Pd-(MOP) Chemistry:  Novel Bonding Modes and Interesting Charge Distribution

The new Pd-MOP acetyl acetonate complexes [Pd(acac)(10a or 10b)]BF₄, 12a,b, were prepared starting from [Pd(acac)(CH₃CN)₂]BF₄, whereas [Pd(acac)(11-H)], 13, was obtained directly from Pd(acac)₂ by adding 11. [Ligand 10a, MeO-MOP = (R)-2-(diphenylphosphino)-2‘-methoxy-1,1‘-binaphthyl; ligand 11, HO-MOP = (R)-2-(diphenylphosphino)-2‘-hydroxy-1,1‘-binaphthyl]. The solid-state structures for cationic 12a and neutral 13 were determined via X-ray diffraction methods and reveal that both structures contain Pd−C σ-bonds arising from the MOP naphthyl backbone. In structure 13, the hydroxyl function in 11 has lost a proton to afford a keto-anionic chelating ligand. ¹³C NMR studies confirm that the solution structures are the same as those found in the solid state and, for 12, describe how the organic cation distributes the positive charge.