Main Group: Multiple Bonding

This chapter summarizes the many quite remarkable discoveries that have been made in recent years regarding multiple bonding of the heavier main group elements. While the general concept of multiple bonding is well established and easily embraced in organic chemistry, this is not the case for much of organometallic chemistry. The criteria that are routinely employed to assign double and triple bond character in organic compounds, that is, bond distance and bond strength, are of little significance in many cases involving the heavier main group elements. For example, the EE (E = Sn or Pb) double bond is both longer and weaker than the corresponding E E single bond. This chapter will discuss such seminal discoveries as the syntheses of the first digallyne (GaGa), dibismuthene (BiBi), and disilyne (SiSi). Central to these breakthroughs is the incorporation of sterically demanding ligand systems, which both stabilize and inhibit decomposition pathways of the heavier main group atoms.

Keywords: bond; double bond; linear; multiple bonding; trans-bent; triple bond