Ruthenium(II) complexes of the thiacyclophane ligands 2,5,8-trithia[9]-o-cyclophane (TT[9]OC) and 5-oxa-2,8-dithia[9]-o-cyclophane (ODT[9]OC). Structures of RuCl2(DMSO)(TT[9]OC) and RuCl2(PPh3)(ODT[9]OC)

Abstract

Ruthenium(II) complexes of the thiacyclophane ligands 2,5,8-trithia[9]-o-cyclophane (TT[9]OC) and 5-oxa-2,8-dithia[9]-o-cyclophane (ODT[9]OC) were synthesized by ligand displacement reactions employing RuCl2(DMSO)4, RuCl2(PPh3)3, and RuHCl(PPh3)3 as starting materials. X-ray crystal structures of two of these complexes, RuCl2(DMSO)(TT[9]OC) and RuCl2(PPh3)(ODT[9]OC), demonstrate how TT[9]OC and ODT[9]OC bind to Ru(II). RuCl2(DMSO)(TT[9]OC) crystallized as the DMSO solvate in the orthorhombic space group Pbca with a = 19.590(5), b = 16.849(4), c = 13.149(4) Å, V = 4340(3) Å3, and Z = 8. The structure refined to R = 5.27% and Rw = 6.27% for 2472 reflections with Fo2 > 3σ(Fo2). RuCl2(PPh3)(ODT[9]OC) crystallized as a ClCH2CH2Cl solvate in the monoclinic space group P21/c with a = 7.912(1), b = 22.419(5), c = 18.794(3) Å, β = 101.12(1),° V = 3271.2(9) Å3, and Z = 4. The structure refined to R = 4.96% and Rw = 5.14% for 1800 reflections with Fo2 > 3σ(Fo2). Both compounds are octahedral with the thiacyclophane ligand bound through three donor atoms in a facial coordination mode, cis chlorine atoms, and the unique ancillary ligand, DMSO or PPh3, bound trans to the central S or O donor of the macrocycle. The X-ray structures support 1H NMR spectral evidence which shows that the ligands are bound in an "endo" mode for L = DMSO and in an "exo" mode when L = PPh3. The reaction of RuHCl(PPh3)3 with TT[9]OC yields the ruthenium hydride complex RuHCl(PPh3)2(TT[9]OC). 1H and 31P NMR spectroscopy are consistent with an octahedral species for which the macrocycle occupies only two coordination sites acting as a bidentate η2-chelating ligand. Keywords: thioether, macrocycle, hydride, crystal structure.