clear, colorless liquid
1,2-Dihydro-1,2-azaborine is an aromatic chemical compound with properties intermediate between benzene and borazine. Its chemical formula is C4BNH6. It resembles a benzene ring, except that two adjacent carbons are replaced by nitrogen and boron, respectively.
After decades of failed attempts, the compound was synthesized in 2008 and reported in January 2009.
One of the synthetic steps is a ring-closing metathesis (RCM) reaction: