Synthesis and Reactivity of Selones and Dihaloselones: Complexation of Selones with d 8 ‐ and d 10 ‐Metal Ions

The reactivities of the monodentate selone LSe (L = 1,3‐dibutylbenzimidazol‐2‐ylidene; 10a ), the bidentate pyridine‐functionalized selone L′Se (L′ = 1‐pyridyl‐3‐butylimidazol‐2‐ylidene; 10b ) and the multidentate ether‐functionalized selone L′′Se {L′′ = 1,3‐bis[2‐(2‐methoxyethoxy)ethyl]benzimidazol‐2‐ylidene; 10c } with soft transition‐metal halides (PdX 2 , PtX 2 , ZnX 2 , CdX 2 and HgX 2 ; X = Cl, Br, I) are probed. Compounds 10a and 10c react with metal halides to give complexes of the type [Cu 2 (µ‐X) 2 (LSe) 2 ] (X = Br, I; 11 , 12 ), [MX 2 (LSe) 2 ] ( 13 – 22 ) or [M 2 X 2 (µ‐X) 2 (L′′Se) 2 ] (X = Cl, Br, I; 26 – 32 ), whereas 10b and HgX 2 (X = Cl, Br, I) form 1:1 complexes HgX 2 (L′Se) ( 21 – 23 ), in which the pyridine moiety coordinates to the metal centre to form a six‐membered chelate. The reactivity of 10a was compared with those of triphenylphosphine and triethylamine. The reaction of 10c with molecular iodine yields the diiodoselone L′′SeI 2 ( 35 ), which disproportionates to give the selone adduct of the iodonium ion, [(L′′Se) 2 I] + I 3 – ( 36 ). The reactions of LSeX 2 [X = Cl ( 34a ), Br ( 34b ), I ( 34c )] with organotellurium compounds, namely, tellone LTe ( 10d ) and diphenyl telluride ( 37 ), afford the dihalotellones LTeX 2 [X = Cl ( 38a ), Br ( 38b ), I ( 38c )] and Ph 2 TeX 2 [X = Cl ( 39a ), Br ( 39b ), I ( 39c )], respectively. The oxidizing properties of LSeX 2 ( 34a – 34c ) were investigated with rare‐earth metals.