A magnetic study of low moment nickel clusters formed from the solid-state decomposition reaction of nickel bis-1,5-cyclooctadiene.

Variable temperature SQUID magnetometry measurements were made on a sample of commercially available nickel bis-1,5-cyclooctadiene (Ni(COD)2) is reported. The material is shown to be a mixed phase magnetic system where the Ni(COD)2 behaves as a diamagnet containing a paramagnetic component at low temperatures which we believe consists of elemental Ni clusters arising from the decomposition of the material. The magnetic response of the Ni clusters can be described by the combination of two Langevin functions, which indicate cluster magnetic moments of 1.8 μ B and 15 μ B suggesting Ni n clusters with n = 2–3 and n = 14–19. However, we demonstrate that these clusters appear to show a spin transition to an S = 0 state at low temperatures, which may be a consequence of interactions between the clusters and the surrounding organic medium. Nevertheless, our results suggest that Ni(COD)2 is a novel material for the study of Ni clusters embedded in a diamagnetic background material