Reactivity of Pd3(dppm)3(CO)n+ and Pd3(dppm)3(CO)(RCCR)n+ (n = 0, +1, +2) Towards F−. Evidence of Reactive Intermediates and X-Ray Structure of [Pd3(dppm)3(MeO2CC≡CCO2Me)(F)]PF6

AbstractThe reactivity of the trinuclear palladium cluster [Pd 3 (dppm) 3 (CO)] n+ (dppm = bis(diphenylphosphinomethane); n = 2, 1) towards F − was investigated by electrochemical and spectroscopic methods. The reaction depends on the charge of the cluster. The chemical reduction of the cluster dication is observed in the presence of F − generating the paramagnetic monocationic cluster. Spin-trapping experiments with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) provided evidence for the radical F • as an intermediate. In a similar manner to the dication, the monocationic cluster [Pd 3 (dppm) 3 (CO)] + is also reduced, but in a slower process, by the F − ion to produce [Pd 3 (dppm) 3 (CO)] 0 . Additionally, the alkyne cluster adducts [Pd 3 (dppm) 3 (CO)(RCCR)] n+ (n = 2, 1; R = CO 2 Me) are also reactive towards F − . Particularly, the dication adduct leads to a metastable fluoride adduct [Pd 3 (dppm) 3 (CO)(RCCR)(F)] + . The electroreductive behavior of this adduct involves electron-transfer steps and F − exchange equilibriums, for which digital simulation enables the extraction of the thermodynamic parameters (standard potentials and equilibrium constants). Concurrently, the monocation adduct [Pd 3 (dppm) 3 (CO)(RCCR)] + with F − , leads to a disproponation generating 0.5 equiv. of [Pd 3 (dppm) 3 (CO)(RCCR)(F)] + and 0.5 equiv. of [Pd 3 (dppm) 3 (CO)(RCCR)] 0 . The former slowly evolves to [Pd 3 (dppm) 3 (RCCR)(F)] + , which was described by X-ray diffraction method.Graphical Abstract[Pd 3 (ddpm) 3 (CO)] n+ (n = 2, 1) are reduced by F − to form [Pd 3 (dppm) 3 (CO)] (n+)−1 . Concurrently, [Pd 3 (dppm) 3 (CO)(RCCR)] n+ (n = 2, 1) with F − generate the corresponding adducts [Pd 3 (dppm) 3 (CO)(RCCR)(F)] (n+)−1 , but, in the case of n = 1, disproponation is observed into [Pd 3 (dppm) 3 (CO)(RCCR)(F)] + and [Pd 3 (dppm) 3 (CO)(RCCR)] 0 .[IMAGE]