Spectrochemical Study of Microscopic Crystals. XVI. Structure of Cupric Formate, Acetate and Propionate

Abstract

Abstract Dichroisms in the visible and the ultraviolet region have been determined by the microscopic method with cupric formate tetrahydrate, cupric acetate monohydrate, anhydrous cupric propionate and its mono-hydrate. The cupric formate shows an absorption band at about 38–391013/sec. which is considered to be due to the copper ion in combination with the ligands. For this band, electric vector is much more strongly absorbed along the plane of the complex than in the direction normal to the plane. The dichroism and the absorption spectrum of the cupric formate are of the same type as those of most cupric complexes involving no special effect upon the complexes. Cupric acetate monohydrate, anhydrous cupric propionate and its monohydrate show an absorption band of a new kind at about 80×1013/sec., in addition to a band at about 43×1013/sec. which corresponds to the band at about 40×1013/sec. of the cupric formate. The polarization for the band at 80×1013/sec. is the reverse of the polarization for the band at 43×1013/sec. From the appearance of the new band at 80×1013/sec. and the reversal of the polarization property with this band, it has been concluded that the cupric compounds examined in this work, except the formate, consist of dimeric molecules having a structure similar to that of cupric acetate monohydrate. It has also been shown that the water of crystallization has very little effect upon the linkages within the complex molecules. The cupric compounds, except the formate, show in organic solvents a band at 80×1013/sec., involving the dimeric molecules in solution.