In the 1980s, while searching for new hydrocarbon activation catalysts, Crabtree's research group accidentally found that mercury vapour activated photochemically could perform some interesting and unusual alkane activation reactions yielding unusual products.
Some of the work is summarised in this Journal of Chemical Education paper from 1988. The reaction seems to be able to produce some unusual (and hard to get) dimers of hydrocarbons and is also tolerant of other functional groups (eg alcohols, amines) and can also generate cross coupled products (eg it will couple alcohols with hydrocarbons).
At the time it was thought to be an interesting curiosity but with some prospect of yielding easy routes to some hard-to-get targets.
Has it ever been used in a significant synthesis? Or for any industrial processes?