title: Exceedingly Facile Ph-X Activation (X = Cl, Br, I) with Ruthenium(II): Arresting Kinetics, Autocatalysis, and Mechanisms.
abstract: [(Ph3P)3Ru(L)(H)2] (where L = H2 (1) in the presence of styrene, Ph3P (3), and N2 (4)) cleave the Ph-X bond (X = Cl, Br, I) at RT to give [(Ph3P)3RuH(X)] (2) and PhH. A combined experimental and DFT study points to [(Ph3P)3Ru(H)2] as the reactive species generated upon spontaneous loss of L from 3 and 4. The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2, originating from the initial PhI activation with 3, is roughly as reactive toward PhI as 3 itself; and 2) the Ph-I bond cleavage with the just-produced 2 gives rise to [(Ph3P)2RuI2], which quickly comproportionates with the still-present 3 to recover 2. Both the initial and onward activation reactions involve PPh3 dissociation, PhI coordination to Ru through I, rearrangement to a η(2)-PhI intermediate, and Ph-I oxidative addition.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona (Spain).
authors.forename: Fedor M
authors.initials: FM
authors.lastname: Miloserdov
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (UK).
authors.forename: David
authors.initials: D
authors.lastname: McKay
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona (Spain).
authors.forename: Bianca K
authors.initials: BK
authors.lastname: Muñoz
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona (Spain).
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Samouei
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (UK). s.a.macgregor@hw.ac.uk.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Macgregor
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007 Tarragona (Spain). vgrushin@iciq.es.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Grushin
keywords: Ar-X activation; DFT calculations; autocatalysis; kinetics; ruthenium