Synthesis, structures and properties of platinum(ii) complexes of oligoacetylenic sulfides

A series of novel platinum(n) acetylide complexes incorporating sulfur-linked oligoalkynes have been prepared. The Cul-catalysed dehydrohalogenation reactions of the mono-protected dialkyne ligand HC≡CSC≡C(TIPS) (TIPS = Pri3Si) with trans-[Pt(PBu3)2Cl2], cis-[Pt(dppe)Cl2] or cis-[Pt(Me2bipy)Cl2] (Me2bipy = 4,4′-dimethyl-2,2′-bipyridine), in the presence of a base, readily produced trans-[Pt(PBu3)2{C≡CSC≡C(TIPS)}2] 1, cw-[Pt(dppe)-{C≡CSC≡C(TIPS)}2] 3 and cis-[Pt(Me2bipy){C≡CSC≡C(TIPS)}2] 7, respectively, in good yields. Similar synthetic procedures using a diacetylenic sulfide species HC≡CSC≡CC≡CSC≡C(TIPS) afforded trans-[Pt(PBu3)2-{C≡CSC≡CC≡CSC≡C(TIPS)}2] 2 and cis-[Pt(dppe){C≡CSC≡CC≡CSC≡C(TIPS)}2] 4, both of which contain eight triple-bond units within the molecular entity. Two new metallo-end-capped derivatives trans-[Ph(Et3P)2Pt-C≡CSC≡C-Pt(PEt3)2Ph] 5 and trans-[Ph(Et3P)2Pt-C≡CSC≡CC≡CSC≡C-Pt(PEt3)2Ph] 6 were also synthesized in moderate yields by reactions of two equivalents of trans-[PtPh(Cl)(PEt3)2] and the diterminal acetylenic Sulfides HC≡CSC≡CH and HC≡CSC≡CC≡CSC≡CH in a CuI/(Me3Si)2NH system. All of the compounds 1-7 have been characterized by IR, NMR (1H,13C and31P) and UV/VIS spectroscopies, luminescence measurements and mass spectrometry. The solid-state molecular structures of 5 and 7 have been established by X-ray crystallography.