Intra- and inter-molecular exchange on symmetrical hydrazine diradical dications and comparison of the magnetic exchange with ET parameters derived from their optical spectra

The spin alignment in a charged molecular field is important research issue in the molecular magnetism. In order to clarify the interrelation between spin alignment and the charged molecular field, we have investigated intra- and inter-molecular exchanges on some Hydrazine diradical dictations 1-3 s hown in Scheme 1 (see texts) by ESR and magnetic susceptibility measurement . The magnetic behavior of the dication salt 1 has been well analyzed using the alternating linear chain models with J(intra)/k(B)=-106 K, J(inter)/k( B)=-49 K and an alternating parameter alpha=0.46. The magnetic property of 3 has been also fitted to the alternating chain model with J/k(B)=-106 K J( inter)/k(B)=-42 K (alpha=0.40). On the other hand, 2 gives a robust triplet ground state with larger energy separation from other spin states. The ene rgy separation has been estimated to be larger than 300 cm(-1) (J(intra)/k( B)>+190 K) from the temperature dependence of the ESR signal intensity. The se findings indicate that the sign of the intramolecular exchange depends o n the linking position (m- or p-) of the hydrazine cation group, i.e. the t opology of the a orbital network even in the cationic molecular field. The magneto-optical correlation is also discussed based on the intramolecular e lectron transfer (ET) parameters.