[en] In order to develop new phosphine schiff base mixed complexes of ⁹⁹Tc^m used for myocardial imaging, an N₃S ligand (MVNE) and four phosphine ligands are synthesized. ⁹⁹Tc^m-MVNE, which is prepared under room temperature through ligand-exchange reaction, reacts with the four phosphine ligands respectively to obtain mixed complexes of ⁹⁹Tc^m-MVNE-phosphine. Biodistribution of the four complexes in mice indicates that uptake is demonstrated in heart, the activity is cleared rapidly from blood and the clearance half-time is less than 10 min. However, the retention ability of the four complexes in heart is not ideal and heart/background ratios is low. The distribution results in mice indicate these complexes exhibit certain myocardial uptake