Following on from a search for long C-C bonds, here is the same repeated for C=C double bonds. The query restricts the search to each carbon having just two non-metallic substituents. To avoid conjugation with these, they each are 4-coordinated; the carbons themselves are three-coordinated.

The upcoming ACS national meeting in San Diego has a CINF (chemical information division) session entitled "Global initiatives in research data management and discovery". I have highlighted here just one slide from my contribution to this session, which addresses the discovery aspect of the session. Data, if you think about it, is rarely discoverable other than by intimate association with a narrative or journal article.

Previously, I showed how conjugation in dienes and diaryls can be visualised by inspecting bond lengths as a function of torsions.