Synthesis of the diphenylacetylene-based, tetra-amine ligand 12,-bis(3,5-bis[(dimethylamino)metyl)acetylene by palladium-catalysed cross-coupling : Isolation and crystal structure of the catalyst trans-(3,5-bis[(dimethylamino)methyl]-phenyl)bis(triphenylphosphine palladium(II) iodide

Reaction of 3, 5-bis[(dimethylamino)methyl]phenyl iodide with 3,5-bis[(dimethylamino)methyl]phenylacetylene in diethylamine in the presence of bis(triphenylphosphine)palladium(II) dichloride (3.6 mol%) and copper(I) iodide (3.0 mol%) gave 1,2-(bis(3,5-bis[(dimethylamino)methyl]phenyl)acetylene (1) in 82% yield. The palladium catalyst was recovered in 93% yield as trans-(3,5-bis[(dimethylamino)methyl]phenyl)bis(triphenylphosphine)palladium (II) iodide (2). The crystal structure of 2 shows that the coordination geometry of the palladium is distorted square-planar. No inter- or intramolecular interactions between the N-donor atoms and the Pd are observed.