Spontaneous Reduction of a Hydroborane To Generate a B−B Single Bond by the Use of a Lewis Pair

Abstract

The ansa-aminohydroborane 1-NMe2 -2-(BH2 )C6 H4 crystallizes in an unprecedented type of dimer containing a B-H bond activated by one FLP moiety. Upon mild heating and without the use of any catalyst, this molecule liberates one equivalent of hydrogen to generate a diborane molecule. The synthesis and structural characterization of these new compounds, as well as the kinetic monitoring of the reaction and the DFT investigation of its mechanism, are reported.

Frustrated Lewis Pair Mediated Csp3−H Activation

“…Despite the reaction products being thermodynamically slightly uphill, concomitant release of H 2 by a FLP‐type process was calculated to enable favorable thermodynamics (Figure C). A similar hydrogen‐release behavior was recently reported to occur during the formation of a B−B bond from ansa ‐aminoborane 1‐BH 2 ‐2‐NMe 2 ‐C 6 H 4 …”

Boron−Boron Dehydrocoupling of Boranes Initiated by Reaction with Iodine

“…Although low‐barrier boron–boron‐dehydrocoupling reactions are not unprecedented (see the example reported by Fontaine and co‐workers in ref. ), the presence of a catalyst is generally required in most known examples . In contrast, a decrease of the reaction barrier for the dehydrocoupling reaction was already observed in the case of [(RS(H)B(μ‐hpp)] 2 , which eliminates H 2 at room temperature (Scheme ) …”

“…Weller and co‐workers reported the dehydrogenative boron‐homocoupling reaction of amine‐borane at a Rh atom . Fontaine and co‐workers reported an elegant diborane(4) synthesis by thermal H 2 elimination from a diborane(6) precursor . In contrast to other known boron–boron‐dehydrocoupling reactions, no catalyst was needed in this reaction, but quite high temperatures had to be applied.…”

On the Dual Reactivity of a Nucleophilic Dihydrido‐Diborane: Reaction at the B−B Bond and/or the B−H Bond

“…They can be regarded as boryl‐substituted boranes that react as electrophiles. Lately several spectacular results were reported with sp 3 –sp 3 ‐hybridized diborane(4) and also sp 3 –sp 3 ‐diborane(6) derivatives, but nevertheless their chemistry is still underdeveloped. Braunschweig et al.…”