Halogen exchange reactions of diboron tetrahalides

Abstract

Halogen exchange between BCl₃ and B₂F₄ at room temperature occurs in such a way as to concentrate chlorine on the diboron fragment and thus provides a convenient procedure for preparation of B₂Cl₄ in > 80% yield. Halogen exchange between B₂Cl₄ and Me₂BF leads, however, to formation of B₂F₄ and Me₂BCl. I.r. and n.m.r. spectra indicate the presence of hitherto undetected diboron chlorofluorides in this system and in B₂F₄–B₂Cl₄ and BF₃–B₂Cl₄ mixtures.