TECHNETIUM DIAZENIDO-COMPLEXES .2. SUBSTITUTION CHEMISTRY OF [TCCL(NNC6H4CL-4)2(PPH3)2] AND THE SYNTHESIS OF TECHNETIUM DIAZENIDO-COMPLEXES DIRECTLY FROM [NH4][TCO4]

The bis(diazenido)technetium(III) complex [TcCl(NNR)2(PPh3)2] (R = C6H4Cl-4) reacted with bidentate ligands L with loss of one diazenide ligand to give [Tc(NNR)L2(PPh3)] (L = S2CNR2) and (TcCl(NNR)L(PPh3)2] (HL = maltol) in high yield. With dianionic tetradentate ligands L' complexes of the type cis-[Tc(NNR)L'(PPh3)] [L' = dianion of N,N'-bis(salicylidene)ethane-1,2-diamine (salen), S(CH2)2NMe(CH2)2NMe(CH2)2S or O2S(CH2)2NMe(CH2)2NMe(CH2)2SO2] were obtained. The crystal structure of the complex with L' = salen has been determined. It shows pseudo-octahedral co-ordination about the Tc with the NNR and PPh3 ligands cis. Direct reaction of [TcO4]- with arylhydrazine hydrochlorides generated a diazenide species in situ which reacts with S2CNR2 to give [TcCl(NNR)2(S2CNR2)2] and 2.2'-bipyridine (bipy) to give [TcCl(NNR)(bipy)2]+ isolated as a BPh4- salt.