Bis(ortho)-Chelated Bis(phosphanyl)aryl Ruthenium(II) Complexes Containing an η1-P-Monodentate or μ-Bridging η1-P,η1-P′ Bonded R−PCHP Arene Ligand, 1-R-3,5-(CH2PPh2)2C6H3 [R = H, Br, or, Si(n-CH2CH2C8F17)3] — Cyclometalation Reaction Intermediates and Potential Catalysts for Use in Fluorinated Biphasic Systems

Abstract

Mono- and binuclear ruthenium(II) complexes containing ligands derived from the meta-bis(phosphanyl)arene ligand 1-R-3,5-(CH2PPh2)2C6H3 [R-PCHP: R = H (5), Br (3), or Si(n-CH2CH2C8F17)3 (4)] have been synthesized and fully characterized. On reaction of equimolar amounts of the ruthenium starting material (e.g. [RuCl2(PPh3)3]) and the meta-bis(phosphanyl)arene, complexes of the type [RuCl{C6H2(CH2PPh2)2-2,6-R-4}(PPh3)] are invariably isolated, which contain only one [C6H3(CH2PPh2)2-2,6]- monoanionic ligand 3-P,C,P-bonded to Ru. Monitoring of this reaction by 1H and 31P NMR has shown it to proceed via intermediate species having an apparently 3-P,C,P-bonded PCP ligand and a second meta-bis(phosphanyl)arene ligand that is either 1-P-bonded or -1-P,1-P-bridging between two [RuCl(PCP)] units. The synthesis of the first PCP pincer-type ligand with a polyfluorinated pony tail is detailed, viz. compound 4 as well as the corresponding ruthenium complex [RuCl{(n-C8F17CH2CH2)3Si-PCP}], 7. The latter compound is soluble in fluorinated solvents and hence represents the first ruthenium pincer complex that may find use in fluorinated biphasic systems.