Syntheses, structures, and Berry pseudorotation of ruthenium-phosphorane complexes

Ruthenium complexes containing a hypervalent phosphorus ligand, [Cp(CO)(2)R u{P-(OC6H4E)(2)}] (E = NH (2a), NMe (2b), O (4a)), [Cp(CO)(2)Ru{P(OC10H6O)( 2)}] (4b), and [Cp- (CO)(2)Ru{P(OC7H6O)(2)}] (4c), were prepared in the rea ction of [Cp(CO)(2)Ru{P(OPh)(3)}]BF4 (1) spectroscopic data of [Cp(CO)(2)M{ P(OC6H4E)(2)}] (M = Ru, Fe) (E = NH, NMe, O) reveals that the Ru-P bonding is more polarized as Mdelta-=Pdelta- than the Fe-P bonding. During the cour se of preparation of 2b, a phosphite complex [Cp(CO)(2)Ru{P(OC6H4NMe)(OC6H4 NMeH)}]-BF4 (3) was isolated, which reacted with a Lewis base to give 2b. T he X-ray structures of 2b, 4b, and 3 were determined. 2b and 4b have slight ly distorted trigonal-bipyramidal geometries. From the variable-temperature P-31 NMR study for 4c, the activation parameters for Berry pseudorotation around the pentacoordinate phosphorus were determined to be Delta H-double dagger = 42.1 +/- 0.5 kJ mol(-1), Delta S-double dagger = -91.1 +/- 1.6 J m ol(-1) K-1, and Delta G(340)(double dagger) = 73.1 +/- 0.7 kJ mol(-1). This constitutes the first determined activation parameters of Berry pseudorota tion for a metallaphosphorane complex.