Novel Basic Ligands for the Homogeneous Catalytic Carbonylation of Methanol, XXVIl). -Dynamic and Reactive Behaviour of (Ether-Phosphane)Ruthenium(II) Complexes in Dependence on the 0-Basicity Reaction of the ether-phosphane ligand Ph2PCH2C4H702 (3a) irradiation cis&, trans-6a is retransformed at 40°C into 4a via with C12Ru(PPh3), (2) results in the formation of the bis(che1ate) all-trans-?a and 5a. The latter and the corresponding comcomplex tran~-Cl~Ru(P"O)~ (4a). (P -0 = ql-P-coordinated; plexes 5b, e, containing THF and CH,0CH3 as ether substit-P"0 = q2-0,P-coordinated). With CO both Ru-0 bonds are uents, show fluxional behaviour. The coalescence temperacleaved to give all-tran~-Cl~Ru(CO)~(P-O), (?a). At 35°C 7a is tures (10, 80, and 55"C, resp.) and the estimated AG * values transformed into the rnonocarbonyl ruthenium complex trans-(52, 65, and 59 kJ/mol, resp.) of the exchange process indicate Cl,(PnO)(P-O)RuCO (5a) with elimination of one CO mole-the weakest Ru-0 contact in 5a compared to 5b, c. The lower cule. On heating all-trans-?a to 110°C in toluene the thermo-basicity of the dioxanyl function is also responsible for the dynamically more stable complex cis-C12(OC)2Ru(frans-different reaction behaviour of 4a, 5a, and ?a compared to the P N O )~ (6a) is obtained. All reaction steps are reversible. Upon corresponding complexes with the ligands 3b, c.
Three equivalents of the ether-phosphane ligands 2a-c react with Cl2Ru(PPh3)3 (1) to give the complexes trans-Cl2Ru(P ̑O)(P∼O)2 (3a-c) (P∼O = η1-P-coordinated; P ̑O = η2-Ο,Ρ-coordinated). The hemilabile character of the P,O–ligands is becoming evident by the fluxional behaviour of 3 a-c. The coalescence temperatures in the AB part of their 31P{1H} NMR spectra are found at -10, 15 and -15 °C (AG* = 48, 53 and 47 kJ/mol). Because of steric effects, 3 a, in which the ether oxygen atom has the lowest basicity, and 3c, with the smallest ether substituent, show nearly the same dynamic properties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.