Reaction of CpRu(PPh₃)₂Cl with six-member cyclothioethers. Structures of the [CpRu(PPh₃) _x L]Y complexes (L = pentamethylene sulfide, x = 2, Y = BF₄ ⁻; L = 1,3-dithiane; 1,3,5-trithiane, x = 2, Y = CF₃SO₃ ⁻; L = 1,4-dithiane, x = 1, Y = BF₄ ⁻)

Abstract

The synthesis of a series of ruthenium complexes with cyclothioether ligands is reported. The compounds were characterized by X-ray diffraction techniques. The molecular structures of [CpRu(PPh₃)₂(pms)]BF₄ (1), [CpRu(PPh₃)₂(1,3-dithiane)]OTfl (2), [CpRu(PPh₃)₂(1,3,5-trithiane)]OTfl (3), and [CpRu(PPh₃)(1,4-dithiane)]BF₄ (4) show chelation occurs only when the sulfur atoms are separated by at least two C atoms, creating a ligand bite size large enough to chelate. Cell parameters: 1, space group P2₁/c, a = 14.601(4), b = 19.102(10), c = 14.751(7) Å, β = 98.28(3)^○; 2, space group P2₁/c, a = 12.859(7), b = 15.576(3), c = 22.126(11) Å, β = 102.22(4)^○; 3, space group P2₁/c, a = 12.7320(20), b = 15.571(5), c = 22.287(4) Å, β = 101.812(14)^○; 4, space group Pbca, a = 11.2010(10), b = 16.321(7), c = 28.966(4) Å. Compounds 2 and 3 are X-ray isomorphous. The Ru–S bond lengths range from 2.341(3), 2.365(3) Å in compound 4 to 2.382(4) Å in compound 2. Upon chelation (compound 4), with subsequent loss of PPh₃, the Ru–P bond shortens to 2.327(3) Å. This may be due to reduced steric hindrance about the Ru atom. No evidence for C–S bond lengthening is observed.