Borylene

Last updated
Typical borylene Typical borylene.png
Typical borylene

A borylene is the boron analogue of a carbene. [1] [2] [3] [4] The general structure is R-B: with R an organic moiety and B a boron atom with two unshared electrons. Borylenes are of academic interest in organoboron chemistry. A singlet ground state is predominant with boron having two vacant sp2 orbitals and one doubly occupied one. With just one additional substituent the boron is more electron deficient than the carbon atom in a carbene. For this reason stable borylenes are more uncommon than stable carbenes. Some borylenes such as boron monofluoride (BF) and boron monohydride (BH) the parent compound also known simply as borylene, have been detected in microwave spectroscopy and may exist in stars. Other borylenes exist as reactive intermediates and can only be inferred by chemical trapping.

Contents

The first stable terminal borylene complex [(OC)5WBN(SiMe3)2] was reported by Holger Braunschweig et al. in 1998. [5] [6] In this compound a borylene is coordinated to a transition metal. Borylenes are also stabilized as Lewis base adducts, e.g. with a NHC carbene. [7] Other strategies are the use of cyclic alkyl amino carbenes (CAACs) [8] and other Lewis bases, [9] and their use as bis-adducts. [10]

Free borylenes

Above: Upon reduction of the arylboron dichloride, a borylene is liberated. This intermediate adds into a C-C bond in the mesityl group. Below: Reduction of an dichloroaminoborane with Na/K yields a transient aminoborylene. Four equivalents of this species attack toluene to give a particularly complex product. Reactions of free borylenes.jpg
Above: Upon reduction of the arylboron dichloride, a borylene is liberated. This intermediate adds into a C-C bond in the mesityl group. Below: Reduction of an dichloroaminoborane with Na/K yields a transient aminoborylene. Four equivalents of this species attack toluene to give a particularly complex product.

As discussed above, free borylenes have yet to be isolated, but they have been the subject of a number of computational studies and have investigated spectroscopically and experimentally. B-R (R=H, F, Cl, Br, I, NH2, C2H, Ph) have been observed via microwave or IR spectroscopy at low temperature via elaborate procedures. [13] [14] [15] [16] When generated as reactive intermediates, borylenes have been shown to activate strong C-C single bonds, yielding products analogous to an organometallic oxidative addition reaction. Most commonly, these are generated via reduction of an organoborane dichloride, but photolysis of other boranes can also afford short-lived borylene species.

As might be expected, calculations have demonstrated that the HOMO is composed of the nonbonding electrons on boron (nσ-type, sp character). The LUMO and LUMO+1 are empty, orthogonal pπ-type orbitals and are degenerate in energy except in the case where R breaks the symmetry of the molecule, thus lifting the degeneracy. Unlike carbenes, which can exist in either singlet or triplet ground states, calculations have indicated that all yet-studied borylenes have a singlet ground spin state. The smallest singlet-triplet gap was calculated to be 8.2 kcal/mol for Me3Si-B. Aminoborylene (H2NB) is a slight exception to the above paradigm, as the nitrogen lone pair donates into an unoccupied boron p orbital. Thus, there is formally a double bond between boron and nitrogen; the π* combination of this interaction serves as the LUMO+1. [17]

Diborene B-B p-bonding HOMO. HOMO diborene.png
Diborene B-B π-bonding HOMO.

Mono-Lewis base-stabilized borylenes

Above: Diborene dimer generated via reduction of an (NHC)borane adduct. Middle and bottom: two examples of mono-Lewis base-stabilized borylenes using CAAC and DAC ligands. MonoLewisBaseBorylene.png
Above: Diborene dimer generated via reduction of an (NHC)borane adduct. Middle and bottom: two examples of mono-Lewis base-stabilized borylenes using CAAC and DAC ligands.

The first example of a borylene stabilized by a single Lewis base was reported in 2007 and exists as a dimer—a diborene. An (NHC)BBr3 adduct was reduced to generate a probable (NHC)B-H intermediate that subsequently dimerized to form the diborene. A similar species with a boron–boron single bond was also observed. The diborene has an incredibly short boron–boron bond length of 1.560(18) Å, further supporting the assignment of a double bond. DFT and NBO calculations were performed on a model system (with Dipp moieties replaced by H). Although some differences between the calculated and crystal structures were evident, they could primarily be ascribed to distortions from planarity caused by the bulky Dipp groups. The HOMO was calculated to be a B-B π-bonding orbital and the HOMO-1 is of mixed B-H and B-B σ-bonding character. NBO calculations supported the above assessments, as populations for the B-B σ- and π-bonding orbitals were calculated to be 1.943 and 1.382 respectively. [18]

Diborene B-B s-bonding HOMO-1. LUMO diborene.png
Diborene B-B σ-bonding HOMO-1.

A number of similar compounds have been generated and isolated, and several studies involving putative mono-Lewis base-stabilized borylene intermediates have been reported. However, an isolable example remained elusive until 2014. [19] Betrand et al. argued that due to boron's electropositivity and thus preference to be electron-poor, CAAC (cyclic (alkyl)(amino)carbene) might serve as a better Lewis base than the more commonplace NHC. [21] The (NHC)borane adduct was prepared then reduced with Co(Cp*)2. One equivalent of reductant yielded an aminoboryl radical and a second reduction event lead to the desired (CAAC)borylene. [19] Another group followed a similar synthetic strategy using DAC(diamidocarbene); the reduction of a (DAC)borane derivative afforded an analogous (DAC)borylene (see figure). [20] Although the C=B=NR2 structure is similar in nature to aminoboraalkenes, an exploration of molecular orbitals gives an entirely different picture: as expected, the HOMO is a bond of π symmetry derived from the donation of boron's lone pair into the empty orbital on carbon. As previously discussed, a nitrogen lone pair donates into an empty boron p-orbital to form a π bond; the out of phase combination serves as a high-energy LUMO+2. [19]

Diborene B-B s-bonding-derived NBO. BB sigma NBO.png
Diborene B-B σ-bonding-derived NBO.
Braunschweig's 2018 dinitrogen activation with a transient borylene species Boron dinitrogen activation.png
Braunschweig's 2018 dinitrogen activation with a transient borylene species
Diborene B lone pair-derived NBO. B lp NBO.png
Diborene B lone pair-derived NBO.

The first example of dinitrogen fixation at a p-block element was published in 2018 by Holger Braunschweig et al., whereby one molecule of dinitrogen is bound by two transient mono-Lewis base-stabilized borylene species. [22] The resulting dianion was subsequently oxidized to a neutral compound, and reduced using water.

Bis-Lewis base-stabilized borylenes

DiLewisBaseBorylene DiLewisBaseBorylene.png
DiLewisBaseBorylene
Bis(CAAC)BH LUMO. BisLB LUMO.png
Bis(CAAC)BH LUMO.

Taking inspiration from Robinson's above diborene synthesis, [21] [18] Bertrand et al. swapped NHC for CAAC and successfully isolated the first bis-Lewis base-stabilized borylene in 2011. [24] Reduction of (CAAC)BBr3 with KC8 in the presence of excess CAAC afforded the bis(CAAC)BH. A labeling study indicated that the H-atom was abstracted from an aryl group associated with the CAAC. Reduction of (CAAC)BBr3 yields the same terminal borylene even in the absence of additional Lewis base via a mechanism that remains poorly understood. [24] Exploitation of this procedure has been used to form mixed bis-Lewis base-stabilized borylenes as well. [25] Several other routes have also been proposed. A more novel one employs methyl triflate to abstract a hydride from (CAAC)BH3. Treatment with a Lewis base, followed by triflic acid and KC8 afford the desired (CAAC)(Lewis base)BH. [26] Although the reported case uses only specific Lewis bases, the approach is argued to be highly generalizable. [21] [26] A number of other compounds in this class have been generated using borylene-transition metal complexes as precursors. Treatment of (OC)5M=B-Tp with carbon monoxide or acetonitrile yields the corresponding adducts: (CO)2B-Tp and (MeNC)2B-Tp. [27]

Bis(CAAC)BH HOMO. BisCAACborylene HOMO.png
Bis(CAAC)BH HOMO.

Bonding in these complexes is quite similar to that in mono-Lewis base compounds. At least one π-acceptor ligand is present in all known examples of these compounds, and the B-L bond strength tends to scale with the π-acidity of the Lewis base. Low-energy σ-donation orbitals from the base to boron are present in these compounds, and the π-interaction from boron's lone pair to the Lewis base serves as the HOMO. Calculated electronic structure for a number of borylene complexes were compared with their isoelectronic homologues: carbone complexes (CL2) and nitrogen cation complexes ((N+)L2). [28]

Borylene-transition metal complexes

The first transition metal complex reported by Braunschweig et al. featured a borylene ligand bridging between two manganese centers: [ μ-BX{η5-C5H4R}Mn(CO)2}2] (R=H, Me; X=NMe2). [29] The first terminal borylene complex [(CO)5MBN(SiMe3)2] was prepared by the same group several years later. Two previous structures – [(CO)4Fe(BNMe2)] and [(CO)4Fe{BN(SiMe3)2}] – had been proposed by other groups but disqualified due to inconsistent 11B-NMR data. [30] A number of diborylene complexes have also been described. The first of these, [(η5-C5Me5)Ir{BN(SiMe3)2}2], was prepared by the photochemical reaction of [(η5-C5Me5)Ir(CO)2] with [(OC)5Cr{BN(SiMe3)2}]. [31] One unusual reaction exhibited by these complexes is coupling of borylene and carbon monoxide ligands. Catenation of an iron borylene complex has generate an iron complex of a tetraboron (B4) chain. [32]

Orbitally, the interactions between transition metals and borylenes tend to be similar to the above Lewis acids and borylenes. A number of computational studies have been performed on these systems. A sample paper from 2000 employed NBO to analyze a series of related complexes. Taking [(CO)4Fe{BN(SiH3)2}] as an example, it was calculated that—as expected—the boron moiety is relatively electron-poor (+0.59 charge). The Fe-B π-bonding orbitals were found to have populations of 0.39 and 0.48 whereas the σ-bonding had 0.61. Thus, the Wiberg bond index of the Fe-B bond was a relatively strong 0.65 (compare: Fe-CO was 0.62 in the same complex. The analogous tungsten complex had a bond index value of 0.82. Overall, the paper concludes that transition metal-borylene bonds are very strong. However, the bonding has strong ionic contributions. Orbital attractions are primarily σ- accompanied by weaker π-interactions. Unlike corresponding metal-carbyne complexes, the bond order in all studied cases was less than 1. [33]

Related Research Articles

<span class="mw-page-title-main">Organoboron chemistry</span> Study of compounds containing a boron-carbon bond

Organoboron chemistry or organoborane chemistry is the chemistry of organoboron compounds or organoboranes, which are chemical compounds of boron and carbon that are organic derivatives of borane (BH3), for example trialkyl boranes..

<span class="mw-page-title-main">Germylene</span> Class of germanium (II) compounds

Germylenes are a class of germanium(II) compounds with the general formula :GeR2. They are heavier carbene analogs. However, unlike carbenes, whose ground state can be either singlet or triplet depending on the substituents, germylenes have exclusively a singlet ground state. Unprotected carbene analogs, including germylenes, has a dimerization nature. Free germylenes can be isolated under the stabilization of steric hindrance or electron donation. The synthesis of first stable free dialkyl germylene was reported by Jutzi, et al in 1991.

Boroles represent a class of molecules known as metalloles, which are heterocyclic 5-membered rings. As such, they can be viewed as structural analogs of cyclopentadiene, pyrrole or furan, with boron replacing a carbon, nitrogen and oxygen atom respectively. They are isoelectronic with the cyclopentadienyl cation C5H+5(Cp+) and comprise four π electrons. Although Hückel's rule cannot be strictly applied to borole, it is considered to be antiaromatic due to having 4 π electrons. As a result, boroles exhibit unique electronic properties not found in other metalloles.

<span class="mw-page-title-main">Boranylium ions</span>

In chemistry, a boranylium ion is an inorganic cation with the chemical formula BR+
2, where R represents a non-specific substituent. Being electron-deficient, boranylium ions form adducts with Lewis bases. Boranylium ions have historical names that depend on the number of coordinated ligands:

<span class="mw-page-title-main">Cyclic alkyl amino carbenes</span> Family of chemical compounds

In chemistry, cyclic(alkyl)(amino)carbenes (CAACs) are a family of stable singlet carbene ligands developed by the research group of Guy Bertrand in 2005 at UC Riverside. In marked contrast with the popular N-heterocyclic carbenes (NHCs) which possess two "amino" substituents adjacent to the carbene center, CAACs possess one "amino" substituent and an sp3 carbon atom "alkyl". This specific configuration makes the CAACs very good σ-donors and π-acceptors when compared to NHCs. Moreover the reduced heteroatom stabilization of the carbene center in CAACs versus NHCs also gives rise to a smaller ΔEST.

<span class="mw-page-title-main">Holger Braunschweig</span>

Holger Braunschweig is Head and Chair of Inorganic Chemistry at the Julius-Maximilians-University of Würzburg in Würzburg, Germany. He is best known for founding the field of transition metal-boron multiple bonding, the synthesis of the first stable compounds containing boron-boron and boron-oxygen triple bonds, the isolation of the first non-carbon/nitrogen main-group dicarbonyl, and the first fixation of dinitrogen at an element of the p-block of the periodic table. By modifying a strategy pioneered by Prof. Gregory Robinson of the University of Georgia, Braunschweig also discovered the first rational and high-yield synthesis of neutral compounds containing boron-boron double bonds (diborenes). In 2016 Braunschweig isolated the first compounds of beryllium in the oxidation state of zero.

<span class="mw-page-title-main">Silylone</span> Class of organosilicon compounds

Silylones are a class of zero-valent monatomic silicon complexes, characterized as having two lone pairs and two donor-acceptor ligand interactions stabilizing a silicon(0) center. Synthesis of silylones generally involves the use of sterically bulky carbenes to stabilize highly reactive Si(0) centers. For this reason, silylones are sometimes referred to siladicarbenes. To date, silylones have been synthesized with cyclic alkyl amino carbenes (cAAC) and bidentate N-heterocyclic carbenes (bis-NHC). They are capable of reactions with a variety of substrates, including chalcogens and carbon dioxide.

<span class="mw-page-title-main">Plumbylene</span>

Plumbylenes (or plumbylidenes) are divalent organolead(II) analogues of carbenes, with the general chemical formula, R2Pb, where R denotes a substituent. Plumbylenes possess 6 electrons in their valence shell, and are considered open shell species.

<span class="mw-page-title-main">Germanium(II) dicationic complexes</span>

Ge(II) dicationic complexes refer to coordination compounds of germanium with a +2 formal oxidation state, and a +2 charge on the overall complex. In some of these coordination complexes, the coordination is strongly ionic, localizing a +2 charge on Ge, while in others the bonding is more covalent, delocalizing the cationic charge away from Ge. Examples of dicationic Ge(II) complexes are much rarer than monocationic Ge(II) complexes, often requiring the use of bulky ligands to shield the germanium center. Dicationic complexes of Ge(II) have been isolated with bulky isocyanide and carbene ligands. Much more weakly coordinated Germanium (II) dications have been isolated as complexes with polyether ligands, such as crown ethers and [2.2.2]cryptand. Crown ethers and cryptands are typically known for their ability to bind metal cations, however these ligands have also been employed in stabilizing low-valent cations of heavier p-block elements. A Ge2+ ion's valence shell consists of a filled valence s orbital but empty valence p orbitals, giving rise to atypical bonding in these complexes. Germanium is a metalloid of the carbon group, typically forming compounds with mainly covalent bonding, contrasting with the dative bonding observed in these coordination complexes.

<span class="mw-page-title-main">Triboracyclopropenyl</span>

The triboracyclopropenyl fragment is a cyclic structural motif in boron chemistry, named for its geometric similarity to cyclopropene. In contrast to nonplanar borane clusters that exhibit higher coordination numbers at boron (e.g., through 3-center 2-electron bonds to bridging hydrides or cations), triboracyclopropenyl-type structures are rings of three boron atoms where substituents at each boron are also coplanar to the ring. Triboracyclopropenyl-containing compounds are extreme cases of inorganic aromaticity. They are the lightest and smallest cyclic structures known to display the bonding and magnetic properties that originate from fully delocalized electrons in orbitals of σ and π symmetry. Although three-membered rings of boron are frequently so highly strained as to be experimentally inaccessible, academic interest in their distinctive aromaticity and possible role as intermediates of borane pyrolysis motivated extensive computational studies by theoretical chemists. Beginning in the late 1980s with mass spectrometry work by Anderson et al. on all-boron clusters, experimental studies of triboracyclopropenyls were for decades exclusively limited to gas-phase investigations of the simplest rings (ions of B3). However, more recent work has stabilized the triboracyclopropenyl moiety via coordination to donor ligands or transition metals, dramatically expanding the scope of its chemistry.

Aluminium(I) nucleophiles are a group of inorganic and organometallic nucleophilic compounds containing at least one aluminium metal center in the +1 oxidation state with a lone pair of electrons strongly localized on the aluminium(I) center.

Gallium monoiodide (GaI or Ga4I4) is a low-valent gallium species that acts as a reactive intermediate for many gallium-based products. Gallium(I) halides were first crystallographically characterized by Schnöckel and coworkers and have allowed a synthetic route to many low-valent gallium species. However, chemical syntheses that employ “GaI” rather than gallium(I) halide precursors have been increasingly investigated given the ease of synthesis of this reagent. While the synthetic method of Schnöckel and coworkers to synthesize gallium(I) halides require extraordinarily high temperatures, the straightforward preparation of “GaI” at near room temperature has allowed for the exploration of new gallium-based chemistries.

Karsten Meyer is a German inorganic chemist and Chair of Inorganic and General Chemistry at the Friedrich-Alexander University of Erlangen-Nürnberg (FAU). His research involves the coordination chemistry of transition metals as well as uranium coordination chemistry, small molecule activation with these coordination complexes, and the synthesis of new chelating ligands. He is the 2017 recipient of the Elhuyar-Goldschmidt Award of the Spanish Royal Society of Chemistry, the Ludwig-Mond Award of the Royal Society of Chemistry, and the L.A. Chugaev Commemorative Medal of the Russian Academy of Sciences, among other awards. He also serves as an Associate Editor of the journal Organometallics since 2014.

<span class="mw-page-title-main">9-Borafluorene</span> Class of chemical compounds

9-borafluorenes are a class of boron-containing heterocycles consisting of a tricyclic system with a central BC4 ring with two fused arene groups. 9-borafluorenes can be thought of as a borole with two fused arene rings, or as a trigonal planar boron atom with an empty p orbital bridging two biphenyl rings. However, 9-borafluorenes are generally less reactive than boroles due to less antiaromatic character and Lewis acidity. Containing highly conjugated π systems, 9-borafluorenes possess interesting photophysical properties. In addition, 9-borafluorenes are good Lewis acids. This combination of properties enables potential uses such as in light-emitting materials, solar cells, and sensors for some molecules.

Intrinsic bond orbitals (IBO) are localized molecular orbitals giving exact and non-empirical representations of wave functions. They are obtained by unitary transformation and form an orthogonal set of orbitals localized on a minimal number of atoms. IBOs present an intuitive and unbiased interpretation of chemical bonding with naturally arising Lewis structures. For this reason IBOs have been successfully employed for the elucidation of molecular structures and electron flow along the intrinsic reaction coordinate (IRC).

<span class="mw-page-title-main">Carbones</span> Class of molecules

Carbones are a class of molecules containing a carbon atom in the 1D excited state with a formal oxidation state of zero where all four valence electrons exist as unbonded lone pairs. These carbon-based compounds are of the formula CL2 where L is a strongly σ-donating ligand, typically a phosphine (carbodiphosphoranes) or a N-heterocyclic carbene/NHC (carbodicarbenes), that stabilises the central carbon atom through donor-acceptor bonds. Carbones possess high-energy orbitals with both σ- and π-symmetry, making them strong Lewis bases and strong π-backdonor substituents. Carbones possess high proton affinities and are strong nucleophiles which allows them to function as ligands in a variety of main group and transition metal complexes. Carbone-coordinated elements also exhibit a variety of different reactivities and catalyse various organic and main group reactions.  

<i>N</i>-Heterocyclic carbene boryl anion Isoelectronic structure

An N-heterocyclic carbene boryl anion is an isoelectronic structure of an N-heterocyclic carbene (NHC), where the carbene carbon is replaced with a boron atom that has a -1 charge. NHC boryl anions have a planar geometry, and the boron atom is considered to be sp2-hybridized. They serve as extremely strong bases, as they are very nucleophilic. They also have a very strong trans influence, due to the σ-donation coming from the boron atom. NHC boryl anions have stronger electron-releasing character when compared to normal NHCs. These characteristics make NHC boryl anions key ligands in many applications, such as polycyclic aromatic hydrocarbons, and more commonly low oxidation state main group element bonding.

<span class="mw-page-title-main">Borepin</span> Aromatic, boron-containing rings

Borepins are a class of boron-containing heterocycles used in main group chemistry. They consist of a seven-membered unsaturated ring with a tricoordinate boron in it. Simple borepins are analogues of cycloheptatriene, which is a seven-membered ring containing three carbon-carbon double bonds, each of which contributes 2π electrons for a total of 6π electrons. Unlike other seven-membered systems such as silepins and phosphepins, boron has a vacant p-orbital that can interact with the π and π* orbitals of the cycloheptatriene. This leads to an isoelectronic state akin to that of the tropylium cation, aromatizing the borepin while also allowing it to act as a Lewis acid. The aromaticity of borepin is relatively weak compared to traditional aromatics such as benzene or even cycloheptatriene, which has led to the synthesis of many fused, π-conjugated borepin systems over the years. Simple and complex borepins have been extensively studied more recently due to their high fluorescence and potential applications in technologies like organic light-emitting diodes (OLEDs) and photovoltaic cells.

<span class="mw-page-title-main">Organoberyllium chemistry</span> Organoberyllium Complex in Main Group Chemistry

Organoberyllium chemistry involves the synthesis and properties of organometallic compounds featuring the group 2 alkaline earth metal beryllium (Be). The area remains understudied, relative to the chemistry of other main-group elements, because although metallic beryllium is relatively unreactive, its dust causes berylliosis and compounds are toxic. Organoberyllium compounds are typically prepared by transmetallation or alkylation of beryllium chloride.

Main-group element-mediated activation of dinitrogen is the N2 activation facilitated by reactive main group element centered molecules (e.g., low valent main group metal Ca, dicoordinate borylene, boron radical, carbene, etc.).

References

  1. ↑ Braunschweig, H.; Colling, M. (2003). "The Chemistry of Borylene Complexes". Eur. J. Inorg. Chem. 2003 (3): 393–403. doi:10.1002/ejic.200390054.
  2. ↑ Soleilhavoup, M.; Bertrand, G. (2017). "Borylenes: An Emerging Class of Compounds". Angewandte Chemie International Edition. 56 (35): 10282–10292. doi: 10.1002/anie.201705153 . PMID   28577325.
  3. ↑ Braunschweig, Holger; Dewhurst, Rian D.; Gessner, Viktoria H. (2013). "Transition metal borylene complexes". Chemical Society Reviews. 42 (8): 3197–3308. doi:10.1039/C3CS35510A. PMID   23403460.
  4. ↑ Braunschweig, Holger; Dewhurst, Rian D.; Schneider, Achim (2010-07-14). "Electron-Precise Coordination Modes of Boron-Centered Ligands". Chemical Reviews. 110 (7): 3924–3957. doi:10.1021/cr900333n. ISSN   0009-2665. PMID   20235583.
  5. ↑ Braunschweig, H.; Kollann, C.; Englert, U. (1998). "Synthesis and Structure of the First Terminal Borylene Complexes". Angewandte Chemie International Edition. 37 (22): 3179–3180. doi:10.1002/(SICI)1521-3773(19981204)37:22<3179::AID-ANIE3179>3.0.CO;2-Z. PMID   29711330.
  6. ↑ Braunschweig, H; Shang, R (2015). "Reactivity of transition-metal borylene complexes: recent advances in B-C and B-B bond formation via borylene ligand coupling". Inorg Chem. 54 (7): 3099–106. doi:10.1021/acs.inorgchem.5b00091. PMID   25760461.
  7. ↑ Wang, Y; Quillian, B; Wei, P; Wannere, CS; Xie, Y; King, RB; Schaefer, HF 3rd; Schleyer, PV; Robinson, GH (2007). "A stable, neutral diborene containing a B=B double bond". J Am Chem Soc. 129 (41): 12412–3. doi:10.1021/ja075932i. PMID   17887683.
  8. ↑ Dahcheh, F.; Martin, D.; Stephan, D. W.; Bertrand, G. (2014). "Synthesis and Reactivity of a CAAC–Aminoborylene Adduct: A Hetero-Allene or an Organoboron Isoelectronic with Singlet Carbenes". Angewandte Chemie International Edition. 53 (48): 13159–13163. doi:10.1002/anie.201408371. PMID   25267591.
  9. ↑ Braunschweig, Holger; Dewhurst, Rian D.; Hupp, Florian; Nutz, Marco; Radacki, Krzysztof; Tate, Christopher W.; Vargas, Alfredo (2015). "Multiple complexation of CO and related ligands to a main-group element". Nature. 522 (7556): 327–330. Bibcode:2015Natur.522..327B. doi:10.1038/nature14489. PMID   26085273. S2CID   4454142.
  10. ↑ Kinjo, R; Donnadieu, B; Celik, MA; Frenking, G; Bertrand, G (2011). "Synthesis and characterization of a neutral tricoordinate organoboron isoelectronic with amines". Science. 333 (6042): 610–3. Bibcode:2011Sci...333..610K. doi:10.1126/science.1207573. PMID   21798945. S2CID   8642916.
  11. ↑ Grigsby, Warren J.; Power, Philip P. (1996-01-01). "Isolation and Reduction of Sterically Encumbered Arylboron Dihalides: Novel Boranediyl Insertion into C−C σ-Bonds". Journal of the American Chemical Society. 118 (34): 7981–7988. doi:10.1021/ja960918j. ISSN   0002-7863.
  12. ↑ Meller, Anton; Seebold, Uwe; Maringgele, Walter; Noltemeyer, Mathias; Sheldrick, George M. (1989-10-01). "Synthesis and structure of novel polycyclic species from toluene and m-xylene and the dehalogenation product of difluoro(diisopropylamino)borane". Journal of the American Chemical Society. 111 (21): 8299–8300. doi:10.1021/ja00203a052. ISSN   0002-7863.
  13. ↑ Bettinger, Holger F. (2006-03-01). "Phenylborylene: Direct Spectroscopic Characterization in Inert Gas Matrices". Journal of the American Chemical Society. 128 (8): 2534–2535. doi:10.1021/ja0548642. ISSN   0002-7863. PMID   16492027.
  14. ↑ Andrews, Lester; Hassanzadeh, Parviz; Martin, Jan M. L.; Taylor, Peter R. (1993-06-01). "Pulsed laser evaporated boron atom reactions with acetylene. Infrared spectra and quantum chemical structure and frequency calculations for several novel organoborane BC2H2 and HBC2 molecules". The Journal of Physical Chemistry. 97 (22): 5839–5847. doi:10.1021/j100124a010. ISSN   0022-3654.
  15. ↑ Timms, Peter L. (1973-04-01). "Chemistry of boron and silicon subhalides". Accounts of Chemical Research. 6 (4): 118–123. doi:10.1021/ar50064a002. ISSN   0001-4842.
  16. ↑ Nomoto, Miho; Okabayashi, Toshiaki; Klaus, Thomas; Tanimoto, Mitsutoshi (1997). "Microwave spectroscopic study of the BBr molecule". Journal of Molecular Structure. 413–414: 471–476. Bibcode:1997JMoSt.413..471N. doi:10.1016/s0022-2860(97)00145-2.
  17. ↑ Krasowska, Małgorzata; Edelmann, Marc; Bettinger, Holger F. (2016-08-18). "Electronically Excited States of Borylenes". The Journal of Physical Chemistry A. 120 (32): 6332–6341. Bibcode:2016JPCA..120.6332K. doi:10.1021/acs.jpca.6b04502. ISSN   1089-5639. PMID   27494640.
  18. 1 2 3 4 5 6 7 Wang, Yuzhong; Quillian, Brandon; Wei, Pingrong; Wannere, Chaitanya S.; Xie, Yaoming; King, R. Bruce; Schaefer, Henry F.; Schleyer, Paul v. R.; Robinson, Gregory H. (2007-10-01). "A Stable Neutral Diborene Containing a BB Double Bond". Journal of the American Chemical Society. 129 (41): 12412–12413. doi:10.1021/ja075932i. ISSN   0002-7863. PMID   17887683.
  19. 1 2 3 4 Dahcheh, Fatme; Martin, David; Stephan, Douglas W.; Bertrand, Guy (2014-11-24). "Synthesis and Reactivity of a CAAC–Aminoborylene Adduct: A Hetero-Allene or an Organoboron Isoelectronic with Singlet Carbenes". Angewandte Chemie International Edition. 53 (48): 13159–13163. doi:10.1002/anie.201408371. ISSN   1521-3773. PMID   25267591.
  20. 1 2 Ledet, Anthony D.; Hudnall, Todd W. (2016-06-14). "Reduction of a diamidocarbene-supported borenium cation: isolation of a neutral boryl-substituted radical and a carbene-stabilized aminoborylene". Dalton Transactions. 45 (24): 9820–9826. doi:10.1039/c6dt00300a. ISSN   1477-9234. PMID   26843319.
  21. 1 2 3 Soleilhavoup, Michele; Bertrand, Guy (2017-08-21). "Borylenes: An Emerging Class of Compounds". Angewandte Chemie International Edition. 56 (35): 10282–10292. doi: 10.1002/anie.201705153 . ISSN   1521-3773. PMID   28577325.
  22. ↑ Broere, Daniël L. J.; Holland, Patrick L. (2018-02-23). "Boron compounds tackle dinitrogen". Science. 359 (6378): 871. Bibcode:2018Sci...359..871B. doi:10.1126/science.aar7395. ISSN   0036-8075. PMC   6101238 . PMID   29472470.
  23. 1 2 Huang, Pin-Qi; Lai, Chin-Hung (2015). "Computational study of unsaturated and saturated cyclic (alkyl) (amino) carbene borane complexes". Computational and Theoretical Chemistry. 1051: 17–23. doi:10.1016/j.comptc.2014.10.029.
  24. 1 2 Kinjo, Rei; Donnadieu, Bruno; Celik, Mehmet Ali; Frenking, Gernot; Bertrand, Guy (2011-07-29). "Synthesis and Characterization of a Neutral Tricoordinate Organoboron Isoelectronic with Amines". Science. 333 (6042): 610–613. Bibcode:2011Sci...333..610K. doi:10.1126/science.1207573. ISSN   0036-8075. PMID   21798945. S2CID   8642916.
  25. ↑ Arrowsmith, Merle; Auerhammer, Dominic; Bertermann, Rüdiger; Braunschweig, Holger; Bringmann, Gerhard; Celik, Mehmet Ali; Dewhurst, Rian D.; Finze, Maik; Grüne, Matthias (2016-11-07). "Generation of Dicoordinate Boron(I) Units by Fragmentation of a Tetra-Boron(I) Molecular Square". Angewandte Chemie International Edition. 55 (46): 14464–14468. doi:10.1002/anie.201608429. ISSN   1521-3773. PMID   27730749.
  26. 1 2 Ruiz, David A.; Melaimi, Mohand; Bertrand, Guy (2014-06-24). "An efficient synthetic route to stable bis(carbene)borylenes [(L1)(L2)BH]". Chem. Commun. 50 (58): 7837–7839. doi:10.1039/c4cc03497j. ISSN   1364-548X. PMID   24909943.
  27. ↑ Braunschweig, Holger; Dewhurst, Rian D.; Hupp, Florian; Nutz, Marco; Radacki, Krzysztof; Tate, Christopher W.; Vargas, Alfredo; Ye, Qing (June 2015). "Multiple complexation of CO and related ligands to a main-group element". Nature. 522 (7556): 327–330. Bibcode:2015Natur.522..327B. doi:10.1038/nature14489. ISSN   1476-4687. PMID   26085273. S2CID   4454142.
  28. ↑ Celik, Mehmet Ali; Sure, Rebecca; Klein, Susanne; Kinjo, Rei; Bertrand, Guy; Frenking, Gernot (2012-04-27). "Borylene Complexes (BH)L2 and Nitrogen Cation Complexes (N+)L2: Isoelectronic Homologues of Carbones CL2". Chemistry – A European Journal. 18 (18): 5676–5692. doi:10.1002/chem.201103965. ISSN   1521-3765. PMID   22434609.
  29. ↑ Braunschweig, Holger; Wagner, Trixie (1995-04-13). "Synthesis and Structure of the First Transition Metal Borylene Complexes". Angewandte Chemie International Edition in English. 34 (7): 825–826. doi:10.1002/anie.199508251. ISSN   1521-3773.
  30. ↑ Braunschweig, Holger; Kollann, Carsten; Englert, Ulli (1998-12-04). "Synthesis and Structure of the First Terminal Borylene Complexes". Angewandte Chemie International Edition. 37 (22): 3179–3180. doi:10.1002/(sici)1521-3773(19981204)37:22<3179::aid-anie3179>3.0.co;2-z. ISSN   1521-3773. PMID   29711330.
  31. ↑ Bertsch, Stefanie; Braunschweig, Holger; Christ, Bastian; Forster, Melanie; Schwab, Katrin; Radacki, Krzysztof (2010-12-03). "Towards Homoleptic Borylene Complexes: Incorporation of Two Borylene Ligands into a Mononuclear Iridium Species". Angewandte Chemie International Edition. 49 (49): 9517–9520. doi:10.1002/anie.201004103. ISSN   1521-3773. PMID   21053226.
  32. ↑ Braunschweig, Holger; Shang, Rong (2015-04-06). "Reactivity of Transition-Metal Borylene Complexes: Recent Advances in B–C and B–B Bond Formation via Borylene Ligand Coupling". Inorganic Chemistry. 54 (7): 3099–3106. doi:10.1021/acs.inorgchem.5b00091. ISSN   0020-1669. PMID   25760461.
  33. ↑ Uddin, Jamal; Boehme, Christian; Frenking, Gernot (2000-02-01). "Nature of the Chemical Bond between a Transition Metal and a Group-13 Element: Structure and Bonding of Transition Metal Complexes with Terminal Group-13 Diyl Ligands ER (E=B to Tl; R=Cp, N(SiH3)2, Ph, Me)". Organometallics. 19 (4): 571–582. doi:10.1021/om990936k. ISSN   0276-7333.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.