Synthesis and characterization of cationic selenium-nitrogen heterocycles from tert-butyl-DAB (DAB =
June 28th, 2008 | by admin |Synthesis and characterization of cationic selenium-nitrogen heterocycles from tert-butyl-DAB (DAB = 1,4-di-tert-butyl-1,3-diazabutadiene) and SeX(4)via the reductive elimination of X(2) (X = Cl, Br): a distinct contrast with tellurium.
The synthesis and comprehensive characterisation of a series of 1,2,5-selenadiazolium salts, which were generated from the direct reaction between the neutral bidentate ligand tert-butyl-DAB and a variety of heavy chalcogen halides, are reported. The formation of the cationic heterocycle from the reaction of SeX(4) (X = Cl, Br) and the ligand results in a two electron redox process where the chalcogen undergoes a two electron reduction concomitant with the elimination of X(2), the oxidation by-product. A reaction pathway for this chemistry has been proposed necessitating several key intermediates. These species have been synthesized and used in a stepwise series of transformations that strongly supports this very unusual reactivity for the chalcogens. In contrast, the reaction between tert-butyl DAB and TeX(4) (X = Cl, Br, I), does not result in redox, rather an octahedral Te(iv).DAB complex is formed or no reaction was observed.
Dutton JL, Sutrisno A, Schurko RW, Ragogna PJ.
Department of Chemistry, The University of Western Ontario, 1151 Richmond St., London, Ontario, CANADA, N6A 5B7. pragogna@uwo.ca.