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-[Ru-III(AsPh3)(2)Cl-3(CH3OH)] (green powder) with 2-thiopyrimidine-1,3, HTPYM, in ethanol, produced red crystals of trans,cis,cis-[Ru-II(AsPh3)(2)((N,S) under bar -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) angstrom, respectively. The AsPh3 ligands assume a semi-trefoil C-1 arrangement and have C-H center dot center dot center dot S intra-molecular hydrogen bond type interactions to TPYM- ligands. These latter ligands are also involved in C-H center dot center dot center dot N and C-H center dot center dot center dot S interactions that pair two thiobase ligands via an unusual way. Density functional computational studies on [Ru(AsH3)(2)((N,S) under bar -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).