Synthesis and Characterization of Novel ~(99g)Tc(V) and Re(V) Complexes with Water-Soluble Tetraaza Diamido Dipyridino Ligands:Single-Crystal X-ray Structural Investigations of Mono- and Dinuclear Complexes

摘要

Rhenium and technetium are known for their useful applications in nuclear medicine with similar properties.In this study,new diamido dipyridino (N_4) water-soluble ligands (2-C_5H_4NCH_2NHCO)_2CH_2,1 (L~1H2),(2-C_5H_4NNHNHCO)_2CH_2,2,and [2-C_5H_4N~+(O)~-CH_2NHCO]_2CH_2,3,were synthesized.Reaction of L~1H_2 with ReOCI_3(PPh_3)_2 resulted in the novel six-coordinated rhenium(V) complex,trans-ReO(L~1)(OEt),4.The complex was characterized by spectroscopic methods,and its X-ray crystallographic analysis revealed that rhenium is coordinated to four nitrogen atoms of the ligand and to two oxygen atoms from the deprotonated ethanol and the oxo group respectively in a distorted octahedral geometry.In solution,complex 4 was transformed to a new complex 5,which was proved to be the dinuclear complex mu-OXO [ReO(L~1)]_2O.Reaction of 1 with [n-Bu_4N][ReOCI_4] resulted in the neutral complex 6,frans-[ReO(L1)]CI.Similarly,when ligand 1 was reacted with [n-Bu_4N][~99gTcOCI_4],the neutral trans-[~(99)TcO(L~1)]CI complex 7 was formed,which upon dissolution transformed into a cationic complex 8,trans-[~99TcO(L~1)(OH_2)]~+CI~-.The single-crystal X-ray structure of 8 reveals that the coordination sphere about technetium is a distorted octahedron with four nitrogen atoms in the equitorial plane,while doubly bonded oxygen and coordinated water occupy the apical positions.Further dissolution of 8 resulted in the formation of dinuclear mu-oxo (TcO(L~1)]_20,9.This study shows that Tc and Re have similar metal core structures in solution for diamido dipyridino systems,besides similarity in geometrical structure,proved by the X-ray structures on the same ligands.