An X-ray investigation of silver nitrate: a unique metal nitrate structure

Abstract

The crystal structure of silver nitrate has been elucidated from an X-ray analysis. The crystals are orthorhombic, a= 6·997, b= 7·325, c= 10·118 Å, z= 8, space group Pbca (D_2h¹⁵). Silver atoms lie essentially in planes parallel to (010) and separated by b/2. These planes are linked by the symmetry-related nitrate groups in such a way that two of the three oxygens for any nitrate are each equidistant from two silver atoms in adjacent layers; the third oxygen is much closer to one layer and lies equidistant from three silver atoms in that layer. Thus, no oxygen is uniquely associated with any one silver atom. The resulting three-dimensional ionic structure, attributable to the high polarising power of the small silver ions, is unlike any other known metal nitrate structure or, indeed, the structure of any other substance of type AXO₃.