SYNTHESIS AND CHARACTERIZATION OF NEUTRAL TECHNETIUM(III)-99 AND TECHNETIUM(III)-99M COMPLEXES WITH O,P-BIDENTATE PHOSPHINO-CARBOXYLATE LIGANDS - CRYSTAL-STRUCTURE OF MER-[TC(O2CCH2CH2PPH2)3]CENTER-DOT-2ME2SO

Reduction-substitution reactions of pertechnetate with a class of O,P- bidentate phosphinocarboxylic acid ligands HL(n) [n = 1, 2-(diphenylph osphino)benzoic acid; n = 2, 3-(diphenylphosphino)propionic acid; n = 3, (diphenylphosphino)acetic acid; n = 4, 3-(diethylphosphino)propioni c acid] afforded a series of neutral and paramagnetic [TcL3n] complexe s. The products have been characterized by means of elemental analysis , IR, H-1 NMR, UV/VIS and FAB mass spectroscopy, and X-ray crystallogr aphy for (TcL2(3)]. The latter crystallizes in the monoclinic space gr oup P2(1)/n with Z = 4, a = 21.718(10). b = 12.954(6), c = 18.038(9) a ngstrom and beta = 106.59(4)-degrees. The final R value was 0.061. Thr ee deprotonated chelates surround the metal in a distorted-octahedral environment adopting a meridional configuration, and consequently ther e are two pairs of like donor atoms trans to one another with the rema ining phosphorus atom trans to an oxygen atom. Similar reduction-subst itution reactions have been performed utilizing the short-lived isotop e Tc-99m. The physicochemical properties of the resulting Tc-99m-label led species match very well those exhibited by the analogues prepared with the long-lived isotope Tc-99m. Thus the chemical structures of [T c(99m)L3n] and [Tc-99L3n] analogues are identical. Female Sprague-Dawl ey rats were injected with pre-purified [Tc(99m)L3n] (n = 1, 2 or 4) a nd the resulting biodistributions evaluated at different times post in jection. All the complexes undergo very low, but significant, brain up take which decreases with time.