New refinement of the crystal structure of o-P2O5

The crystal structure of o-modification of diphosphorus pentaoxide was refined at 295 K. It consists of a network of [PO 4 ] tetrahedra linked by three common apices. Moreover, this o-modification of P 2 O 5 is also found to crystallize in the orthorhombic system with the space group Fdd2 and the lattice parameters a = 16.314(2) A, b = 8.115(3) A, c = 5.265(9) A, Z = 8, and D Calc = 2.705 (g . cm -3 ). The main value of the P-O length is estimated to be 1.543 A. As expected, the nonbridging P-O bonds, equal to 1.445 A, are shorter than the bridging ones which average 1.582 A. The structure parameters are refined to a final R of 0.0351 (wR = 0.0643) for 550 independent reflections [I > 3 σ(I)].