Answer to Question #196700 in Inorganic Chemistry for ella decker

Question

Which parameters determine the value of Δ_o? What is the difference between high spin and low spin complexes?

 

Answer 1

While studying the Crystal Field Theory I was told Dq

Dq is a unit, related to the unit Δ

O

ΔO by the relation Δ

O

=10 Dq

ΔO=10 Dq. But aren't Δ

O

ΔO and Dq

Dq variables, not units? The unit is of energy, such as eV

eV or Joules, these are symbols to represent a particular value of energy, which could be anything. So what do we mean when we say Δ

O

=10 Dq

ΔO=10 Dq? What exactly is Dq

Dq (I haven't been able to find this in any of my textbooks, they just either state this relation, or not at all) and are they actually units of energy?

Spiling energy have different coordination number have different energy .

High spin and low spin are two possible classifications of spin states that occur in coordination compounds. These classifications come from either the ligand field theory, which accounts for the energy differences between the orbitals for each respective geometry, or the crystal field theory, which accounts for the breaking of degenerate orbital states, compared to the pairing energy.

So, one electron is put into each of the five d orbitals before any pairing occurs in accord with Hund's rule resulting in what is known as a "high-spin" complex. Complexes such as this are called "high-spin" since populating the upper orbital avoids matches between electrons with opposite spin.

A low spin (or spin-paired) complex, such as [Co(NH3)6]3+ is one in which the electrons are paired up to give a maximum number of doubly occupied d orbitals and a minimum number of unpaired electrons. Usually inner orbital complexes (d2sp3) are low-spin (or spin paired) complexes.