Facile Csp–Csp bond formation prompted by an electrophilic fluorinating reagent from bis(alkynyl) platinum complexes†

Abstract

Electrophilic fluorination of bis(phenylacetylene)-platinum(II) complexes containing bipy or dppe as ancillary ligands at room temperature leads to C_sp–C_sp reductive elimination. In this regard, Selectfluor (N-chloromethyl-N′-fluorotriethylenediammonium bis(tetrafluoroborate)) was used in the reactions at room temperature, under air and without using dry solvents. Through experimental and computational studies, the influence of ancillary ligands on the C_sp–C_sp reductive elimination reaction was investigated. Based on density functional theory (DFT) calculations, the dissociation of acetonitrile (ACN) as a coordinated solvent is the rate-determining step. Therefore, in addition to the influence of the electronic properties of the ancillary ligands on the C_sp–C_sp coupling reaction, the energy required for the dissociation of acetonitrile from the Pt(IV) complexes significantly impacts the rate of the appearance of the experimentally observed products. The effect of various functional groups on the energy needed for the dissociation of acetonitrile and C_sp–C_sp reductive elimination was theoretically estimated. Our calculations show that the NMe₂ group has a greater impact on the reduction of the energy requirement for the two steps necessary for observation of the C_sp–C_sp coupling reaction product, particularly in the dppe Pt(IV) complex.