Biselenienyl series. II. Synthesis and resolution of 2,2′-dinitro-3,3′-biselenienyl-4,4′-dicarboxylic acid

2,2′-Dinitro-3,3′-biselenienyl-4,4′-dicarboxylic acid (VI), the first recorded compound of the 3,3′-biselenienyl series, has been prepared and resolved into its optical antipodes by fractional crystallization of its brucine salt. On the basis of the quasi-racemate method of Fredga and the O.R.D. spectra, to the dextrorotatory acid is assigned the R configuration.