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(C≡CH)₂, in a basic medium, afforded the mononuclear trans-[Ph(Et₃P)₂PtC≡CSiPh₂C≡CH] (1) and the dinuclear trans[Ph(Et₃P)₂PtC≡CSiPh₂C≡CPt(PEt ₃)₂Ph] (2). Complex 1 can be utilized as a key starting material for access to the triplatinum(II) system trans-[Ph(Et₃P)₂PtC≡CSiPh₂C≡CPt(PBu ₃)₂C≡CSiPh₂C≡Pt(PEt₃) ₂Ph] (3). Attempted oxidative coupling of 1 only led to the isolation of the triacetylenic species trans-[Ph(Et₃P)₂PtC≡CC≡CC≡CPt(PEt₃ )₂Ph] (5), involving cleavage of Si-C(alkyne) bonds. Soluble and thermally stable platinum(II) poly-yne silane polymer trans-[-Pt(PBu₃)₂C≡CSiPh₂C≡C-] _n (4) was prepared in good yield by CuI-catalyzed polymerization of trans-[Pt(PBu₃)₂Cl₂] and Ph₂Si(C≡CH)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.