THE SYNTHESIS OF NITROSYL COMPLEXES OF TECHNETIUM WITH SULFUR-CONTAINING CORES

The reaction of [Tc(NO)Cl-2(PPh(3))(2)(NCCH3)] with 1 equiv. of potass ium alkylxanthate in CH2Cl2 yields complexes of the type [Tc(NO)Cl(PPh (3))(2)(S(2)COiBu)], in which the weakly coordinated acetonitrile liga nd and one of the chloride ligands have been replaced by the bidentate , monoanionic xanthate ligand. The H-1 NMR spectrum of this complex di splays equivalent triphenylphosphine ligands, indicating mutually tran s coordination geometry. The IR spectrum of this complex displays the absorption associated with nu (N=O) at 1702 cm(-1) from the linearly c oordinated nitrosyl ligand. The FAB(+) mass spectrum of this complex c ontains the parent ion of 837 m/z which corresponds to [Tc(NO)Cl(PPh(3 ))(2)(S(2)COiBu)](+) plus various fragments associated with the loss o f the chloride and phosphine ligands. The reaction of [Tc(No)Cl-2(PPh( 3))(2)(NCCH3)] with excess potassium alkylxanthate in CH2Cl2 yields co mplexes of the type [Tc(NO)(PPh(3))(S(2)COiBu)(2)], in which two, bide ntate alkylxanthate ligands have been incorporated into the reaction p roduct. The IR spectrum of this complex displays the absorption from n u (N=O) at 1701 cm(-1) which indicates a linearly coordinated nitrosyl ligand. The FAB(+) mass spectrum of the species displays the parent i on of 689 m/z which corresponds to [Tc(NO)(PPh(3))(S(2)COiBu)(2)](+). The H-1 NMR spectrum of this species displays inequivalent alkylxantha te ligands which indicates that the phosphine and nitrosyl ligands are coordinated in a cis conformation. The analogous reaction chemistry o f [Tc(NO)Cl-2(PPh(3))(2)(NCCH3)] with the potentially bidentate ligand 2-mercaptopyridine is also presented.