10.Explain as to how the two complexes of nickel [Ni(CN)4 ]2- and Ni(CO)4 have different structures but do not differ in their magnetic behaviours. (At. no. of Ni = 28).
In [Ni(CN)4]2−[Ni(CN)4]2− the ground state valence shell electronic configuration of nickel atom is Ar[18]3 d84 s2Ar[18]3 d84 s2. The oxidation state of nickel is +2+2, so the electronic configuration of Ni2+Ni2+ is Ar[18]3 d84 s2Ar[18]3 d84 s2. Due to the presence of a strong field ligand CN−CN−the pairing in the electrons starts and [Ni(CN)4]2−[Ni(CN)4]2− gets dsp 22 hybridized having a square planar geometry. Due to the presence of two unpaired electron in 3 d3 d sub shell, [Ni(CN)4]2−[Ni(CN)4]2− is diamagnetic in nature. In Ni(CO)4Ni(CO)4, nickel has zero oxidation state, so the electronic configuration of nickel will be Ar[18]3 d84 s2.Ar[18]3 d84 s2. As, COCO is a strong field ligand, the pairing in the electrons starts, all the ten valence electrons moves to the 3 d3 d sub shell and are paired. Therefore, Ni(CO)4Ni(CO)4 is sp3sp3 hybridized having a tetrahedral geometry. As there are no unpaired electrons, Ni(CO)4Ni(CO)4 is diamagnetic
