Synthesis of new ruthenium(II) carbonyl hydrido, alkenyl, and alkynyl complexes with chelating diphosphines

Article abstract of DOI:10.1021/om00021a037

Substitution of one or two triphenylphosphine ligands of Ru(CO)ClH(PPh₃)₃ by bidentate diphosphines Ph₂P(CH₂)_nPPh₂ (L-L) (n = 1, dppm; n = 2, dppe; n = 3, dppp; n = 4, dppb) or 1,1′-bis(diphenylphosphino)ferrocene (dppf) led to hydrides Ru(CO)ClH(PPh₃)₂(L-L) or Ru-(CO)ClH(PPh₃)(L-L). The hydrido complexes were characterized spectroscopically and by one X-ray structure. Hydride Ru(CO)ClH(PPh₃)(dppf) crystallizes in the monoclinic space group P2₁/n, with a = 17.768(1) ?, b = 25.252(2) ?, c = 11.213(1) ?, β = 92.83(1)°, Z = 4, and V = 4459.3(6) ?³. Reaction of Ru(CO)ClH(PPh₃)₃ or [Ru(CO)H(MeCN)₂(PPh₃)₂]+PF₆-with 2 equiv of diphosphines L-L led to [Ru(CO)H(L-L)₂]⁺A^- (L-L = dppm, dppe, dppp) (A = Cl, PF₆). Hydrides Ru(CO)ClH(PPh₃)₂(L-L) react with 1-alkynes to give alkenyl complexes Ru(CO)Cl(CH=CHR)(PPh₃)(L-L) with a chelating diphosphine ligand. Ru(CO)ClH(PPh₃)-(L-L) gave σ-alkynyl complexes Ru(CO)Cl(C≡CR)L(L-L) directly in their reactions with 1-alkynes. The hydride with dppb as the ligand showed the highest reactivity. The preparation of hexacoordinated alkenyl derivatives Ru(CO)Cl(CH=CHR)(PPh₃)(L-L) with a chelating diphosphine was carried out by treatment of other alkenyl derivatives with the diphosphines. Surprisingly, reaction of alkenyls Ru(CO)Cl(CH=CHR)(Me₂Hpz)(PPh₃)₂ (R = CMe₃, P-MeC₆H₄) with dppf led to complexes Ru(CO)Cl(CH=CHR)(Me₂Hpz)(dppf) by substitution of both PPh₃ ligands instead of the dimethylpyrazole. Ruthenium alkenyls Ru-(CO)Cl(CH=CHR)L(dppf) (L = Me₂Hpz, PPh₃) react cleanly with 1-alkynes at room temperature to give alkynyl complexes Ru(CO)Cl(C=CR)L(dppf) in good yield. This reaction was applied to the synthesis of a bimetallic complex Ru(CO)Cl(PPh₃)(dppf)(C≡C-p-C₆H ₄C≡C)-Ru(CO)Cl(PPh)(dppf) as a mixture of meso and dl diastereomers.