Question

Limiting radius ratio of complex Ni(CN)4 2-

Answer 1

The answer 0.414 – 0.732

The coordination no. of [Ni(CN)₄]^2- is 4 as Ni is bonded to 4 CNs and is planar in structure.Hence its Limiting Radius Ratio must be between 0.225 and 0.414 .

But the answer is 0.414 to 0.732 (which is the limiting radius ratio for coordination no. 6 i.e. Octahedral void) .

Here, limiting radius ratio for geometry of this complex is square planar because CN−CNX− is a strong field ligand and causes pairing of unpaired electrons. So we can relate that Ni2+NiX2+ occupies a square planar void of the CN−CNX− lattice. The square planar void is a cross section of the octahedral void.