Syntheses and characterization of ruthenium(0) and ruthenium(II) complexes of two flexible chelating triphosphine ligands

Article abstract of DOI:10.1021/om00078a001

Treatment of RuCl₃·3H₂O with the triphosphine ligands PhP(CH₂CH₂CH₂PR₂)₂ (ttp, R = Ph; Cyttp, R = c-C₆H₁₁) produces the complexes [RuCl₂(ttp)]_x, 1, and RuCl₂(Cyttp), 2, respectively. The ttp complex is polymeric whereas the Cyttp product is monomeric, presumably due to steric effects of the larger cyclohexyl (Cy) group. Treatment of 1 with carbon monoxide gives cis and trans carbonyl complexes, depending on the method of preparation; only a trans-dichloro carbonyl complex was obtained in the case of Cyttp. On the basis of infrared data (v(S-O) 1280, 1112 cm^-1), the SO₂ adduct of 2 has a planar geometry around the sulfur atom. Both chloride ligands of 1 can readily be substituted with CH₃CN or CO by using Tl⁺ as a halogen scavenger; the acetate ion replaces only one chloride in the absence of Tl⁺. Treatment of 1 with NaBH₄ produces RuH(η²-BH₄)(ttp), which undergoes substitution reactions to yield the cationic hydrido ligand complexes [RuH(L)(L′)(ttp)]Y (L = P (OCH₃)₃, PF₃, CO, NCCH₃; L′ = P(OCH₃)₃, NCCH₃, CO; Y = BF₄) by treatment with HBF₄ and the appropriate ligands. If the ligand substitution reactions are performed in basic solutions, the ligand dihydrido complexes RuH₂(L)(ttp) result. The ruthenium(0) complexes Ru(CO)₂(ttp), 10, and Ru(CO)₂(Cyttp), 11, can be prepared by (i) Na/Hg reduction of 1 or 2, (ii) reduction of the dicarbonyl complexes [Ru(CO)₂(ttp)][BF₄]₂ or [RuH(CO)₂(ttp)]BF₄, or (iii) triphosphine substitution of Ru₃(CO)₁₂. The complex Ru(CO)₂(Cyttp), 11, undergoes oxidative addition reactions with halogens and acids to form the cationic, six-coordinate ruthenium(II) dicarbonyls [RuX(CO)₂(ttp)]Y (XY = HCl, HBr, HBF₄, Cl₂, Br₂) and with molecular oxygen to give Ru(CO₃)(CO)(Cyttp). The preparation and characterization of these new ruthenium(II) and ruthenium(0) triphosphine complexes are reported, and structures are proposed on the basis of their conductivity, elemental compositions, and infrared, ¹H, ³¹P, and ¹⁹F NMR spectroscopy.