Study in eight-co-ordination. Part IV. Single-crystal electronic spectrum and magnetic anisotropy of tetraphenylarsonium tetrakis(trifluoroacetato)cobaltate(II)

Abstract

The single-crystal polarised spin-allowed d–d spectra and megnetic anisotropy of [Ph₄As]₂[Co(O₂C·CF₃)₄] are reported and interpreted by use of a point-charge crystal-field model. The spectral and magnetic properties are generally consistent with the elongated tetrahedral environment provided by the four carboxylato-oxygen atoms at 200(3) pm from the metal. However, the sense of the polarisation of the ‘⁴A₂→⁴T₁(F)’ transition suggests that the crystal-field at the cobalt(II) includes a small contribution from the four carboxylato-oxygens 311(3) pm away. Spectral data for certain spin-forbidden transitions are also reported.