The doubly charged metal ions of the first row transition elements with the configuration d 1 , d 2 — Physical Chemistry — Electrochemistry Chemistry Question
Octahedral complexes
The doubly charged metal ions of the first row transition elements with the configuration d 1 , d 2 , … d 9 form mainly octahedral complexes of the general formula ML6 2+ (L = neutral monodentate ligand). From the magnetic behavior point of view these complexes are of two types. Those with the same number of unpaired electrons with the M(g) 2+ , the so called “high spin” complexes, and those in which this number is smaller or even zero, the “low spin” ones.
If the separation between the energy levels t2g and eg is Δ and the pairing energy (the energy necessary for two electrons to be coupled into a singlet) is P, predict the ground state electron configuration for these complexes. Hint: The Aufbau principle and the Pauli exclusion principle must be obeyed.
Model Answer
d 1 : tg 1 eg 0
d 2 : tg 2 eg 0
d 3 : tg 3 eg 0
d 4 : tg 4 eg 0 (Δ > P) or tg 3 eg 1 (Δ < P)
d 5 : tg 5 eg 0 (Δ > P) or tg 3 eg 2 (Δ < P)
d 6 : tg 6 eg 0 (Δ > P) or tg 4 eg 2 (Δ < P)
d 7 : tg 6 eg 1 (Δ > P) or tg 5 eg 2 (Δ < P)
d 8 : tg 6 eg 2
d 9 : tg 6 eg 3