The Molecular Structure of P4O6, P4O8, P4O10 and As4O6 by Electron Diffraction

Abstract

Molecular structures of P₄O₆ and As₄O₆ were determined from electron diffraction data. P₄O₆ was found to have the symmetry of the point group T_d with an angle P–O–P of 128.5±1.5°, and a P–O distance of 1.67±0.03A. In this structure the phosphorus oxygen distances and the phosphorus valence angles were preserved with resulting deformation of the oxygen valence angle. The separation of the arsenic atoms in As₄O₆ was found to be 3.20±0.05A. Because of the predominant scattering of the arsenic atoms it was difficult to determine the oxygen valence angle, As–O–As. Values of 120°, 127.5° and 140° gave approximate agreement between the observed and calculated positions of maxima. Electron diffraction photographs obtained from P₄O₁₀ differ considerably from those found for P₄O₆. It was not possible to explain all of the features of the P₄O₁₀ diffraction pattern by a model having the symmetry of the point group T_d and it is thought that the structure might be one of lower symmetry. Data were obtained on P₄O₈ which indicated that it has approximately the same electron diffraction pattern as P₄O₁₀.