Molecular Metal Wires Built from a Linear Metal Atom Chain Supported by Oligopyridylamido Ligands

Abstract

Molecular wires incorporating four oligopyridylamine ligands and a metal atom chain have been synthesized. The structures show that the metal atom chain is in a linear arrangement and is helically wrapped by four ligands. The metal atom chain may adopt a symmetrical or unsymmetrical arrangement depending on the crystallization environment, the nature of the metal ions, the oxidation states of the complexes, and the nature of the axial ligands. The strength of metal-metal interactions in the neutral form of linear multinuclear metal compounds is in the order Cr>Co>Ni. Upon oxidation of the complexes, the chromium and nickel complexes exhibit significant changes in the metal-metal interactions while the cobalt analogs show slight changes. Electrochemical studies show that these complexes have rich redox properties. Some of the complexes have more than two stable oxidation states. The oxidation of nickel and chromium complexes becomes easier as the number of metal atoms in the metal chains increases. The first oxidation potential increases with an increasing atomic number for the first-row transitionmetals. STM studies of multinuclear metal string complexes show significant differences in the conductivity of the oxidized and neutral forms. This scenario provides a paradigmfor the use of molecular electronics such as molecular switches, molecular wires, and storage devices.