (not paramagnetic)
D. [Ni(CN)4]2-: Ni2+, 3d8; CN- is strong ⇒ pairing ⇒ dsp2, square planar, diamagnetic ✓
∴ A, B and D only
Answer: (4)