Structural roles of water in potassium nitrilosulphonate dihydrate,K3N(SO3)3.2H2O

The structural roles of the two types of lattice water in K₃N(SO₃)₃.2H₂O have been determined from the geometries of their immediate environments. Through hydrogen bonds of different lengths (and hence strengths), H₂O(1) links adjacent N(SO₃)₃^3?ions belonging to the same unit cell and lying on the same crystallographic mirror plane as O(1).H₂O(2) links identical N(SO₃)₃^3?ions contained in unit cells adjacent in the b direction, by very weak, equivalent hydrogen bonds. The hydrogen atoms of H₂O(1) are assigned to C_s sites in the unit cell and those of H₂O(2) are assigned to C₁ sites. The proposed site occupancies are verified by infrared spectroscopy using the “isotopic dilution” technique.