Amazing progress in nanoelectronics has made it possible to fabricate devices whose macroscopic behavior depends on the quantum state of a few ( one) atomic spins. This includes NV centers in diamond,  single Mn-doped semiconductor  quantum dots, both probed optically, as well as single  magnetic adatoms and mollecules  probed with STM and/or break junctions transport experiments.   Quantized spins with integer spin have very different electronic properties from those with semi-integer spins.
In this talk I discuss, from the theory standpoint,  the effect of spin-parity on the spin dynamics of these systems and how it affects their functionality.  I will also propose an experiment to measure the so called diabolic points using inelastic electron tunneling spectroscopy.