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

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