A Computational Investigation of the Nitrogen-Boron Interaction in o-(N,N-Dialkylaminomethyl)arylboronate Systems

o-(N N-Dialkylaminomethyl)arylboronate systems are an important class of compounds in diol-sensor development We report results from a computational investigation of fourteen o-(N N-dialkylaminomethyl)-arylboronates using second-order Moller-Plesset (MP2) perturbation theory Geometry optimizations were performed at the MP2/cc-pVDZ level and followed by single-point calculations at the MP2/aug cc-pVD7(cc pVTZ) levels These results are compared to those from density functional theory (DFT) at the PBE1PBE(PBE1PBE-D)/6-311++G(d p)(aug-cc-pVDZ) levels as well as to experiment Results from continuum PCM and CPCM solvation models were employed to assess the effects of a bulk aqueous environment Although the behavior of o-(N N-dialkylaminomethyl) free acid and ester proved to be complicated we were able to extract some important trends from our calculations (1) for the free acids the intramolecular hydrogen-bonded B-O-H N seven-membered ring conformers 12 and 16 are found to be slightly lower in energy than the dative-bonded N -> B five-membered ring conformers 10 and 14 while conformers 13 and 17 with no direct boron nitrogen interaction are significantly higher in energy than 12 and 16 (2) for the esters where no intramolecular B-O-H N bonded form is possible the N -> B conformers 18 and 21 are significantly lower in energy than the no-interaction forms 20 and 23 (3) H2O insertion reactions into the N -> B structures 10 14 18, and 21 leading to the seven-membered intermolecular hydrogen-bonded B OH2 N ring structures 11 15 19 and 22 are all energetically favorable