A Window into the Workings of -BH Luminescence-Blue-Fluorescent Isomeric Pair 3,3'-Cl-BH and 3,4'-Cl-BH (and Others).

The action of AlCl on room-temperature tetrachloromethane solutions of -BH () results in a mixture of fluorescent isomers, 3,3'-Cl-BH () and 3,4'-Cl-BH (), together isolated in a 76% yield. Compounds and are capable of the stable emission of blue light under UV-excitation. In addition, small amounts of other dichlorinated isomers, 4,4'-Cl-BH (), 3,1'-Cl-BH (), and 7,3'-Cl-BH () were isolated, along with blue-fluorescent monochlorinated derivatives, 3-Cl-BH () and 4-Cl-BH (), and trichlorinated species 3,4,3'-Cl-BH () and 3,4,4'-Cl-BH ().