Magnetic phenomena in nonrigid metal-nitroxide systems

Abstract
For NiL ₂ heterospin bischelates, stereochemical nonrigidity in solution has been found, which leads to solids with varying structure and composition. While investigating the products of Cu(hfac) ₂ interaction with spin-labeled pyrazole 4,4,5,5-tetramethyl-2-(1-methyl-1H-pyrazol-4-yl)-imidazoline-3-oxide-1-oxyl we have isolated a family of heterospin compounds differing in the structure and composition in the solid state. In synthetic systems, these compounds often co-crystallize and must be separated mechanically. It is also shown that minor variations in the structure of solid heterospin complexes substantially change the magnetic properties of the compounds. Key words. Nitroxides - metal complexes - structure - magnetic properties.