Metal Acetylide Oligomers as Building Blocks for the Engineering of Molecular Devices

A systematic study directed towards the preparation of metal acetylide oligomers of the formula [-CºC-Ar-CºC-M(L)m-]n via a palladium-catalysed Extended One Pot (EOP) synthetic protocol has shown that, for M = Pt, Pd, palladium catalysis leads to the selective formation of bistinacetylydes Bu3Sn-CºC-Ar-CºC-SnBu3 (Ar = C6H4, C6H2(3,6-bis-OC8H17)). The coupling of the latter compounds with Cl2M(L)2 (M = Pt, Pd) to form metal acetylide oligomers is a thermally activated process that efficiently takes place, yielding short oligomers, only in the absence of any palladium catalyst. The GPC technique has proved to be a reliable method to estimate the chain lengths of polymers bearing branched aromatic spacers, despite the rigid-rod shape of their backbone. Single crystal X-ray determinations of model compounds have demonstrated the fundamental role of the side substituents in the aryl spacers to control the supramolecular order of the oligomeric materials.