Answer
Few unpaired electrons (Pairing energy is lower than splitting energy) - low spin
More unpaired electrons(Pairing energy is higher than splitting energy) - high
Work Step by Step
A complex can be classified as high spin or low spin. When talking about all the molecular geometries, we compare the crystal field splitting energy ( Δ ) and the pairing energy ( P ). Normally, these two quantities determine whether a certain field is low spin or high spin.The electrons will take the path of least resistance--the path that requires the least amount of energy. If the paring energy is greater than Δ , then electrons will move to a higher energy orbital because it takes less energy. If the pairing energy is less than Δ , then the electrons will pair up rather than moving singly to a higher energy orbital.
