Synthesis and reactivity of water-soluble arene–ruthenium(II) complexes and dimerization of terminal alkynes in organic and aqueous media

•We reported new method for synthesis of water-soluble arene–ruthenium(II) complexes.•Reaction of arene–ruthenium(II) complex with HCC(O)OR1 in R2OH was studied.•Arene–ruthenium(II) complex catalyzes the dimerization of some terminal alkynes HCCR in organic and aqueous medium.•Their structures are elucidated by IR, NMR and X-ray crystallography.

Treatment of the dimeric precursor [{RuCl(μ-Cl) (η6-C6H5OCH2CH2OH)}2] (1) with HNCPh2 in the presence of H2O afforded the arene–ruthenium(II) complex [(η6-C6H5OCH2CH2OH) (HN]CPh2)RuCl2] (2), as well as the aquo-species [(η6-C6H5OCH2CH2OH) (H2O)RuCl2] (3). The hydroxyethoxy substituent on the arene induces water-solubility of the resulting complexes. Reaction of 2 with HCC(O)OR1 in R2OH afforded the chelate vinyl ether complexes [Tp(PPh3)Ru–C(OR2)CHC(O)OR1] (4a, R1 = Me, R2 = Me; 4b, R1 = Et, R2 = Me; 4c, R1 = Et, R2 = Et; 4d, R1 = Me, R2 = Et), respectively. Preliminary results on the catalytic activity of 2 are also accessible. Intriguingly, complex 2 catalyzes the dimerization of some terminal alkynes HCCR in organic and aqueous medium. Whereas with R = COOMe, E-selective head-to-head dimerization takes place exclusively, in the case of R = SiMe3, t-Bu isomeric mixtures of head-to-head and head-to-tail coupling products are obtained. The structure of 3 has been determined by X-ray diffraction analysis.

Graphical abstractTreatment of the dimeric precursor 1 with HNCPh2 in the presence of H2O afforded 2, as well as the aquo-species 3. Reaction of 2 with HCC(O)OR1 in R2OH afforded the chelate vinyl ether complexes. Preliminary results on the catalytic activity of 2 are also accessible.Figure optionsDownload full-size imageDownload as PowerPoint slide