Luminescent Heterometallic Branched Alkynyl Complexes of Rhenium(I)−Palladium(II):  Potential Building Blocks for Heterometallic Metallodendrimers

The photophysical and electrochemical behavior of a novel series of luminescent rhenium(I) complexes bearing a trialkynyl ligand, [1,3-(HC⋮C)2-5-{(N∧N)(CO)3ReC⋮C}C6H3] (N∧N = t Bu2bpy 1, Me2bpy 2, bpy 3), and their heterometallic branched complexes, [1,3-{Cl(PEt3)2PdC⋮C}2-5-{(N∧N)(CO)3ReC⋮C}C6H3] (N∧N = Me2bpy 4, bpy 5), have been studied; the X-ray crystal structures of 2 and 5 have been determined. Density functional theory calculations have also been carried out in order to probe the bonding in these compounds.