Reactivity of Pd 3 (dppm) 3 (CO) n + and Pd 3 (dppm) 3 (CO)(RCCR) n + ( n = 0, +1, +2) Towards F − . Evidence of Reactive Intermediates and X-Ray Structure of [Pd 3 (dppm) 3 (MeO 2 CC≡CCO 2 Me)(F)]PF 6

The reactivity of the trinuclear palladium cluster [Pd3(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 [Pd3(dppm)3(CO)]+ is also reduced, but in a slower process, by the F− ion to produce [Pd3(dppm)3(CO)]0. Additionally, the alkyne cluster adducts [Pd3(dppm)3(CO)(RCCR)] n+ (n = 2, 1; R = CO2Me) are also reactive towards F−. Particularly, the dication adduct leads to a metastable fluoride adduct [Pd3(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 [Pd3(dppm)3(CO)(RCCR)]+ with F−, leads to a disproponation generating 0.5 equiv. of [Pd3(dppm)3(CO)(RCCR)(F)]+ and 0.5 equiv. of [Pd3(dppm)3(CO)(RCCR)]0. The former slowly evolves to [Pd3(dppm)3(RCCR)(F)]+, which was described by X-ray diffraction method. [Pd3(ddpm)3(CO)] n+ (n = 2, 1) are reduced by F− to form [Pd3(dppm)3(CO)](n+)−1. Concurrently, [Pd3(dppm)3(CO)(RCCR)] n+ (n = 2, 1) with F− generate the corresponding adducts [Pd3(dppm)3(CO)(RCCR)(F)](n+)−1, but, in the case of n = 1, disproponation is observed into [Pd3(dppm)3(CO)(RCCR)(F)]+ and [Pd3(dppm)3(CO)(RCCR)]0.