Bifunctional tridentate pyrazolyl containing ligands for re and tc tricarbonyl complexes

4 55 521 3 2 6 2n64 2n6 n65 2n6 2n66 13324 5 The present invention relates to a chelating agent of the general formula: (I), wherein m is 0 or 1; X is NRor S; Y is SR, NHRor P(R); Rand Rare the same or different and are selected from H, alkyl or aryl; Ris H, COOH, NHRor (CH)COOR; Ris H, alkyl, aryl, (CH)COORor (CH2)OR; Ris H, alkyl, aryl, (CH)COORor (CH)OR, Ris H, alkyl or aryl; n is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; and when R═R═CH, R, Rand Rare not all three H. The invention further relates to a method and kit for the preparation of radiolabeled biomolecules while using the chelating agent.