Complex halides of the transition metals. Part III. Electronic spectra and ligand field parameters of octahedral and tetrahedral halogeno-complexes of manganese(II)

Abstract

The electronic spectra of a number of compounds of manganese(II) in which the metal is surrounded by an octahedral arrangement of halogen atoms have been analysed, and values for the Racah parameters, B and C, and the ligand-field parameters, Δ, calculated. The compounds include MnX₂(X = F, Cl, Br, I), (MeNH₃)₂MnCl₄, α-Cs₂MnCl₄, K₄MnCl₆, KMnCl₃, Me₄NMnCl₃, and Me₄NMnBr₃. The values obtained for Δ are 7500, 5200–6200, 5600–5800, and 5500 cm.^–1 for the fluorine, chlorine, bromine, and iodine compounds respectively, and they are compared with those for the tetrahedral arrangement of the ligands about the metal ion. X-Ray diffraction data have shown that (MeNH₃)₂MnCl₄ has the K₂NiF₄ structure with unit cell dimensions a 7·20, c 19·37 Å, and that the structures of Me₄NMnCl₃ and Me₄NMnBr₃, with unit cell dimensions a 9·13, c 6·49, and a 9·44′c 6·76 Å, respectively, are related to that of CsNiCl₃.