Synthesis and characterization of wire-like Ru2(ap)4-[σ-oligo(phenylene ethynyl)] compounds

Reported herein are the synthesis, electrochemical and structural characterization of wire-like Ru2-alkynyl compounds, Ru2(ap)4(Ln)x, where ap is 2-anilinopyridinate, and Ln is –(Ctriple bond; length of mdashCC6H4)nSCH2CH2SiMe3 with n = 1 (1) and 2 (2), and x can be 1 (a) and 2 (b). Reactions between Ru2(ap)4Cl and one equiv. of LiLn yielded the mono-alkynyl compound only, while the use of 4–5 equiv. of LiLn resulted in a mixture of both the mono and bis-alkynyl species. Single crystal X-ray diffraction studies of compounds 1a and 1b revealed structural similarities to Ru2(ap)4(C2Ph) and Ru2(ap)4(C2Ph)2, respectively. Magnetic, spectroscopic and voltammetric measurements also revealed a minimal perturbation on electronic structures due to the functionalization of OPE ligands with thiol-TMSE group (–SCH2CH2SiMe3). Most significantly, it can be estimated based on the structure of 1a that the Ru–OPE2–S– linkage in 2a is significantly longer than the depth of C11 thiol SAM and hence enables the insertion of 2a into the latter.