Electron spin resonance and optical spectroscopic studies on Cu2+ and Co2+ in Cs2[Zn(N3)4]

Abstract

The e.s.r. spectra of crystalline powders of Cs₂[Zn(N₃)₄] containing up to 0.2 mol % of either Cu²⁺ or Co²⁺ have been studied at Q-(34 GHz) and X-band (9.2 GHz) frequencies at temperatures down to 2 K. Comparison with electronic reflectance spectra at 77 K indicates that in a dehydrated form, the Cu²⁺ ion occupies the zinc site but with compressed tetrahedral geometry. As crystallized however, the crystals contain water and it is suggested that in this case the Cu²⁺ co-ordination is trigonal bipyramidal, having one water molecule in the equatorial plane. For Co²⁺, optical spectra indicate a distorted tetrahedral geometry and in the e.s.r. spectra the major component is consistent with, but not diagnostic of, this. At least two other minor e.s.r. subspectra are also observed.