REACTIONS OF THE TECHNETIUM(V) PHENYLIMIDO COMPLEX [TCX3(NPH)(PPH3)2]WITH AROMATIC THIOLATE LIGANDS (WHERE X=CL, BR)

The reaction of KTcO4 with triphenylphosphine and 1-acetyl-2-phenylhyd razine in methanol with HBr gives the Tc(V) phenylimido complex [TcBr3 (NPh)(PPh3)2], analogous to the published reaction with HCl. The pheny limido complex reacts with unsubstituted thiophenol and a proton scave nger (R3N) in methanol to give the Tc(V) oxo complex (R3NH)[TcO(SPh)4] in excellent yield. The IR spectrum of this complex shows an absorpti on at 936 cm-1 associated with nu(Tc=O). The Tc(V) complex [TcCl3(NPh) (PPh3)2] reacts with a four-fold excess of the sterically-hindered thi ol 2,3,5,6-tetramethylbenzenethiol (TMBTH) and a proton sponge to give the Tc(V) complex [Tc(NPh)(TMBT)3(PPh3)]. The IR spectrum of this com plex displays an absorption at 1100 cm-1 which is associated with nu(T c=N). The positive mode fast atom bombardment mass spectrum of this sp ecies displays an extensive fragmentation profile, including fragment of 947 m/z, which corresponds to the parent ion [Tc(NPh)(TMBT)3(PPh3)] +. The analogous reaction with a five-fold excess of 2,6-dimethylbenze nethiol (DMBTH) and a proton sponge gives the anionic Tc(V) complex (R 3NH)[Tc(NPh)(SAr)4]. The IR spectrum of this complex displays an absor ption at 1100 cm-1 which is associated with nu(Tc=N). The positive mod e fast atom bombardment mass spectrum of this anionic species displays an extensive fragmentation profile, including fragments of 998 m/z, w hich corresponds to {(R3NH)2[Tc(NPh)(DMBT)4]}+ and 868 m/z which corre sponds to {(R3NH)[Tc(NPh)(DMBT)4]}+. The reaction of the Tc(V) complex [TcCl3(NPh)(PPh3)2] with the tetradentate phosphine-trithiol ligand [ P(C6H4-o-SH)3], and a proton scavenger in methanol gives the neutral T c(III) complex [Tc(PPh3)(PS3)]. The FAB(+) mass spectrum of this compl ex shows the parent ion of 716 m/z and the peak associated with the fr agment generated by the loss of the triphenylphosphine of 454 m/z. The IR spectrum shows no absorptions in either the region associated with nu(Tc=O) or nu(Tc=N). The H-1 NMR spectrum of the diamagnetic Tc(III) complex shows only narrow-line signals associated with the aryl proto ns.