Two Linear Undecanickel Mixed-Valence Complexes: Increasing the Size and the Scope of the Electronic Properties of Nickel Metal Strings

摘要

The importance of one-dimensional (1D) transition-metal complexes stems from their ability to provide a fundamental understanding of metal-metal interactions and electron transport along an extended metal-atom chain (EMAC), and from the perspective of taking advantage of their specific properties for potential applications, such as molecular metal wires and switches. A series of string complexes of oligo-α-pyridylamino ligands ranging from 3 to 9 core metal atoms has been synthesized and characterized by Cotton's group and our group. Attempts to characterize such very long EMACs with high electron conductivity were hindered by the synthetic difficulties rapidly increasing with the size of the metal chain. We synthesized [Ni9(μ9-peptea)4Cl2] ten years ago, but all attempts to characterize a longer chain of Ni atoms have, to date, been unsuccessful, owing to very low yields and to the instability of the target compound, probably because of the high flexibility of large pyridylamino ligands.