Reaction of the Tetrachalcogenides [ME4(dppe)] (M = Pd, E = S; M = Pt, E = S, Se) with Activated Alkynes to Form Dithiolenes and Diselenolenes

Abstract

The tetrachalcogenides [ME 4 (dppe)] (M = Pd, E = S; M = Pt, E = S, Se) react with the activated alkynes RO 2 CCϵCCO 2 R (R = Me, Et) to form the dithiolenes and diselenolenes [M{E 2 C 2 (CO 2 R) 2 }(dppe)]; the structures of the compounds [a] 933 with E = S, R = Et have been determined by X-ray crystallography; [PdS 4 (dppe)] also reacts with the carbene complex [W(CO) 5 {C(OEt)CϵCPh}] to yield the bimetallic dithiolene [Pd{S 2 C 2 [C(OEt)W(CO) 5 ]Ph}(dppe)].Scheme 2 precursors and the elemental chalcogen. In an extension of the work of Dudis et al. [12] stirring [MS 4 (dppe)] (M ϭ Pd, Pt) with an activated alkyne (dimethyl or diethyl acetylenedicarboxylate) in dichloromethane at reflux leads to formation of the dithiolenes 1a,b (M ϭ Pd) and 2a,b (M ϭ Pt) (Scheme 3). Scheme 3The tetraselenide [PtSe 4 (dppe)] reacts in an analogous fashion to yield the diselenolenes 3a,b (Scheme 4). A similar reaction of the MSe 4 fragment has previously been observed for the anionic tungsten complex [WSe(Se 4 ) 2 ] 2-. [16] Scheme 4