Bis(benzonitrile)palladium(II) Dihalides:  Structures and Cocrystallization of the Cubic Cluster Pd<sub>6</sub>Cl<sub>12</sub> with (<i>E</i>)-Stilbene and with Bis(benzonitrile)palladium(II) Dichloride

Crystals of the planar, trans complexes, bis(benzonitrile)palladium(II) dichloride and bis(benzonitrile)palladium(II) dibromide, suitable for single-crystal X-ray diffraction studies are obtained by growth from solutions in benzonitrile and their structures determined. While bis(benzonitrile)palladium(II) dichloride readily loses benzonitrile to form the cubic cluster Pd<sub>6</sub>Cl<sub>12</sub>, which cocrystallizes with a variety of planar aromatic hydrocarbon molecules, the much less soluble complex bis(benzonitrile)palladium(II) dibromide does not act as a source of the so far unknown cluster Pd<sub>6</sub>Br<sub>12</sub>. Attempts to prepare the hypothetical bis(benzonitrile)palladium(II) diiodide by reaction of PdI<sub>2</sub> with benzonitrile were not successful. A solution of bis(benzonitrile)palladium(II) dichloride in <i>p</i>-xylene on standing produces crystals of Pd<sub>6</sub>Cl<sub>12</sub>·(PhCN)<sub>2</sub>PdCl<sub>2</sub>·<i>p</i>-xylene, which contain columns of alternating Pd<sub>6</sub>Cl<sub>12</sub> and (PhCN)<sub>2</sub>PdCl<sub>2</sub> molecules in face-to-face orientations along with similar columns in which Pd<sub>6</sub>Cl<sub>12</sub> and <i>p</i>-xylene molecules are interleaved in face-to-face arrays. A solution of bis(benzonitrile)palladium(II) dichloride and (<i>E</i>)-stilbene in benzene solution leads, not to coordination of palladium to the olefin, but to deposition of crystals of the ternary molecular compound, Pd<sub>6</sub>Cl<sub>12</sub>·0.5((<i>E</i>)-stilbene)·2(benzene). In this solid, two Pd<sub>6</sub>Cl<sub>12</sub> clusters make face-to-face contact with phenyl rings on opposite sides of the (<i>E</i>)-stilbene molecule, but the olefinic portion is far from the palladium cluster. Additionally, one of the two benzene rings abuts the Pd<sub>6</sub>Cl<sub>12</sub> cluster in a face-to-face fashion.