ELECTRONIC-STRUCTURE AND CONFORMATIONAL PROPERTIES OF VINYLPHOSPHONICACID AND SOME RELATED DERIVATIVES

The electronic structure and conformational properties of vinylphospho nic acid, vinylphosphoryl dichloride, and vinylphosphine oxide have be en studied by ab initio quantum mechanical methods. Furthermore, the v inylphosphonic acid has been studied experimentally by means of C-13 N MR and ultraviolet spectroscopy. This compound has been synthesized by a modification of the McKenna hydrolysis reaction, improving signific antly the yield. The ab initio calculations have been performed with d ifferent basis sets, including correlation energy at the MP2/6-31G le vel. Topological analysis of charge density has also been carried out. Two conformers, s-cis and s-trans-gauche, have been determined for th e internal rotation around the C-P bond, with low rotational barriers. Two transition structures, s-cis-gauche and s-trans, have been locate d. A partially polarized strong triple bond for the phosphoryl group h as been found. A weak pi conjugation has been detected in the C=C/P=O system. The chemical shifts and absorption coefficients determined exp erimentally are in agreement with the electronic structure and conform ational properties calculated by ab initio methods.