Cationic arylpalladium complexes with chelating diamine ligands, [PdAr(N-N)(solv)]BF4 (N-N = N,N,N′,N′-tetramethylethylenediamine, 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine).: Preparation, intermolecular coupling of the aryl ligands, and insertion of alkyne and allene into the Pd-C bond

Iodo(aryl)palladium complexes, [PdI{C6H3(CF3)(2)-3,5}(N-N)] (N-N = tmeda, bpy, 4,4'dimethyl-2,2'-bipyridine (Me(2)bpy), react with AgBF4 in CH3CN, acetone, and THF to yield stable cationic arylpalladium complexes [PdIC6H3(CF3)(2)-3,5}(N-N)(solv)]BF4. A similar reaction of AgBF4 with [PdI(C6H3Me2-3,5)(bpy)] in CH3CN gives [Pd(C6H3Me2-3,5)(bpy)-(CH3CN)]BF4. The complex does not change its NMR spectrum for Ih at room temperature in CD3CN but undergoes decomposition upon dissolution in acetone to release 3,3',5,5'-tetramethylbiphenyl. Addition of AgBF4 to acetone or THF solutions of [PdI(Ar)(bpy)] (Ar = Ph, C6H3Me2-3,5) and of [PdI(Ar)(Me(2)bpy)] (Ar C6H4OMe-4, C6H3Me2-3,5) does not lead to isolation of the cationic arylpalladium complexes and causes intermolecular coupling of the ryl ligands to yield the corresponding biaryls. The reaction of AgBF4 with [PdI(C6H3Me2-3,5)(bpy)] in the presence of an excess amount of dimethyl acetylenedicarboxylate (DMAD) in CH3CN gives [Pd(CZ=CZ-CZ=CZ-C6H3Me2-3,5)(bpy)(CH3CN)]BF4 (Z = COOMe) via insertion of two acetylene molecules into the Pd-aryl bond. A similar reaction in acetone or THF causes insertion of three DMAD molecules into the Pd-aryl bond and cyclization of the formed Pd-(CZ=CZ)(3)-Ar group to give the product containing a cyclopentadiene structure in the ligand. [PdI(CZ=CZ-C6H3Me2-3,5)(bpy)] reacts with AgBF4 in CH3CN to form a cationic complex, [Pd(CZ=CZ-C6H3Me2-3,5)(bpy)(CH3CN)] BF4. A series of cationic Pd complexes, formed through insertion of one, two, and three alkyne molecules into the Pd-aryl bond, are characterized by X-ray crystallography or NMR spectroscopy. Phenylallene reacts with [PdI(C6H3Me2-3,5)(bpy)] in the presence of AgBF4 to give [Pd{eta (8)-CH2C(C6H3Me2-3,5)CHPh}(bpy)]BF4 via insertion of the C=C double bond of the allene into the Pd-C bond of the cationic arylpalladium complex. The pi -allylpalladium complex crystallizes exclusively in a form with a syn-oriented phenyl substituent but exists in solution as a mixture of the isomers with a syn or anti phenyl substituent.