X-ray Diffraction, PGSE Diffusion, and Related NMR Studies on a Series of Cp*-Based Ru(IV)(Cp*)(η³-CH₂−CH−CHPh) Allyl Complexes

The new ruthenium (IV) allyl complexes [Ru(Cp*)Cl(DMF)(η 3 -CH 2 −CH−CHPh)](PF 6 ) ( 2b ) and [Ru(Cp*)Cl(t-BuCN)(η 3 -CH 2 −CH−CHPh)](PF 6 ) ( 2c ) have been prepared and their structures determined. These results are compared with the analogous X-ray data for [Ru(Cp*)Cl(CH 3 CN)(η 3 -CH 2 −CH−CHPh)](PF 6 ), [Ru(Cp*){OC(O-t-Bu)O}(η 3 -CH 2 −CH−CHPh)](PF 6 ), [Ru(Cp*)(CH 3 CN) 2 (η 3 -CH 2 −CH−CHPh)](PF 6 ) 2, and [Ru(Cp*)(DMF) 2 (η 3 -CH 2 −CH−CHPh)](PF 6 ) 2 . In all of the structures, the Ru−((η 3 -CH 2 −CH−CHPh) moiety is markedly distorted such that Ru−CPh(allyl) separation is much longer than the remaining two Ru−C(allyl) distances. The DMF and acetonitrile ligands are shown to exchange on the NMR time scale via both variable-temperature and 2-D exchange spectroscopy. Pulsed gradient spin−echo (PGSE) diffusion and 1 H, 19 F HOESY NMR methods show that there is relatively little ion pairing in these salts in DMF and acetonitrile solutions. The PF 6 anions take up specific positions with respect to the Ru(IV) cations.