Question

Which of the following statements are correct?
(A) $[ Ni ( H _{2} O )_{6}]^{2+}$ and $[ Ni ( NH _{3})_{6}]^{2+}$ have same value of CFSE
(B) $[ Ni ( H _{2} O )_{6}]^{2+}$ and $[ Ni ( NH _{3})_{6}]^{2+}$ have same value of magnetic moment
(C) $[Ni ( H _{2} O )_{6}]^{2+} $ and $ [ Ni ( NH _{3})_{6}]^{2+}]$ have same hybridisation of nickel

• A. (A) and (C) only
• B. (B) and (C) only
• C. (A) and (B) only
• D. All of these

Answer 1

Answer: (B)

(A) Ammonia is a stronger field ligand than water. So $\left[ Ni \left( NH _{3}\right)_{6}\right]^{2+}$ will have higher $CFSE$ than $\left[ Ni \left( H _{2} O \right)_{6}\right]^{2+}$

(B) Both complexes $\left[ Ni \left( H _{2} O \right)_{6}\right]^{2+}$ and $\left[ Ni \left( NH _{3}\right)_{6}\right]^{2+}$ have sp $^{3} d ^{2}$ hybridisation with two unpaired electrons. So, they possess same magnetic moment ('spin only')