The frozen solution E.P.R. spectrum of the bis(2,2′:6′,2″-terpyridyl)copper(II) cation

Summary A quite anomalous signal, found in the frozen solution e.p.r. spectrum of bis(2,2 6,2-terpyridyl)copper(II) is presented, discussed and ascribed to overlap between an Isotropic and an anisotropic spectrum. At liquid helium temperature the isotropic spectrum disappears and the entire anisotropic signal can be seen without interference. Dynamic Jahn-Teller effects are invoked to account for this behaviour. The experimental data are compared with those associated with analogous systems containing 2,2-bipyridyl and 1,10-phenanthroline ligands.