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

The bis(diazenido)technetium(III) complex [TcCl(NNR)2(PPh3)2] (R = C6H 4Cl-4) reacted with bidentate ligands L with loss of one diazenide lig and to give [Tc(NNR)L2(PPh3)] (L = S2CNR2) and (TcCl(NNR)L(PPh3)2] (HL = maltol) in high yield. With dianionic tetradentate ligands L' compl exes of the type cis-[Tc(NNR)L'(PPh3)] [L' = dianion of N,N'-bis(salic ylidene)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 th e complex with L' = salen has been determined. It shows pseudo-octahed ral co-ordination about the Tc with the NNR and PPh3 ligands cis. Dire ct reaction of [TcO4]- with arylhydrazine hydrochlorides generated a d iazenide 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]+ isola ted as a BPh4- salt.