Many boron-capped Tc oximes TcCl (oxime)3 BR (BATO complexes) show myocardial or brain uptake. For this reason we developed an improved synthesis for the tin-capped complexes Tc(oxime)3 (μ - OH) SnCl3, previously described by Deutsch and Libson, to compare the chemistry and biodistribution of these tin-capped compounds to those of our boron-capped BATO complexes. The 99-Tc tin-capped compounds were made by heating DMG or CDO in EtOH/HCI with 2 eq. of SnCl2 (DMG = dimethylglyoxime, CDO = cyclohexanedionedioxime). Full analysis of the compounds indicated that they are Tc(III), not Tc(V), as was previously proposed. The complex 99m-Tc(CDO)3(μ-OH)SnCl3 was prepared by SnCl2 reduction of TcO4− in the presence of SnCl4. The isolated product proved unstable in the absence of Sn(IV). Rat biodistribution data (n=3) showed little brain or heart uptake (>0.05% I.D./organ at 60 min.). Lung and liver uptake were 18 ± 1.93 and 25.8 ± 1.2% I.D./organ at 5 min.; after 60 min., most activity had cleared from the liver. We conclude that the boron-capped BATO complexes are more suitable than the tin-capped Tc-CDO complex for heart or brain imaging.