Abstract
The crystal structures of two layered metal phosphites M(HPO3)H2O where M = Ca and Sr are reported. These compounds are the first examples of inorganic phosphites structurally related to metal phosphonates with the general formula of M(RPO3)H2O. They crystallize in monoclinic system with space group P21/c and are isostructuml. The structures consist of two-dimensional sheets formed by linked metal and phosphorus polyhedra, which are held together by O-H…O hydrogen bonds.