Recent X-ray work, IR and other spectroscopic methods have proved that Turnbull's blue is identical — Coordination Compounds Chemistry Question

💡 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).