On the basis of stability of complex ion in the solution, complexes may be of two types, perfect and β Coordination Compounds Chemistry Question
Question
On the basis of stability of complex ion in the solution, complexes may be of two types, perfect and imperfect complexes. The stability depends upon the extent of dissociation which in turn depends upon the strength of metal-ligand bond. The stability of complex also depends upon charge on central metal atom, basic nature of ligand, chelation, and nature of metal ion and ligand according to HSAB principle.

π‘ Solution & Explanation
Step 1: Note that the estimation of Ni^2+ with dimethylglyoxime (dmgH) produces a square planar bis(dimethylglyoximato)nickel(II) complex, [Ni(dmg)2]. Step 2: Inside this square planar complex, the nitrogen atoms of the two dmg^- ligands coordinate to the Ni^2+ ion. Step 3: The complex is uniquely stabilized by symmetrical, intramolecular O-H...O hydrogen bonds bridging the oxime oxygen atoms across the plane, which corresponds to option (d).