Question

NiCl₂ in the presence of dimethyl glyoxime (DMG) gives a complex which precipitates in the presence of NH₄OH, giving a bright red colour. 

(a) Draw its structure and show H-bonding 

(b) Give oxidation state of Ni and its hybridisation 

(c) Predict whether it is paramagnetic or diamagnetic

Answer 1

(a) Structure of the complex is

(b) The oxidation state of Ni in this compound is +2 and it shows dsp² hybridisation. 

(c) Since the coordination number of Ni in this complex is 4, the configuration of Ni²⁺ is,

at first sight, gives the idea that the complex is paramagnetic with sp³-hybridisation as it has two unpaired electrons. However the experiments show that the complex is diamagnetic ie, it does not have any unpaired electron. This is only possible when the 3d-electrons rearrange themselves against the Hund's rule ie,

This is also in accordance with the fact that the ligand involve here is very strong.