The electronic and electron spin resonance spectra of complexes of the copper(II) ion with di-(2-pyridyl)amine

Abstract

New and more extensive spectroscopic data (electronic, e.s.r., and i.r.) for complexes CuL₂XY and CuL₂Z₂[L = di-(2-pyridyl)amine; X^–= I^–, NCS^–, and Y^–= ClO₄^–; Z^–= ClO₄^–, PF₆^–, Cl^–, Br^–, I^–, NO₂^–, and NO₃^–) are evaluated in terms of recent advances made in the understanding of the relationship between spectra and structure for copper(II) complexes. CuL₂(ClO₄)₂ is isomorphous with ZnL₂(ClO₄)₂ and contains non-planar CuL₂²⁺ ions as does CuL₂(PF₆)₂, whereas CuL₂(NO₃)₂ and CuL₂Br₂ are tetragonal complexes with planar CuL₂²⁺ units. There is good evidence that [CuL₂Cl]Cl is trigonal bipyramidal but the nature of CuL₂I₂ is less certain. The remaining complexes are believed to contain six-co-ordinate copper(II) with cis-bis(di-2-pyridylamine)copper(II) units. Evidence is presented to suggest that a novel dimeric complex is [(dipyam)₂(HF₂)Cu(dipyam)Cu(HF₂)(dipyam)₂]-(PF₆)₂ with one bridging di-(2-pyridyl)amine group.