Synthesis and Reactivity toward Isonitriles of (2-Aminoaryl)palladium(II) Complexes

Mixtures of “Pd(dba) 2 ” (dba = dibenzylideneacetone) and 2,2‘-bipyridine (bpy; 1:2) or N, N, N ‘, N ‘-tetramethylethylenediamine (tmeda; 1:1) react with 2-bromo-4-nitroaniline to give [Pd{C 6 H 3 NH 2 -2-NO 2 -5}Br(N−N)] (N−N = bpy ( 1b ), tmeda ( 1b ‘)). Reactions of 2-iodoaniline with mixtures of “Pd(dba) 2 ” and isonitriles RNC (R = C 6 H 3 Me 2 -2,6 (Xy), 2:1:2 molar ratios; R = t Bu, 2.9:1:2 molar ratios) result in the formation of the complexes [Pd{κ 2 C,N -C( NXy)C 6 H 4 NH 2 -2}I(CNXy)] ( 2a ) and trans -[Pd{C( N t Bu)C 6 H 4 NH 2 -2}I(CN t Bu) 2 ] ( 3a* ). The reactions of [Pd{C 6 H 4 NH 2 -2}I(bpy)] and 1b ‘ with RNC give the complexes trans -[Pd{C( NR)C 6 H 3 NH 2 -2-Y-5}}X(CNR) 2 ] (Y = H, X = I, R = Xy ( 3a ), t Bu ( 3a* ); Y = NO 2, X = Br, R = Xy ( 3b ), t Bu ( 3b* )). Complexes 3 react with Tl(TfO) (TfO = CF 3 SO 3 ) to give decomposition products, with the exception of 3a, which gives the cyclopalladated complex cis - [Pd{κ 2 C,N -C( NXy)C 6 H 4 NH 2 -2}(CNXy) 2 ]TfO ( 4a ). Complex 2a or 3 reacts with Tl(TfO) in the presence of the corresponding ligand, L or L 2, to give the cationic complex [Pd{C( NR)C 6 H 3 NH 2 -2-Y-5}(CNR)L 2 ]TfO (L = t BuNC, Y = H ( 5a* ), NO 2 ( 5b* ); L 2 = bpy, Y = H, R = Xy ( 6a ), t Bu ( 6a* )). When L = PPh 3, the resulting complexes trans -[Pd{C( NR)C 6 H 3 NH 2 -2-Y-5}(CN t Bu) 2 (PPh 3 )]TfO (Y = H ( 7a* ), NO 2 ( 7b* )) decompose easily to the Pd(I) complex [Pd 2 (CN t Bu) 4 (PPh 3 ) 2 ](TfO) 2 ( 8 ). The reaction of 2a with Tl(TfO) affords [{Pd[κ 2 C,N -C( NXy)C 6 H 4 NH 2 ](CNXy)} 2 (μ-I)]TfO ( 9a ), and that with a mixture of bpy and Tl(TfO) in acetone with subsequent bubbling of CO through the solution gives [Pd(R)(CNXy)(bpy)](TfO) 2 ( 10 ), where R is 2-(xylylamino)-3-xylylquinazolinium-4-yl. The crystal structures of 2a, 3a, 4a, 6a, 8, 9a ·CH 2 Cl 2, and 10 ·1.5CH 2 Cl 2 have been determined by X-ray diffraction studies. Some hydrogen bond interactions (C sp 3 −H···Pd, N−H···π−arene, N−H···I−Pd; eight-membered rings ···O−S−O···H−N−C−C−H··· and ···I−Pd−N−H···I−Pd−N−H···) lead to interesting supramolecular structures.