摘要
Whereas the study of the Cotton's quadruple bonding between two metal atoms has been mature, exploration of bonding, potential applications and reactivity in linear oligonuclear metal complexes and quintuple bonded dinuclear compounds is currently underway. Stabilized by four long-chain organic ligands containing various numbers (3-13) of nitrogen donors, many metal string complexes featuring a linear metal framework have been recognized. These novel linear oligonuclear metal complexes not only have interesting metal-metal bonding, but also display potential applications as metal wires for electron conductance. In the relatively young metal-to-metal quintuple bonding, the thus far structurally characterized examples are limited to univalent chromium and molybdenum ions supported by sterically encumbered bidentate ligands. These low-coordinate quintuple bonded dinuclear compounds display ultrashort metal-metal bond lengths, and interesting reactivity towards inorganic small molecules and unsaturated organics, including complexation, reductive cleavage, and cycloaddition. © 2014 The Chemical Society Located in Taipei &Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.