Development of novel water-soluble, organometallic compounds for potentialuse in nuclear medicine: Synthesis, characterization, and H-1 and P-31 NMRinvestigations of the complexes fac-[ReBr(CO)(3)L] (L = bis(bis(hydroxymethyl)phosphino)ethane, bis(bis(hydroxymethyl)phosphino)benzene)

The bidentate, water-soluble phosphine ligands, bis(bis(hydroxymethyl)phosp hino)benzene (HMPB, 1) and bis(bis(hydroxymethyl)phosphino)ethane (HMPE, 2) were reacted with the organometallic precursor fac-[ReBr3- (CO)(3)](2-), 3 , to produce the complexes fac-[Re(OH2)(CO)(3)L](+) and fac-[ReBr(CO)(3)L] (L = HMPE, HMPB), respectively, in good yields. The rhenium complexes fac-[ ReBr(CO)(3)HMPB], 5, and fac-[R3Br(CO)(3)HMPE], 8, were characterized using H-1 and P-31 NMR spectroscopy. The structure of fac-[ReBr(CO)(3)HMPB] was confirmed by single-crystal X-ray spectroscopy. The substitution reactions of HMPE/HMPB with the rhenium precursor 3 in aqueous solution were monitore d using time-dependent P-31 NMR techniques. A significant discrepancy in th e reaction kinetics and the substitution mechanism between the two bidentat e ligands could be observed presumably due to the different chemical backbo nes.