The electronic properties of trigonal bipyramidal complexes of the copper(II) ion

The e.s.r. and electronic spectra and magnetic moments of Cu(NH3)2Ag(SCN)3 and [Cu(tren)NCS]SCN (tren = 2,2′,2″-triaminotriethylamine) are reported and compared with the previously reported data for trigonal bipyramidal complexes of the copper(II) ion. Theoretical expressions for the g-values for a copper(II) ion in a trigonal bipyramidal configuration are derived and are shown to apply only to the Cu(NH3)2Ag(SCN)3 complex. The energy levels 2E″ and 2E′ are shown to be separated by less than 2000 cm.–1 and the magnetic moments of the trigonal bipyramidal complexes are in the range normally observed for copper(II) complexes with an orbitally non-degenerate ground state.