Syntheses, structures and catalytic properties of ruthenium(II) nitrosyl complexes with bidentate and tetradentate Schiff base ligands

Treatment of Ru(NO)Cl3·xH2O with bi- or tetra-dentate Schiff base ligands afforded the corresponding ruthenium(II) nitrosyl complexes in the refluxing DMF/THF. Molecular structures of all ruthenium(II) nitrosyl complexes have been established by X-ray crystallography and their catalytic properties of the transfer hydrogenation of acetophenone were also investigated. [Display omitted] •A series of anionic and neutral ruthenium(II) nitrosyl complexes were synthesized.•All the synthesized complexes were characterized by X-ray crystallography.•The ruthenium complexes were tested as catalyst for the transfer hydrogenation. Treatment of Ru(NO)Cl3·xH2O with 1 equiv. bidentate Schiff bases in the presence of triethylamine in DMF/THF afforded a series of anionic ruthenium(II) nitrosyl complexes of the type [Et3NH][Ru(κ2-N,O-LR)(NO)Cl3] (HLR = 2-butyliminomethyl-phenol 1, 2-(benzylimino-methyl)-phenol 2, 2-[(4-chloro-phenylimino)-methyl]-phenol 3, 2-[(4-nitro-phenylimino)-methyl]-phenol 4, 2-[(2,6-diisopropyl-phenylimino)-methyl]-phenol 5). Interaction of Ru(NO)Cl3·xH2O and 1 equiv. tetradentate Schiff bases under the same condition led to isolation of an anionic complex [Et3NH][Ru(κ2-N,O-L-CH2CH2-NOH)-(NO)Cl3] (HL-CH2CH2-NOH = N,N′-disalicylidene-1,2-ethanediamine 6) and a neutral complex [Ru(salen-phn)(NO)Cl] (H2salen-phn = N,N′-disalicylidene-1,2-phenyldiamine 7). The molecular structures of 1·½C2H5OH, 2–6, and 7·CH2Cl2 have been determined by single-crystal X-ray crystallography. Investigation of the catalytic properties of ruthenium(II) nitrosyl complexes 1–7 showed that they are efficient catalytic precursors for the transfer hydrogenation of acetophenone.