Phosphinoborane interception at magnesium by borane-assisted phosphine-borane dehydrogenation

Abstract

Ph2PBH2 is generated and trapped on-metal by addition of B(C6F5)3 to a β-diketiminato magnesium phospidoborane complex, similar reactivity is meanwhile prevented for the analogous calcium-based system by formation of a stable η6-toluene complex.

Molecular Main Group Metal Hydrides

“…Compound 283 was found to be resistant to dehydrogenative coupling in the presence of further amounts of Ph 2 PH·BH 3 . In a subsequent advance, an attempt to induce hydride elimination by reaction of the Lewis acid B­(C 6 F 5 ) 3 with [( Dipp Nacnac)­Ca­{H 3 BPPh})] ( 284 ) resulted in the formation of a phosphinodiboronate complex [( Dipp Nacnac)­Ca­(η 6 -toluene)­{H 3 B-PPh 2 -B­(C 6 F 5 ) 3 }], ( 285 ), which, in contrast to comparable magnesium-based reactivity, was shown by DFT calculations to be stabilized toward further dehydrogenation by a pronounced π-(toluene) interaction …”

Titanium‐Catalyzed Polymerization of a Lewis Base‐Stabilized Phosphinoborane

“…[3] In addition to metalinduced dehydropolymerization which has been comprehensively studied, [4] advances on the dehydrocoupling with earth abundant main group Lewis acid catalysts have also been reported recently. [5] The heavier homologue H 3 P • BH 3 is very labile even at low temperatures, but nonetheless has been reported to yield a polymer in dehydrocondensation reaction catalyzed by B(C 6 F 5 ) 3 . [6] Polyphosphinoboranes [RHP-BH 2 ] n have been prepared over the past decades as high molar mass materials by rhodium-and iron-catalyzed dehydrocoupling reactions of primary phosphine-boranes.…”

Synthesis of Phosphinoboranes via Coordination-Induced Bromine Abstraction of an Isolable Phosphinyl Radical with Bromoboranes

“…1,2 Bulky substituents hamper association and allow phosphinoboranes to be monomeric forms, and the physical properties and reactivities of phosphinoboranes depend remarkably on the substituents. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] For instance, Ph2PBMes2 A (Mes: mesityl) has a pyramidal phosphorus atom and a longer P-B bond (Figure 1b), 7 while (t-Bu)2PB(C6F5)2 B possesses an almost planar tricoordinate phosphorus atom, a coplanar phosphinoborane core, and a shorter P-B bond of B. 8 The structure of B suggests an effective dative π-bond between B and P atoms.…”