The structures of phenylphosphonic-acid-mono-(2-hydroxy-phenyl)ester and phenylphosphonic-acid-mono-(3-hydroxy-naphthalen-2-yl)ester - A combined experimental and theoretical study

Two ester derivatives of phenylphosphonic acid were prepared from vicinal aromatic diols and phenylphosphonic dichloride in one-step procedures. The products were characterized by means of multi-nuclear NMR spectroscopy (H-1, C-13, P-31) mass spectrometry, elemental analysis. UV-Vis spectroscopy, and melting point as well as vibrational spectroscopy. Their molecular structures were determined by single crystal X-ray diffraction and found to be open-chain half-esters of the respective diols. Intermolecular contacts and hydrogen bonding were analyzed. Born-Haber-cycles based on DFT calculations were conducted for the partial hydrolysis of the assumed cyclic phenylphosphonates to assess the reaction energies for the partial P-O-C cleavage of the chelate rings. The observed partial hydrolysis was rationalized on grounds of molecular orbital considerations. Experimental data were correlated to DFT data. The bonding situation of the two compounds was described by means of NBO analyses. (C) 2014 Elsevier Ltd. All rights reserved.