JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Coordination Compounds

The dimethylglyoximato complex of nickel(II) is a neutral, square planar, rosy-red precipitate, so statement A is true. Being a neutral chelate that precipitates from mildly basic solution, it is only sparingly soluble in water, so statement B is false. The ${\text{Ni}}^{2+}$ ion is $d^8$ and in the square planar ($ds{p}^2$) field all electrons are paired, so it has no unpaired electrons and statement C is false. The square planar geometry sets the coordinating nitrogen atoms at angles close to $90^{\circ }$, so statement D is true. Each dimethylglyoxime ligand forms a single five-membered chelate ring with the metal, giving two such metallacycles rather than four, so statement E is incorrect. The incorrect statements are B, C and E.