Phosphine‐Stabilized Diiododiborenes: Isolable Diborenes with Six Labile Bonds

Muessig, Jonas H.; Thaler, Melanie; Dewhurst, Rian D.; Paprocki, Valerie; Seufert, Jens; Mattock, James D.; Vargas, Alfredo; Braunschweig, Holger

doi:10.1002/anie.201814230

Cited by 32 publications

(59 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is noteworthy that, with the exception of the recently published B 2 Br 4 (PCy 3 ) 2 , the tetrabromodiborane bis(phosphine) adducts presented herein are among the first crystallographically characterized compounds of their kind. Furthermore, B 2 I 4 (CN t Bu) 2 is the first structurally characterized tetraiododiborane–bis(isonitrile) adduct.…”

Section: Resultsmentioning

confidence: 82%

Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity

Englert

Stoy

Arrowsmith

et al. 2019

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

A series of 22 new bis(phosphine), bis(carbene), and bis(isonitrile) tetrahalodiborane adducts has been synthesized, either by direct adduct formation with highly sensitive B2X4 precursors (X=Cl, Br, I) or by ligand exchange at stable B2X4(SMe2)2 precursors (X=Cl, Br) with labile dimethylsulfide ligands. The isolated compounds have been fully characterized using NMR spectroscopy, elemental analysis, and, for 20 of these compounds, single‐crystal X‐ray diffraction, revealing an unexpected variation in the bonding motifs. In addition to the classical B2X4L2 diborane(4) bis‐adducts, certain more sterically demanding carbene ligands induce a halide displacement which led to the first halide‐bridged monocationic diboron species, [B2X3L2]A (A=BCl4, Br, I). Furthermore, low‐temperature 1:1 reactions of B2Cl4 with sterically demanding N‐heterocyclic carbenes led to the formation of kinetically unstable mono‐adducts, one of which was structurally characterized. A comparison of the NMR spectra and structural data of new and literature‐known bis‐adducts shows several trends pertaining to the nature of the halides and the stereoelectronic properties of the Lewis bases employed.

show abstract

Section: Resultsmentioning

confidence: 82%

Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity

Englert

Stoy

Arrowsmith

et al. 2019

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…Seitdem erweiterten wir unsere Studien zu Dibortetrahalogeniden mit der Entwicklung einfacher, nasschemischer Methoden zur Darstellung der übrigen B 2 X 4 ‐Spezies (X=F, Cl, I) ausgehend von B 2 Br 4 . Unsere anschließenden Untersuchungen bezüglich der Reaktivität von B 2 I 4 offenbarten deutliche Unterschiede zwischen diesem hochreaktiven Molekül und den leichteren Dibortetrahalogeniden, was einerseits durch die Reaktivität gegenüber niedervalenten Metallkomplexen ersichtlich ist, andererseits kann B 2 I 4 (wie auch B 2 Br 4 ) zwar als Vorstufe für die Synthese von Dihalogendiboranen eingesetzt werden, die Produkte unterscheiden sich allerdings drastisch von den entsprechenden Bromderivaten . Weiterhin wurde seither die Quaternisierung der Boratome in B 2 I 4 mittels zweifacher Addition von Lewis‐Basen (unter Bildung von Addukten der Form B 2 I 4 L 2 ) beziehungsweise von Halogenidanionen (unter Bildung des Dianions [B 2 I 6 ] 2− ) erreicht …”

Section: Figureunclassified

“…Anhand quantenchemischer Simulation der IR‐Spektren der beiden Strukturen im Festkörper wurde gezeigt, dass die experimentellen IR‐Spektren demjenigen Konformer zuzuordnen sind, das bei höherer Temperatur eingenommen wird. Die enorme Diskrepanz zwischen den Festkörperstrukturen von B 2 I 4 und denen der leichteren Homologen B 2 X 4 (X=F–Br) unterstreicht die fundamentalen Unterschiede, die bereits aus den wenigen verfügbaren Reaktivitätsstudien hervorgehen und liefert einen Vorgeschmack auf die Überraschungen, die die Chemie der Dibortetrahalogenide noch bereithält.…”

Section: Figureunclassified

Dibortetraiodid (B₂I₄) ist im Festkörper ein Polymer aus sp³‐hybridisiertem Bor

et al. 2020

Self Cite

View full text Add to dashboard Cite

Anhand der ersten Festkörperstrukturen von Dibortetraiodid (B2I4) wird gezeigt, dass dieses nicht, wie lange angenommen, analog zu den leichteren Dibortetrahalogeniden B2F4, B2Cl4 und B2Br4 in allen Aggregatzuständen in Form diskreter Moleküle mit planaren, dreifach koordinierten Boratomen vorliegt. Röntgenstrukturanalysen, Festkörper‐NMR‐ und IR‐Messungen zeigen, dass B2I4 im Festkörper in zwei polymeren Konformeren vorkommt, die tetraedrisch koordinierte Boratome enthalten. Anhand von DFT‐Rechnungen werden die IR‐Spektren in Lösung und im Festkörper simuliert und mit den experimentellen Daten verglichen.

show abstract

“…[16] In contrast, the direct hydrogenation of diborenes has eluded our efforts,w ith the exception of our recently reported diiododiborene, (PCy 3 ) 2 B 2 I 2 ,w hich undergoes stepwise hydrogenation, first to the rather unstable 1,2-dihydrodiborane,( Cy 3 P) 2 B 2 H 2 I 2 , and then to the (dihydro)iodoborane (Cy 3 P)BH 2 Iw ith concomitant B À Bb ond cleavage. [17] Herein we report the catalyst-free transfer hydrogenation of apolar diborenes with DMAB and propose anew mechanism for the observed transselectivity.…”

mentioning

confidence: 99%

Spontaneous trans‐Selective Transfer Hydrogenation of Apolar Boron–Boron Double Bonds

et al. 2019

Self Cite

View full text Add to dashboard Cite

The transfer hydrogenation of N-heterocyclic carbene (NHC)-supported diborenes with dimethylamine borane proceeds with high selectivity for the trans-1,2-dihydrodiboranes.D FT calculations,s upported by kinetic studies and deuteration experiments,s uggest as tepwise proton-first-hydride-second reaction mechanism via an intermediate m-hydrodiboronium dimethylaminoboratei on pair.Since the 1925 landmark discovery by Meerwein and Verley of the aluminum alkoxide-promoted hydrogenation of ketones using alcohols as sacrificial hydrogen donors, [1] transfer hydrogenation has become an attractively mild and selective alternative to direct hydrogenation. [2] Being easy-tohandle hydrogen-storage materials, [3] ammonia borane (AB = H 3 N·BH 3 )a nd amine boranes (R 2 NH·BH 3 )h ave also demonstrated their usefulness in catalytic transfer hydrogenation reactions. [4] While the majority of these reactions are applied to polar substrates,s uch as imines and ketones, [5] there are several examples of transition-metal-and main-group-catalyzed transfer hydrogenations of apolar N=N, [6] C=C, [7] and CC bonds [8] using AB or dimethylamine borane (DMAB) as the hydrogen source.S pontaneous,u ncatalyzed transfer hydrogenation reactions with AB or DMAB have only been reported for imines, [9] highly polarized olefins, [10] aminoboranes [11] and, most recently,i minoboranes. [12] Detailed experimental and theoretical studies have shown that, in the case of imines and iminoboranes,t he reaction proceeds via pre-coordination of the protic amine hydrogen to the more electronegative nitrogen atom, followed by concerted delivery of both the protic and hydridic hydrogen atoms to the unsaturated bond, via the six-membered transition state depicted in Figure 1a. [9,12] In contrast, the Angewandte Chemie Communications 9783

show abstract

Phosphine‐Stabilized Diiododiborenes: Isolable Diborenes with Six Labile Bonds

Cited by 32 publications

References 43 publications

Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity

Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity

Dibortetraiodid (B₂I₄) ist im Festkörper ein Polymer aus sp³‐hybridisiertem Bor

Spontaneous trans‐Selective Transfer Hydrogenation of Apolar Boron–Boron Double Bonds

Contact Info

Product

Resources

About

Phosphine‐Stabilized Diiododiborenes: Isolable Diborenes with Six Labile Bonds

Cited by 32 publications

References 43 publications

Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity

Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity

Dibortetraiodid (B2I4) ist im Festkörper ein Polymer aus sp3‐hybridisiertem Bor

Spontaneous trans‐Selective Transfer Hydrogenation of Apolar Boron–Boron Double Bonds

Contact Info

Product

Resources

About

Dibortetraiodid (B₂I₄) ist im Festkörper ein Polymer aus sp³‐hybridisiertem Bor