Abstract
Metal-metal bonded cluster complexes represent one of the important groups of compounds of group 7 elements, technetium and rhenium. While the chemistry of rhenium-rhenium bonded cluster complexes has developed extensively in these years, corresponding chemistry of technetium remains largely unrevealed. A general rule to classify the metal-metal bonded structural cores in terms of the number of d electrons, is presented, and existing Re-Re bonded cluster complexes are summarized accordingly. Recent progress of hexarhenium cluster complexes has been introduced as a typical example. From these overviews on the Re-Re cluster complexes, it is suggested that the chemistry of Tc-Tc bonded cluster complexes is highly promising.
