Main-group elements as transition metals

The chemistry of heavier main-group elements such as aluminium, silicon and phosphorus is very different from that of the lighter ones such as boron, carbon and nitrogen, yet discussions of this topic have been dominated by comparisons with the light elements. Philip Power's review focuses on advances in chemistry of the heavier main-group elements that reveal them as having more in common with the transition metals than the lighter members of the main groups. The concept of heavier main-group elements as 'transition metals' is supported by recent work showing that many of the new compounds react with small molecules such as H2, NH3, C2H4 and CO under mild conditions and display potential as catalysts. The last quarter of the twentieth century and the beginning decade of the twenty-first witnessed spectacular discoveries in the chemistry of the heavier main-group elements. The new compounds that were synthesized highlighted the fundamental differences between their electronic properties and those of the lighter elements to a degree that was not previously apparent. This has led to new structural and bonding insights as well as a gradually increasing realization that the chemistry of the heavier main-group elements more resembles that of transition-metal complexes than that of their lighter main-group congeners. The similarity is underlined by recent work, which has shown that many of the new compounds react with small molecules such as H2, NH3, C2H4 or CO under mild conditions and display potential for applications in catalysis.