A computational investigation of the geometrical structure and protodeboronation of boroglycine, H2N-CH2-B(OH)2.
In this article the geometrical structure of the simple, achiral, alpha-amino boronic acid boroglycine, H2N-CH2-B(OH)2, was investigated using density functional theory (DFT), second-order Møller-Plesset (MP2) perturbation theory, and coupled cluster methodology with single- and double-excitations (CCSD); the effects of an aqueous environment were incorporated into the results by using a few explicit water molecules and/or self-consistent reaction field (SCRF) calculations with the IEF polarizable continuum model (PCM). Neutral reaction mechanisms were investigated for the direct protodeboronation (hydrolysis) of boroglycine (H2O+H2N-CH2-B(OH)2-->B(OH)3+H2N-CH3), for which DeltaH degrees 298 was -21.9 kcal/mol at the MP2(FC)/aug-cc-pVDZ level, and for the 1,2-carbon-to-nitrogen shift of the -B(OH)2 moiety (H2N-CH2-B(OH)2-->H3C-NH-B(OH)2), for which the corresponding value of DeltaH degrees 298 was -18.2 kcal/mol. A boron-oxygen double-bonded intermediate was found to play an important role in the 1,2-rearrangement mechanism.
Larkin
Joseph D
JD
Department of Chemistry, Bloomsburg University of Pennsylvania, Bloomsburg, Pennsylvania 17815, USA. jlarkin@bloomu.edu
Bhat
Krishna L
KL
Markham
George D
GD
Brooks
Bernard R
BR
Lai
Jack H
JH
Bock
Charles W
CW
D001896:Boron Compounds / Q000737:chemistry*; D001897:Boronic Acids / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D011789:Quantum Theory; D013816:Thermodynamics
D001896:Boron Compounds; D001897:Boronic Acids; C522272:boroglycine; D005998:Glycine