Syntheses and solid-state structures of mono- and dialkyl(methylsulfonato)boranes

Abstract

R 3B reacts with MeSO 3H at elevated temperature in toluene to give liquid R 2B(OSO 2Me) [R=Et ( 1a), 61%; R=Bu ( 1b), 58%; R=Pr i ( 1c), 23%] and, in the case of Et 3B and Bu 3B, solid RB(OSO 2Me) 2 [R=Et ( 2a), 13%; R=Bu ( 2b), 11%]. As Pr i 3B is less reactive, pivalic acid must be added as catalyst, and no formation of the disulfonatoborane is observed. Complexes 1a–c and 2a–b were characterised spectroscopically (IR, 1H-, 13C-, 11B-NMR), and crystal structure determinations were carried out on 1a, which is monomeric even in the solid state, and 2a and 2b, which are dimeric in the solid state and have two differently bonded sulfonate groups (terminal and bridging).