6161-78-0Relevant articles and documents
Electronic Structure and 31P NMR Chemical Shift of Substituted Triaryl, Diaryl Methyl and Dimethyl Aryl Phosphates - a Semi-empirical Molecular Orbital Approach
Silva, J. F. Cajaiba da,Pedrosa, M. S.,Nakayama, H. T.,Neto, C. Costa
, p. 97 - 106 (2007/10/03)
The 31P NMR chemical shift of triaryl phosphate, diaryl methyl phosphate and dimethyl aryl phosphate series was determined.The δ31P values exhibit an increasing downfield trend when aryl substituents are exchanged for alkyl groups and δ31P values show an increasing upfield trend as the electron withdrawing ability of the substituent in the aromatic ring is increased.Semi-empirical calculations showed an increasing positive charge on phosphorus atom and an increasing phosphoryl bond order when δ31P values go upfield.These results are in good agreement with the effect of "back bonding" from the phosphoryl oxygen to the phosphorus atom. - Keywords: 31P NMR chemical shifts; structural effects; molecular orbitals; triaryl phosphates; diaryl alkyl phosphates; dialkyl aryl phosphates