Question

using valence bond theory show that [Ni (CN4)]2- complex ion is diamagnetic in in nature
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Answer 1

Answer:

CN being a strong field ligand pair up electrons in d-orbital of Ni and shows dsp2 hybridisation.the pairing of all the d electrons makes it diamagnetic.

for further explanation you can follow the link;

https://www.quora.com/How-do-you-know-that-NiCl4-2-has-tetrahedral-geometry-whereas-Ni-CN-4-2-has-square-planar-geometry