“…An important aspect of our ongoing studies on organic complexes of penta-and hexacoordinate (hypervalent) silicon, germanium and tin with C,O-chelating amidomethyl and lactamomethyl ligands (L n CH 2 , n = lactam ring size, [5][6][7][8] is the effect of the substituent nature on the structure and rigidity of the coordination environment around the central atom. The results of these studies are discussed in reviews [1][2][3][4] and research papers [5][6][7][8][9][10][11][12].…”