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

Abstract

A series of novel platinum(II) acetylide complexes incorporating sulfur-linked oligoalkynes have been prepared. The CuI-catalysed dehydrohalogenation reactions of the mono-protected dialkyne ligand HCCSCC(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{CCSCC(TIPS)}2] 1, cis-[Pt(dppe){CCSCC(TIPS)}2] 3 and cis-[Pt(Me2bipy){CCSCC(TIPS)}2] 7, respectively, in good yields. Similar synthetic procedures using a diacetylenic sulfide species HCCSCCCCSCC(TIPS) afforded trans-[Pt(PBu3)2{CCSCCCCSCC(TIPS)}2] 2 and cis-[Pt(dppe){CCSCCCCSCC(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–CCSCC–Pt(PEt3)2Ph] 5 and trans-[Ph(Et3P)2Pt–CCSCCCCSCC–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 HCCSCCH and HCCSCCCCSCCH in a CuI/(Me3Si)2NH system. All of the compounds 1–7 have been characterized by IR, NMR (1H, 13C and 31P) 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.