Selenium Heterocycles: Reactions of SeX₄ (X = Cl, Br) with the Enamine Form of β‐Diketiminato Ligands

Abstract

Abstract Treatment of SeX 4 (X = Cl, Br) with either MesnacnacLi(nacnac = [{N(Ar)C(Me)} 2 CH] – , Ar = Mes = C 6 H 2 Me 3 ‐2,4,6) or DmpnacnacLi (Ar = Dmp = C 6 H 3 Me 2 ‐2,6) affords four new Se II six‐membered heterocycles, [MesnacnacHCl 2 SeCl] ( 2 ), [MesnacnacH 2 Se] + Br – ( 3 ), [DmpnacnacH 2 Cl 3 Se] + Cl – ( 4 ), and [MesnacnacH 2 (O)Br 2 Se] ( 5 ). All have been characterized in the solid state by X‐ray crystallography. Each of the four complexes is proposed to have formed from the initial reaction of SeX 4 with the C–C double bond that results from the enamine form of the ligand, giving rise to an Se–C single bond. Subsequent nucleophilic attack by either the more distant nitrogen atom or the remaining C–C double bond of the enamine form results in the Se heterocycle. In complexes 2 , 4 , and 5 varying degrees of halogenation of the newly formed heterocycles was observed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)