Synthesis, structure and computational studies of a cationic T-shaped Pd-complex

Reaction of [(cod)Pd(Me)(thf)][SbF6] or [(cod)Pd(Me)(MeCN)][B(ArF)(4)] (cod = 1,5-cyclooctadiene, B(ArF)(4) = [3,5-(F3C)(2)C6H3](4)B) with one or two equivalents of tBu(3)P gives [(tBu(3)P)(2)Pd(Me)](+) (3) exclusively. The two sterically encumbered tBu-groups prevent solvent coordination. In addition, this formally three coordinate complex is stabilized by a gamma-agostic interaction in solid state, whereas solution NMR studies confirm that this interaction is rather weak. The strength of the gamma-agostic interaction was evaluated using density functional theory (DFT) calculations. Surprisingly, [(tBu(3)P)(2)Pd(Me)](+) is unreactive toward CO, H-2, C2H4 and norbornene.