Synthesis of a 1,3-dioxa-2,4-diboretane, an oxoborane precursor

Pachaly, Bernd; West, Robert

doi:10.1021/ja00296a034

Cited by 63 publications

(27 citation statements)

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“…Due to their unsaturated nature and reactive polar B=O bonds, oxoboranes have only been identified within low temperature matrices or in the gas phase . However, encouraging work by Pachaly and West revealed the intermediacy of the bulky oxoborane (2,4,6‐ t Bu 3 C 6 H 2 )BO through trapping experiments . This study was complemented by impressive work by Braunschweig and co‐workers who used metal‐boron complexation to stabilize triply bonded B≡O as a monodentate ligand .…”

Section: Methodsmentioning

confidence: 93%

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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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Section: Methodsmentioning

confidence: 93%

“…Monomerico xoboranes (RBO) representafundamental building block of the synthetically useful boroxine (RBO) 3 compound class. [1] Due to their unsaturatedn ature and reactive polar B=Ob onds,o xoboranes have only been identified within low temperature matrices or in the gas phase.…”

mentioning

confidence: 96%

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

Swarnakar

Hering‐Junghans

Ferguson

et al. 2017

Chemistry A European J

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“…Compounds containing boron-oxygen double bonds, i.e . oxoboranes (R−B=O), have been invoked as reactive intermediates for some time18, but they have defied most attempts at isolation and characterization18–23; the oxophilicity of boron makes the formation of a B−O−B linkage more facile than formation of a boron-oxygen multiple bond16–17. Recently, however, Vidovic et al 24.…”

Section: Introductionmentioning

confidence: 99%

A Computational Characterization of Boron−Oxygen Multiple Bonding in HN═CH−CH═CH−NH−BO

et al. 2008

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Structures, relative energies, and bonding characteristics for various conformers of 3-imino-N-(oxoboryl)prop-1-en-1-amine, HN=CH−CH=CH−NH−BO, and the corresponding borocycle (−HN=CH−CH=CH−NH−B−)O are discussed using results from second-order Møller-Plesset (MP2) perturbation theory with the Dunning-Woon correlation-consistent cc-pVDZ, aug-cc-pVDZ, and cc-pVTZ basis sets. These MP2 results are compared to those from computationally-efficient density functional theory (DFT) calculations using the LDA, PBE, TPSS, BLYP, B3LYP, BVP86, OLYP, O3LYP, and PBE1PBE functionals in conjunction with the economical Pople-type 6−311+ +G(d,p) basis set, to evaluate the suitability of these DFT/6−311++G(d,p) levels for use with larger boron-containing systems. The effects of an aqueous environment were incorporated into the calculations using COSMO methodology. The calculated boron-oxygen bond lengths, orbital compositions, and bond orders in all the (acyclic) HN=CH−CH=CH−NH−BO conformers were consistent with the presence of a boron-oxygen triple bond, similar to that found in H−B≡O and H 2 N−B≡O. The (−HN=CH−CH=CH−NH−B−)O borocycle is predicted to be planar (C 2v symmetry) and it is ~30 kcal/mol lower in energy than any of the (acyclic) HN=CH−CH=CH−NH−BO conformers; the boron-oxygen bond in this borocycle has significant double bond character, a bonding scheme for which there has been only one experimental structure reported in the literature

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“…14−16 However, oxoboranes are very reactive due to the highly polar boron−oxygen bond and readily form oligomers to compensate for their intrinsic electron deficiency. 17,18 As a result, the dehydration of boronic acids lead to the formation of oligomers of oxoborane instead of monomers. 17 Further, Bock et al reported the synthesis of methyloxoborane (CH 3 BO) via thermolysis of methyl-1,3,2-diborolane-4,5-dione, but the product promptly underwent cyclo-oligomerization to (CH 3 BO) 3 .…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Synthesis of Boronylallene (H₂CCCH(BO)) under Single Collision Conditions: A Crossed Molecular Beams and Computational Study

et al. 2014

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The gas phase reaction between the boron monoxide radical (BO; XΣ) and allene (HCCCH; XA) was investigated experimentally under single collision conditions using the crossed molecular beam technique and theoretically exploiting ab initio electronic structure and statistical (RRKM) calculations. The reaction was found to follow indirect (complex forming) scattering dynamics and proceeded via the formation of a van der Waals complex (BOCH). This complex isomerized via addition of the boron monoxide radical (BO; XΣ) with the radical center located at the boron atom to the terminal carbon atom of the allene molecule forming a HCCCHBO intermediate on the doublet surface. The chemically activated HCCCHBO intermediate underwent unimolecular decomposition via atomic hydrogen elimination from the terminal carbon atom holding the boronyl group through a tight exit transition state to synthesize the boronylallene product (HCCCHBO) in a slightly exoergic reaction (55 ± 11 kJ mol). Statistical (RRKM) calculations suggest that minor reaction channels lead to the products 3-propynyloxoborane (CH(BO)CCH) and 1-propynyloxoborane (CHCCBO) with fractions of 1.5% and 0.2%, respectively. The title reaction was also compared with the cyano (CN; XΣ)-allene and boronyl-methylacetylene reactions to probe similarities, but also differences of these isoelectronic systems. Our investigation presents a novel gas phase synthesis and characterization of a hitherto elusive organyloxoborane (RBO) monomer-boronylallene-which is inherently tricky to isolate in the condensed phase except in matrix studies; our work further demonstrates that the crossed molecular beams approach presents a useful tool in investigating the chemistry and synthesis of highly reactive organyloxoboranes.

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Synthesis of a 1,3-dioxa-2,4-diboretane, an oxoborane precursor

Cited by 63 publications

References 0 publications

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

A Computational Characterization of Boron−Oxygen Multiple Bonding in HN═CH−CH═CH−NH−BO

Gas-Phase Synthesis of Boronylallene (H₂CCCH(BO)) under Single Collision Conditions: A Crossed Molecular Beams and Computational Study

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Synthesis of a 1,3-dioxa-2,4-diboretane, an oxoborane precursor

Cited by 63 publications

References 0 publications

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

Oxoborane (RBO) Complexation and Concomitant Electrophilic Bond Activation Processes

A Computational Characterization of Boron−Oxygen Multiple Bonding in HN═CH−CH═CH−NH−BO

Gas-Phase Synthesis of Boronylallene (H2CCCH(BO)) under Single Collision Conditions: A Crossed Molecular Beams and Computational Study

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Gas-Phase Synthesis of Boronylallene (H₂CCCH(BO)) under Single Collision Conditions: A Crossed Molecular Beams and Computational Study