Spedrochemical Study of Microscopic Crystals. XVIII. The Color and the Structure of Compounds of a Magnus Green Salt Type

The color and the structure of the compounds of a Magnus green salt type, [Pt(amine)4] [PtCl4], have been studied. The dichroism with crystals of [Pt(methylamine)4] [PtCl4] and [Pt(ethylamine)4] [PtCl4] has been quantitatively determined at room temperature in the visible and ultraviolet region by the microscopic method. From the measurements, the unusually deep color of the former has been shown to be ascribed to a direct type of interaction between platinum atoms. No interaction of this sort is present in the crystal of the latter, which is pink in color. It is suggested that the compounds having a formula of [Pt(alkylamine)4] [PtCl4] may generally be classified into two kinds, one being colored green and the other pink. In the crystals of the former there is a direct type of interaction between platinum atoms at the center of the planar complexes, but no interaction of such a sort is operative in the crystals of the latter.