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

Abstract

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 -(C≡CC₆H₄)_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.