Technetium diazenido-complexes. Part 2. Substitution chemistry of [TcCl(NNC6H4Cl-4)2(PPh3)2] and the synthesis of technetium diazenido-complexes directly from [NH4][TcO4]

Abstract

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.