Preparation of the technetium(VI) aquanitrido complexes (NEt4)[TcNX4(OH2)] (X= Cl or Br). Crystal structures of (NEt4)[TcNBr4(OH2)] and Cs2[TcNCl5]

Preparation and ESR studies of salts of crown ether complex cations and nitridotechnetium(VI) anions: structures of the twinned ‘infinite sandwich’ [Cs(18-crown-6)][TcNCl 4 ] complex and of [Rb(15-crown-5) 2 ] [TcNCl 4 (OH 2 )]

“…Large cations such as R = AsPh4 or NBu4 result in the precipitation of R[TcNC14] while small cations such as Cs+ give Cs2[TcNX5]. The intermediate-size cation NEt+ allows the isolation of (NEt4)[TcNX4(OH2)] (Baidas et al 19916). The present work extends these studies to salts of [TcNC14]-and related anions with the bulky cations formed by crown-ether: alkali-metal complexation.…”

“…The i r T c= N stretching frequency in the [TcNC14L]-anion is sensitive to the nature of the trans ligand L and provides a useful diagnostic of the structural category of [M(crown)] [TcNC14L] compounds. The absence of L in (AsPh4) [TcNCl4] gives r(Tc=N) 1076 cm-1 (Baidas et al 1984), while the presence of the strong electron donor L = CL in Cs2[TcNC15] lowers the T c=N stretching frequency to 1027 cm-1 (Baidas et al 19916). The weak neutral donor H20 has little effect as is seen in (NEt4)[TcNCl4] and (NEt4)[TcNCl4(OH2)], where r(Tc=N) is 1070 and 1065 cm-1 respectively (Baidas et al 19916).…”

“…The absence of L in (AsPh4) [TcNCl4] gives r(Tc=N) 1076 cm-1 (Baidas et al 1984), while the presence of the strong electron donor L = CL in Cs2[TcNC15] lowers the T c=N stretching frequency to 1027 cm-1 (Baidas et al 19916). The weak neutral donor H20 has little effect as is seen in (NEt4)[TcNCl4] and (NEt4)[TcNCl4(OH2)], where r(Tc=N) is 1070 and 1065 cm-1 respectively (Baidas et al 19916). In a linear polymeric [TcNClJ-chain the nitrido ligand acts as L, i.e .-----T c= N -----T c= N -----.…”

Final Report, Research Program to Investigate the Fundamental Chemistry of Technetium

“…In order to pursue these investigations, however, it was first necessary to devise improved methods for preparation of common starting materials. A number of technetium and rhenium complexes possessing terminal oxo or nitrido groups and halide ligands have been reported in the literature, but their widespread use has been hindered by difficult and low-yield syntheses (Cotton 1979, Davison 1982, Nelson 1954, Rulfs 1955, Liese 1981, Baldas 1991, Cotton 1966, Rose 1996, Baldas 1984 -, and MOX 3 (L) 2 (M = Tc, Re; X = Cl, Br, I; L = THF, MeCN) were devised. Vibrational and electronic spectroscopies proved best suited to characterize the metal oxohalide complexes; EPR spectroscopy was also utilized to examine the paramagnetic species in the series.…”

“…This observation is significant in light of the fact that nitrogen-based reductants such as hydrazine and hydroxylamine are commonly used to generate Tc(IV) in situ for environmental speciation and stability studies (Pikaev 1996). The technetium nitride moiety is quite robust under a range of conditions, and its behavior is very different from that of Tc(IV) (Baldas 1991, Baldas 1986, Baldas 1984. Reduction of pertechnetate with hydroxylamine in the presence of complexants appears to be significantly slower than reductions using hydrazine under comparable conditions.…”