What factors can perturb the g value in compounds?

The g value, or the g-factor, is a dimensionless quantity that reflects the magnetic moment and angular momentum of a particle or compound, often used in the context of electron paramagnetic resonance (EPR) spectroscopy among other measurements. It is influenced by various factors related to the electronic environment of the unpaired electrons in a paramagnetic species.

Spin-orbit coupling is a significant factor in perturbing the g value because it describes the interaction between an electron's spin and its orbital motion around the nucleus. This coupling leads to changes in the energy levels of electronic states due to the relativistic effects of moving electrons, affecting their magnetic properties. In transition metal complexes or systems with heavy atoms, the spin-orbit coupling becomes substantial, leading to noticeable shifts in g values. Thus, the effect of spin-orbit coupling is critical for understanding how and why g values deviate from the free electron g-value of 2.0023.

While temperature fluctuations, electron density, and vibrational energy changes do impact various aspects of molecular and electronic structure, they do not directly modify the intrinsic spin-orbit coupling effect within the electron cloud to the same extent as spin-orbit coupling does. Temperature fluctuations can cause changes in the dynamical behavior of molecules but do