Synthesis, structures and optical spectroscopy of photoluminescent platinum-linked poly(silylacetylenes)

Synthetic routes to a series of novel oligomeric and polymeric platinum(II)-containing silylacetylenes have been developed. The CuI-catalyzed reaction of trans-[Pt(PEt3)2PhCl] with the alkynylsilane Ph2Si(CCH)2, in a basic medium, afforded the mononuclear trans-[Ph(Et3P)2PtCCSiPh2CCH] (1) and the dinuclear trans-[Ph(Et3P)2PtCCSiPh2CCPt(PEt3)2Ph] (2). Complex 1 can be utilized as a key starting material for access to the triplatinum(II) system trans-[Ph(Et3P)2PtCCSiPh2CCPt(PBu3)2CCSiPh2CCPt(PEt3)2Ph] (3). Attempted oxidative coupling of 1 only led to the isolation of the triacetylenic species trans-[Ph(Et3P)2PtCCCCCCPt(PEt3)2Ph] (5), involving cleavage of Si–C(alkyne) bonds. Soluble and thermally stable platinum(II) poly-yne silane polymer trans-[–Pt(PBu3)2CCSiPh2CC–]n (4) was prepared in good yield by CuI-catalyzed polymerization of trans-[Pt(PBu3)2Cl2] and Ph2Si(CCH)2. The single-crystal X-ray structural analyses and DFT calculations were performed on 1, 2 and 5. We report the optical absorption and photoluminescence spectra of these new metal-based oligomeric and polymeric silylacetylenes and the results are compared with platinum(II) poly-ynes with purely acetylenic and (hetero)aromatic conjugated units.