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Despite the potential of silver to mediate synthetically valuable cross-coupling reactions, the operating mechanisms have remained unknown. Here, we use a combination of rapid-injection NMR spectroscopy, electrospray-ionization mass spectrometry, and quantum chemical calculations to demonstrate that these transformations involve argentate(i) and (iii) complexes as key intermediates.

A new decarbonylation reaction is observed for [(K 2 -acetate)Pd(K 2 -diphosphine)] + complexes. Gas-phase IR experiments identify the product as [CH 3 Pd(OP(Ph 2 )CH 2 PPh 2 )] + . DFT calculations uncovered a plausible mechanism involving O atom abstraction by the diphosphine ligand within the coordination sphere to yield the acetyl complex, [CH 3 COPd(OP(Ph 2 )CH 2 PPh 2 )] + , which then undergoes decarbonylation.

A new palladium mediated "one pot" synthesis of thioamides from aromatic carboxylic acids (ArCO 2 H + RNCS → ArC(S)NHR + CO 2 ) was discovered by gas-phase experiments and theoretical studies. Palladium-mediated decarboxylation of aromatic carboxylic acids followed by addition of substituted isothiocyanates leads to the corresponding thioamide derivatives.