Synthesis, resolution, and chemistry of chiral octahedral complexes of the type fac-[RuX(CO)L(triphos)]X′ (L = tertiary phosphine, isocyanide; X = halide, alkyl; X′ = halide, PF6-; triphos = 1,1,1-tris((diphenylphosphino)methyl)ethane)

Article abstract of DOI:10.1021/om00138a014

Treatment of complexes of the type [RuR(CO)₂(triphos)]⁺ (R = alkyl) with several isocyanides and tertiary phosphines in the presence of trimethylamine oxide leads to the formation of complexes of the type fac-[RuR(CO)L(triphos)]⁺, the ease of CO substitution being limited by the steric requirements (cone angles) in the cases of the phosphines. The new complexes are chiral, and resolution has been achieved in the case of [RuMe(CO)(t-BuNC)(triphos)]⁺, which has been isolated enantiomerically pure as the hexafluorophosphate and (R,R)-hydrogendibenzoyltartrate (HBDT) salts. The crystal structure of [RuMe-(CO)(t-BuNC)(triphos)][HDBT] (monoclinic space group P2₁; a = 19.356 (5) ?, b = 10.841 (3) ?, c = 15.262 (3) ?, β = 108.33 (2)°, Z = 2; structure refined to R = 0.032, R_w = 0.049) shows that the absolute configuration of the complex cation can be designated by the Sloan modification of the Cahn-Ingold-Prelog procedures as OC-6-43-A. Electrophilic cleavage reactions of the resolved methyl complex with HCl, Cl₂, I₂, and HgBr₂ proceed cleanly and quantitatively to yield the corresponding haloruthenium complexes and CH₄, MeCl, MeI, or MeHgCl, respectively. All reactions appear to be stereoselective, at least, but the halo products are configurationally labile and neither the extent of the stereoselectivity nor the absolute configurations can be determined. Attempts to determine the stereoselectivity by NMR spectroscopy utilizing chiral shift reagents were inconclusive. The second-order ¹³C{¹H} NMR spectra of a series of chiral complexes [RuX(CO)(¹³CO)(triphos)]⁺ (X = alkyl, halide) in the carbonyl region are analyzed in detail, and reasonable suggestions concerning the absolute signs of ²J(P-C) (cis and trans) are made.