1,2,4,3-Triazaborole-based neutral oxoborane stabilized by a Lewis acid

Loh, Ying Kai; Chong, Che Chang; Ganguly, Rakesh; Li, Yongxin; Vidović, Dragoslav; Kinjo, Rei

doi:10.1039/c4cc03379e

Cited by 44 publications

(39 citation statements)

References 39 publications

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“…Recrystallization from CH 2 Cl 2 and hexanes produced compound 10 as dark‐purple crystals in 15 % yield. Complex 10 gave rise to a broad singlet in its 11 B NMR spectrum centred at 18.3 ppm that is consistent with other oxoboranes, as well as a singlet in the 27 Al NMR spectrum (89.1 ppm) corresponding to an oxygen‐bound AlCl 3 fragment. The highly delocalized, nitrogen‐rich backbone of formazanate ligands has been shown previously to stabilize radical anions based on formazanate complexes of B, Zn, and Group 14 atoms .…”

Section: Methodssupporting

confidence: 62%

“…In contrast, the boron atom in complex 10 deviates marginally from the ligand plane [0.065(2) Å] and is sp 2 ‐hybridized, as evidenced by the sum of the bond angles about the boron atom (359.99(12)°). Furthermore, the short boron oxygen bond (1.3059(19) Å) in compound 10 is indicative of a BO double bond and is significantly shorter than the average length of the single BO bonds in compound 11 (1.412(3) Å).…”

Section: Methodsmentioning

confidence: 91%

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Oxoborane Formation Turns on Formazanate‐Based Photoluminescence

Maar

Hoffman

Staroverov

et al. 2019

Chemistry A European J

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The synthesis of compounds containing multiple bonds to boron has challenged main-group chemists for decades. Despite significant progress, the possibility that the formation of such bonds can turn on photoluminescence hasr eceivedminimal attention. We report an oxoborane (B=O) complex that is electronicallys tabilized by af ormazanate ligand in the absence of significant steric bulk and, unlikethe common BX 2 (X = F, Cl) formazanate adducts,e xhibitsi ntense photoluminescence. The latter propertyw as rationalized throughd ensity-functional calculations whichi ndicated that the B=Ob ond enhances photoluminescence by drastically reducing differences between the ligand's geometries in the ground and excited states. The title oxoborane compound was synthesized from an air-and moisture-stable BCl 2 formazanate complex and subsequently converted to ar edox-activeb oroxine. Each of these species may also serve as ap recursor to functional materials.The discoveryo fm ain-group compounds with unusuals tructure and bonding is am ajor focuso fi nterest in synthetic chemistry. [1,2] In this context, the preparation of stablec ompounds containing multiple bonds to boron presentsaparticular challenged ue to the electron-deficient character and compactness of the valence orbitals of the Ba tom. To address these challenges, early efforts by the Berndt, Power,a nd Nçth groups utilized strong reducing agents to access anionic diboron speciesw ith boron-boron multiple-bond character. [3] More recent strategies of stabilizing double and triple bonds to boron have relied upon Lewis bases and/ors terically bulky substituents, as exemplified by compounds 1-7. [4] The first example of an eutrald iborene, compound 1,w as reported by the Robinsong roup. [4a] This molecule is stabilized by two sterically bulky and strongly s-donating N-heterocyclic carbene ligands. Notablef eatures of 1 include the short B=B bond of 1.560(18) and its trans-bent molecular structure. More recently,B raunschweig and co-workers [4d] isolated di-boryne 2,t he first example of ab oron-boront ripleb ond. This molecule has an effectively linear geometry of the core atoms (C!BB ! C) and as hort BBb ond length of 1.449(3) .C ompounds with boron-chalcogen multiple bonds [5, 6] have been isolated through the combination of strongly donating and sterically bulky ligands, as in compound 3,w hich wasprepared by insertion of elemental Te into aB = Mn bond. [4f] The Cui group [4c] reported the anionic b-diketiminate oxoborane complex 4,s tabilized through ah ydrogen-bonding interaction, whereas the Aldridge group has recently reported an acid-free, anionic oxoborane 5. [7] Thioxoborane 6 is the first cationic, electron-precise species containing aB =Sb ond. [4e] The Braunschweig group has also prepared compound 7, [4b] which containsthe first example of ab oron-oxygen triple bond.Apart from their intrinsic appeal from af undamentalp erspective, [8,9] species with multiple bond character at boron show promise as reagents that allow one to carry out difficult che...

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Section: Methodssupporting

confidence: 62%

Section: Methodsmentioning

confidence: 91%

Oxoborane Formation Turns on Formazanate‐Based Photoluminescence

Maar

Hoffman

Staroverov

et al. 2019

Chemistry A European J

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“…A similar B−O bond length [1.304(2) Å] present in Cowley's nacnac complex HC{C(CH 3 )N(C 6 F 5 )} 2 BO⋅AlCl 3 , however the B=O linkage in 3 is substantially longer than the B−O triple bond length of 1.210(3) Å found in Braunschweig's trans ‐PhS(Cy 3 P) 2 PtBO . A diagnostic

\overset{ν}{true}

(BO) IR band is present at 1646 cm −1 in 3 which is comparable to the

\overset{ν}{true}

(BO) vibration noted in Kinjo's 1,2,3,4‐triazaborole‐based oxoborane (1636 cm −1 ) …”

Section: Methodsmentioning

confidence: 58%

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

Swarnakar

Hering‐Junghans

Ferguson

et al. 2017

Chemistry A European J

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Donor-acceptor complexes of the oxoboranes ClB=O and HOB=O were synthesized and each feature short multiply bonded B=O linkages. The retention of high Lewis acidic character within these encapsulated monomeric oxoboranes was manifested by their ability to support C-F and Si-O bond activation/functionalization. The reported ClB=O complexes can be regarded as synthetic surrogates of the [BO] cation, an inorganic analogue of CO.

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“…[6] Great attention is paid to the uncharged congeners and, as a result, there are several reports about main-group-element compounds marked by high degree of B = O double-bond and B O triple-bond character. [7,8] If the focus is shifted to molecular complexes of the heavier chalcogens, examples for B À E interactions of higher bond order are almost unknown. The existence of the transient thioxoborane IV has been proposed in seminal work by Tokitoh et al (Figure 1).…”

mentioning

confidence: 99%

Isolation of a Three‐Coordinate Boron Cation with a Boron–Sulfur Double Bond

2014

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The reaction of the bulky bis(imidazolin-2-iminato) ligand precursor (1,2-(L(Mes)NH)2-C2H4)[OTs]2 (1(2+) 2[OTs](-); L(Mes) = 1,3-dimesityl imidazolin-2-ylidene, OTs = p-toluenesulfonate) with lithium borohydride yields the boronium dihydride cation (1,2-(L(Mes)N)2-C2H4)BH2[OTs] (2(+) [OTs](-)). The boronium cation 2(+) [OTs](-) reacts with elemental sulfur to give the thioxoborane salt (1,2-(L(Mes)N)2-C2H4)BS[OTs] (3(+) [OTs](-)). The hitherto unknown compounds 1(2+) 2[OTs](-), 2(+) [OTs](-), and 3(+) [OTs](-) were fully characterized by spectroscopic methods and single-crystal X-ray diffraction. Moreover, DFT calculations were carried out to elucidate the bonding situation in 2(+) and 3(+). The theoretical, as well as crystallographic studies reveal that 3(+) is the first example for a stable cationic complex of three-coordinate boron that bears a B=S double bond.

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1,2,4,3-Triazaborole-based neutral oxoborane stabilized by a Lewis acid

Cited by 44 publications

References 39 publications

Oxoborane Formation Turns on Formazanate‐Based Photoluminescence

Oxoborane Formation Turns on Formazanate‐Based Photoluminescence

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

Isolation of a Three‐Coordinate Boron Cation with a Boron–Sulfur Double Bond

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