OPTICAL OUTER-SPHERE LIGAND TO METAL CHARGE-TRANSFER IN BIS(N-ETHYLSALICYLALDIMINATO)NICKEL(II) TRIS(OXALATO)FERRATE(III)

A mixture of [Ni(Et-sal)2] ( = bis(N-ethylsalicylaldiminato)nickel (II)) and [Fe(Ox)3]3- (tris-(oxalato)ferrate(III) ion) displays longwavelength absorption at lambda-max = 472 nm. This new absorption band is assigned to an outer-sphere LMCT transition from the coordinated ethylsalicyladimine of [Ni(Et-sal)2] to Fe(III) of [Fe(Ox)3]3-. Mixing free ethylsalicyldimine or [M(Et-sal)2] (where M = Co(II), Cu(II) or Zn(II)) and [Fe(Ox)3]3- also shows the same phenomenon; the maximum of the new absorption band is independent on the nature of the metal.