The exchange of Pb by Sn in high-refractive index and low temperature process glasses is a common need in pollution control. Here it is planned to study the structure of binary tin phosphate glasses and similar materials doped with heavy metal oxides (TiO2, La2O3). Similar to Pb(II) the Sn(II) sites possess lone pair electrons which can behave sterically active. Thus, the Sn sites can form trigonal pyramids or other oxygen polyhedra with Sn-O distances well detectable between P-O bond lengths and O-O edges of PO4 tetrahedra. We expect the oxygen polyhedra to change in dependence on the glass composition. Combination with x-ray diffraction is planned to separate Sn-O from Ti-O distances. A small content of Sn(IV) sites of few percent will not make problems.