Abstract: | The structure of dipepide AcMet‐Gly was determined by X‐ray crystallographic analysis. It possesses mono‐clinic, space group P21 (No. 4). with cell dimensions of α=0.8571(2) nm, b=0.5871(2) nm, c= 1.197(3) nm, β= 99.290(10)°. V=0.5944(15) nm3, Z=2, μ=2.74 cm?1. Mononuclear chelates, described as Pd(X)(S,N,O‐AcMet‐Gly)]?, in which Pd(II) is coordinated by thioether, deprotonated amide nitrogen, carbonyl oxygen of me‐thionine and X (AcMetGly or other ligands present in aqueous solution or in mobile phase solution), were detected 5 min after mixing AcMet‐Gly with Pd(H2O)4]2‐ at room temperature using electrospray ionization mass spectrometry. The geometry of Pd(H2O)(S,N,O‐AcMet‐Gly)]? is optimized at density functional B3LYP/LanL2DZ level. The fused five‐ and six‐membered chelate is responsible for cleavage of Met‐Gly bond. This is the first time to provide a direct evidence for Pd(II)‐mediated cleavage of dipeptides via external solvent attack. |