Metal‐Free Dehydrogenation of Amine‐Boranes by Tunable N‐Heterocyclic Iminoboranes

Abstract

We report the synthesis of structurally tunable boron complexes supported by N-heterocyclic imine ligands IPr=N-BR (IPr=[(HCNDipp) C], Dipp=2,6-iPr C H , R=Cl and/or Ph) that have the ability to abstract dihydrogen from amine-boranes, and instigate their dehydrocoupling. In one instance, mild heating of the hydrogen addition product IPr=NH-B(Ph)HCl releases H to regenerate the starting N-heterocyclic iminoborane; accordingly IPr=N-B(Ph)Cl can be used as a metal-free catalyst to promote the dehydrocoupling of MeNH ⋅BH to yield N-methylaminoborane oligomers [MeNH-BH ] .

Synthesis and Reactivity of Cationic Boron Complexes Distorted by Pyridine‐based Pincer Ligands: Isolation of a Photochemical Hofmann–Martius‐type Intermediate

“…The N‐boryl imine C9‐N2‐B1 bond angle of 128.4(1)° suggests the presence of a lone pair of electrons not involved in π‐donation to boron. N‐boryl imines electronically prefer to have linear C=N=B geometry analogous to allenes, however Rivard showed in a series of (IPr=N)BCl x Ph y ( x + y= 2) compounds that this C‐N‐B bond angle is sensitive to sterics, varying from 132–180° . Other metric parameters match up well with a related BN heterocycle reported by Weber …”

MeCAAC=N−: A Cyclic (Alkyl)(Amino)Carbene Imino Ligand

“…The overnight reactiono f Me CAAC=NSiMe 3 with one equivalent of DurBBr 2 (Dur = duryl = 2,3,5,6-tetramethylphenyl) in hexane afforded colorless crystals of Me CAAC= NBBrDur( 4). [18] The N(1)ÀB(1) bond length (1.338 (2) )i so nly very slightly shortert han that of IDipp=NBClPh (1.350 (3) ). The compound was characterizedb ys ingle-crystal X-ray crystallography and the resulting molecular structure is shown in Figure 5.…”

“…[11] The ligands have also started to find use in stabilizing av ariety of interesting main-group species. [18] Very recently,I noue and coworkers alsou sed ab ulky imidazolin-2-iminato ligand to stabilize ab orasilene, [19] and Dielmann and co-workersw ere able to isolatea nd characterize three-coordinate phosphorus dications. [12] More recently,t his ligand type has been used to obtain av ariety of unusual germanium, [13] aluminum, [14] silicon, [15] tin, [16] and other compounds.…”

Isolation of an N‐Heterocyclic Carbene Complex of a Borasilene

“…[1b, 5-7] Accordingly, we chose Rivard's dichloroborane 1 [12] as an NHI-substituted electrophile and reactedi tw ith potassium hypersilanide KSi(SiMe 3 ) 3 as as ilicon-centered nucleophile (Scheme 1). These were reacted with the nucleophilic silicon source (MeSitBu 2 ) 2 SiLi 2 or the ambiphilics ilylene Si(CH 2 C(SiMe 3 ) 2 ) 2 .T he SiÀBb ond formation occurs through nucleophilic substitution at boron or silylene insertioninto the BÀCl bond, respectively.…”