A bidentate borane as colorimetric fluoride ion sensor

The bright yellow bidentate diborane (3), obtained by reaction of 10-bromo-9-thia-10-boraanthracene (1) with dimesityl-1,8-naphthalenediylborate (2), serves as a colorimetric anion sensor and selectively complexes fluoride with an association constant greater than 5 x 10(9) M-1 in THF.