X-ray photoelectron spectroscopic study of charge distributions in tetracovalent compounds of nitrogen and phosphorus

Core electron binding energies for ten phosphorus and four nitrogen compounds have been measured by X-ray photoelectron spectroscopy in the gas phase.The chemical shifts have been correlated by the electrostatic potential equation using charge distributions from extended Ruckel theory and CND0/2 molecular orbital calculations.The data indicate that resonance structures of the type R I+ -R..--t-1-X.I R contribute significantly to the charge distributions in the tetracovalent compounds.The data for the phosphorus compounds can be quantitatively rationalized without the inclusion of any pTI 7 dTI bonding between the central atom and the X ligand, but the effects of electronic relaxation upon the core binding energy chemical shifts must be included.