New aspects of high-spin chemistry

As a novel high-spin molecule, a through-bond spin-frustrated organic molecule 4,4′,4″-trisdiphenylmethyleneamine (TDMA) and its anion and cation was studied by cw-ESR spectroscopy. TDMA is a spin frustrated system composed of three S = 1 units coupled antiferromagnetically. This molecule was shown to have a triplet ground-state which is asymmetrical in its exchange interaction as well as its molecular conformation. The TDMA ions were generated at low temperature via successive radiolysis and photolysis of its diazo precursor. It was shown that the ground states of the anion and cation are quartet and sextet, respectively. This means that upon ionization the ground state changed from the intermediate-spin state of TDMA to the high-spin state of the ions, showing the interrelation between spin alignment and excess charge in a molecular field. On the other hand, in order to identify and discriminate the spin multiplicities of complicated spin assemblages in amorphous materials, we have developed electron spin transient nutation spectroscopy based on FT pulsed ESR and applied it to a pseudo one-dimensional high-spin polymer with effective spin S≥2.