title: Dimers of boroglycine and methylamine boronic acid: a computational comparison of the relative importance of dative versus hydrogen bonding.
abstract: Boronic acids are widely used in materials science, pharmacology, and the synthesis of biologically active compounds. In this Article, geometrical structures and relative energies of dimers of boroglycine, H2N-CH2-B(OH)2, and its constitutional isomer H3C-NH-B(OH)2, were computed using second-order Møller-Plesset perturbation theory and density functional theory; Dunning-Woon correlation-consistent cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ basis sets were employed for the MP2 calculations, and the Pople 6-311++G(d,p) basis set was employed for a majority of the DFT calculations. Effects of an aqueous environment were incorporated into the results using PCM and COSMO-RS methodology. The lowest-energy conformer of the H2N-CH2-B(OH)2 dimer was a six-membered ring structure (chair conformation; Ci symmetry) with two intermolecular B:N dative-bonds; it was 14.0 kcal/mol lower in energy at the MP2/aug-cc-pVDZ computational level than a conformer with the classic eight-centered ring structure (Ci symmetry) in which the boroglycine monomers are linked by a pair of H-O...H bonds. Compared to the results of MP2 calculations with correlation-consistent basis sets, DFT calculations using the PBE1PBE and TPSS functionals with the 6-311++G(d,p) basis set were significantly better at predicting relative conformational energies of the H2N-CH2-B(OH)2 and H3C-NH-B(OH)2 dimers than corresponding calculations using the BLYP, B3LYP, OLYP, and O3LYP functionals, particularly with respect to dative-bonded structures.
authors: Department of Chemistry, Bloomsburg University of Pennsylvania, Bloomsburg, Pennsylvania 17815, USA. jlarkin@ bloomu.edu
authors: Joseph D
authors: JD
authors: Larkin
authors: Matt
authors: M
authors: Milkevitch
authors: Krishna L
authors: KL
authors: Bhat
authors: George D
authors: GD
authors: Markham
authors: Bernard R
authors: BR
authors: Brooks
authors: Charles W
authors: CW
authors: Bock
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D001897:Boronic Acids / Q000737:chemistry*; D019281:Dimerization; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006860:Hydrogen Bonding; D008744:Methylamines / Q000737:chemistry*
chemical_list: D001896:Boron Compounds; D001897:Boronic Acids; D008744:Methylamines; C522272:boroglycine; C027451:methylamine; D005998:Glycine