Synthesis and fluxional behaviour of (cyclopentadienyl) and (pentamethylcyclopentadienyl)ruthenium(II) complexes with hemilabile ether-phosphines. 31P DNMR spectroscopic studies and line shape analysis

Abstract

A series of Cp *RuCl(P∼O) 2 complexes ( 3a-e) (Cp * = η 5-C 5Me 5) were prepared in situ by reaction of [Cp *RuCl 2] n (1) with the ether-phosphine ligands Ph 2PCH 2-D ( 2a-e) (D = CH 2OCH 3 ( a), 1,3-dioxolane-2-yl ( b), 1,3-dioxane-2-yl ( c), 1,3-dioxepane-2-yl ( d), tetrahydrofuran-2-yl ( e)) in the presence of zinc. Treatment of 3a-e and CpRuCl(P ∼ O) 2 ( 4b,c) with AgSbF 6 and NaBPh 4, respectively, afforded cationic, monochelated ruthenium(II) complexes of the type [η 5-C 5R 5)Ru(P ∼ O)(P ⌢ O)] + ( 5a-e: R = CH 3; 6b,c: R = H). The fluxional behaviour of 5a-e and 6c was studied by temperature dependent 31P NMR investigations. In the case of 5a-e computer-generated spectra were fitted to the experimental by using DNMR5. Thermodynamic parameters Δ H≠, Δ S≠ and Δ G≠ were obtained via graphic application of the Eyring equation to the kinetic data. Stirring 5c, 6c under an atmosphere of carbon monoxide results in the formation of [(η 5-C 5R 5)Ru(CO)(P ⌢ O) 2][SbF 6] ( 7c: R = CH 3; 8c: R = H).