Regularities in the Crystal Structures of Heterocationic Octacyanometallates(IV) Molybdenum and Tungsten

A review of the crystal structures of octacyanomolybdates(IV) and octacyanotungstates(IV) of {[K(H2O)][Ln(H2O)4][M(CN)8]•2H2O}n (M4+ = Mo and Ln3 + = Y, La, Sm, Gd, Yb, M4+ = W and Ln3+= Tb, Dy, Ho, Er, Lu) composition has been done. These compounds have 3D-structures and contain infinite chains –C≡N–M–N≡C–Ln–, which extend in three dimensions, unlike CeH3O[W(CN)8]•6H2O, which has 2D-structure. The coordination polyhedra [M(CN)8]4- (M4+ = Mo, W) is different (dodecahedron, square antiprism, bicapped trigonal prism), depending on the nature of the rare-earth elements.