Abstract: The present invention relates to cardiac tropism radiopharmaceutical products incorporating a nitride complex os a transition metal and having a rapid myocardial clearance.These complexes are based on the formula:(M.tbd.N)L.sup.1 L.sup.2 (I)in which M is a transition metal such as .sup.99m Tc and L.sup.1 and L.sup.2 comply with the formula: ##STR1## in which at least one of the R and R' represents a branched alkyl group having one or more ether functions, a tetrahydrofurfuryl or ether group, a tetrahydrofurfuryl or dioxaspiro or dialkoxy piperidino groups.

Abstract: Process for the preparation of nitride complexes of transition metals for use as radiopharmaceutical products or for the synthesis of novel pharmaceutical products. The process consists in reacting an oxygenic transition metal compound such as 99m.sub.Tc, 186.sub.Re or 188.sub.Re, with a first nitrogenous ligand such as sodium nitride or a nitrogenous compound such as S-methyl, N-methyl dithiocarbazate, and a reducing agent consisting of either tin (II) or a dithionite. The product so obtained can be used for the preparation of radiopharmaceutical products by a reaction with a second ligand such as sodium dithiocarbamate.