Synthesis of technetium-99 nitrido complexes with chelating diphosphine and diimine ligands

Abstract

The reaction of [TcNCl₄]^– with bidentate diphosphines P–P gives the cationic complexes [TcNCl(P–P)₂]⁺[A]^–[P–P = Ph₂PCH₂CH₂PPh₂ or Me₂PCH₂CH₂PMe₂(dmpe), A = BPh₄ or PF₆] in good yield. An analogous complex was prepared with Me₂PCH₂CH₂NMe(CH₂)₃NMeCH₂CH₂PMe₂ whereas the bulky Prⁱ₂PCH₂CH₂PPRⁱ₂(dippe) gave a binuclear complex [Tc₂N₂Cl₄(dippe)₂] which on the basis of ³¹P NMR spectroscopy has bridging chloride groups. An X-ray crystal structure of [TcNCl(dmpe)₂][BPh₄] revealed a distorted trans-octahedral geometry about technetium with an exceptionally long TcN bond distance of 1.853(6)Å. Reaction of [TcNBr₄]^– with 2,2′-bipyridyl (bipy) in ethanol gives [TcNBr(bipy)₂]₂[TcBr₄]. An X-ray crystal structure revealed a cis-octahedral structure for the nitrido-cation [TcN 1.621(20)Å] with the novel tetrahedral tetrabromotechnetate(II) dianion.