Synthesis and stereochemical studies of the chiral ruthenium complexes [Ru(η-C5H5){(S)dpompyr-PP′}X][dpompyr =N-diphenylphosphino-2-(diphenylphosphinoxymethyl)pyrrolidine, X = H or Cl]. Crystal structure of [(S)Ru(η-C5H5){(S)dpompyr-PP′}Cl]

Abstract

A simple procedure for the preparation of [(S)Ru(η-C₅H₅){(S)dpompyr-PP′}H][dpompyr =N-diphenylphosphino-2-(diphenylphosphinoxymethyl)pyrrolidine] from [Ru₃(CO)₁₂] is described. The hydride reacts stereospecifically with chloroform or carbon tetrachloride to give [(S)Ru(η-C₅H₅){(S)dpompyr-PP′}Cl] whose structure is reported. The crystals are monoclinic, space group P2₁ with a= 11.076(2), b= 10.908(2), c= 12.825(3)Å, β= 92.26(2), and Z= 2. The structure was solved by the heavy-atom method and refined to R= 0.0322 using 2 306 diffractometer data with I > 3σ(I). Synthesis of this chloro-complex from [Ru(η-C₅H₅)(PPh₃)₂Cl] and (S)dpompyr proceeds with only modest diastereoselectivity whereas reduction of [(S)Ru(η-C₅H₅){(S)dpompyr-PP′}Cl] using LiAlH₄ regenerates 88%[(S)Ru(η-C₅H₅){(S)dpompyr-PP′}H]. Mechanisms are proposed to explain the observed diastereoselectivities. Circular dichroism and ¹H, ¹³C, and ³¹P n.m.r. spectra of all new compounds are also reported.