CFSE of Ni²⁺ (d⁸, octahedral)

Configuration: t₂g⁶ eg² CFSE = 6(−0.4Δₒ) + 2(+0.6Δₒ) = −1.2Δₒ

Nickel's oxidation states:

• Most common: +2 (Ni²⁺) — found in NiCl₂, NiSO₄, most coordination complexes
• Also known: 0 (Ni(CO)₄), +1 (rare), +3 (NiOOH), +4 (NiO₂)