Nitrogen Fixation by Borabenzene

Abstract

Borabenzene is stabilized in an extremely mild fashion in the matrix‐isolated borabenzene–nitrogen adduct 4, which was identified by IR spectroscopy. In general, boraarenes and boraethenes can only be isolated when the electron deficiency on boron is satisfied by a donor. Compound 4 is formed via 3 upon flash pyrolysis of 1 in N2 as carrier gas.

1,2‐Azaborine: The Boron‐Nitrogen Derivative of ortho‐Benzyne

“…This band is reminiscent of the dinitrogen stretching vibration ν(NN) observed previously by Maier et al for the borabenzene-dinitrogen adduct. When employing 15 N 2 the isotopic shift is 75 cm −1 , in good agreement with Maier et al [11] (73.3 cm −1 ) for borabenzene-dinitrogen and with computations at the CCSD(T)/TZ2P level of theory. The remaining signals of 3 have at most slight isotopic shifts, in agreement with theoretical calculations (Supporting Information Table S1).…”

Quantum-Chemical Ab Initio Calculations on Borabenzene (C5H5B) and its Adducts with Ne, Ar, Kr, and N2. Could Free Borabenzene be Observed in Rare Gas Matrices?

“…In addition, we present some results not only for the lowest triplet state of borabenzene but also for the adducts of singlet borabenzene to N 2 , Ne, Ar, and Kr. We then compare some of the computational results obtained in this study with the available experimental spectroscopic and theoretical structural data for the N 2 adduct from refs [9] to [10]. This comparison enables assessment of the quality of the applied methods and, therefore, a judgement to be made of the reliability of our predictions regarding the UV-vis and IR spectra of C 5 H 5 B and those of its adducts to Ne, Ar, Kr, and N 2 .…”

“…[10] It was studied theoretically more recently by Semenov and Sigolaev. [8] In 1988, Maier et al [9] observed and characterized the adduct of nitrogen to borabenzene spectroscopically when they generated the title compound pyrolytically. To determine the most likely structure of the nitrogen adduct we performed quantum-chemical calculations on the C 5 H 5 B/N 2 system.…”

“…[3][4][5][6][7][8][9][10][11] Thus Schulman and Dish [3] evaluated aspects of the thermochemistry of the title compound and compared them to the corresponding properties of borepine, which is isoelectronic with the tropylium cation. Using a homodesmic reaction, HF/6-31G * energies, and a correction for strain energy they obtained a resonance energy A of 19.2 kcal mol À1 (1 kcal mol À1 ¼ 4.186 kJ mol À1 ) for borabenzene, which is only ,23% less than the values found for benzene (24.7-24.8 kcal mol À1 ) and pyridine (25.4 kcal mol À1 ).…”

2,2′‐Diborabiphenyl: A Lewis Acid Analogue of 2,2′‐Bipyridine

“…Building on methodology first used by Maier et al [7] and then developed by Fu and co-workers, [8] the silated stannacycle shown was used as the precursor to the desired boracycle. To direct the crucial CÀC bond-forming step to the position ortho to the boron atom, it was necessary to first block the para position.…”