Co-ordination of copper(II) ions doped in pentacyanonitrosylferrate(2–) and tetrathiocyanatometallate(II) salts: an electron spin resonance study
Abstract
Pentacyanonitrosylferrate(2–) salts, M[Fe(CN)5NO](M = Cd or Zn), doped with low concentrations of copper(II) ions give e.s.r. spectra characteristic of square-planar copper with the unpaired electron in the dx2–y2 level on copper and strongly interacting with four equivalent nitrogen atoms. The g- and A(63Cu)-tensor components provide evidence for extensive in-plane π bonding. Similarly, metal tetrathiocyanates, M1[M2(SCN)4](M1, M2= Zn, Cd, or Hg), doped with CuII ions give complexes having a distorted square-planar geometry (again dx2–y2 for the outer electron), with strong hyperfine coupling to four equivalent nitrogen atoms for Cu2+ in Zn[Hg(SCN)4], two equivalent nitrogen atoms in Cd[Cd(SCN)4], and none in the Zn[Cd(SCN)4]. These results are discussed in terms of the co-ordinating power of the thiocyanate ligands.