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Reversible Formation of Organyl(oxo)boranes (RBO) (R = C6H5 or CH3) from Boroxins ((RBO)3):  A Matrix Isolation Study

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journal contribution
posted on 02.04.2020, 15:01 by Holger F. Bettinger
Flash vacuum pyrolysis of triphenyl- and trimethylboroxin and subsequent trapping of the gas phase products in a large excess of argon at T < 20 K allows matrix isolation and characterization by IR spectroscopy of phenyl(oxo)borane and methyl(oxo)borane. The nature of the matrix isolated species, monomeric CH3BO, 1:1 dimer complex of CH3BO, (CH3BO)2, and (CH3BO)3, depends strongly on the trapping temperature and matrix host gas (Ar vs Xe) with the boroxin dominating at 30 K (Ar) or 55 K (Xe). An ab initio investigation (second-order Møller−Plesset perturbation theory) of the potential energy surface for trimerization of CH3BO is in agreement with the experimental observations.