Magnetic properties of nitronylnitroxide and iminonitroxide triradicals as model compounds for generalized ferrimagnets

A novel iminonitroxide triradical, p-triIN (1), has been synthesized, in which a π-conjugated biradical with a singlet ground state and a doublet monoradical are united by σ-bonds. The intramolecular exchange interaction within the para-phenylene-based biradical moiety has been found to be antiferromagnetic (2J(π)/kB = −30.8 K) from magnetic susceptibility measurements on a parent biradical, p-bisIN (2). The magnetic properties of 1 have been examined by magnetic susceptibility χm. Upon cooling, the χmT value for 1 has decreased and passed across 0.38 emu mol−1 K, which is expected for one mol of S = 1/2 spin with g = 2.0. The magnetic behavior of 1 indicates that the ground state of the molecular assemblage of 1 in the crystal is diamagnetic, which is attributable to one of the exotic spin states as predicted in a theoretical model of generalized ferrimagnetism. The possible occurrence of the generalized ferrimagnetic spin alignment is concluded in view of the magnetic properties of 1.

An iminonitroxide triradical (1) has been synthesized, in which a ground-state singlet π-biradical and a π-monoradical are united by σ-bonds. The ground state of the molecular assemblage of 1 has been found to be nonmagnetic, which is attributable to an exotic spin alignment predicted in the theory of generalized ferrimagnetism.Figure optionsDownload as PowerPoint slide