Multiple bonds between heavier elements used to be thought impossible - scientists rationalised that the long bond distances between these elements would not allow sufficient p-orbital overlap for multiple bonding to occur. However, in the last thirty years chemists have found that introducing bulky substituents can stop oligomerisation of these reactive double bonds, and so a number of kinetically-stabilised compounds containing double bonds between heavier main group elements have been reported.

In their Dalton Transactions Perspective, Takahiro Sasamori and Norihiro Tokitoh from Kyoto University, Japan outline their success in making kinetically-stabilised compounds containing double bonds between heavier Group 15 elements.   The properties of these diphosphenes, distibenes, dibismuthenes and heteronuclear doubly-bonded compounds are also discussed.

These compounds 'are no longer imaginary species', say the Japanese chemists. They believe such chemistry could soon play an important role in materials science.