Structure of Cupric Mono-, Di- and Tri-bromoacetates

Abstract

IT was concluded in our former communication¹ that cupric mono- and di-chloroacetates in the crystalline state and in ordinary organic solvents might consist of the binuclear molecules with a sort of copper-to-copper linkage, though cupric trichloroacetate does not have a similar binuclear molecule in the crystalline state or in dioxan. The exceptional structure of cupric trichloroacetate may be ascribed to the accumulation of the inductive effect of the three chlorine atoms. In this connexion, it seems interesting to see what type of structure may be involved in the cupric bromoacetates. Therefore, we examined the structure of cupric mono-, di- and tri-bromoacetates, using the criteria previously derived: (1) the cupric monocarboxylates involving the binuclear molecules show, in addition to a band at about 40 to 44 × 10¹³ c./s., a special absorption band at about 80 × 10¹³ c./s., which was regarded as possibly due to the presence of the copper-to-copper linkage; (2) the polarization of the latter band is the reverse of the polarization of the former.