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

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)A. 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)A] with the novel tetrahedral tetrabromotechnetate(II) dianion.