Sixteen novel derivatives of 1,1,1-tris (salicylaldiminomethyl)ethane have been synthesized for the purpose of encapsulating 9 9 m Tc(IV) ions and generating new 9 9 m Tc radiopharmaceuticals. Two methods for the preparation of the 9 9 g Tc(IV) analog complexes are presented; one utilizes SnCl 2 reduction on 9 9 g TcO 4 - and the other a direct substitution route starting with [ 9 9 g TcCl 6 ] 2 - . Free ligands (H 3 L) are characterized by melting points, 1 H NMR, 1 3 C NMR, mass spectroscopy, TLC, and/or elemental analyses. [ 9 9 g TcL] + complexes are characterized by FAB-ms, UV-VIS, IR and/or CV. An X-ray structural analysis was performed on a crystal of [M(6,6 -[[2-[[((4-Methoxy-2-hydroxyphenyl)methylene)-amino]methyl]-2-methyl -1,3-propanediyl]bis(nitrilomethylidyne)]-bis-3-methoxyphenol)] tetraphenylborate, where M represents a 13 isomorphous mixture of 9 9 g Tc/Sn as determined by SEM. The metal coordination site is 6-coordinate, composed of N 3 O 3 donor atoms, and intermediate between octahedral and trigonal prismatic geometry. The [ 9 9 m TcL] + complexes were prepared in a stannous environment; equivalence of the 9 9 m Tc and 9 9 g Tc complexes is demonstrated by HPLC techniques. The [SnL] + complex was prepared for comparison purposes. An unusual ligand oxidation occurs for one series of ligands in which in situ amine → imine conversion is observed during the complexation reaction in reducing media. Guinea pig, rat, dog, and human metabolism studies are reported for selected [ 9 9 m TcL] + complexes, the myocardial uptake of which approaches 2% of the injected dose.