Synthesis and characterization of technetium(V) complexes with tridentate schiff base ligands. X-ray crystal structure of chloro[N-(2-hydroxyphenyl)salicylideneiminato]oxotechnetium(V)

Five-coordinate technetium(V) complexes of the form TcO(L)Cl where L is one of the two tridentate Schiff base ligands N-(2-oxidophenyl)salicylideneiminate or N-(2-mercaptophenyl)salicylideneiminate have been synthesized and characterized. These neutral complexes precipitate from methanol upon reaction of the Schiff base ligand with TcOCl₄^?. A single crystal X-ray structure determination shows that the chloro N-(2-oxidophenyl)salicylideneiminato](2?)-N,O,O′]oxotechnetium(V) complex, TcO(C₁₃H₉NO₂)Cl], formula weight 362, has a distorted square pyramidal coordination geometry with the oxo ligand in the axial position. The steric requirements of the oxo group cause the Tc atom to be displayed 0.67 Å out of the mean equatorial plane of the other four donor atoms. This complex crystallizes in the monoclinic space group P2₁/a with a = 13.423(6) Å, b = 12.570(5) Å, c = 7.769(3) Å, β = 106.53(5)°, V = 1256.7(9) ų, and Z = 4. The structure has been refined to R = 0.047 for 1775 observed reflections.