Thiosemicarbazonates of ruthenium(II): Crystal structures of [bis(diphenylphosphino)butane][bis(pyridine-2-carbaldehydethiosemicarbazonato)] ruthenium(II) and [bis(triphenylphosphine)][bis(benzaldehydethiosemicarbazonato)] ruthenium(II)

The reaction of Ru2Cl4(dppb)3 {dppb = Ph2P–(CH2)4–PPh2} with pyridine-2-carbaldehyde thiosemicarbazone {C5H4NC(H)N3N2HC(S)NH2, Hpytsc}, and that of RuCl2(PPh3)3 with benzaldehyde thiosemicarbazone {C6H5C(H)N3N2HC(S)NH2, Hbtsc}, in the presence of Et3N base led to loss of the –N2H– proton in each case, and yielded [Ru(pytsc)2(dppb)] (1) and [Ru(btsc)2(Ph3P)2] (2), respectively. The complexes are characterized with the help of analytical data, IR, NMR (1H, 13C, 31P) and single crystal X-ray study. In both compounds 1 and 2, the thiosemicarbazone ligands coordinate to Ru(II) via the hydrazinic nitrogen (N2) and sulfur atoms forming four membered rings, and the pyridyl group is pendant in 1. The geometry is distorted octahedral with cis:cis:trans P, P:N, N:S, S dispositions of donor atoms. Proton NMR confirmed loss of the –N2H– proton in both compounds, and the 31P NMR spectra reveal the presence of equivalent phosphorus atoms in both the compounds. Compound 1 represents the first example of a Ru(II)-thiosemicarbazone complex with a chelating diphosphine and it reveals the stability of a seven membered P,P-chelate ring in the presence of a potentially tridentate pytsc− ligand.

Graphical abstractThe first example of a ruthenium(II) complex (1) with a chelating diphosphine forming a stable seven membered P,P-chelate ring in the presence of a potentially tridentate pyridine-2-carbaldehyde thiosemicarbazonate anion coordinating via N2, S-donor atoms is described.Figure optionsDownload full-size imageDownload as PowerPoint slide