Towards Ruthenium‐Based Building Blocks for CuAAC Click Reactions: Challenges in Generating Ruthenium(II) Polypyridine Alkynes

Abstract

Abstract Ag + ‐free complexation of alkyne‐bipyridines at ruthenium(II) polypyridine centers proceeds with surprisingly low yields. The alkyne‐bipyridine‐substituted ruthenium(II) polypyridine complexes in this work were characterized by NMR spectroscopy, ESI spectrometry, and single‐crystal X‐ray structural analysis. A detailed analysis of the side products revealed an unexpected carbon–carbon alkyne bond splitting promoted by the ruthenium(II) center, leading to the formation of a CO–Ru II species, methyl‐bipyridine, and a methyl‐bipyridine‐substituted ruthenium(II) complex accompanying the target product. The side products were characterized using complimentary methods including X‐ray crystallography. A possible mechanism is suggested based on these side products and exemplary reaction studies.