Extended metal atom chains

Source: Wikipedia, the free encyclopedia.

In

bottom-up approach to nanoelectronics, although no applications are near term.[1]

Structure

An Ni9 EMAC.[2]

An EMAC molecule contains a linear string of transition metals (typically Cr, Co, Ni, or Cu) that are bonded to each other and surrounded helically by organic ligands. The metal chains are usually end-capped by anions, usually halides. The organic ligands often pyridylamide, pyridone, naphthyridine, or their derivatives. Each metal atom is six-coordinate, bonded to two other metals along the axis of the molecule (except terminal metals, which are bonded to one metal and one capping anion) and to four nitrogen atoms perpendicular to the axis.

The organic ligands template the formation of the chains by bringing the metal ions together and aligning them into a linear string. The number of nitrogen atoms in the ligand determines the number of metal atoms that will be incorporated into the chain. Thus, the synthesis yields molecular wires of predetermined length. This feature, in combination with the fact that the molecules have well-defined ends, differentiates EMACs from other kinds of molecular wires: EMACs exist only as distinct molecular entities, they do not aggregate and they do not form periodic structures of repeating units.

Most known EMACs contain from three to nine metal atoms. The longest EMACs that have been constructed so far incorporate eleven Ni atoms and have a length of approximately 2 nanometers, although it is estimated that chains with up to 17 metal atoms (4-5 nanometers) could be accessed with currently available ligands.[3]

In contrast with EMACs, linear chain compounds are infinite in length. They are not terminated with capping ligands.

Early development and debate

The first EMACs with three metal atoms were synthesized in the early 1990s independently by the groups of

electronic configurations.[4] The Pantazis-McGrady model is currently used to understand the different electronic states and interpret the magnetic
properties of EMACs.

Potential applications

EMACs have no commercial applications, but they are of potential use as

rheostats, switches, and transistors
. These possibilities have been demonstrated:

See also

References

  1. ^ F. Albert Cotton, Carlos A. Murillo and Richard A. Walton (eds.), Multiple Bonds Between Metal Atoms, 3rd edition, Springer (2005).
  2. PMID 20372713
    .
  3. ^ Two Linear Undecanickel Mixed-Valence Complexes: Increasing the Size and the Scope of the Electronic Properties of Nickel Metal Strings† Authors Rayyat H. Ismayilov, Wen-Zhen Wang, Gene-Hsiang Lee, Chen-Yu Yeh, Shao-An Hua, You Song, Marie-Madeleine Rohmer, Marc Bénard, Shie-Ming Peng .11 February 2011. DOI: 10.1002/anie.201006695
  4. doi:10.1021/ja0581402
    .
  5. doi:10.1021/nl0519027
    .
  6. doi:10.1002/anie.200600800
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Extended_metal_atom_chains&oldid=1114123269"