Phosphaniminato‐Komplexe von Bor. Synthese und Kristallstrukturen von [BBr2(NPMe3)]2, [B2Br3(NPiPr3)2]Br, [B2(NPEt3)4]Br2, [B2Br2(NPPh3)3]BBr4 und [{B2(NMe2)2}2(NPEt3)2]Cl2

Möhlen, M.; Neumüller, Bernhard; Faza, Naim; Müller, C.; Massa, Werner; Dehnicke, Kurt

doi:10.1002/zaac.19976231016

Cited by 19 publications

(25 citation statements)

References 24 publications

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“…In contrast to previously reported borinium ions,6 this cation has a unique extended structure that contains a linear arrangement of the five atoms of the P=N−B−N=P linkage. This stands in marked contrast to boron derivatives of sterically less demanding phosphinimides for which the dimeric species [(Et 3 PN) 2 B) 2 ] 2+ ( I ),7 the cyclic trications [(Et 3 PNBH) 3 ] 3+ 8 and [(Et 3 PNBH) 4 NPEt 3 ] 3+ ( II ),9 or the neutral borane (Ph 3 PN) 3 B ( III ) have been observed 10…”

Section: Methodsmentioning

confidence: 87%

The Extended Borinium Cation: [(tBu3PN)2B]+

et al. 2002

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Much of the recent interest in main group metallocenes has arisen from applications as materials precursors for chemical vapor deposition and as activators or catalysts in olefin polymerization. Nonetheless, structure and bonding considerations continue to motivate researchers, as less is known about these main group systems than the transition metal analogues. In this regard, recent studies by Cowley and coworkers, who have described the first examples of decamethylgallocenium [1] and decamethylborocenium cations, [2] and by Schnˆckel et al, who have reported the decamethylalumocenium cation, [3] have begun to redress the balance. Only the Al species displays the symmetric bis-h 5 -bonded structure analogous to ferrocene. The Ga species exhibits only marginal stability, while the boron compound is described as ™tightly squeezed∫ presumably because of the high effective charge of the boron cation. It is noteworthy that the unsubstituted cyclopentadienyl (Cp) analogues of these cations are not known. In recent work, we employed bulky phosphinimide ligands as steric equivalents to cyclopentadienyl in the development of new active olefin polymerization catalysts. [4,5] Herein, we employ this concept in the formation of a steric Figure 1. 3 H NMR spectrum of crude 6 (slow addition of TiCl 4 ) dissolved in CD 2 Cl 2 acquired with simultaneous 1 H-and 2 H-decoupling (288 K, 640 MHz, 5-kHz spectral width, 2.8-s repetition time).strategy for the synthesis of chiral N,N-ditosylmethylamine is an improvement on the Floss approach: [7b] 5 steps compared to 7 in previous reports, and an overall yield of 30 %, compared to < 5 % in the Floss synthesis. Our strategy affords chiral ditosylmethylamine with 66 % ee (62 % for the Schmidt degradation) and can also be used to synthesize the opposite enantiomer starting from commercially available (1R,2S)-2amino-1,2-diphenylethanol.

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Section: Methodsmentioning

confidence: 87%

The Extended Borinium Cation: [(tBu3PN)2B]+

et al. 2002

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“…The bond length B(1)−Br(1) [1.930(2) Å] is close to the sum of the covalent radii of boron (0.81 Å) and bromine (1.14)14 and compares well with the B−Br distances in [(2,4,6‐Me 3 C 6 H 2 )(Br)B] 2 [1.928(4) and 1.932(4) Å] 15. B−Br bond lengths involving sp 2 ‐hybridized boron atoms range from 1.87(1) Å in [ i Pr 3 P=N a −B a (Br)N b (=P i Pr 3 )B b Br 2 ]Br( N a − B b )16 or 1.902(5) Å in 2,6Mes 2 C 6 H 3 BBr 2 (Mes = 2,4,6‐Me 3 C 6 H 2 )17 to 2.00(1) Å in the triborane [(Me 2 N)(Br)B] 2 BNMe 2 18. Atomic distances and valence angles within the diazaborole ring are in good agreement with the corresponding data for (2,6‐Me 2 C 6 H 3 )N a −CH=CH−N b (2,6‐Me 2 C 6 H 3 )BI( N a − B ) 18.…”

Section: Resultsmentioning

confidence: 99%

Chiral 2,3-Dihydro-1H-1,3,2-diazaboroles

Weber¹,

Rausch²,

Wartig³

et al. 2002

Eur. J. Inorg. Chem.

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A series of differently substituted chiral 2,3-dihydro-1H-1,3,2-diazaboroles has been prepared by various methods. 2-were formed from the reaction of the corresponding 1,4-diazabutadienes and boron tribromide and the subsequent reduction of the resulting borolium salts [R 1 N a = CH−CH= N b (R 2 )BBr 2 ]Br(N a −B) [2a: R 1 = tBu, R 2 = CH(Me)Ph; 2b: R 1 = R 2 = CH(Me)Ph; 2c: R 1 = R 2 = CH(Me)(cC 6 H 11 )] with sodium amalgam. Treatment of (S)-3a with LiAlH 4 or methyllithium afforded 1-tert-butyl-2-hydro-3-[(S)-1-phenylethyl]-2,3-dihydro-1H-1,3,2-diazaborole [(S)-6] and 1-tert-butyl-2-methyl-3-[(S)-1-phenylethyl]-2,3-dihydro-1H-1,3,2-diazaborole [(S)-7], respectively. Aminolysis of the BBr bond of (S)-3a by tertbutylamine or (S)-1-phenylethylamine gave the corresponding 2-tert-butylamino-and 2-[1-phenylethylamino]-2,3-dihy-

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“…Dehnicke and co‐workers described a variety of phosphoranimino‐substituted boron cations . Outstanding is the isolation of the dication salt 51 [Br] 2 which derived from the reaction of BBr 3 with Et 3 PN(SiMe 3 ) (3 equiv) in boiling benzene (Figure ).…”

Section: Boron Cationsmentioning

confidence: 99%

“…Notably, an 11 B NMR signal at 21.1 ppm was found for 51 [Br] 2 which suggests the trigonal planar coordination of the boron centers to persist in solution. Interestingly, the authors reported that the conversion of the related phosphoranimine Ph 3 PN(SiMe 3 ) with BBr 3 under very similar conditions as those implemented for the synthesis of 51 [Br] 2 did not yield an analogous boron dication salt …”

Section: Boron Cationsmentioning

confidence: 99%

“…Though we found a pioneering study in this field dating back to the late nineties of the last century the number of related examples remains comparably small to date. An early account on a complex that corresponds to the title category was given by the group of Dehnicke in 1997 who isolated the dicationic boron complex salt 52 [Cl] 2 (Figure ) . The compound readily formed upon bringing together the diborane‐4 reagent (B(Cl)NMe 2 ) 2 and the phosphoranimine Et 3 PN(SiMe 3 ) in dichloromethane, thus, pursuing a synthetic approach similar to the one used for the crafting of 51 [Br] 2 (vide supra).…”

Section: Boron Cationsmentioning

confidence: 99%

See 1 more Smart Citation

Cationic Complexes of Boron and Aluminum: An Early 21st Century Viewpoint

Franz

Inoue

2018

Chemistry A European J

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Boron and aluminum share one main group, they are found in daily life commodities, and considered environmentally benign. Nevertheless, they markedly differ in their element properties (e.g. metal character, atomic radius). The use of Lewis acidic complexes of boron and aluminum for methods of bond activation and catalysis (e.g. hydrogenation of unsaturated substrates, polymerization of olefins and epoxides) is quickly expanding. The introduction of cationic charge may boost the metalloid-centered Lewis acidity and allows for its fine-tuning particularly with regard to preference for "hard" or "soft" Lewis bases (i.e. substrates). Especially, the isolation of low-coordinate cations (number of ligand atoms smaller than 4) demands for elaborate techniques of thermodynamic and kinetic stabilization (i.e. electronic saturation and steric shielding) by a ligand system. Furthermore, the properties of the solvent and the counteranion have to be considered with care. Herein, we revise selected examples for boron and aluminum cations.

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Phosphaniminato‐Komplexe von Bor. Synthese und Kristallstrukturen von [BBr₂(NPMe₃)]₂, [B₂Br₃(NPⁱPr₃)₂]Br, [B₂(NPEt₃)₄]Br₂, [B₂Br₂(NPPh₃)₃]BBr₄ und [{B₂(NMe₂)₂}₂(NPEt₃)₂]Cl₂

Cited by 19 publications

References 24 publications

The Extended Borinium Cation: [(tBu3PN)2B]+

The Extended Borinium Cation: [(tBu3PN)2B]+

Chiral 2,3-Dihydro-1H-1,3,2-diazaboroles

Cationic Complexes of Boron and Aluminum: An Early 21st Century Viewpoint

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