Ruthenium-thiobase complexes: Synthesis, spectroscopy, density functional studies for trans,cis,cis-[RuII(AsPh3)2 (N,S-2-Thiopyrimidinato)2] and structural analysis of selected weak C–H⋯N and C–H⋯S interactions

The reaction of trans-[RuIII(AsPh3)2Cl3(CH3OH)] (green powder) with 2-thiopyrimidine-1,3, HTPYM, in ethanol, produced red crystals of trans,cis,cis-[RuII(AsPh3)2(N,S-2-thiopyrimidinato)2]. The compound has two TPYM− chelating anions in the equatorial plane, whereas the As atoms occupy the apical positions. It is stable in the solid state but the yellow chloroform solutions turn to green quickly in air atmosphere. The Ru–As, Ru–S and Ru–N bond distances average 2.432(1), 2.440(2) and 2.078(6) Å, respectively. The AsPh3 ligands assume a semi-trefoil C1 arrangement and have C–H⋯S intra-molecular hydrogen bond type interactions to TPYM− ligands. These latter ligands are also involved in C–H⋯N and C–H⋯S interactions that pair two thiobase ligands via an unusual way. Density functional computational studies on [Ru(AsH3)2(N,S-TPYM)2] model molecules show that the cis,cis,trans isomer is more stable than the trans,cis,cis one by some 5 kcal mol−1.

Graphical abstractThe reaction of trans-[RuIII(AsPh3)2Cl3(CH3OH)] with 2-thiopyrimidine produced the reduction of the metal center and formation of title compound (as deep red crystals) that is characterized by a trans arrangement of the AsPh3 ligands, by intra- and inter-molecular unusual C–H⋯S and C–H⋯N interactions that were structurally investigated via XRD and DFT.Figure optionsDownload full-size imageDownload as PowerPoint slide