Abstract:The new diorganotin complex ((C6HS),Sn(OC,,H6CH=NCH2COO)) was prepared and characterized by 'H NMR, IR, elemental analysis, and a single crystal X-ray diffraction study. The crystals are monoclinic, space group P2,la with a = 16.9167(9) A, b = 19.1276(16) A, c = 26.538(2) A, P = 100.534(6)", V = 8442.5(11) A3, Z = 16, and DCaIc = 1.574 Mg m-3. The final discrepancy factors are R, = 0.030, and Rw = 0.02 1 for 6524 significant reflections. The tin atom has a distorted trigonal bipyramidal coordination, with no short intermolecular contacts. The two axial Sn-0 bonds of 2.12 A and 2.09 A and the equatorial Sn-N bond of 2.14 8, are among the shortest found in related complexes.Key words: diorganotin(IV), bicycloazastannoxide, trigonal bipyramidal, antitumour.