Structure and reactivity of an Al/P-based frustrated Lewis pair bearing relatively small substituents at aluminium

Pleschka, Damian; Layh, Marcus; Rogel, Friedhelm; Uhl, Werner

doi:10.1098/rsta.2017.0011

Cited by 28 publications

(33 citation statements)

References 30 publications

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“…The Al−N and Ga−N bonds (196.4(2) and 208.0(2) pm) are expectedly (bonding situation, charge) shorter than those of 6 and 7 . The P−N bond lengths are with 163.8 pm on average longer than in iminophosphoranes, but similar to distances observed for azide adducts of these FLPs or nitrene complexes obtained from these adducts by release of N 2 . The N atoms are further bound to a terminal alkenyl group (C=C: 134 pm) which has the unchanged cis ‐arrangement of both phenyl substituents.…”

Section: Resultssupporting

confidence: 71%

“…IR spectra were recorded as KBr pellets on a Shimadzu Prestige 21 spectrometer, EI mass spectra on a Varian mass spectrometer (only the most intense peak of the correct isotopic pattern). The FLPs 1 , 2 , and 4 , diphenylazirine, 1‐isobutyl‐ and 1‐ p ‐tolyl‐4‐(1‐cyclohexenyl)‐1‐aza‐but‐1‐en‐3‐yne, diphenyl‐thiocyclopropenone, and N,2,3‐triphenyl‐cyclopropenimine were obtained according to literature procedures. Diphenylcyclopropenone was used as purchased.…”

Section: Methodsmentioning

confidence: 99%

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Al/P‐ and Ga/P‐Based Frustrated Lewis Pairs and Electronically Unsaturated Substrates: Ring Cleavage and Ring Closure, C−C and C−N Bond Formation

Pleschka

Uebing

Lange

et al. 2019

Chemistry A European J

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Al/P‐ and Ga/P‐based frustrated Lewis pairs (FLPs) reacted with an azirine under mild conditions under cleavage of the heterocycle on two different positions. Opening of the C−C bond yielded an unusual nitrile–ylide adduct in which a C−N moiety coordinated to the FLP backbone. Cleavage of a C−N bond afforded the thermodynamically favored enamine adduct with the N atom bound to P and Al or Ga atoms. Ring closure was observed upon treatment of an Al/P FLP with electronically unsaturated substrates (4‐(1‐cyclohexenyl)‐1‐aza‐but‐1‐en‐3‐ynes) and yielded by C−N bond formation hexahydroquinoline derivatives, which coordinated to the FLP through P−C and Al−C bonds. Diphenylcyclopropenone showed a diverse reactivity, which depending on steric shielding and the polarizing effect of Al or Ga atoms afforded different products. An AltBu2/P FLP yielded an adduct with the C=O group coordinated to P and Al. The dineopentyl derivative gave an equilibrium mixture consisting of a similar product and a simple adduct with O bound to Al and a three‐coordinate P atom. Both compounds co‐crystallize. The Ga/P FLP only formed the simple adduct with the same substrate. Rearrangement resulted in all cases in C3‐ring cleavage and migration of a mesityl group from P to a former ring C atom by C−C bond formation. Diphenylthiocyclopropenone (evidence for the presence of P=C bonds) and an imine derivative afforded similar products.

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Section: Resultssupporting

confidence: 71%

Section: Methodsmentioning

confidence: 99%

Al/P‐ and Ga/P‐Based Frustrated Lewis Pairs and Electronically Unsaturated Substrates: Ring Cleavage and Ring Closure, C−C and C−N Bond Formation

Pleschka

Uebing

Lange

et al. 2019

Chemistry A European J

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“…However, such mechanism would presumably lead to a different product than 5 . Related compounds have been referred to as formal FLP adducts of nitrenes . Based on this finding of N 2 loss in the TMS−N 3 reactions, we explored the possibility of similar N 2 extrusion for the Ph‐, t Bu‐ and Mes‐substituted azide products; according to DFT calculations, N 2 loss is thermodynamically favorable in all cases (see Table S1 in the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…The α,γ‐nitrogen coordination mode F was found by treating a geminal FLP with mesityl azide . In analogy to the reactivity of NHCs ( C ; Figure ), dinitrogen elimination occurs when TMS azide was reacted with a P/Al‐based FLP affording heterocycle G , yet in this case no follow‐up chemistry has been investigated.…”

Section: Introductionmentioning

confidence: 99%

New Insights in Frustrated Lewis Pair Chemistry with Azides

Boom

Jupp

Nieger

et al. 2019

Chemistry A European J

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The geminal frustrated Lewis pair (FLP) tBu2PCH2BPh2 (1) reacts with phenyl‐, mesityl‐, and tert‐butyl azide affording, respectively, six, five, and four‐membered rings as isolable products. DFT calculations revealed that the formation of all products proceeds via the six‐membered ring structure, which is thermally stable with an N‐phenyl group, but rearranges when sterically more encumbered Mes−N3 and tBu−N3 are used. The reaction of 1 with Me3Si−N3 is believed to follow the same course, yet subsequent N2 elimination occurs to afford a four‐membered heterocycle (5), which can be considered as a formal FLP‐trimethylsilylnitrene adduct. Compound 5 reacts with hydrochloric acid or tetramethylammonium fluoride and showed frustrated Lewis pair reactivity towards phenylisocyanate.

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“…Grimme and co-workers [3] provide a discussion of the theoretical considerations of the quintessential reaction of FLPs, the activation of H 2 , while Erker and co-workers [4] report on the development of FLPs derived from carbon-Lewis bases and boron-Lewis acids. Melen and co-workers [5] discuss reactions of FLPs inspired by biologically relevant systems and Uhl and co-workers [6] describe aluminiumphosphorus based FLPs. Gowda & Chen [7] apply FLPs in selective polymerizations of butyrolactones.…”

mentioning

confidence: 99%