Lutidine/B(C₆F₅)₃: At the Boundary of Classical and Frustrated Lewis Pair Reactivity

Abstract

Classical Lewis acid-base adducts, previously thought to be unreactive, can provide access to the unique reactivity of frustrated Lewis pairs. This was demonstrated with a mixture of 2,6-lutidine and B(C(6)F(5))(3) where an equilibrium affords the adduct and yet also effects the heterolytic activation of H(2) and the ring opening of THF.

Main Group Lewis Acids in Frustrated Lewis Pair Chemistry: Beyond Electrophilic Boranes

“…27 Classical Lewis acidbase adducts have also been shown to exhibit FLP reactivity, usually in cases where the dative bond is relatively weak, thus allowing for solventinduced adduct dissociation. 28,29 A notable example is hydrogen activation by B(C 6 F 5 ) 3 and diethyl ether. 30 Closely related to the FLP activation of H 2 is the activation of SiH bonds.…”

Synthesis and characterization of metal (M = Al or Ga) 2-phosphino(phenolate/benzenethiolate) complexes and their electrochemical behavior in the presence of CO2

“…1) [3,7]. With the expansion of FLPs to include Lewis pairs which are not sterically encumbered, [8] one could certainly consider our previous main-group complexes to satisfy the criteria required for FLP status.…”

Elusive Silane–Alane Complex [SiH⋅⋅⋅Al]: Isolation, Characterization, and Multifaceted Frustrated Lewis Pair Type Catalysis

“…Highly Lewis-acidic and chemically robust organoboranes, especially B(C 6 F 5 ) 3 ,h ave proven their broad applications in catalysis for small-molecule transformation and macromolecular synthesis. [1] Such boranes continue to receive much attention because of their recent success in frustrated Lewis pair (FLP) chemistry which was pioneered by Stephan and Erker.…”

“…[2] While earlier contributions emphasized the importance of orthogonal reactivity derived from sterically induced separation of the Lewis pairs,accumulated evidence suggests that electronically FLPs possessing aweak Lewis acid-Lewis base (LA-LB) bond can be effective as well. [3] Indeed, aprototype can be traced back to 1996 when Parks and Piers [4] reported the first example of the B(C 6 F 5 ) 3 -catalyzed hydrosilylation of C=Ob onds with hydrosilanes by unusual SiÀH bond activation rather than intuitive carbonyl activation. [5] Such ar eaction was proposed to proceed through the cleavage of the Si À Hb ond with ad issociating carbonylborane Lewis pair (i.e., FLP-type bond activation).…”

“…[6] Since then, much effort has been invested in the direct spectroscopic and structural characterizations of the proposed, yet elusive,s ilane-borane complex containing the crucial [Si À H···B] moiety,b ut the attempts with B(C 6 F 5 ) 3 proved futile and only indirect spectroscopic clues pointing to this intermediate could be obtained. Almost 20 years after the original report, Piers and co-workers successfully isolated and structurally characterized the silane-borane adduct derived from Et 3 SiH and 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene,aperfluoroborole sophisticatedly tailored for higher Lewis acidity than B(C 6 F 5 ) 3 .…”