AbstractReactions of 2,5‐dibromothiophene, 1, with [Pd2(dba)3]•dba [Pd(dba)2; dba = dibenzylideneacetone] in the presence of N‐donor ligands such as 2,2′‐bipyridine (bpy) and 4,4′‐di‐tert‐butyl‐2,2′‐bipyridine (dtbbpy) give arylpalladium complexes of cis‐[2‐(5‐BrC4H2S)PdBrL2], 2a, b [L2 = bpy (2a), L2 = dtbbpy (2b)], and cis‐cis‐L2PdBr[2,5‐(C4H2S‐)PdBr(L2)], 3a, b [L2 = bpy (3a), L2 = dtbbpy (3b)]. Treatment of cis complexes 2a, b and 3a, b with CO causes the insertion of CO into the PdC bond to give the aroyl derivatives of palladium complexes of cis‐[2‐(5‐BrC4H2S)COPdBrL2], 4a, b [L2 = bpy (4a), L2 = dtbbpy (4b)], and cis‐cis‐[(L2)(CO)BrPdC4H2S‐PdBr(CO)(L2)], 5a, b [L2 = bpy (5a) and L2 = dtbbpy (5b)], respectively. Treating complexes 2a, b with 1 mole equivalent of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) gave iminoacyl complexes cis‐[2‐(5‐BrC4H2S)CNXyPdBrL2], 6a, b [L2 = bpy (6a), L2 = dtbbpy (6b)], and a 3‐fold excess of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) gave triiminoacyl complexes [2‐(5‐BrC4H2S)(CNXy)3 PdBr], 7. Cyclization reactions of 6a, b with 3 mole equivalents of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) or cyclization reaction of 7 with 1 mole equivalent of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) both gave tetraiminoacyl complexes of [2‐(5‐BrC4H2S)(CNXy)4PdBr], 8, which was also obtained by the reaction of 1 or 2a, b with a 4‐fold excess of isocyanide XyNC with or without add Pd(dba)2. Similarly, complexes 3a and b were also reacted with 2 mole equivalents of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) to give iminoacyl complexes cis‐cis‐[(L2)(CNXy)BrPdC4H2S‐PdBr(CNXy)(L2)], 10a, b [L2 = bpy (10a), L2 = dtbbpy (10b)] and an 8‐fold excess of isocyanide XyNC (Xy = 2,6‐dimethylphenyl) afforded tetraiminoacyl complexes of [2,5‐(C4H2S)(CNXy)8Pd2Br2], 11. Complexes 2a, b and 3a, b reacted with TlOTf [(TfO = CF3SO3)] in CH2Cl2 to give 9a, b and 12a, b, respectively, in a moderate yield. Copyright © 2007 John Wiley & Sons, Ltd.